Ordovician trilobites from the Horn Valley Siltstone ...

Ordovician trilobites from the Horn Valley Siltstone and basal Stairway Sandstone, Amadeus Basin, Northern Territory JOHN R. LAURIE LAURIE, J.R., 2006:07:29. Ordovician trilobites from the Horn Valley Siltstone and basal Stairway Sandstone, Amadeus Basin, Northern Territory. Memoirs of the Association of Australasian Palaeontologists 32, 287-345. ISSN 0810-8889 The trilobite fauna from the Bendigonian to Yapeenian Horn Valley Siltstone of the Amadeus Basin is revised for the first time in over 100 years based on material obtained from several measured sections and cores from wells drilled mostly in the western parts of the basin. Described are the species Lycophron howchini (Etheridge, 1894), L. freemani sp. nov., Eisarkaspis etheridgei gen. et sp. nov., Madiganaspis madigani gen. et sp. nov., M. olifentensis gen. et sp. nov., Rodingaia nielseni gen. et sp. nov., Basilicus (Basiliella) illarensis (Etheridge, 1893), Basilicus (Parabasilicus) winneckei sp. nov., indeterminate Asaphidae sp. A, Lonchodomas sp., Carolinites genacinaca Ross, 1951, Prosopiscus aff. praecox Fortey & Shergold, 1984 and ?Galbagnostus sp. These species are distributed between two assemblages; the lower Lycophron howchini Assemblage and the upper Lycophron freemani Assemblage. The former assemblage is found wherever the Horn Valley Silstone occurs, while the latter assemblage is restricted to the westerly parts of the basin, having been eroded prior to deposition of the overlying Stairway Sandstone. Indeterminate Asaphidae sp. B and Prosopiscus tatei sp. nov. are also recorded from the basal Stairway Sandstone in Rodinga No. 6 well. John R. Laurie ([email protected]) Geoscience Australia, GPO Box 378 Canberra ACT 2601. Received 25 May 2006 Keywords: Ordovician, Australia, Northern Territory, Amadeus Basin, trilobite, taxonomy, biostratigraphy

THE AMADEUS BASIN is a large intracratonic basin which occupies most of the southern quarter of the Northern Territory (Fig. 1). It consists of about 9000 metres of predominantly Proterozoic to Devono-Carboniferous strata, within which the Cambro-Ordovician Larapinta Group attains a maximum thickness of over 2100 metres (Wells et al. 1970). The constituent units of the Larapinta Group are, in ascending order, the Pacoota Sandstone, Horn Valley Siltstone, Stairway Sandstone, Stokes Siltstone and Carmichael Sandstone (Fig. 2). It is the trilobite fauna and stratigraphy of the Horn Valley Siltstone which are the predominant subject of this work. The name Horn Valley Beds was coined by Madigan (1932, p. 694) for a 150 m thick fossiliferous succession predominantly of calcareous shale “enclosed between great thicknesses of quartzite below and above”. One measured section, located in Ellery Creek, was given as an example. The geographic name from which the formation name was taken has fallen into disuse, but was apparently coined by members of the Horn Expedition of 1894 (Spencer 1896; Winnecke 1897) for the latitudinal valley occupied by these fossiliferous shales in the

Macdonnell Ranges (Madigan 1932, p. 675). Prichard & Quinlan (1962, p. 20) formalised the unit as the Horn Valley Formation and retained Madigan’s (1932) sample section at Ellery Creek as the type section. The base of the unit was placed at the top of the last resistant quartzose sandstone bed of the Pacoota Sandstone and its top at the base of the first resistant sandstone bed of the Stairway Sandstone. Wells et al. (1965, p. 25) emended the name of the unit to Horn Valley Siltstone. A summary of the stratigraphy of the Horn Valley Siltstone was presented by Wells et al. (1970, p. 68). The formation is very fossiliferous and contains polymerid and rare agnostid trilobites, calciate and lingulate brachiopods, nautiloids, gastropods, bivalves, monoplacophorans, ostracodes, graptolites, conodonts and chitinozoa (Shergold 1986, p. 9). The trilobite fauna described herein has not been studied in detail since the late 1800s, when collections were made from this and adjacent units by a Mr Thornton of Tempe Downs Station. These collections were passed for description to Etheridge (1892, 1893, 1894) by the South Australian Government Geologist, H.Y.L. Brown. Further collections

Fig.1. Approximate outline of the Amadeus Basin, with localities indicated. Spot locality LA112 is on or near the Mt Olifent Section. Spot locality LA51 is 20 km to the ENE of the Mt Olifent Section.

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Fig. 2. Formations of the Larapinta Group. P.G. = Pertaoorrta Group.

were made from the Horn Valley Siltstone by members of the Horn Scientific Expedition to central Australia and were described by Tate (1896). Since that time, little work on the trilobite fauna has been undertaken, but passing references have been made by Prichard & Quinlan (1962), who noted the presence of cf. Ampyx and two asaphids, and by Ritchie & Gilbert-Tomlinson (1977) who, though concerned with the Stairway Sandstone, listed Annamitella, Carolinites and Prosopiscus from the Horn Valley Siltstone. In describing trilobites from the Nora Formation (Georgina Basin), Fortey & Shergold (1984) illustrated the holotype of Lycophron howchini (Etheridge, 1894). Shergold (1986) reviewed the Cambrian and Ordovician biostratigraphy of the Amadeus Basin and listed the trilobites ‘Asaphus’ illarensis Etheridge, 1893, ‘Asaphus’ lissopeltis Tate, 1896, Lycophron howchini (Etheridge), Ampyx sp., Carolinites sp., aff. Prosopiscus sp. and aff. Ptychopyge sp. This was later expanded upon by Shergold & Laurie (in Shergold et al. 1991), who noted that there were two trilobite assemblages in the formation; the lower comprising L. howchini, ‘Basiliella’ illarensis, n. gen. aff Ogygitoides sp. and Encrinurella sp. and the upper comprising Lycophron sp. nov., ?Birmanites sp. nov., ?Fitzroyaspis aff. irritans

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Fortey & Shergold, 1984 and ‘Parabasilicus’ sp. Carolinites genacinaca and Prosopiscus sp. were recorded from both assemblages. DISTRIBUTION OF HORN VALLEY SILTSTONE The Horn Valley Siltstone is recessive and outcrop is usually poor in the deep alluvium- and scree-covered strike valleys which it occupies. It underlies most of the northern central and western parts of the basin (Fig. 1) and crops out in the following areas in the listed 1:250 000 map sheets: RODINGA; Oliffe and James Ranges. HERMANNSBURG; Macdonnell and Gardiner Ranges. HENBURY; James, Gardiner, Seymour, Levi, Middle and Househill Ranges, Petermann Hills, low hills east of The Sisters, to the south of the Chandler Range and in the unnamed range to the north and northeast of Tempe Downs Station. MOUNT LIEBIG; Idirriki, Gardiner and Watson Ranges. LAKE AMADEUS; north and east of Parana Hill, near Ochre Hill, east of Mount Olifent, in several small ranges of hills south of the George Gill Range and in several small hills in the Mount Murray area. MOUNT RENNIE; two unnamed ranges of hills in the southeastern and south central portions of the sheet area. The unit has been cored in both stratigraphic coreholes and hydrocarbon exploration wells. They are: BMR Lake Amadeus No.1 (Barrie 1964) BMR Rodinga No.6 (Owen & Morris 1985) BMR Henbury No.4 (Owen & Morris 1985) BMR Henbury No.6 (Owen & Morris 1985) BMR Mt Liebig No.2 (Owen 1986) Tempe Vale No.1 (Marsden et al. 1983) Tent Hill No.1 (Marsden et al. 1984) Mt Winter No.2A (Gorter 1986) STRATIGRAPHY Horn Valley Siltstone The Horn Valley Siltstone is a usually poorly outcropping unit of siltstone, calcareous siltstone, claystone, limestone with minor sandstone, sandy siltstone and silty dolostone. The siltstones and claystones are grey-green, pale green or pale brown in outcrop, but dark grey or black in the subsurface. The limestones are buff to pale brown or light to dark grey in outcrop, but are usually light to dark grey in the subsurface. The sandstone and sandy siltstone are commonly orange to light brown or medium brown in outcrop, and grey in the subsurface whereas the dolostone ranges

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from medium reddish-brown to bright orange in outcrop and is also grey in the subsurface. Base of the Horn Valley Siltstone. As Gorter (1984, p. 70) noted, there has been variation in the definition of its boundaries. Prichard & Quinlan (1962, p. 20) placed the base of the formation “at the top of a hard quartzite bed (Pacoota Sandstone)”. They further noted that this was succeeded by 55 metres of siltstone with interbeds and lenses of quartz sandstone and quartz greywacke. Most subsequent workers have followed Prichard & Quinlan in placing the lower boundary of the formation at the top of the last resistant bed of “quartzite”. This practice has led to the maximum thickness of the unit being recorded at about 450 metres in the Idirriki and far western Macdonnell Ranges. However, this includes 180 metres of siltstone and shale “of doubtful affinities” below what appears to be the first carbonate. Consequently, the true maximum may be only about 270 metres (Wells et al. 1970, p. 68). To facilitate recognition of the lower boundary in the subsurface, Huckaba (1970) placed the top of the Pacoota Sandstone at the top of a prominent gamma-ray and sonic log spike which was correlatable in all wells logged at that time. This spike corresponds with a glauconitic, sandy dolomitic limestone or dolomitic sandstone unit, and places the lower boundary of the Horn Valley Siltstone at the first carbonate above the resistant Pacoota Sandstone. As a consequence, the 180 metres of siltstones and sandstones placed in the lower Horn Valley Siltstone by Wells et al. (1970), would be assigned to the P1 unit of the Pacoota Sandstone (Huckaba 1970). This was the placement favoured by Gorter (1984, p. 70) in his study of the petroleum source potential. In a more recent sequence stratigraphic study of the upper Pertaoorrta Group and the Larapinta Group, Gorter (1991) has assigned a siltstone and sandstone unit underlying the lowest carbonate to his Parasequence Set 14 of his Horn Valley Sequence and by inference to the Horn Valley Siltstone. Further east, in the Waterhouse Range, this has been shown by Nicoll et al. (1991) to be unconformable on the Pacoota Sandstone. Top of the Horn Valley Siltstone. Prichard & Quinlan (1962, p. 20) believed the Horn Valley Siltstone to be conformably overlain by the “hard beds” of the Stairway Sandstone. By this term they presumably meant the lowest resistant sandstone unit to be the base of the Stairway Sandstone. Below these cliff-forming sandstones, in Ellery Creek, the type section of the Horn Valley Siltstone, there is a 6 metre thick unit of

AAP Memoir 32 (2006) less resistant siltstone and fine sandstone which is included in the Horn Valley Siltstone (Gorter 1984, p. 70). Nicoll et al. (1991) have shown that the relationship between the Horn Valley Siltstone and the Stairway Sandstone is unconformable in the Waterhouse Range and Walton (1985) illustrated an unconformable contact between the Horn Valley Siltstone and the Stairway Sandstone in the eastern James Range “B” anticline. Nicoll et al. (1991) apply the name Maloney Creek Eustatic Event to the regression associated with this unconformity. Subdivision of the Horn Valley Siltstone. Prichard & Quinlan (1962, p. 20) noted three lithological units in the Horn Valley Siltstone in its type section at Ellery Creek. Having placed the base of the formation at the last resistant “quartzite” of the Pacoota Sandstone, they assigned the overlying 55 metres of interbedded siltstone, quartz sandstone and quartz greywacke to the basal Horn Valley Siltstone. Above this was 73 metres of siltstone and thin interbedded fossiliferous limestones. This in turn was overlain by 6 metres of siltstone and fine grained quartz greywacke. More recently, Elphinstone (1989) and Elphinstone & Gorter (1991) defined ten informal members of the Horn Valley Siltstone (HV1 at the base to HV10 at the top) based on lithological, sedimentological and palaeontological analyses of drillcore from Henbury No. 4, Henbury No. 6, Rodinga No. 6, Tempe Vale No. 1, Tent Hill No. 1 and Mt Liebig No. 2. The criteria taken into consideration in this analysis were: the presence or absence of body fossils; mode of preservation; fossil group associations; presence or absence and type of bioturbation; lithology; and bedding character. Gorter (1991), in a sequence stratigraphic study of the Late Cambrian and Early Ordovician sediments of the Amadeus Basin, has identified four shoaling cycles or parasequence sets (PS14 at the base to PS17 at the top) within the Horn Valley Siltstone. As noted above, the lowest parasequence set (PS14) was previously included within the upper P1 unit of the Pacoota Sandstone (Towler 1986; Do Rozario & Baird 1987). It consists of basal mudstone and siltstone which grade upwards into more glauconitic and calcareous, bioturbated sandstone and siltstone (Gorter 1991). The second parasequence set (PS15) forms part of the lower Horn Valley Siltstone of Wells et al. (1970, p. 68) and is divisible into three subunits which generally become coarser and more calcareous upwards. To the east, this set is overlain unconformably by the Stairway Sandstone (Gorter 1991). The third parasequence set (PS16) is a shoaling


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Stairway Sandstone The Stairway Sandstone unconformably overlies the Horn Valley Siltstone and like the Horn Valley Siltstone, is restricted to the central and western parts of the basin, having been eroded in the east (Wells et al. 1970; Nicoll et al. 1991). To the Fig. 4. Section through the Horn Valley Siltstone at Maloney Creek, with ranges of selected trilobites. Abbreviations as in Fig. 3.

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cycle whose base is transitional westward but abrupt in the east. This set also exhibits a general coarsening upwards and an increase in carbonate content upwards. In the Waterhouse Range, this set is overlain unconformably by the Stairway Sandstone. The uppermost parasequence set (PS17) of the Horn Valley Siltstone, consists of small-scale parasequences grading from shale to carbonate. East of Palm Valley this set has been truncated by pre-Stairway Sandstone erosion (Gorter 1991).

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Fig. 3. HYR7 Section through the Horn Valley Siltstone, 5 km ENE of The Sisters, with occurrences of selected trilobites. SS = Stairway Sandstone; PS = Pacoota Sandstone.

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south and southeast the unit oversteps the Horn Valley Siltstone and overlies progressively older rocks. The formation comprises two sandstone units separated by fine clastics, phosphorites and carbonates (Cook 1972; Shergold 1986). The basal sandstone is massive, cross-bedded and pebbly and contains occasional pyritised oolitic beds and sheets of pipe-rock. The middle unit comprises mostly siltstone and mudstone with interbedded sandstone and nodular phosphorite beds which pass laterally into mudstone and carbonates to the southeast and redbeds to the northeast. The upper unit is mainly sandstone which is conglomeratic at the base (Shergold 1986). Measured Sections Because of the generally poor outcrop of the Horn Valley Siltstone, more sections were investigated than were measured and collected. The following are those measured and collected: HYR7, 5 km ENE of The Sisters (Fig. 3) Location: HENBURY, 133° 22’ 52” E, 24° 32’ 0” S; This is near the southern extremity of outcrop of the Horn Valley Siltstone and here the unit is quite thin (less than 20 metres). Outcrop is fairly poor with only about 15% exposure, most of that occurring in the basal 8 metres. This section has previously been illustrated by Ranford et al. (1965, pl. 12). Sample Numbers: 85/3038-85/3044.

Fig. 5. Section through the Horn Valley Siltstone in the Gardiner Range, SW of Namatjira Copper Prospect, with ranges of trilobites. Abbreviations as in Fig. 3.

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SW of Namatjira Copper Prospect (Fig. 5) Location: HENBURY, 132° 21’ 0” E, 24° 8’ 48” S; This section is in the eastern Gardiner Range and is very poorly outcropping, with 80 metres

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Maloney Creek (Fig. 4) Location: HENBURY, 133° 15’ 36” E, 24° 30’ 24” S; This section is located in a man-made channel immediately east of, and parallel to the Stuart Highway, to the NE of the bridge over Maloney Creek in the Chandler Range. This is the best outcropping section of the Horn Valley Siltstone with outcrop being about 80% at the time that it was measured and collected. Percentage of outcrop varies seasonally, presumably depending on amount and distribution of rainfall. The degree of variation can be seen when comparing the section presented here and that given by Cooper (1981, p. 151). Here the Horn Valley Siltstone is about 49 metres thick. Sample Numbers: 84/3011-84/3026, 85/3037.


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Fig. 6. Section through the Horn Valley Siltstone near Mt Olifent, with ranges of selected trilobites. Samples numbered 84/3031/1-4 are from a small outcrop about 50 m lateral to the main line of section and are approximately equivalent to 84/3030/9-6 respectively. Abbreviations as in Fig. 3.


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between the last resistant sandstone of the Pacoota and the lowest siltstone outcrop being obscured by scree from both the Pacoota and Stairway Sandstone. Sample Numbers: 85/3083-85/3092.

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Mount Olifent (Fig. 6) Location: LAKE AMADEUS, 131° 11’ 25” E, 24° 8’ 30” S; This section is located approximately 12 km ESE of Mount Olifent and is only approachable along old seismic survey tracks. This is perhaps the most interesting of the sections through the unit as it exhibits to advantage both the lower and upper faunas. Sample Numbers: 84/3029/1-84/3029/5, 84/3030/1-84/3030/13, 84/3031/1-84/3031/4. Gardiner Range, near Tent Hill Creek (Fig. 7) Location: MOUNT LIEBIG, 131° 54’ 48” E, 23° 55’ 24” S; This section is in the western Gardiner Range near Tent Hill Creek and is fairly poorly outcropping with only thin resistant beds of carbonate protruding through the alluvium. Sample Numbers: 85/3065-85/3081. Coreholes BMR Henbury No. 4 (Fig. 8) Location: HENBURY, 132° 14’ 38” E, 24° 33’ 33” S; Approximately 12 km NW of Wallera Hotel, 500 m N of the King’s Canyon Road (Owen & Morris 1985). BMR Rodinga No. 6 (Fig. 9) Location: RODINGA, 133° 42’ 12” E, 24° 22’ 46” S; In the James Range, about 3 km NW of the bridge of the Standard Gauge railway line over the Hugh River (Owen & Morris 1985). Tempe Vale No. 1 (Fig. 10) Location: LAKE AMADEUS, 131° 18’ 29” E, 24° 00’ 48” S; 11 km NNW of the Vale of Tempe. Tent Hill No. 1 (Fig. 11) Location: HENBURY, 132° 02’ 30” E, 24° 13’ 45” S; Adjacent to Tent Hill. Mount Winter No. 2A (Fig. 12) Location: MOUNT LIEBIG, 130° 47’ 49” E, 23° 51’ 51” S; 7 km WSW of Mount Winter. Spot Localities LA51 Location: LAKE AMADEUS, 131° 22’ 52” E, 24° 06’ 35” S; On the northeastern limb of the Fig. 7. Section through the Horn Valley Siltstone in the Gardiner Range, near Tent Hill Creek, with ranges of selected trilobites. Abbreviations as in Fig. 3.

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Fig. 9 (above). BMR Rodinga No. 6 stratigraphic corehole, with ranges of selected trilobites. Abbreviations as in Fig. 3.

Fig. 8 (to left). BMR Henbury No. 4 stratigraphic corehole, with ranges of selected trilobites. Abbreviations as in Fig. 3.


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Fig. 10. Ranges of selected trilobites in Pancontinental Petroleum Pty Ltd Tempe Vale 1 well. Abbreviations as in Fig. 3, depth in metres.

Ochre Hill Anticline (20 km ENE of the Mount Olifent Section). LA112 Location: LAKE AMADEUS, 131° 11’ 26” E, 24° 09’ 08” S; On or near Mount Olifent Section. BIOSTRATIGRAPHY Trilobite biostratigraphy of the Horn Valley Siltstone Lycophron howchini Assemblage Zone. The lower assemblage is found wherever the Horn Valley Siltstone outcrops and contains L. howchini (Etheridge, 1894), Madiganaspis madigani gen. et sp. nov., Basilicus (Basiliella) illarensis (Etheridge, 1893), Rodingaia nielseni gen. et sp. nov., Carolinites genacinaca Ross, 1951, Lonchodomas sp., Encrinurella sp. and Prosopiscus aff. praecox Fortey & Shergold, 1984.

Fig. 11. Ranges of selected trilobites in Pancontinental Petroleum Pty Ltd Tent Hill 1 well. Abbreviations as in Fig. 3, depth in metres.

This assemblage is represented by the few identifiable specimens of Madiganaspis madigani gen. et sp. nov. in The Sisters section (Fig. 3); by the presence of L. howchini, M. madigani and B. (B.) illarensis in the Maloney Creek section (Fig. 4); by the presence of the same three species in the lower 25 metres of the Mount Olifent section (Fig. 6), the lower 19 m of the Horn Valley Siltstone in BMR Henbury 4 corehole (Fig. 8) and in the lower part of the collected intervals in Tent Hill 1 (Fig. 11) and Mount Winter 2A (Fig. 12); and by the presence of L. howchini, M. madigani and R. nielseni in BMR Rodinga 6 corehole (Fig. 9). This assemblage was not seen in Tempe Vale 1 (Fig. 10) as no samples were taken low in the unit; it was not identified in the Tent Hill Creek section (Fig. 7; samples low in the unit had no identifiable trilobites); nor was it identified in the Namatjira Copper Prospect section (Fig. 5; the lower 80 m of the unit do not outcrop). Lycophron freemani Assemblage Zone. The upper assemblage is more restricted in its occurrence,


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Fig. 12. Ranges of selected trilobites in Pancontinental Petroleum Pty Ltd Mount Winter 2A well. Abbreviations as in Fig. 3, depth in metres.

having been truncated eastwards by pre-Stairway Sandstone erosion (see above). It contains L. freemani sp. nov., Eisarkaspis etheridgei gen. et sp. nov., Madiganaspis olifentensis gen. et sp. nov., Basilicus (Parabasilicus) winneckei sp. nov., Carolinites genacinaca Ross, 1951, Prosopiscus aff. praecox and ?Galbagnostus sp. This assemblage is not known from The Sisters section (Fig. 3), Maloney Creek section (Fig. 4) or BMR Rodinga 6 (Fig. 9). However, it contains L. freemani, E. etheridgei and M. olifentensis in the upper reaches of the unit in the Namatjira Copper Prospect section (Fig. 5) and in the middle of the unit in Tent Hill 1 (Fig. 11); L. freemani, E. etheridgei, M. olifentensis and B. (P.) winneckei in the middle of the unit at Mt Olifent (Fig. 6), near Tent Hill Creek (Fig. 7), in Tempe Vale 1 (Fig. 10) and in Mt Winter 2A (Fig. 12); L. freemani, M. olifentensis and B. (P.) winneckei in the middle of the unit in BMR Henbury No. 4 (Fig. 8). Correlations of the Horn Valley Siltstone Öpik (1956, p. 47) recorded the presence of Didymograptus nitidus above the “No.4 Quartzite” (Pacoota Sandstone) and therefore

assigned the enclosing rocks, later termed the Horn Valley Siltstone, to the Lower Ordovician. Thomas (1960, p. 15) recorded forms “very close to Didymograptus patulus” from Stokes Pass in the Idirriki Range for which he gave an Arenig age. Skwarko (1967, p. 176) recorded two occurrences of graptolites in the Amadeus Basin: Mount Watt (SE part of basin) yielded “incomplete monoserial stipes ... which may belong to an extensiform Didymograptus”; Mount Olifent produced “complete extensiform Didymograpti”. However, he did not give an age for these occurrences. Samples of very well preserved graptolites from the Lycophron freemani Assemblage have recently been examined by Dr R.A. Cooper (N.Z., DSIR) who has identified Didymograptus extensus, represented by forms very close to that of the type, as well as rare specimens of Xiphograptus sp. indet. Although D. extensus is most common in deeper water faunas of Early Arenig age, its range in shelf faunas may well be greater. On the other hand, the genus Xiphograptus has a very restricted range. In the opinion of Cooper (personal communication, February, 1991), the association of these two species indicates an age of Castlemainian to Yapeenian. Conodonts from the Horn Valley Siltstone were first described in detail by Cooper (1981) who correlated them with the latest Latorp to early Volkhov Oepikodus evae and Baltoniodus triangularis-Baltoniodus navis Zones of Löfgren (1978) on the Baltic Platform and the top of Fauna E, Fauna 1 and basal Fauna 2 (late Ibexian to early Whiterockian) in the North American succession of Ethington & Clark (1971) and Sweet et al. (1971). Cooper (1981) based his analysis on two sections, the type section at Ellery Creek and the Maloney Creek section, both of which are towards the eastern extremity of outcrop of the formation. The former section has only a very thin representation of the Lycophron freemani Assemblage, whereas in the latter section this assemblage is apparently absent. In a much more extensive examination of the conodont faunas than that undertaken by Cooper (1981), Nicoll (in Shergold et al. 1991) recorded three conodont assemblages from the unit which he considered ranged in age from early to late Arenig. The lowest, which he termed Fauna AC-D, is found in the basal part of the formation and contains Bergstroemognathus hubeiensis An and Oepikodus communis (Ethington & Clark). This fauna is found throughout the basin, but was not seen by Cooper (1981). Overlying this is Fauna AC-E, which contains Jumudontus gananda, Prioniodus amadeus, Erraticodon patu and Protoprioniodus aranda, all of which

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were described by Cooper (1981). This fauna is also found throughout the basin. The succeeding Fauna AC-F, which contains Periodon flabellum (Lindström) and Microzarkodina sp. indet., is only found in the central and western parts of the basin, as is the L. freemani trilobite assemblage. This conodont fauna also remained unseen by Cooper (1981). Georgina Basin. Webby (in Webby et al. 1981), correlated the Horn Valley Siltstone directly with the Nora Formation of the Georgina Basin, but did not explain why. Cooper (1981, p. 153), on the other hand correlated the Horn Valley with the Coolibah Formation and the lower Nora Formation. The correlation based on trilobite faunas supports Cooper’s assertion. Carolinites genacinaca occurs throughout the Horn Valley Siltstone, and is also found in the basal part of the Nora Formation (Fortey & Shergold 1984). Furthermore, the small Lycophron sp. A from the basal Nora Formation illustrated by Fortey & Shergold (1984, pl. 43, figs 11-12) is similar to the early growth stages of Lycophron freemani from the upper part of the Horn Valley Siltstone. Therefore a correlation between the upper Horn Valley Siltstone and the basal Nora Formation is likely. The conodont fauna of the Coolibah Formation has been studied by Stait & Druce (1993) and shown to have much in common with that of the Horn Valley Siltstone. They found that Oistodus multicorrugatus, Protoprioniodus nyinti, Triangulodus larapintinensis and Protopanderodus primitus were common to both formations and concluded that the lower part of the Horn Valley Siltstone was coeval with the uppermost Coolibah Formation. This supports the correlation obtained by Cooper (1981) and is supported by that based on the trilobite evidence. Canning Basin. Webby (in Webby et al. 1981) correlated the Horn Valley Siltstone with the middle of the outcropping Gap Creek Formation, and in the subsurface, with the middle of the Willara Formation and the Wilson Cliffs Sandstone. Cooper (1981, p. 152) tentatively correlated the Horn Valley conodont fauna with informal zones OCD and OCE of McTavish & Legg (1976) from the Canning Basin. This led Cooper to propose a correlation of the Horn Valley Siltstone with the uppermost Emanuel Formation and the lower half of the Gap Creek Formation. The trilobite faunas of the Emanuel and Gap Creek Formations were originally analysed by Legg (1976, 1978) and subsequently by Laurie & Shergold (1996a, b) and Laurie (1997). The

AAP Memoir 32 (2006) specimens assigned to Carolinites bulbosa by Legg (1976, p. 5) have been tentatively assigned to Carolinites genacinaca by Jell & Stait (1985b, p. 41), although they express some reservations about the illustrated librigena (Legg 1976, pl. 1, fig. 29) which has the inflated subocular band characteristic of C. tasmaniensis. Unfortunately, Legg (1976) did not give any detailed locality information, so the two species cannot be separated based on specimen associations. Furthermore, the specimens listed as C. bulbosa by Legg (1978, fig. 3) from the Emanuel Formation are almost certainly incorrectly assigned (Shergold et al. 1995b, p. 93; Laurie & Shergold 1996a, p. 69) and probably represent Ompheter priscus and Opipeuterella emanuelensis. Laurie & Shergold (1996a) record no specimens of Carolinites in the Emanuel Formation. However, Laurie (1997) has identified Carolinites ?genacinaca and Shergold et al. (1995b) have recorded the conodont Oepikodus communis from the overlying Gap Creek Formation. Both species are common in the Horn Valley Siltstone and the two formations are probably coeval. In the subsurface, Legg (1976) has recorded Carolinites pardensis Legg from the lower part of the Goldwyer Formation. This has been placed in synonymy with C. ekphymosus by Fortey (1980a) and Fortey & Shergold (1984), which is probably the species present in almost all except the basal Nora Formation (Fortey & Shergold 1984, p. 350). On this basis it seems that the Horn Valley Siltstone is older than the Goldwyer Formation. However, a few asaphid specimens recorded from the lower Goldwyer Formation and assigned to ?Aulacoparia sp. by Legg (1976, p. 9) are similar in gross morphology and surface ornament to Lycophron freemani sp. nov. (see below). Northeastern Queensland. The fauna from the Rollston Range Formation in the Mount Windsor Subprovince in northeastern Queensland contains Carolinites genacinaca (referred to C. bulbosus by Henderson 1983; see Jell & Stait 1985b), a species occurring throughout the Horn Valley Siltstone. Consequently a correlation with the Horn Valley Siltstone is considered likely. Western New South Wales. The Tabita and Pingbilly formations from the Mt Arrowsmith area in western New South Wales contains the trilobites Carolinites genacinaca Ross, 1951, Prosopiscus lauriei Paterson, 2004, Lycophron sp. nov., Basilicus (Parabasilicus) sp. and Asaphellus? sp., among others (Paterson 2001, 2002, 2004). The presence of C. genacinaca indicates a broad correlation with the Horn Valley Siltstone. Available conodont data further refines

AAP Memoir 32 (2006) this correlation and indicates that the Tabita and Pingbilly formations correlate with the lower part of the Horn Valley Siltstone (Zhen et al. 2003). Paterson (2006) has recently recorded Prosopiscus tatei (recorded herein from the basal Stairway Sandstone), Carolinites sp., Lycophron sp., Asaphellus sp. and protopliomerids from the middle Rowena Formation in the Bynguano Range. This is some 460 m from the base of the formation, so it is possible that the lower Rowena Formation correlates with the Horn Valley Siltstone, while the middle correlates with the Stairway Sandstone. Conodonts recorded from the lower Rowena Formation by Zhen & Percival (2006) also indicate a correlation with the Horn Valley Siltstone. Tasmania. Correlations to Tasmania can be achieved only indirectly as Tasmanian faunas have little in common with those from the Horn Valley Siltstone. In northern Tasmania, the upper parts (Lithosome B of Laurie 1991) of the Caroline Creek Sandstone contain Carolinites tasmaniensis (see Jell & Stait 1985b; Laurie & Shergold 1996a), a species which predates C. genacinaca, the form found in the Horn Valley Siltstone. However, near the top of the Caroline Creek Sandstone (Lithosome C of Laurie 1991), representatives of the brachiopod genus Aporthophyla have been recorded. This genus is also known from the Horn Valley Siltstone as A. dichotomalis (Tate, 1896) and possibly one other species. Therefore, it is likely that the Horn Valley Siltstone postdates most of the Caroline Creek Sandstone, but it may be coeval with its uppermost levels (Lithosome C). Aporthophyla as well as the gastropod Teiichispira are known from about the middle of the Karmberg Limestone in southern Tasmania (Laurie 1991) while a species of the pliomerid trilobite Canningella is found near the base of the unit. As noted above, Aporthophyla is found in the Horn Valley Siltstone, while Teiichispira and Canningella are present in the Gap Creek Formation of the Canning Basin in association with poorly preserved Carolinites considered by Laurie (1997) to be probably referrable to C. genacinaca. It therefore seems likely that the Karmberg Limestone is, at least in part, coeval with the Gap Creek Formation and is, in turn, probably coeval with the Horn Valley Siltstone. Intercontinental. The faunas of the Horn Valley Siltstone come from a period of time relatively well represented in fossiliferous successions around the world. The conodonts and telephinid trilobites are the most useful for intercontinental correlation and both allow fairly straightforward

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correlation to the well documented successions from western North America where fairly detailed trilobite and conodont zonal schemes have been established (Ross et al. 1993, 1997). The presence of the conodont species Bergstroemognathus hubeiensis An and Oepikodus communis (Ethington & Clark) in the AC-D fauna of Nicoll (in Shergold et al. 1991) indicates a correlation with the O. communis Zone of Ross et al. (1993, 1997) from western North America. The succeeding fauna of Nicoll (op. cit.), ACE, contains, among other species, Jumudontus gananda and Protoprioniodus aranda, both of which are found in the Reutterodus andinus Zone of Ross et al. (1993, 1997). The uppermost fauna AC-F contains Microzarkodina flabellum (Lindstom), a species found in the Tripodus laevis Zone of Ross et al. (1993, 1997). Carolinites genacinaca is known from the Presbynileus ibexensis (Zone I) and lower Pseudocybele nasuta (Zone J) zones of the western USA (Ross et al. 1993, 1997; McCormick & Fortey 2002). These both fall within the Reutterodus andinus Conodont Zone (Ross et al. 1993, 1997). Dean (1989) has recorded Carolinites genacinaca from the upper 111.8 m of the Outram Formation at Wilcox Pass, Alberta, Canada, but an illustrated specimen (Dean 1989, pl. 19, figs 7, 8) of a librigena from one of his localities (92293) almost certainly belongs to C. tasmaniensis (it has a strongly inflated subocular band). This locality is near the lower end of the range reported by Dean for C. genacinaca. However, the next highest locality (92315) is the topmost in the Outram Formation (Dean 1989, p. 55). It seems, therefore, that C. genacinaca does not appear until the very top of the Outram Formation and that all records of it below this point probably belong to C. tasmaniensis. In correlating with the Ross (1951) and Hintze (1952) successions from Utah, Dean (1989, p. 14) considered it convenient to draw the base of Zone J at the first appearance of Lachnostoma latucelsum, which is recorded only from the Pseudocybele nasuta (J) Zone by Ross et al. (1993, 1997). However, in the Outram Formation the range of Lachnostoma latucelsum predates that of C. genacinaca (as revised above); its first appearance even predates the first appearance of Carolinites tasmaniensis, which is known only from the upper Trigonocerca typica (H) Zone of Utah (Ross et al. 1993, 1997). This is considerably different from the arrangement in Utah detailed by Ross et al. (1993, 1997) in which C. genacinaca is found in the Presbynileus ibexensis (Zone I) and lower Pseudocybele nasuta (Zone J) Zones, while Lachnostoma latucelsum is known only

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from the lower P. nasuta (J) Zone. To further complicate matters, other species known from the P. nasuta (J) Zone in Utah first appear at a much higher level than the first appearance of L. latucelsum in the Outram Formation. Of these, Pseudocybele nasuta, Goniotelina brevis and Ptyocephalus declevitus first appear about 80 m above the first appearance of L. latucelsum, while Cybelopsis speciosa, Benthamaspis diminutiva and Ischyrotoma cf. caudanodosa all appear near the top of the Outram Formation or in the base of the overlying Skoki Formation, some 115 m above the first appearance of L. latucelsum (see Dean 1989, fig. 9). Furthermore, at about the same level as the first appearance of L. latucelsum, Dean (1989, fig. 9) also records Ptyocephalus acclivus, a species only recorded from the Trigonocerca typica Zone (Zone H) by Ross et al. (1993, 1997), although it was recorded as rare in the P. ibexensis Zone (Zone I) by Hintze (1952). This coupled with the presence, at this level, of Carolinites tasmaniensis, also only known from Zone H in Utah, indicates a correlation with the latter zone is more likely for this part of the Outram Formation, rather than a correlation with Zone J as proposed by Dean (1989, p. 14). The succession of Carolinites species is very well known from the Valhallfonna Formation on Spitsbergen (Fortey 1975). The species recorded from the Horn Valley Siltstone, C. genacinaca, is known from between 15 m and 102 m from the base of the Olenidsletta Member of the Valhallfonna Formation. This species is preceded by C. tasmaniensis (recorded as C. genacinaca nevadensis by Fortey 1975) and is succeeded by C. ekphymosus. Little else can be inferred from comparison of other trilobites from Spitsbergen because of the dissimilar biofacies and palaeobiogeography. Within this stratigraphic range of C. genacinaca, Cooper & Fortey (1982) have recorded graptolites which they correlate with the Bendigonian Be4 to Castlemainian Ca1 Zones. SYSTEMATIC PALAEONTOLOGY Descriptive terminology follows Whittington & Kelly (1997). Class TRILOBITA Walch, 1771 Order ASAPHIDA Salter, 1864 Superfamily ASAPHOIDEA Burmeister, 1843 Family ASAPHIDAE Burmeister, 1843 Remarks. The familial and generic taxonomy of the asaphid trilobites has long been problematic. This confusion is, to a large extent, due to the effacement of structural details of the glabella, precluding any detailed morphological analysis.

AAP Memoir 32 (2006) Because of this difficulty, reliance has often been placed on other morphological features for taxonomic discrimination, even in less effaced forms. Balashova (1964, 1971, 1976) in her classification scheme for the asaphids, based her familial and subfamilial diagnoses largely on extra-axial cranidial morphology, panderian organ structure and hypostome morphology. While these features are of taxonomic importance I believe they are less significant than the detailed glabellar structure. Jaanusson (1959) gave considerable emphasis to the glabellar structure in defining his taxonomic units and assumed that all the lateral lobes located near the rear of the glabella were homologous and part of the glabella. Fortey (1980b, p. 256) reinterpreted these structures in the Asaphinae (sensu Jaanusson 1959) as being of extra-axial origin (bacculae) which had been variably incorporated within the “axial structure”. While Fortey’s interpretation of the structure seems entirely reasonable when dealing with his illustrated specimen of “Asaphus sp. of expansus type” (Fortey 1980b, fig.1) and with some species of Asaphus (Neoasaphus) and the related genera Ogmasaphus and Plectasaphus (e.g. see Jaanusson 1953a, pl. 1, fig. 1, pl. 6, fig. 7, pl. 7, fig. 6; Jaanusson 1953b, pl. 2, fig. 4), it cannot very easily be applied to the lectotype of the type species of Asaphus (Asaphus), A. (A.) expansus, illustrated by Jaanusson (1956, pl. 1, figs 1-5). This specimen shows clearly a glabella slightly constricted opposite the palpebral lobes with well developed S1 furrows nearly perpendicular to the axial furrows. Medially these furrows curve backwards to intersect the occipital furrow and in so doing, separate the glabellar mid-body from two pre-occipital lateral lobes. These lobes are in turn separated from the fixigenae by axial furrows and are the structures Fortey (1980b) would interpret as bacculae. This argument amounts to whether or not it is possible for glabellar furrows to be essentially collinear with the anterior portions of the axial furrows. Such a collinear appearance is not uncommon among some other groups of trilobites, notably the Dalmanitoidea and Proetoidea, and is presumed to be the case in the group under discussion. A misleading impression of the structure arises because of the effacement of the posterior part of the axial furrow in some species and the deep incision of the S1 furrow as noted by Jaanusson (1959, p. 334). Furthermore, Fortey’s (1980b) interpretation of asaphine glabellar structure clearly cannot be applied to some other genera assigned to the subfamily (e.g. Lonchobasilicus, Nobiliasaphus,

AAP Memoir 32 (2006) Birmanites and Huochengia). This group possesses bacculae, but they are more similar in size and disposition to those of the Niobinae than those envisaged for the Asaphinae by Fortey (1980b). This is perhaps best illustrated by reference to particular specimens. For example, in the species Madiganaspis madigani gen. et sp. nov., the bacculae are moderately well defined as raised areas outside the faint axial furrows immediately behind the palpebral lobe. A similar arrangement can be seen in Basilicus mckeei Ross (1970, pl. 12, figs 1, 4-5, 12) in which the bacculae are separated from the lateral preoccipital lobes by a well developed axial furrow. I interpret the glabellar structure of Lonchobasilicus gansuensis Qu (Zhou & Fortey 1986, pl. 6, fig. 11) in a similar way. The bacculae are the narrow, slightly raised areas immediately abaxial of the palpebral lobes. It can be seen in all of these examples that the glabella is nearly parallel-sided, with well to weakly developed oblique S1 furrows and large subtriangular preoccipital lateral glabellar lobes with adjacent, narrow bacculae. This is similar to the interpretation given by Lee & Choi (1999) for Basiliella kawasakii Kobayashi, 1934 and Dolerobasilicus yokusensis (Kobayashi, 1934). Many other asaphids seem to efface the axial furrow between the bacculae and the lateral preoccipital glabellar lobes, a feature common in the Niobinae (Fortey 1980b, p. 256). In some asaphids, these conjoined structures can be misconstrued as large subtriangular bacculae occupying the re-entrants in the strongly constricted glabella. However, the bacculae sensu stricto can usually be distinguished, even in the absence of the axial furrow, as narrow, often weak prominences adjacent to the lateral preoccipital glabellar lobes. Examples of this can be seen in the following specimens: Basiliella carinata Harrington (Harrington & Leanza 1957, fig. 61.2-61.4), Birmanites aff. asiaticus (Petrunina) (Zhou & Dean 1986, pl. 59, fig. 14), and Megistaspis heroica Bohlin (1960, pl. 7, fig. 8, pl. 10, fig. 2). This group itself exhibits some variation in glabellar structure, ranging from species with very well defined S1 furrows which extend backwards to intersect the occipital furrow, separating the frontal glabellar lobe from two large triangular structures presumably representing the fused lateral preoccipital lobes and bacculae (e.g. Basilicus (Basiliella) zhenbaensis Zhou et al., 1982, pl. 65, fig. 2) to species in which the S1 furrows are very faint or incomplete and separate off relatively small lateral preoccipital lobes with adjacent small bacculae. This latter form usually has other glabellar furrows impressed (eg. Basiliella carinata Harrington in Harrington

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& Leanza, 1957, fig. 61.4; Megistaspis heroica Bohlin, 1960, pl. 7, fig. 6). This interpretation of the glabellar structure, which is much as Jaanusson (1959) proposed, therefore makes it very difficult to justify the separation of Asaphus and Isotelus at a subfamilial level. Comparison of these type genera shows them to be very similar in that they both have a large, broad glabella, constricted about the level of the eyes, with a posteriorly located glabellar node. Both also have a strongly forked hypostome with weakly developed maculae and a short to very short middle body. Therefore I think it preferable to assign them to the same subfamily within the Asaphidae. As a consequence, this subfamily (Asaphinae Burmeister, 1843) contains the following genera; Asaphus (Asaphus), A. (Neoasaphus), A. (Onchometopus), Ogmasaphus, Plectasaphus, Eoisotelus, Nahannia, Isoteloides, Isotelus, Pseudogygites, Xenasaphus, Lycophron, Pseudoasaphus and probably Pseudomegalaspis and Ectenaspis. A revised diagnosis for this subfamily is presented below. The genera excluded from this subfamily (eg. Basilicus, Basiliella, Pseudobasilicus, etc.) are tentatively referred to the Ptychopyginae Balashova, 1964. This assignment is tentative because few details of the glabellar structure of Ptychopyge angustifrons (Dalman), the type species of the type genus are known to me, however the occurrence of “nodes” behind the eyes (Jaanusson 1959, p. 339) suggests the presence of true bacculae. The hypostome of Ptychopyge is also similar to that of the Basilicus group in having a well developed notch in the posterior margin, a large, elongate middle body and well developed maculae. Subfamily ASAPHINAE Burmeister, 1843 Diagnosis. Effaced to en grande tenue with elongate glabella constricted between palpebral lobes. Glabellar node located immediately in front of occipital furrow or area corresponding to it. Cranidium widest posteriorly because of strong divergence of postocular branches of facial suture. Preocular branches of facial suture subparallel to axial furrows, preocular fixed cheek narrow (tr.). Preglabellar area usually short, may be produced into tongue-like process. Hypostome with short, usually poorly defined middle body, poorly defined maculae, deeply to very deeply notched posterior margin. Pygidium with long, tapered, commonly poorly defined axis. Lycophron Fortey & Shergold, 1984 Type species. Lycophron rex Fortey & Shergold,

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Fig. 13. Lycophron howchini (Etheridge, 1894). All x0.55. A-B, CPC 34748, weathered cranidium and part thorax, loc LA112; A, stereo pair; B, lateral view. C-D, CPC 34749, weathered cephalon and part thorax, loc LA112; C, stereo pair; D, anterior view. E, CPC 34750, stereo pair, weathered cranidium with associated librigenae, from float near 84/3029 section. F, CPC 34751, weathered librigena, from 84/3029/3. G, CPC 34752, stereo pair, weathered cranidium, from 84/3029/3. H, CPC 34753, small weathered partial hypostome, from LA112. I, CPC 34754, doublure of weathered, partial librigena, from LA112.

AAP Memoir 32 (2006) 1984. Other species. Asaphus (Megalaspis) howchini Etheridge, 1894, Lycophron freemani sp. nov., Lycophron sp. nov. (Paterson 2001, 2002). Emended diagnosis. Large, effaced or en grande tenue, with subtriangular cephalon. Cephalic border very narrow. Glabella elongate, constricted between palpebral lobes, anterior margin variably rounded, S1 furrows absent to weakly impressed, occipital furrow absent to weakly impressed. Hypostome narrow, with very strongly forked posterior margin and weakly developed maculae. Pygidium subtriangular, border lacking or developed behind axis, disappearing laterally or being replaced by a very narrow, threadlike border. Remarks. This genus was erected by Fortey & Shergold (1984, p. 340) for a “large, effaced isoteline” (L. rex) from the Nora Formation in the Georgina Basin. To this genus, they also assigned L. howchini (Etheridge, 1894) from the Amadeus Basin and another, smaller, unnamed species from the basal Nora Formation. In the Horn Valley Siltstone, two species belonging to the genus are recognised; L. howchini and L. freemani sp. nov. Both of these species differ considerably from the type species in having their axial furrows impressed, consequently a revised diagnosis is required. The presence of axial furrows and details of glabellar structure in the two Horn Valley species allows a much more confident comparison of this genus with other asaphid genera than that made by Fortey & Shergold (1984, p. 341). Lycophron is most closely related to Eoisotelus Wang, 1938 in glabellar structure and pygidial axial structure, but differs in that the glabella does not reach the anterior cephalic margin, the hypostome has relatively longer prongs (compare Chang 1950, pl. 2, fig. 13 with Figs 13H, 15N, 16A herein) and the pygidium lacks a well defined border laterally. Fortey & Shergold (1984) assigned Lycophron to the subfamily Isotelinae while Zhou & Fortey (1986) assigned Eoisotelus to the Asaphinae. The reasons for assigning both genera to the Asaphinae are outlined in the discussion of the family Asaphidae. Lycophron howchini (Etheridge, 1894) (Figs 13-14) 1894 Asaphus (Megalaspis) howchini; Etheridge, p. 23, pl. 3, fig. 1. 1894 Asaphus (Isotelus or Basilicus?) sp.; Etheridge, p. 23, pl. 3, fig. 2.

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1896 Asaphus illarensis?; Tate, p. 112, pl. 3, fig. 22. 1896 Asaphus howchini? Etheridge; Tate, p. 112, pl. 3, fig. 23. ?1969 Isotelus sp.; Hill et al., pl. Ov, fig. 4. 1984 Lycophron howchini (Etheridge); Fortey & Shergold, p. 341, text-fig. 11. Holotype. By monotypy; South Australian Museum type collection, F 7104, pygidium and partial thorax, Etheridge (1894, pl. 3, fig. 1). Reillustrated and incorrectly labelled as lectotype by Fortey & Shergold (1984, text fig. 11). Other material. CPC 34748-34749, 34753-34754 from LA112; CPC 34750, 34755 from float near 84/3029 section; CPC 34751-34752, 34756 from 84/3029/3; CPC 34757 from LA51. Diagnosis. Large, mostly smooth Lycophron with axial furrows clearly impressed and lacking occipital furrow. Palpebral lobes located level with glabellar constriction, at about one third glabellar length from front. Pygidium subtriangular with angular to rounded posterior margin, with clearly to weakly defined axis usually lacking segmentation. Pleural region showing no segmentation. Description. Large, mostly smooth, moderately to strongly convex Lycophron with available specimens indicating a maximum length for the species of about 220 mm. Cephalon about 80% as long as pygidium, while pygidium is about 95% as long as thorax. Cranidium about 73% as long as wide, widest near posterior margin, narrowest (41% maximum width) immediately in front of eyes. Glabella of very low convexity with moderately concave lateral margins defined by clearly impressed axial furrows and moderately to strongly convex anterior margin defined by variably developed axial furrows, about 69% as wide as long, with maximum width at posterior margin of occipital ring. Glabella is narrowest (59% maximum width) at about one third length from front, width anteriorly about 79% maximum width. Occipital furrow not impressed, S1 furrows usually absent, rarely very weakly impressed. Probable, weakly developed glabellar node located immediately in front of area corresponding to occipital furrow. Palpebral lobes small, about 15% as long as glabella, elevated above remainder of cranidium, located forward at about the level of the glabellar constriction. Forward of palpebral lobes, facial sutures diverge slightly for a short distance, remaining more or less parallel to axial furrows. The sutures then turn abruptly inwards to run intramarginally,

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Fig. 14. Lycophron howchini (Etheridge, 1894). All x0.55. A-B, CPC 34755, pygidium and part thorax, from float near 84/3029 section; A, dorsal view; B, lateral view. C, CPC 34757, weathered, nearly complete exoskeleton, from LA51. D-E, CPC 34756, damaged pygidium, from 84/3029/3; D, stereo pair; E, lateral view.

bounding a spatulate to triangular extension of the frontal area. Behind the palpebral lobes, facial sutures are, for a short distance, nearly parallel to the axial furrows then curve laterally such that they are parallel to the posterior margin. The sutures then curve backwards to intersect the well developed posterior border furrow at an acute angle, whereupon they curve medially to intersect the posterior margin at an obtuse angle. Librigena long, moderately to strongly convex (exsag., tr.), in life position, posterolateral portions almost vertical, with rounded genal angle. Eye raised on low socle. Posterior border furrow shallows abruptly laterally. Genal field smooth except towards border where terrace lines subparallel to border become prominent. Lateral border very narrow and threadlike in dorsal view, vertical outer face covered by about 10 parallel, closely spaced terrace lines. Only one small hypostome is available for study. The anterior margin is damaged. The middle body is undefined, maculae are clearly defined but not prominent, the posterior margin is very strongly forked such that the prolongations are about twice as long as wide. Thorax of 8 segments strongly convex, with broad axial region and narrow pleural

regions, each of which is about 75% as wide (tr.) as axis. Anterior six segments all of similar dimensions with the two posterior segments having progressively narrower (tr.) axes. Pleurae with anteriorly convex, deeply incised, oblique pleural furrow extending about 75% of distance from axial furrow to lateral margin. Pleural furrows become progressively less oblique and less curved posteriorly. Pleurae clearly divided into proximal and distal portions by well defined fulcra. Proximal portion nearly horizontal and distal portion steeply sloping. Articulating facets long (tr.), narrow (exsag.), rounded distally. Fulcra become progressively more distally located towards posterior. Pygidium subtriangular, strongly convex, about 90% as long as wide, about 40% as high as long, with angular or narrowly rounded posterior margin. Axis clearly to weakly defined; apart from deeply incised, backwardly bent articulating furrow, usually lacking visible segmentation; occupying about 84% of pygidial length; for most of its length tapering gently rearward to a rounded posterior extremity. Anteriorly, however, the axial furrow swings abruptly outwards to intersect the very deeply incised anterior pleural furrow which posteriorly bounds a very prominent half-rib. The

AAP Memoir 32 (2006) articulating facet is large, slightly larger than those of the thoracic segments, teardrop-shaped, slightly concave and oriented approximately vertically. Pleural field smooth, laterally very steeply sloping to a very narrow, thread-like border. At the posterior extremity of the pygidium a variably developed, narrow (sag.) border is evident. It is only visible directly posterior to the termination of the axis and disappears abruptly toward the sides. Remarks. See remarks for L. freemani below. Lycophron freemani sp. nov. (Figs 15-16) 1976 ?Aulacoparia sp.; Legg, p. 9, pl. 2, fig. 12, pl. 3, figs 8, 10, 11. ?1984 Lycophron sp. A; Fortey & Shergold, p. 344, pl. 43, figs 11-12. Etymology. After Mr M.J. Freeman, formerly of the Northern Territory Geological Survey, Alice Springs. Holotype. CPC 34758, damaged cranidium from 84/3031/2 (Fig. 15A-B). Other material. CPC 34759, 34771 from 84/3030/4; CPC 34760 from LA112; CPC 3476134762, 34764-34766, 34769-34770, 34772, 34775, 34777, 34780 from 84/3031/2; CPC 34763, 34768, 34779 from 84/3085; CPC 34767, 34773-34774 from 84/3072; CPC 34776 from 84/3031/1; CPC 34778 from LA112. Diagnosis. Large Lycophron with prosopon of fine pustules axially and adaxially and with reticulate terrace lines abaxially, with axial furrows clearly impressed, S1 furrows weakly developed, occipital furrow weakly impressed. Palpebral lobes located level with glabellar constriction, at about glabellar midlength. Pygidium subtriangular with posterior margin truncate to slightly concave, with clearly defined axis with 16 very weakly defined axial rings. Pleural region with 9 or 10 very weakly defined ribs. Description. Large Lycophron with prosopon varying considerably from one part of the exoskeleton to another. On the cranidium, anterolaterally are elongate anastomosing terrace lines, which medially break up into pustules (Fig. 15B). On and adjacent to the palpebral lobes and distally on the posterolateral limbs of the cranidium, the lineation is equidimensionally reticulate rather than elongate with pustules slowly increasing in concentration and size adaxially. The genal field is covered by polygonally anastomosing terrace

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lines. On pygidia the anastomosing terrace lines are restricted to the sides, with the axis and adaxial portions of the pleurae being pustulose, with an intervening narrow zone of overlap where the pustules are superimposed on the reticulation. The largest cranidium available is about 35 mm long (sag.) and the largest pygidium available is about 45 mm long (sag.), though available fragments and one large hypostome indicate that a much greater size was probably attained. Cranidium similarly proportioned to that of L. howchini but more strongly convex. Glabella of low (tr., sag.) convexity except anteriorly where it is moderate (tr.) to low (sag.) with moderately concave lateral margins defined by clear axial furrows and a semicircular anterior margin defined by an abrupt change in slope or by a weakly impressed axial furrow. Glabella about 63% as wide as long with maximum width at posterior margin of occipital ring, narrowest (64% maximum width) at a little over half its length from the front, where width is about 86% maximum width. S1 furrows weakly impressed, occipital furrow weakly impressed. Strong glabellar node located immediately in front of occipital furrow. Palpebral lobes small, about 20% as long as glabella, elevated strongly above remainder of cranidium, located at about glabellar midlength, level with glabellar constriction. Forward of the palpebral lobes, facial sutures diverge strongly at up to 60°, remaining more or less parallel to the axial furrows. They then turn abruptly inwards to run intramarginally bounding a convex (sag., tr.), spatulate to subtriangular extension of the frontal area. Behind the palpebral lobes the facial sutures are, for a very short distance, parallel to the axial furrows, then curve laterally such that they are parallel to the posterior margin. The sutures then curve backwards to intersect the posterior margin perpendicularly. Posterior border furrow very deeply incised adaxially, becoming broader and shallower laterally. Librigena long, moderately (exsag.) to strongly (tr.) convex with broadly rounded genal angles anterior to which is a distinct indentation in the lateral margin. Eye raised on a low socle. Lateral border very narrow in dorsal view, vertical outer face covered by about 10 parallel, closely spaced terrace lines. Doublure not preserved posteriorly, narrow, convex (tr.), inner margin concentric, covered by fine, irregular, vaguely concentric terrace lines. Only two hypostomes are available for study, one is quite small and the other very large but with only its posterior preserved. Anterior margin broadly arcuate, middle body undefined, maculae clearly defined on smaller specimen, very poorly defined on larger specimen. Posterior margin is

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AAP Memoir 32 (2006) very strongly forked such that the prolongations are between two and three times as long as wide. Only disarticulated (usually broken) thoracic segments were found. Thorax strongly convex with broad axial region and narrow pleural regions, each of which is about 75% as wide as axis. Axial ring backwardly bent, articulating furrow deep and broad, articulating ring narrow (sag.), bent very slightly forward. Pleural furrow slightly anteriorly convex, deeply incised, oblique pleural furrow, abruptly disappearing a short distance abaxial of fulcrum. Pleurae divided into proximal and distal portions by clearly defined fulcra. Proximal portion nearly horizontal and distal portion nearly vertical. Articulating facet large, teardrop shaped. Pygidium subtriangular, very strongly convex (tr.), with very variable length to width ratio (from 75% to 125% as long as wide) and about 50% as high as long. Posterior extremity truncate or slightly concave. Axis clearly defined by well incised axial furrows, occupying about 81% of pygidial length (sag.), for the most part tapering gently rearward to a rounded posterior termination. Anteriorly the axial furrows swing abruptly outwards to intersect the very deeply incised anterior pleural furrow which posteriorly bounds a very prominent, strongly convex halfrib. Axial segmentation consisting of very well defined articulating half-ring in front of deep articulating furrow, plus 16 narrow (sag.) axial rings which are broadly V-shaped for most of axial length, becoming transverse posteriorly and in most cases obtaining an inverted V shape near very short subtriangular terminal piece. Pleural field weakly segmented, with anterior pleural furrow very deeply incised, subdividing first pleural rib plus 9 or 10 other weakly defined pleural ribs, oriented perpendicular to the lateral margin of the pygidium. Pleural field strongly convex (tr.), laterally sloping very steeply such that the very narrow, threadlike border cannot be seen in dorsal view. At the posterior extremity of the pygidium is a well developed, narrow (sag.) border. It is only evident posterior and posterolateral to the axial termination and disappears abruptly laterally. Articulating facet

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very large, teardrop shaped, slightly concave, oriented approximately vertically. Doublure narrow, concave (tr.), inner margin concentric. Surface covered by three concentric zones of fine terrace lines, with the outermost and innermost zones having subparallel, concentric lines and the middle zone having anastomosing lines. Ontogeny. Several quite small specimens of cranidia (Fig. 15G) and pygidia (Fig. 16D-I) were available for study and show this species to have some unusual ontogenetic variation. Small cranidia have a much more strongly convex (tr., sag.) glabella, narrower preocular fixed cheek and very deeply impressed S1 furrows. Small pygidia are more strongly convex (sag., exsag.), have a much greater width-length ratio with some specimens being nearly twice as wide as long. They also possess a distinct border, widest anterolaterally and narrowing posteriorly, disappearing adjacent to the axis which extends to the posterior margin of the pygidium. With growth, this border disappears, the lateral margins of the pygidium becoming much more steeply sloping, eventually disappearing from dorsal view entirely. Thus the small pygidium illustrated by Fortey & Shergold (1984, pl. 43, figs 11, 12) as Lycophron sp. A, which has a distinct border and its axis extending to the posterior margin, is undoubtedly a juvenile of the genus and may be conspecific with L. freemani. The prosopon of the pygidium also varies ontogenetically. In smaller pygidia the pleurae are smooth or very faintly ornamented and the axis variably pustulose. With increasing size, the axis and pleural lobes exhibit a prosopon of very fine, reticulate ridges which, on the axis and adaxial part of the pleural lobes have pustules at many intersections of the reticulation. With further increase in size this reticulation disappears from the axis and adaxial parts of the pleural lobes and is coupled with an increase in the density of the pustules. Remarks. Like Lycophron howchini (Etheridge), L. freemani sp. nov. differs from L. rex Fortey & Shergold, 1984 in having its glabella and pygidial axis outlined by clearly defined axial furrows.

Fig. 15. Lycophron freemani sp. nov. A-B, CPC 34758, holotype damaged cranidium, from 84/3031/2; A, stereo pair, x1.0; B, detail of anterolateral portion, x4.0. C, CPC 34760, exfoliated part cranidium, from La112, x1.0. D, CPC 34763, exfoliated cranidium, from 84/3085, x2.0. E, CPC 34761, partly exfoliated cranidium, from 84/3031/2, x2.0. F, CPC 34764, stereo pair, partly exfoliated cranidium, from 84/3031/2, x2.0. G, CPC 34759, small cranidium, from 84/3030/4, x4.0. H, CPC 34762, exfoliated cranidium, from 84/3031/2, x2.0. I, CPC 34767, stereo pair, exfoliated librigena, from 84/3072, x1.0. J, M, CPC 34765, part librigena, from 84/3031/2; J, normal view, x1.0; M, detail of surface and margin, x4.0. K, CPC 34766, stereo pair, ventral surface of librigena with cuticle removed near midlength and with internal mould of doublure preserved anteriorly, from 84/3031/2, x1.0. L, CPC 34768, stereo pair, exfoliated librigena, with eye attached, from 84/3085, x1.0. N, CPC 34772, stereo pair, part of small hypostome, from 84/3031/2, x4.0.

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Fig. 16. Lycophron freemani sp. nov. A, CPC 34771, part of large hypostome, from 84/3030/4, x1.0. B-C, CPC 34769, partly exfoliated thoracic segment, from 84/3031/2, x2.0; B, stereo pair; C, lateral view. D, G, CPC 34770, small pygidium, from 84/3031/2, x8.0; D, stereo pair; G, lateral view. (continued opposite)

AAP Memoir 32 (2006) Lycophron freemani differs from L. howchini (Etheridge) in being more strongly convex and in having a reticulate and pustulose prosopon over the entire exoskeleton. The eyes are more posteriorly located in L. freemani, consequently the constriction of the glabella is also more posteriorly located and the posterior limbs of the fixigenae are narrower (exsag.). The anterior tongue-like extension of the preglabellar area is shorter in L. freemani. The axis of the pygidium is more clearly defined in L. freemani and the segmentation of the axis and pleural fields is always, though faintly, visible. In L. howchini it is only rarely visible. In L.howchini the termination of the pygidium is narrowly rounded or pointed whereas in L. freemani it is broadly rounded to slightly concave.

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Pygidium with narrow, poorly defined abaxially sloping border and very poorly defined axis of more than 13 axial rings with articulating furrow effaced. Pleural lobe mostly smooth, convex, with weakly defined anterior pleural furrow and clearly defined articulating facet.

Type species. Eisarkaspis etheridgei gen. et sp. nov.

Remarks. This genus is similar in effacement to Priceaspis Legg and Fitzroyaspis Legg, both of which were synonymised by Laurie (in Laurie & Shergold 1996b). However, Eisarkaspis differs in having a much wider (exsag.), shorter (tr.), postocular fixed cheek; in lacking a posterior cephalic border furrow; or development of glabellar or occipital furrows; and in having rounded rather than spinose genal angles; a narrower pygidial doublure with a concentric inner margin; as well as a wider glabella and thoracic and pygidial axis. These characters also separate it from all other effaced asaphids. Fitzroyaspis irritans Fortey & Shergold, 1984, from the Nora Formation in the Georgina Basin should also be assigned to Eisarkaspis, because, like E. etheridgei gen. et sp. nov., the species has wide (exsag.), short (tr.) postocular fixed cheeks, a wide glabella and wide pygidial axis, rounded genal angles and lacks a posterior cephalic border furrow.

Other species. Fitzroyaspis irritans Fortey & Shergold, 1984.

Eisarkaspis etheridgei gen. et sp. nov. (Fig. 17-19)

Diagnosis. Glabella poorly defined, broad, extending to anterior border furrow; glabellar furrows effaced; glabellar node posteriorly located; palpebral lobes moderately large, level with midlength of glabella; postocular fixed cheek broadly triangular, forming widest part of cranidium; posterior border furrow effaced; bacculae occasionally visible, narrow; preocular fixed cheek small, triangular; anterior border furrow broad, indistinct; border moderately wide, narrower sagittally; librigena narrow (tr.), with border furrow broad, indistinct; border narrowing towards rounded genal angle; genal field steeply inclined, convex. Hypostome with poorly defined ovate middle body and sharply defined transverse maculae; lateral border of even width over posterior two thirds hypostome length; posterior border deeply notched.

Etymology. Named after Robert Etheridge Jnr, who first described fossils from the Horn Valley Siltstone during the 1890s.

?Subfamily PTYCHOPYGINAE Balashova, 1964 Eisarkaspis gen. nov. Etymology. Eisarkos (Gr.), corpulent, with aspis (Gr.) shield.

Holotype. CPC 34821, damaged cranidium from 84/3031/1 (Fig. 17A). Other material. CPC 34822, 34824, 34828 from float near 84/3031; CPC 34823, 34829-34830, 34838 from 84/3031/2; CPC 34825, 34832, 34844, 34846, 34849 from 84/3031/3; CPC 34826, 34834-34837, 34840-34842, 34850, 34852 from 84/3031/1; CPC 34827, 34848 from 84/3031/4; CPC 34831, 34833 from 84/3030/9; CPC 34839, 34847 from 84/3030/8; CPC 34843, 34851, 34853, 34855-34856 from 84/3085; CPC 34845, 34854 from 84/3086.

E, H, CPC 34773, small pygidium, from 84/3072, x8.0; E, stereo pair, H, lateral view. F, CPC 34774, stereo pair, small pygidium with attached thoracic segment, from 84/3072, x10.0. I, CPC 34776, stereo pair, small pygidium, from 84/3031/1, x2.0. J-K, CPC 34777, exfoliated pygidium, from 84/3031/2, x1.0; J, lateral view showing external mould of doublure; K, normal view. L, N-O, Q, CPC 34778, well preserved pygidium, from La112; L, stereo pair, x1.0; N, lateral view, x1.0; O, detail of lateral surface and margin, x4.0; Q, detail anterolateral portion, x4.0. M, CPC 34775, exfoliated pygidium, from 84/3031/2, x1.0. P, R, CPC 34780, small pygidium, from 84/3031/2; P, lateral view, x2.0; R, dorsal view, x2.0. S, CPC 34779, damaged, partly exfoliated pygidium, from 84/3085, x1.0.

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AAP Memoir 32 (2006) Diagnosis. Cranidium about 90% as long as wide, with relatively broad (tr.) posterior limbs of the fixed cheeks; palpebral lobes strongly arched; glabella relatively narrowly rounded anteriorly; anterior border flat laterally, but slopes strongly forward sagittally. Description. Large, smooth, moderately convex with available specimens indicating a maximum length (sag.) for the cephalon of about 42 mm. Cranidium about 89% as long as wide, widest at posterior margin, narrowest (52% maximum width) immediately in front of palpebral lobes. Width across anterior part of the fixigenae about 76% maximum width. Glabella large, occupying 91% of cranidial length (sag.), broad, indistinctly defined but appears to be narrowest at about the level of the palpebral lobes, expanding slightly forward and rearward, in the latter case presumably occupying the area between the prominent articulating notches. Glabella posteriorly of low (sag.) to moderate (tr.) convexity, anteriorly steeply inclined to anterior border such that anterior portion of glabella is strongly convex (tr.) and has a bulbous appearance. Anterolaterally, the glabella is often separated from the steeply dipping anterior part of the fixigenae by a weakly developed axial furrow. Glabellar node usually not visible dorsally on larger specimens but in exfoliated and smaller specimens it is located posteriorly, a short distance in front of the area corresponding to the occipital furrow. Structure of the glabella is obscure with few if any features visible on the dorsal surface of larger specimens. However, several smaller specimens exhibit weakly developed glabellar furrows as well as what appear to be narrow bacculae alongside the glabella, adjacent to the posterior extremity of the palpebral lobes. The anterior border is narrowest sagittally, where it is steeply dipping forward and widens laterally where it is nearly horizontal in aspect. Palpebral lobes moderately large, semicircular, horizontal, slightly less elevated than glabella and about 25% as long as glabella. Forward of palpebral lobes, facial sutures diverge strongly (at about 90°),

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until near the cephalic margin where they curve inwardly to run intramarginally, meeting each other to bound a very obtusely angled cranidial anterior. Behind the palpebral lobes the facial sutures diverge very strongly (at about 110°), curving backwards to intersect the posterior margin at about 80°. Librigena longer than wide with moderately large eye located in anterior half of moderately convex (tr.), steeply sloping genal field, raised on low socle. Border becomes narrower and finally disappears towards narrowly rounded genal angle. There is a fine, thread like ridge on the entire margin of the librigena. Doublure moderately wide with well developed vincular furrow which is parallel to cheek margin and arises a short distance in front of the genal angle and gradually fades out anteriorly. Panderian organ a discrete, circular opening located a short distance from inner margin of doublure, with a low ridge extending anteriorly from it for a short distance. Doublure covered by subparallel, concentric terrace lines except for vincular furrow where they are oblique. Only two hypostomes, probably assignable to this species are available. The middle body is only clearly defined anteriorly, the border furrow becoming indistinct towards deep, well defined maculae. Posterior lobe short (sag.), broad, only clearly defined adjacent to the maculae. Lateral border very narrow anteriorly, expanding very sharply backwards. Posterior border deeply notched, with notch being about half as long as wide. Middle body covered by transverse terrace lines which laterally curve forward, crowding into the region of the border furrow. Posterior part of lateral border covered by oblique terrace lines which arise from border furrow and notch margin and extend anterolaterally to near lateral margin where they curve forward to intersect the margin at a very acute angle. On the anterior part of the lateral borders the terrace lines form elongate, concentric loops. Only disarticulated thoracic segments (mostly broken) have been found. Their axial region is broad, moderately and evenly convex. Pleural

Fig. 17. Eisarkaspis etheridgei gen. et sp. nov. A, CPC 34821, stereo pair, holotype cranidium, from 84/3031/1, x1.0. B, CPC 34827, stereo pair, small, partly exfoliated cranidium, from 84/3031/4, x2.0. C, CPC 34828, stereo pair, small, partly exfoliated cranidium, from float near 84/3031 section, x1.0. D, CPC 34822, stereo pair, largely exfoliated cranidium, from float near 84/3031 section, x1.0. E, CPC 34826, stereo pair, small cranidium showing faint bacculae, from 84/3031/1, x4.0. F, CPC 34829, stereo pair, small cranidium, from 84/3031/2, x4.0. G, CPC 34823, stereo pair, cranidium, from 84/3031/2, x2.0. H, CPC 34830, stereo pair, small cranidium, from 84/3031/2, x2.0. I, CPC 34825, stereo pair, partly exfoliated cranidium, from 84/3031/3, x2.0. J, CPC 34833, small cranidium, from 84/3030/9, x4.0. K, CPC 34824, partial cranidium, from float near 84/3031 section, x0.9. L, CPC 34832, small, partly exfoliated cranidium, from 84/3031/3, x2.0. M, P, CPC 34834, librigena with posterior margin broken, from 84/3031/1, x2.0; M, stereo pair; P, lateral view. N, CPC 34831, small exfoliated cranidium, from 84/3030/9, x1.0. O, Q, CPC 34835, small librigena with small genal spine, from 84/3031/1, x4.0; O, normal view; Q, lateral view.

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Fig. 19 (above). Eisarkaspis etheridgei gen. et sp. nov. A, CPC 34851, stereo pair, partly exfoliated pygidium, from 84/3085, x2.0. B, CPC 34853, stereo pair, large, exfoliated pygidium showing details of axial segmentation, from 84/3085, x2.0. C, CPC 34856, stereo pair, large, broken, mostly exfoliated pygidium showing details of axial segmentation, from 84/3085, x2.0.

regions are narrow (tr.), each about 85% as wide as axis. Pleural furrows barely visible dorsally, most prominent near fulcrum. Pleurae vaguely divided into distal and proximal portions by fulcra. Proximal portion dipping slightly towards axial furrow, distal portion moderately steeply dipping outwards. Articulating facets long (tr.), narrow

(exsag.), broadly rounded posterolaterally and narrowly rounded or angular anterolaterally. Pygidium transverse, moderately convex, about 66% as long as wide, with broadly and evenly rounded margin. Axis usually very weakly defined on large specimens, often only defined by vague posterior termination and prominent

Fig. 18 (opposite). Eisarkaspis etheridgei gen. et sp. nov. A, CPC 34836, stereo pair, ventral surface of partial librigena showing panderian opening, from 84/3031/1, x2.0. B, CPC 34839, librigena with external mould of doublure exposed anteriorly, from 84/3030/8, x2.0. C, CPC 34838, internal mould of librigena, showing panderian opening, from 84/3031/2, x1.0. D, CPC 34837, stereo pair, partial doublure of librigena showing panderian opening, from 84/3031/1, x1.0. E, CPC 34842, stereo pair, hypostome, from 84/3031/1, x1.0. F, CPC 34840, partly exfoliated thoracic segment, from 84/3031/1, x2.0. G, CPC 34841, thoracic segment, from 84/3031/1, x2.0. H-I, CPC 34844, large pygidium, from 84/3031/3, x1.0; H, normal view; I, lateral view. J, CPC 34843, partly exfoliated hypostome, from 84/3085, x2.0. K, M, CPC 34846, small pygidium, from 84/3031/3, x2.0; K, stereo pair; M, lateral view. L, CPC 34845, stereo pair, pygidium with external mould of doublure exposed on left hand side, from 84/3086, x2.0. N, CPC 34852, small pygidium, from 84/3031/1, x4.0. O-P, CPC 34847, largely exfoliated pygidium, with external mould of doublure exposed on right hand side, from 84/3030/8, x2.0. O, dorsal view; P, lateral view. Q, CPC 34848, stereo pair, small, largely exfoliated pygidium, from 84/3031/4, x2.0. R, U, CPC 34850, partial pygidium, from 84/3031/1, x2.0; R, lateral view; U, normal view. S, CPC 34849, stereo pair, small pygidium, from 84/3031/3, x2.0. T, CPC 34855, largely exfoliated pygidium, from 84/3085, x2.0. V, CPC 34854, pygidium, from 84/3086, x2.0.

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articulating notches, even lacking an articulating furrow. Axis on smaller specimens tapers strongly with axial furrows slightly concave outwards. On exfoliated larger specimens the axis occupies about 82% of pygidial length, with well impressed musculature, indicating the presence of 13 axial rings and a very small terminal piece. Pleural fields rarely segmented except for broad anterior pleural furrow which bounds a well developed half-rib. Articulating facet narrowly (exsag.) subtriangular, covered by transverse terrace lines. Border weakly defined, occupying about 8% of pygidial length sagittally, tending to be wider posterolaterally. Doublure of moderate width, dorsally convex, with a concentric inner margin, covered by two concentric zones of fine terrace lines. The inner zone is formed by concentric lines over the entire inner half of the doublure whereas the outer zone has concentric terrace lines posteriorly which anteriorly become oblique, intersecting the pygidial margin at a very acute angle. Near the anterolateral extremities of the pygidium these terrace lines extend transversely onto the dorsal surface, occupying about half the border width. Ontogeny. The many quite small cranidia (Fig. 17B, C) and pygidia (Fig. 18N, Q, S) available show this species to have considerable ontogenetic variation. Small cranidia tend to have a more clearly defined glabella, although it is still relatively indistinct, and to have relatively larger palpebral lobes. Small fixigenae consequently have a relatively larger eye and a small genal spine. Small pygidia are slightly wider, their axes are more clearly defined, the border relatively wider and more clearly defined. On the smallest specimens available, the axial rings are also commonly visible. Remarks. Eisarkaspis irritans (Fortey & Shergold, 1984) is the only other species currently assigned to the genus. It differs from E. etheridgei gen. et sp. nov. in having relatively narrower (tr.) posterior limbs on the fixed cheeks such that the cranidium is nearly as long as wide. In E. etheridgei the cranidium is about 90% as long as wide. Also, the palpebral lobes of E. irritans

AAP Memoir 32 (2006) have less strongly arched ocular margins. As a consequence the constrictions of the cranidium in front of and behind the palpebral lobes in E. etheridgei are more pronounced. The glabella of E. etheridgei is more narrowly arched anteriorly and on many specimens is separated from the anterior part of the fixigena by a very weakly developed axial furrow. In E. irritans the glabellar anterior is more broadly arched and the axial furrow is totally effaced. The anterior cranidial border of E. irritans is “virtually flat” (Fortey & Shergold 1984, p. 340), whereas that of E. etheridgei is nearly flat laterally, but slopes quite strongly forward sagittally. Madiganaspis gen. nov. Etymology. After C.T. Madigan, one of the first geologists to do detailed work on the Amadeus Basin + aspis (Gr.), shield. Type species. Madiganaspis olifentensis sp. nov. Other species. Madiganaspis madigani sp. nov. Diagnosis. Cranidium of low convexity; glabella narrow, nearly parallel-sided, rounded anteriorly, with weakly developed S1 furrows, other glabellar furrows absent or weakly developed. Glabellar node immediately in front of weakly impressed occipital furrow. Palpebral lobes small, located well in front of S1 furrows, postocular fixed cheek triangular, bacculae narrow. Frontal area long (sag.). Librigena broad (tr.), with sharply defined steeply outwardly sloping marginal face, broad border becoming better defined posterolaterally and a broad genal spine. Hypostome with well defined ovate middle body and sharply defined transverse maculae with lateral border widening posteriorly. Posterior border deeply notched. Pygidium rounded, moderately convex with broad, poorly defined, concave border, and long, weakly segmented axis. Pleural lobe with 5 weakly impressed pleural furrows. Remarks. The combination of long frontal area and small, relatively forwardly placed eyes, coupled with a hypostome which has an

Fig. 20. Madiganaspis olifentensis gen. et sp. nov. A, CPC 34791, stereo pair, small cranidium, from 84/3031/3, x3.0. B, CPC 34792, stereo pair, small cranidium, from 84/3031/3, x6.0. C, CPC 34793, stereo pair, small cranidium, from 84/3031/3, x3.0. D, CPC 34794, small cranidium, from 84/3031/3, x4.0. E, CPC 34795, stereo pair, small cranidium, from 84/3031/3, x6.0. F, CPC 34797, exfoliated cranidium, from 84/3031/3, x3.0 G, CPC 34798, stereo pair, holotype very large, partly exfoliated cranidium, from float near 84/3031 section, x0.67. H, CPC 34806, slightly obliquely distorted cranidium, from 84/3031/3, x3.0. I, CPC 34801, stereo pair, cranidium, from 84/3031/1, x3.0. J, CPC 34796, stereo pair, small partial cranidium and associated pygidium, from 84/3031/3, x3.0. K, CPC 34803, stereo pair, small cranidium, distorted so it appears relatively short (sag.), from 84/3031/3, x3.0. L, CPC 34804, partly exfoliated cranidium, from 84/3031/3, x3.0. M, CPC 34802, stereo pair, partly exfoliated cranidium, from 84/3031/3, x3.0.


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AAP Memoir 32 (2006) elongate, well defined middle body, clearly differentiates this genus from most other genera of the Ptychopyginae (sensu herein). Genera which have a similarly expanded frontal area (e.g. Nobiliasaphus, Opsimasaphus, Birmanites and Pseudobasilicus) do not have the forwardly placed eyes, whereas Ogygitoides, which has the eyes forwardly placed, differs in having them larger and more widely spaced, and has a well developed border on the cephalon. Madiganaspis olifentensis gen. et sp. nov. (Figs 20-22) Etymology. The type material comes from near Mount Olifent, on LAKE AMADEUS sheet area. Holotype. CPC 34798, large partly exfoliated cranidium, from float near 84/3031 section (Fig. 20G). Other material. CPC 34791-34797, 34800, 34802-34804, 34806, 34808, 34810, 34812, 34815, 35818-34820 from 84/3031/3; CPC 34799, 34805, 34807, 34809, 34811 from 84/3031/4; CPC 34801, 34813 from 84/3031/1; CPC 34814, 34816 from float near 84/3031; CPC 34817 from 84/3031/2. Diagnosis. Cranidium pustulose, with glabella occupying about 69% of cranidial length, with maximum width either across anterior or posterior limbs of fixed cheeks. Pygidium with axis about 38% as wide as long, having 13 or 14 axial rings and a short termination. Pygidial doublure very wide, occupying almost three quarters pleural field width anteriorly. Description. Very large, mostly smooth, but with crests of glabella and pygidial axis pustulose; convexity low. Largest cranidium is 75 mm long and the largest pygidium is estimated to have been about 60 mm long, both of which indicate a maximum length for the species of about 175 mm. Cranidium of low convexity, about 90% as wide as long, with maximum width either

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across anterior or posterior part of fixigenae. Cranidium narrowest (44% maximum width) immediately in front of palpebral lobes. Glabella 55% as wide as long, occupying 69% of cranidial length, with sides broadly waisted level with palpebral lobes, defined by weakly impressed axial furrows laterally and by an abrupt change in slope anteriorly and anterolaterally. Glabella of low convexity behind the palpebral lobes, with convexity restricted to sagittal region, with exsagittal portions being nearly flat. Further rearward, convexity again increases such that the occipital ring is moderately convex. Anteriorly, glabella is moderately convex (tr., sag.) with an evenly rounded anterior margin. In largest specimen, S1 furrows developed as broad, indistinct, subtriangular depressions, in smaller specimens as clearly defined, elongate, oblique furrows extending from the axial furrow approximately level with the midlength of the palpebral lobes, to intersect the occipital furrow. In smaller specimens, from the anterior portion of the S1 furrow arises a short, anteriorly directed, commonly poorly defined accessory furrow, which extends to about level with the midlength of the palpebral lobes. S2 furrows commonly developed as weak, elongate depressions directed transversely or extending slightly obliquely forward from their intersection with the axial furrow at a point approximately level with the anterior extremity of the palpebral lobe. S3 furrows rarely developed as short, oblique depressions a short distance in front of S2 furrows. Occipital ring clearly impressed laterally, weakly or not impressed medially. Glabellar node variably developed, located immediately in front of occiptal furrow. Forward of palpebral lobes, facial sutures diverge strongly, at about 100-120° until they come near the cephalic margin where they turn inwards to run intramarginally, only crossing the narrow outwardly sloping marginal face near the sagittal line. Behind the palpebral lobes, the facial sutures curve outwards and then backwards. Anterior part of fixigenae flat to slightly concave (sag., exsag., tr.). Frontal area long (about 31% cranidial length). Palpebral lobes of moderate size, about 25% as long as glabella,

Fig. 21. Madiganaspis olifentensis gen. et sp. nov. A, CPC 34799, small, exfoliated librigena, from 84/3031/4, x3.0. B, D, CPC 34805, librigena, from 84/3031/4, x3.0; B, stereo pair; D, lateral view. C, CPC 34810, stereo pair, hypostome, from 84/3031/3, x3.0. E, CPC 34808, stereo pair, ventral surface of large librigena, doublure partly exfoliated anteriorly, posteriorly showing panderian opening, from 84/3031/3, x3.0. F, CPC 34809, ventral (anteriorly) and external mould of dorsal surface (posteriorly) of large librigena, from 84/3031/4, x3.0. G, CPC 34800, partly exfoliated hypostome, from 84/3031/3, x4.0. H, CPC 34812, meraspid pygidium with anterior segment approaching release to thorax, from 84/3031/3, x6.0. I, CPC 34811, small meraspid pygidium, from 84/3031/4, x12.0. J, CPC 34813, stereo pair, left pleural lobe of thoracic segment, from 84/3031/1, x3.0. K, CPC 34817, small pygidium, from 84/3031/2, x3.0. L, CPC 34820, small pygidium, from 84/3031/3, x6.0. M, CPC 34816, very large, partly exfoliated pygidium, from float near 84/3031 section. N, CPC 34814, right half of pygidium with external mould of doublure exposed posteriorly, from float near 84/3031 section, x3.0.

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Fig. 22. Madiganaspis olifentensis gen. et sp. nov. A, CPC 34807, external mould of doublure of thoracic segment, showing panderian opening, from 84/3031/4, x3.0. B, CPC 34818, pygidium, from 84/3031/3, x3.0. C, CPC 34816, stereo pair, very large, partly exfoliated pygidium, from float near 84/3031 section, x0.5. D, CPC 34819, pygidium, from 84/3031/3, x3.0. E, CPC 34815, stereo pair, damaged pygidium, from 84/3031/3, x3.0.

elevated above remainder of cranidium, located at about glabellar midlength. Postocular part of fixigenae subtriangular, with posterior border furrow weakly defined adaxially, usually clearly defined laterally. Bacculae narrow, subtriangular, extending from level with posterior extremities of palpebral lobes nearly to posterior border furrow. Librigena broad, with moderately convex (tr.) genal field and a broad, slightly concave border which is very poorly defined anteriorly, becoming moderately well defined posterolaterally. Border covered in well developed terrace lines which are approximately concentric with the margin. Periphery of librigena occupied by a narrow, outwardly sloping face. Socle very low. Genal spine proximally very broad, occupying about one third total length of librigena. Doublure very broad, covered in widely spaced terrace lines approximately concentric with the margin. Panderian opening developed as a long (tr.) slit. Hypostome with ovate, very well defined middle body and very well defined, transverse maculae. Lateral border widens strongly rearward.

Posterior border deeply and widely notched, with notch being about half as long (sag.) as wide. Hypostome covered by well developed, predominantly transverse terrace lines. Thoracic segments with relatively narrow axis and wide (tr.) pleural lobe. Pleural lobe with well developed fulcrum dividing pleurae into a transverse, horizontal, proximal portion and a slightly backwardly bent outwardly sloping distal portion. Pleural furrow deep, narrow (exsag.), deepest level with fulcrum, extending only a short distance abaxially beyond fulcrum. Abaxial extremity falcate, with short, broad spine. Pygidium rounded, moderately convex, about 67% as long as wide. Axis moderately convex, about 38% as wide as long, tapering more distinctly in anterior half, bounded by broad, well developed axial furrows, occupying about 72% of pygidial length, with well defined, rounded termination. Axial rings fairly well defined anteriorly, less so posteriorly, but showing 13 or 14 axial rings plus a short terminal piece. Pleural lobe with broad, poorly defined concave border which is widest posterolaterally. Adaxial portions

AAP Memoir 32 (2006) of pleural field with 6 or 7 ribs. Pleural furrows variably developed, the anterior three fairly sharply incised, the remainder becoming less clear posteriorly. Doublure very broad, in ventral view the abaxial portion is convex, the adaxial portion concave. Adaxial margin generally straight with a very deep notch concordant with the axial termination. Doublure covered by two, more or less concentric zones of widely spaced terrace lines. The innermost (adaxial) zone is fairly broad and consists of very widely spaced terrace lines, which more or less parallel the adaxial margin of the doublure. The outermost (abaxial) zone is the broader of the two and covers the remainder of the doublure. The terrace lines in this zone vary in spacing and posteriorly are concentric with the pygidial margin, but anterolaterally they intersect the margin at an angle of up to 90°. Remarks. Madiganaspis olifentensis gen. et sp. nov. differs from the other species of the genus (M. madigani gen. et sp. nov.) in having a more extensive (sag., tr.) anterior portion of the fixed cheeks and slightly shorter (exsag.) posterior limbs of the fixed cheeks. It also has a pustulose ornament on the glabella and posterior limbs of the fixed cheeks. The pygidium of M. olifentensis also differs from that of M. madigani in having a relatively narrower axis with 13 or 14 axial rings (the latter has 12), and a much wider doublure. Madiganaspis madigani gen. et sp. nov. (Fig. 23) Etymology. After C.T. Madigan, one of the pioneer geologists of the Amadeus Basin. Holotype. CPC 34781, slightly weathered cranidium from LA51 (Fig. 23A). Other material. CPC 34782, 34786-34788 from LA51; CPC 34783-34785 from 84/3029/2; CPC 34789-34790 from float near 84/3029. Diagnosis. Cranidium smooth, with glabella occupying about 77% of cranidial length, with width across anterior portion of fixed cheeks 77% maximum width of cranidium. Pygidium with axis about 50% as wide as long, having 12 axial rings and a short termination. Pygidial doublure of moderate width, occupying slightly less than half pleural field width anteriorly. Description. Large, smooth, of moderate to low convexity. Largest articulated specimen available is about 103 mm long, but largest cranidium is 47 mm long and the largest pygidium is 52 mm long, both of which indicate a maximum length for

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the species of about 145 mm. Cranidium of low convexity, approximately equidimensional with maximum width at posterior margin. Cranidium narrowest (44% maximum width) immediately in front of palpebral lobes, with width across anterior part of fixed cheek being about 77% maximum width. Glabella 55% as wide as long, occupying 77% of cranidial length, with sides subparallel to slightly forwardly tapering, defined by weakly impressed axial furrows laterally and by an abrupt change in slope anteriorly and anterolaterally. Glabella of very low convexity across and immediately behind the palpebral lobes, usually with convexity restricted to sagittal region, with exsagittal portions being flat or slightly concave. Further rearward convexity increases such that occipital ring is weakly to moderately convex. Anteriorly, glabella is moderately convex (tr., sag.) with an evenly rounded to vaguely quadrate anterior margin. S1 furrows weakly developed as oblique depressions behind the level of the palpebral lobes, with poorly defined prolongation extending to occipital furrow. Some specimens also have a transglabellar furrow joining the S1 furrows a short distance in front of the glabellar node. S2 and S3 furrows occasionally present, weakly impressed. Occipital furrow weakly impressed. Glabellar node well developed, located immediately in front of occipital furrow. Forward of palpebral lobes, facial sutures diverge strongly, at about right angles until they come near the cephalic margin where they turn inwards to run intramarginally only intersecting the narrow, outwardly sloping marginal face near the sagittal line. Behind the palpebral lobes the facial sutures are more or less straight and diverge at about 80°. Anterior part of fixed cheek slightly concave (sag., exsag.) to flat (tr.) medially and very slightly convex (tr.) near lateral extremities. Frontal area long (about 23% cranidial length). Palpebral lobes small, about 16% as long as glabella, elevated above remainder of cranidium, located at about glabellar midlength. Postocular part of fixed cheek triangular with posterior border furrow varying from obscure adaxially to weakly impressed laterally. Bacculae weakly defined, narrow, semiovate, evident as prominences mid way between palpebral lobes and posterior border furrow. Librigena broad, with moderately convex (tr.) genal field and a broad, slightly concave border which is very poorly defined anteriorly, becoming moderately well defined posterolaterally. Periphery of librigena occupied by a narrow, steeply outwardly sloping face. Socle very low. Genal spine proximally very broad, length unknown. Doublure visible anteriorly on small librigena where it is very broad (exsag.).

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Fig. 23. Madiganaspis madigani gen. et sp. nov. A, CPC 34781, stereo pair, holotype cranidium, from La51, x1.0. B, CPC 34784, stereo pair, small cranidium, from 84/3029/2, x1.0. C, CPC 34790, stereo pair, cranidium, from float near 84/3029 section, x1.0. D, CPC 34783, exfoliated cranidium, from from 84/3029/2, x1.0. E, CPC 34789, stereo pair of nearly complete, weathered specimen with most of left librigena overlapping thorax, from float near 84/3029 section, x0.67. F, CPC 34782, partial large librigena with associated very small librigena, from La51, x1.0. G, CPC 34788, ventral surface of cranidium, from La51, x1.0. H, CPC 34785, stereo pair, small librigena, from 84/3029/2, x1.0. I, CPC 34786, stereo pair, hypostome, from La51, x1.0. J, CPC 34787, ventral surface of large pygidium, from La51, x1.0.

AAP Memoir 32 (2006) Hypostome with ovate, well defined middle body and well defined, slightly oblique maculae. Lateral border widens strongly rearward. Posterior border deeply notched, with notch being about as wide as long (sag.). Hypostome covered by well developed, mostly transverse terrace lines. Thorax of eight segments with axis evenly tapering rearward with axial lobe being about half as wide (tr.) as each pleural lobe. Axial rings narrowly (sag.) quadrate, laterally bounded by clearly impressed axial furrows. Pleural lobe with well developed fulcrum dividing pleurae into a transverse, horizontal, proximal portion and a backwardly bent, strongly sloping distal portion. Pleural furrow broad, weakly impressed, deflected slightly backwards, extending a short distance abaxially beyond fulcrum. Pygidium rounded, moderately convex, about 67% as long as wide. Axis moderately convex, slightly less than 50% as wide as long, evenly tapering, bounded by broad, shallow axial furrows, occupying about 75% of pygidial length, termination very poorly defined, rounded. Axial rings very poorly defined on pygidial exterior, but pygidial interior shows probably 12 axial rings plus short termination. Pleural field with broad, poorly defined, concave border which is broadest posterolaterally. Adaxial portions of pleural field with 5 or 6 ribs evident. Pleural furrows variably developed, the anterior one well impressed, posteriorly bounding a moderately convex half rib, the remaining four becoming shorter and less well impressed posteriorly such that the posterior furrow is barely visible. Doublure broad, in ventral view the abaxial portion is convex, the adaxial portion concave. The adaxial margin is slightly concave with a very deep notch concordant with the axial termination. Doublure covered by three, more or less concentric zones of fine terrace lines. The innermost (adaxial) zone is very narrow (tr.) and consists of 4 or 5 closely spaced fine terrace lines which parallel the adaxial margin of the doublure. The middle zone is quite broad and covers the doublure from near the adaxial margin to the line of maximum ventral convexity of the doublure. The terrace lines in this zone are subparallel to the pygidial margin. The outermost zone is also quite broad and covers the remainder of the doublure. The terrace lines in this zone posteriorly are concentric with the pygidial margin, but anterolaterally they intersect this margin at an angle of up to 30°. Remarks. See remarks on M. olifentensis above. Rodingaia gen. nov. Etymology. From the BMR Rodinga No. 6

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corehole, whence the type material comes. Type species. Rodingaia nielseni gen. et sp. nov. Diagnosis. Cranidium of low convexity; glabella narrow, anteriorly rounded, slightly constricted behind midlength, with well developed S1 furrows; other furrows weakly developed; glabellar node immediately in front of broad, indistinct occipital furrow; palpebral lobes of moderate size, level with glabellar midlength; postocular fixed cheeks triangular, forming widest part of cranidium; posterior border furrow broad, clearly defined; bacculae narrow, converging forward; frontal area moderately long, border furrow absent; librigena moderately wide, with long genal spine. Hypostome with poorly defined ovate middle body and small, oblique, clearly defined maculae; lateral border widens posteriorly; posterior border deeply notched. Pygidium transverse, subquadrate, of low convexity with large posterolateral spines. Border poorly defined, widest posterolaterally; axis strongly tapering with 10 or 11 axial rings and a short terminal piece; pleural fields broad, with 5 or 6 pleural furrows. Remarks. This unusual monotypic genus has been found only in several pieces of core from a short interval and is represented solely by disarticulated sclerites. However, these sclerites are confidently assigned to the single species, Rodingaia nielseni gen. et sp. nov. because the diversity of the trilobite assemblage in this horizon is low (3 species) and the other two species, Lycophron howchini and Carolinites genacinaca are vastly different morphologically. In general appearance, this genus is most like Asaphelina Bergeron, 1889 in having a posterior pygidial border, between the posterolateral spines, which is nearly straight, and a glabella which does not approach the anterior border of the cranidium. However, there are pronounced differences between the two genera. The type species of Asaphelina, A. barroisi Bergeron, 1889, has a long parallel-sided glabella lacking the well developed strongly oblique S1 furrows and bacculae characteristic of Rodingaia. The hypostome of A. barroisi also lacks the well developed notch in the posterior border which is seen in Rodingaia. These features indicate that Rodingaia is more closely related to such genera as Basilicus, Basiliella and Madiganaspis; genera that I would tentatively include in the Ptychopyginae (see above). Asaphelina, on the other hand, is probably more closely related to genera such as Notopeltis, Kayseraspis, and Hoekaspis. These and other genera were included by Jaanusson (1959) in his

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Fig. 24. Rodingaia nielseni gen. et sp. nov. A, CPC 34900, stereo pair, cranidium, from Rodinga No. 6, 66.2066.24 m, x4.0. B, CPC 34904, stereo pair, small cranidium, from Rodinga No. 6, 66.89-66.90 m, x4.0. C, CPC 34907, doublure of partial librigena, from Rodinga No. 6, 66.15-66.18 m, x2.0. D, CPC 34905, small cranidium, from Rodinga No. 6, 66.15-66.18 m, x4.0. E, CPC 34906, large librigena with doublure exposed along lateral and anterolateral margin, pygidium overlaying at about midlength of margin, from Rodinga No. 6, 66.54-66.55 m, x2.0. F, CPC 34903, latex cast of partial hypostome, from Rodinga No. 6, 66.20-66.24 m, x4.0. G, CPC 34901, large hypostome, from Rodinga No. 6, 66.54-66.55 m, x4.0. H, CPC 34909, partial, distorted, exfoliated pygidium showing most of external surface of doublure, from Rodinga No. 6, 66.20-66.24 m, x2.0. I, CPC 34898, stereo pair, latex cast of partial pygidium, from Rodinga No. 6, 66.20-66.24 m, x4.0. J, CPC 34899, stereo pair, pygidium, from Rodinga No. 6, 66.54-66.55 m, x4.0.


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Fig. 25. Rodingaia nielseni gen. et sp. nov. A, CPC 34908, partial large, mostly exfoliated holotype pygidium showing external mould of doublure, from Rodinga No. 6, 66.28-66.30 m, x2.0. B, CPC 34902, stereo pair, small pygidium, from Rodinga No. 6, 67.76-67.78 m, x4.0. C, CPC 34910, partly exfoliated pygidium, with external surface of doublure exposed posteriorly, from Rodinga No. 6, 66.89-66.90 m, x3.0.

group B of the Subfamily Isotelinae. Rodingaia nielseni gen. et sp. nov. (Figs 2425) Etymology. After Dr. Arne Nielsen, University of Copenhagen, for his work on the trilobite ecostratigraphy of the Horn Valley Siltstone. Holotype. CPC 34908, partial large pygidium from BMR Rodinga No. 6 corehole, 66.28-66.30 metres depth (Fig. 25A). Other material. CPC 34898, 34900, 34903, 34909 from Rodinga No. 6, depth 66.20-66.24 m; CPC 34899, 34901, 34906 from Rodinga No. 6, depth 66.54-66.55 m; CPC 34902 from Rodinga No. 6, depth 67-76-67.78 m; CPC 34904, 34910 from Rodinga No. 6, depth 66.89-66.90 m; CPC 34905, 34907 from Rodinga No. 6, depth 66.1566.18 m. Diagnosis. As for genus. Description. Moderate sized, mostly smooth, convexity fairly low. Largest pygidium is estimated to have had a sagittal length of about 27 mm, indicating a sagittal length for the species of about 75 mm. Only three cranidia have been identified, the largest of which is relatively small (8.3 mm long). This cranidium is of fairly low

convexity, estimated to be about 98% as long as wide, widest across the posterior parts of the fixigenae, with the width across the anterior parts of the fixigenae being about 71% of the maximum width. Cranidium narrowest (47% maximum width) immediately in front of palpebral lobes. Glabella 50% as wide as long, occupying 82% of cranidial length with sides strongly waisted posteriorly; narrowest about level of bacculae. Axial furrow fairly well developed, clearly defining glabella over most of its length; except adaxial to the bacculae where the axial furrow is very weakly developed. Glabella of moderate convexity (tr.) anteriorly, and of low convexity level with and posterior to palpebral lobes. Occipital ring moderately convex. Occipital furrow weakly impressed. S1 furrows elongate, broad, deep, oblique extending backwards from level with posterior extremities of palpebral lobes to a short distance forward of and on either side of the prominent glabellar node. S2 furrows developed as vague triangular depressions about level with midlength of palpebral lobes. S3 furrows as narrow, shallow furrows directed slightly obliquely forward from their intersection with the axial furrow, at a point slightly behind the anterior extremity of the palpebral lobes. S4 furrows as short oblique indentations in the sides of the glabella, approximately parallel with the S3 furrows. Forward of palpebral lobes, facial sutures diverge strongly at about 90° until they come near

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AAP Memoir 32 (2006) the cephalic margin where they curve inwards to run intramarginally. Behind the palpebral lobes the facial sutures curve strongly outwards and then gently backwards. Anterior part of fixigenae flat (tr.) or slightly concave (sag., exsag.). Frontal area fairly short (about 18% cephalic length). Palpebral lobes of moderate size, about 25% as long as glabella elevated above remainder of cranidium, located at about glabellar midlength. Postocular part of fixigenae subtriangular with posterior border furrow weakly defined adaxially, clearly defined laterally. Bacculae not clearly defined, semicircular to ovate, extending from a short distance behind palpebral lobes to about level with glabellar node. Librigenae represented by one flattened nearly complete specimen and the anterior part of the doublure of a second. Librigena broad with long, strong, genal spine occupying over one quarter of the total length of the librigena. Socle very low. Doublure broad, covered by evenly spaced, approximately concentric terrace lines. Hypostome with ovate, poorly defined middle body and relatively small, slightly oblique maculae. Lateral borders widen rearward. Posterior border deeply and narrowly notched, with notch being about two thirds as long (sag.) as wide. Hypostome covered by weakly developed, predominantly transverse terrace lines. Thorax unknown. Pygidium trapeziform, weakly convex, about 64% as long (sag.) as wide. Axis moderately convex, about 55% as wide as long, occupying about 69% of sagittal pygidial length, tapering strongly and bounded by well developed axial furrows. Axial rings not very clearly defined, but numerous with between seven and ten being recorded in addition to a variably long terminal piece. Pleural lobe with slightly convex pleural field and broad, poorly defined, weakly concave border which is widest posterolaterally at which point arise two long, straight to slightly adaxially curved, flattened spines which occupy about one quarter of the total length of the pygidium. Adaxial portions of pleural field with 4 to 6 ribs. Pleural furrows variably developed, with the anteriormost two being fairly clearly defined, the remainder less so. Doublure very broad, underlying the vast majority of each pleural lobe,

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covered by two, more or less concentric zones of terrace lines. The innermost (adaxial) zone is broad and consists of terrace lines which are fairly widely spaced around the termination of the axis, but become more closely spaced anteriorly. The outer (abaxial) zone is narrower and covers the remainder of the doublure. These terrace lines are approximately parallel to the posterior margin, but intersect the lateral margin at about 40°. Basilicus Salter, 1849 Type species. Asaphus tyrannus Murchison, 1839. Basilicus (Basiliella) Kobayashi, 1934 Type species. Asaphus barrandi Hall, 1851. Basilicus (Basiliella) illarensis (Etheridge, 1893) (Figs 26-27) 1893 Asaphus illarensis; Etheridge, p. 5, pl. 1, fig. 1. 1896 Asaphus illarensis Etheridge; Tate, p. 111, pl. 3, fig. 21a-c. ?1896 Asaphus lissopeltis; Tate, p. 112, pl. 3, figs 24-26. Holotype. By monotypy; South Australian Museum type collection, P1416, partial pygidium, Etheridge (1893, pl. 1, fig. 1). Material. CPC 34881, 34892 from LA51; CPC 34882, 34886-34889 from 84/3022; CPC 34883, 34893 from float in Ellery Creek; CPC 3488434885, 34890-34891 from 83/012; CPC 34894 from Henbury No. 4, depth 84.73-84.74 m. Diagnosis. Cephalon finely pustulose; cranidium widest across posterior lobes of fixigenae; anterior angle of cranidium about 110-120°; genal spines long; pygidium semiovate to semicircular, about 58% as long as wide, with axis occupying about 85% pygidial length, with up to 11 axial rings and 6 pleural furrows; in later holaspides, pygidial border is very steeply sloping, with no discernible border furrow.

Fig. 26. Basilicus (Basiliella) illarensis (Etheridge, 1893). A, CPC 34881, stereo pair, cranidium, from La51, x2.0. B, CPC 34882, stereo pair, small cranidium, from 84/3022, x4.0. C, CPC 34883, stereo pair, partial cranidium, from float in Ellery Creek, x2.0. D, CPC 34885, stereo pair, largely exfoliated cranidium, from 83/012, x4.0. E, CPC 34890, stereo pair, partial, broken librigena, from 83/012, x2.0. F, CPC 34884, stereo pair, large, mostly exfoliated cranidium, from 83/012, x4.0. G, I, CPC 34888, posterolateral portion of ventral surface of librigena, from 84/3022; G, detail showing panderian opening, x6.0. I, stereo pair, x2.0. H, CPC 34886, stereo pair, partly exfoliated librigena, from 84/3022, x2.0. J-K, CPC 34887, partly exfoliated pygidium with doublure exposed near left posterolateral margin, from 84/3022; J, stereo pair, x2.0; K, detail of surface ornament, x5.0.

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Fig. 27. Basilicus (Basiliella) illarensis (Etheridge, 1893). A, CPC 34889, stereo pair, partly exfoliated pygidium, from 84/3022, x4.0. B, CPC 34894, small pygidium, from Henbury No. 4, 84.73-84.74 m, x2.0. C, CPC 34891, stereo pair, exfoliated pygidium with doublure exposed posteriorly, from 83/012, x2.0. D, CPC 34893, stereo pair, small pygidium, from float in Ellery Creek, x2.0. E, CPC 34892, stereo pair, partial pygidium, from La51, x2.0.

Description. Of moderate size, moderately convex, with most of cephalon covered in fine, evenly spaced pustules. Largest cranidium is about 19 mm long and the largest pygidium is about 17 mm long, both of which indicate a maximum length for the species of about 52 mm. Cranidium moderately convex, about 94% as long as wide, with maximum width across the posterior part of fixigenae. Cranidium narrowest (47% maximum width) immediately in front of palpebral lobes. Glabella 52% as wide as long, occupying 86% of cranidial length, with sides strongly waisted level with palpebral lobes. Anterior lobe of glabella bulbous, with an evenly rounded anterior margin. Occipital furrow clearly developed laterally, weak to obscure medially. S1 furrows developed as broad, oblique, depressions level with posterior extremities of palpebral lobes. From the posteromedial extremity of these furrows, narrow furrows extend forward to join the S2 furrows which are developed as small, elongate depressions approximately parallel with the S1 furrows. S3 furrows developed as short, weakly impressed pits in the margins of the glabella, about level with the anterior ends of the

palpebral lobes. S4 furrows immediately in front of S3 furrows, weakly developed as pits in the glabellar margin, slightly in front of the anterior extremities of the palpebral lobes. Glabellar node variably developed, located immediately in front of occipital furrow. Forward of palpebral lobes, facial sutures diverge strongly, at about 80-90° until they come near the cephalic margin where they turn inwards fairly sharply to run intramarginally at about an angle of 110-120° to one another, only crossing the outwardly sloping face of the rounded border near the sagittal line. Behind the palpebral lobes, the facial sutures are nearly straight and diverge strongly at about 100°, bounding triangular posterior fixigenal limbs, the lateral extremities of which are relatively sharp. Posterior border furrows very clearly developed. Anterior limb of fixigenae concave (exsag.) to flat (tr.). Frontal area short (about 14% cranidial length), occupied mostly by broad (sag., exsag.) poorly defined border. Palpebral lobes of moderate size, about 23% as long as glabella, elevated above remainder of cranidium, located at about glabellar midlength. Bacculae fairly large, not clearly defined, extending from level

AAP Memoir 32 (2006) with posterior half of palpebral lobes backwards to posterior border furrows, which are bent backwards around the posterior extremities of the bacculae. Librigena of moderate width, with strongly convex genal field and lateral and posterior borders. Lateral border furrow clearly defined anteriorly separating strongly convex border from genal field. Both border and border furrow narrow posteriorly, the border becoming almost thread-like on approach to genal spine. Posterior border furrow well developed adjacent to facial suture separating broad, convex border from genal field. Posterior border furrow becomes shallower laterally, disappearing near base of genal spine. Genal spine proximally stout, fairly long, occupying over one third of total length of librigena. Doublure broad, covered in closely spaced terrace lines. Panderian opening as small perforation atop small bulge in doublure. Hypostome and thorax unknown. Pygidium semiovate to semicircular, strongly convex, about 58% as long as wide. Axis bounded by broad, deep axial furrows, moderately convex, about 50% as wide as long, occupying about 85% pygidial length, tapering evenly such that across the axial terminal piece it is about 45% its anterior width. Axial rings not very clearly defined externally, with between 4 and 8 visible; very clearly defined on internal moulds with as many as 11 visible in addition to a small terminal piece. Pleural lobe with fairly narrow, flat to slightly concave (tr.) border, inclined steeply towards margin. Pleural field with between 4 and 6 pleural furrows visible, only the anterior four on each side being clearly visible, the remaining furrows, if visible at all are usually very weakly developed. Surface covered by anastomosing pattern of fine terrace lines. Pygidial border is well developed and relatively narrow on smaller holaspides, but in later holaspides it becomes very steeply inclined and lacks a border furrow. Doublure quite narrow, not extending very far adaxially beyond border, with inner margin concentric with outer margin, covered by fine, closely spaced, concentric terrace lines. Remarks. This species is unusual among species assigned to the subgenus Basilicus (Basiliella), but most of its morphological peculiarities can be found as parts of differing combinations in many other species. However, it perhaps has most in common with Basiliella satunensis Kobayashi & Hamada, 1964, Basilicus (Basiliella) asper Zhou & Fortey, 1986 and Basiliella mediterranea Dean, 1966. However, B. satunensis has distinctly wider anterior portions of the fixed cheeks. Basilicus (Basiliella) asper has a similar cranidium, but

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its pygidium is smooth, much more compact and has a much broader axis. Basiliella mediterranea has a similar cranidium, but anteriorly it is more obtusely angular; its pygidium is much more elongate and has more (7) clearly developed pleural furrows. Basilicus (Parabasilicus) Kobayashi, 1934 Type species. Parabasilicus typicalis Kobayashi, 1934. Basilicus (Parabasilicus) winneckei sp. nov. (Figs 28-29) Etymology. Named after the botanist, Charles George Alexander Winnecke, the leader of the Horn Expedition to central Australia in 1894. Holotype. Pygidium, CPC 34872, from Locality 84/3081 (Fig. 28P). Other material. CPC 34857 from Rodinga No. 6, depth 71.08-71.09 m; CPC 34858, 34860-34861, 34865, 34867-34868, 34875, 34879-34880 from 84/3030/4; CPC 34859, 34862-34864, 34866, 34870-34871, 34873-34874, 34876-34878 from 84/3030/3; CPC 34869 from 84/3085; CPC 34872 from 84/3081. Diagnosis. Cranidium widest across posterior part of fixigenae; glabella indistinctly outlined; pygidium rounded quadrate, with strongly tapered axis bearing as many as 13 axial rings; pleural fields with anterior two clearly defined, the remaining 2-4 less so; pygidial border broad, poorly defined. Description. Moderate-sized, mostly smooth, moderate to low convexity. Largest cranidium is 34 mm long and the largest pygidium is about 35 mm long, indicating a maximum length for the species of over 90 mm. Cranidium of moderate to low convexity, about 88% as long as wide, with maximum width across posterior part of fixigenae. Cranidium narrowest (45% maximum width) immediately in front of palpebral lobes. Glabella about 56% as wide as long, occupying 84% of cranidial length, evenly rounded anteriorly and with sides broadly waisted level with palpebral lobes. Axial furrows vague or absent laterally, while anterolaterally and anteriorly, the glabella is defined by an indistinct change in slope. Occipital furrow weakly developed. S1 furrows developed as broad, weak depressions about level with posterior extremities of palpebral lobes. No other glabellar furrows developed. Glabellar node immediately in front of occipital

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Fig. 29 (above). Basilicus (Parabasilicus) winneckei sp. nov. A, CPC 34873, stereo pair, largely exfoliated pygidium with external mould of doublure exposed on left hand side, from 84/3030/3, x3.0. B, CPC 34879, stereo pair, small pygidium, from 84/3030/4, x4.0. C, CPC 34874, stereo pair, partly exfoliated pygidium with external mould of doublure exposed on left hand side, 84/3030/3, x1.0. D, CPC 34878, stereo pair, small pygidium, from 84/3030/3, x4.0. E, CPC 34875, stereo pair, meraspid pygidium with anterior segment approaching release to thorax, from 84/3030/4, x8.0. F, CPC 34877, stereo pair, partial ventral surface of pygidium, with inner margin of doublure broken, from 84/3030/3, x2.0. G, CPC 34876, stereo pair, pygidium, from 84/3030/3, x4.0. H, CPC 34880, small pygidium, from 84/3030/4, x8.0. I, CPC 34869, ventral surface of pygidium, from 84/3085, x2.0.

furrow, not very clearly developed. Forward of palpebral lobes, facial sutures diverge strongly, at about 80-100°, until they come near the cephalic margin where they turn fairly sharply inwards to run intramarginally, only extending

to the margin near the sagittal line. Behind the palpebral lobes, the facial sutures curve weakly outwards and then backwards. Anterior part of fixigenae flat (tr., sag., exsag.). Frontal area short (about 16% cranidial length). Palpebral

Fig. 28 (opposite). Basilicus (Parabasilicus) winneckei sp. nov. A, CPC 34858, stereo pair, partly exfoliated portion of a cranidium, from 84/3030/4, x1.0. B, CPC 34859, partly exfoliated cranidium, from 84/3030/3, x2.0. C, CPC 34857, exfoliated cranidium, from Rodinga No. 6, 71.08-71.09 m, x3.0. D, CPC 34861, stereo pair, small cranidium, from 84/3030/4, x8.0. E, CPC 34865, partly exfoliated cranidium, from 84/3030/4, x2.0. F, CPC 34863, partly exfoliated hypostome, from 84/3030/3, x2.0. G, CPC 34860, stereo pair, small cranidium, from 84/3030/4, x8.0. H, CPC 34867, exfoliated hypostome, from 84/3030/4, x2.0. I, CPC 34868, hypostome, from 84/3030/4, x2.0. J, CPC 34862, small exfoliated cranidium, from 84/3030/3, x4.0. K, CPC 34866, hypostome, from 84/3030/3, x4.0. L, O, CPC 34871, exfoliated pygidium, with doublure exposed on left posterior, from 84/3030/3; L, detail of axis showing segmentation, x3.5; O, stereo pair, x2.0. M, CPC 34864, librigena, from 84/3030/3, x4.0. N, CPC 34870, largely exfoliated pygidium, from 84/3030/3, x2.0. P, CPC 34872, stereo pair, holotype pygidium, from 84/3081, x1.0.

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Fig. 30. A, Indeterminate Asaphidae A; CPC 34895, pygidium with doublure exposed on left hand side, from Rodinga No. 6 70.31-70.32 m, x3.0. B-C, Indeterminate Asaphidae B; B, CPC 34896, partial cranidium, from Rodinga No. 6, 44.73-44.80 m, x3.0. C, CPC 34897, hypostome, from Rodinga No. 6, 44.73-44.80 m, x4.0.

lobes of moderate to small size, about 22% as long as glabella, elevated above remainder of cranidium, located at about glabellar midlength. Postocular part of fixigenae subtriangular with posterior border furrow weakly defined or absent adaxially, weakly defined abaxially. Bacculae weakly defined, narrow, semiovate extending from behind posterior extremities of palpebral lobes to posterior border furrow. Librigena of moderate width with moderately convex genal field which is covered in poorly developed terrace lines which are approximately concentric with socle. Border poorly defined, flattened proximally, convex and outwardly inclined distally and covered in fairly evenly spaced terrace lines, which are approximately concentric with the margin. Socle very low. Genal spine proximally fairly broad, length unknown. Doublure unknown. Hypostome with ovate, variably developed middle body and relatively small, variably defined, slightly oblique maculae. Lateral border widens rapidly anterior to midlength of middle body, of fairly even width in posterior half, with deep, wide notch in posterior border; notch being about half as long as wide and subquadrate. Hypostome covered by variably developed, predominantly transverse, terrace lines. Thorax unknown. Pygidium rounded quadrate, moderately convex, about 71% as long as wide. Axis moderately convex, not very clearly defined, occupying about 69% of pygidial length, about 50% as wide as long, tapering fairly evenly so that it is about 37% as wide across the terminal piece as it is anteriorly. Axial rings poorly defined externally, with as few as 5 being obvious. Internally however, the rings are clearly defined

with up to 13 being visible in addition to a short, rounded terminal piece. Pleural lobe with poorly defined, broad, slightly concave border which is widest posterolaterally. Pleural lobe covered by well developed, widely spaced terrace lines which are more or less concentric with the posterior margin, such that they intersect the lateral margins of the pygidium at about 60°. Adaxial portions of pleural field with between 3 and 6 ribs evident. Pleural furrows variably developed, the anterior two usually being fairly clearly defined, the remainder becoming less clear posteriorly. Doublure very broad, in ventral view the abaxial portion is convex, the adaxial portion concave. Adaxial margin generally straight, with a very deep notch concordant with the axial termination. Doublure covered by two, more or less concentric zones of evenly spaced terrace lines. The innermost (adaxial) zone is the narrower of the two and consists of terrace lines which are subparallel to the adaxial margin of the doublure. The outer (abaxial) zone is wider and consists of terrace lines which are approximately concentric with the posterior margin of the pygidium, such that they intersect the lateral pygidial margins at about 45°. Ontogeny. Smaller cranidia (Fig. 28E, G, J) of this species have more clearly impressed axial furrows and the angle between the anteriorly converging sections of the sutures are less strongly obtuse. The eyes are also relatively larger, giving rise to larger palpebral lobes. Smaller pygidia of this species are much more transverse, have a more clearly defined border and a relatively longer, less strongly tapering axis. One specimen seems to be a meraspid pygidium (Fig. 29E) which has not yet fully released the latest of its thoracic


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Fig. 31. Lonchodomas sp. A, CPC 34935, stereo pair, partial cranidium, from float in Ellery Creek, x3.0. B-C, CPC 34936, partly exfoliated cranidium, from float in Ellery Creek; B, enlargement, x6.5; C, stereo pair, x3.0; D, CPC 34937, stereo pair, cranidium, from float in Ellery Creek, x3.0.

segments. This specimen has perhaps the most clearly defined pygidial border. Remarks. This species is unusual for the genus in having a distinctly rounded quadrate pygidium. Parabasilicus vallorus Lu et al., 1976 has a pygidium which is more elongate with a much less obvious axis and a better defined pygidial border. Parabasilicus? lewisi (Kobayashi, 1940b) has a more rounded pygidium with a less well defined axis and lacking visible pleural furrows. Parabasilicus typicalis Kobayashi, 1934 has a narrower (tr.) pygidium, tending towards being subtriangular rather than subquadrate. Indeterminate Asaphidae sp. A (Fig. 30A) Material. One pygidium, CPC 34895 from Horn Valley Siltstone, Rodinga No. 6 at 70.31-70.32 metres depth. Remarks. This pygidium is well preserved with a long axis comprising about 12 rings with an elongate terminal piece, pleural lobes on which there are 7 ribs, a concave border of moderate width and a very short, flattened, posterior spine. In some respects this is similar to the pygidium of species of Ekeraspis, but the paucity of material makes comparisons difficult. Indeterminate Asaphidae sp. B (Fig. 30B-C) Material. One cranidium lacking palpebral lobes, CPC 34896; one partial hypostome, CPC 34897.

Both specimens are from the basal Stairway Sandstone from Rodinga No. 6 at 44.73-44.80 metres depth. Remarks. Both specimens are fairly poorly preserved in a medium grained, buff coloured sandstone and because of their association, are presumed to belong to the same species. The cranidium has a poorly defined glabella which appears to be strongly waisted about level with the palpebral lobes, both of which are missing. A glabellar node is located immediately in front of the weakly developed occipital furrow. The hypsotome is unusual in that it has a well defined middle body with very posteriorly located maculae and a broad, rounded notch in the posterior border. This species probably belongs to the Ptychopyginae, as interpreted above. Superfamily TRINUCLEOIDEA Swinnerton, 1915 Family RAPHIOPHORIDAE Angelin, 1854 Subfamily RAPHIOPHORINAE Angelin, 1854 Lonchodomas Angelin, 1854 Type species. Ampyx rostratus Sars, 1835. Lonchodomas sp. (Fig. 31) Material. Three partial cranidia, CPC 3493534937, all from float in Ellery Creek. Description. Cranidium subtriangular, moderately

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convex with very long frontal spine. Glabella strongly convex, elongate pentagonal, extending well beyond anterior extremity of fixigenae, but with maximum width occurring level with anterior extremity of fixigenae. Occipital furrow broad, deep. Occipital ring short (sag.), poorly defined laterally. Small, ovate muscle scars are visible on the internal mould, and are located a short distance in front of the occipital furrow. Fixigenae short (exsag.), wide (tr.), with broad posterior border furrow anteriorly bounding narrow posterior border and with anterior third covered by fine, obliquely angled terrace lines. Remarks. The relatively poor preservation of the few specimens available, coupled with the absence of a pygidium preclude detailed comparisons. Order PROETIDA Fortey & Owens, 1975 Superfamily BATHYUROIDEA Walcott, 1886 Family TELEPHINIDAE Marek, 1952 Carolinites Kobayashi, 1940 1950 Dimastocephalus Stubblefield 1957 Keidelia Harrington & Leanza Type species. Ptychoparia? tasmaniensis Etheridge, 1919; = Carolinites bulbosa Kobayashi, 1940; = Carolinites quadrata Kobayashi, 1940; = Carolinites genacinaca nevadensis Hintze, 1952. Remarks. For a brief history of the nomenclature of the type species, see Laurie (1997, p. 705). Carolinites genacinaca Ross, 1951 (Fig. 32) 1951 Carolinites genacinaca n. sp.; Ross, p. 84, pl. 18, figs 25-26, 28-36. 1952 Carolinites genacinaca Ross, 1951; Hintze, p. 145, pl. 20, figs 7-9. 1954 Carolinites genacinaca Ross, 1951; Kobayashi, pl. 6, fig. 3a-b. ?1964 Carolinites genacinaca Ross, 1951; Chugaeva et al., p. 44, pl. 1, figs 1-3.

AAP Memoir 32 (2006) 1968 Carolinites genacinaca Ross, 1951; Chugaeva, p. 109, pl. 7, figs 6-8. ?1973 Carolinites sp.; Dean, p. 300, pl. 3, figs 4, 12-13. ?1973 Carolinites genacinaca Ross, 1951; Chugaeva et al., p. 44, pl. 1, figs 5-6. 1975 Carolinites genacinaca genacinaca Ross, 1951; Fortey, p. 112, pl. 37, figs 1-15, pl. 38, figs 1-3. ?1975 Carolinites ichangensis sp. nov.; Lu, p. 100, pl. 2, figs 16-17. ?1977 Carolinites ichangensis Lu; Zhou et al., p. 187, pl. 55, figs 16-17. ?1978 Carolinites zunyiensis Yin sp. nov.; Yin & Li, p. 507, pl. 169, fig. 13. 1983 Carolinites bulbosus Kobayashi, 1940; Henderson, p. 146, figs 1a-h, k, 2a-d. 1984 Carolinites genacinaca Ross, 1951 (s.l.); Fortey & Shergold, p. 349, pl. 45, figs 7-10. ?1985 Carolinites genacinaca genacinaca Ross, 1951; Ingham et al., p. 488, fig. 4l. 1989 Carolinites genacinaca Ross, 1951 in part; Dean, p. 29, pl. 18, figs 2-3, 5-7, 10, pl. 19, figs 1-3 only, not figs 4-5, 7-8. 1994 Carolinites genacinaca Ross, 1951; Vaccari & Waisfeld, p. 82, pl. 1, figs 16-18, pl. 2, fig. 12. ?1997 Carolinites ?genacinaca Ross, 1951; Laurie, p. 707, fig. 6.4-6.5. 1999 Carolinites genacinaca Ross; McCormick & Fortey, fig. 3.1-3.6. 2002 Carolinites genacinaca Ross; McCormick & Fortey, text fig. 2O-R. 2002 Carolinites genacinaca Ross; Turvey & Zhou, pl. 1, fig. 2. 2004a Carolinites genacinaca Ross; Turvey & Zhou, fig. 6L. 2004b Carolinites genacinaca Ross; Turvey & Zhou, fig. 7L. Material. CPC 34911, 34914-34915 from 84/3031/2; CPC 34912 from 84/3081; CPC 34913 from 84/3080; CPC 34916, 34923 from 84/3085; CPC 34917 from 84/3030/4; CPC 34918, 34921 from 84/3072; CPC 34919 from 84/3030/3; CPC 34920 from 84/3031/3; CPC 34922 from

Fig. 32. Carolinites genacinaca Ross, 1951. A, D, CPC 34911, cranidium, from 84/3031/2, x8.0; A, stereo pair; D, anterior view. B, CPC 34913, stereo pair, cranidium, from 84/3080, x8.0. C, CPC 34915, cranidium, from 84/3031/2, x8.0. E, CPC 34917, stereo pair, cranidium, from 84/3030/4, x8.0. F, CPC 34921, partly exfoliated cranidium, from 84/3072, x8.0. G, CPC 34918, largely exfoliated cranidium, from 84/3072, x8.0. H, CPC 34912, stereo pair, cranidium, from 84/3081, x10.0. I, CPC 34916, stereo pair, small cranidium, from 84/3085, x16.0. J, CPC 34923, partial cranidium, from 84/3085, x8.0. K, CPC 34920, stereo pair, cranidium, from 84/3031/3, x8.0. L, CPC 34925, weathered cranidium, from float, Ellery Creek, x8.0. M, CPC 34922, stereo pair, librigena, showing most of genal spine, from 84/3031/1, x8.0. N, R, CPC 34919, librigena, from 84/3030/3, x8.0; N, normal view; R, lateral oblique view. O, CPC 34926, weathered librigena, from Hen 3, x8.0. P-Q, CPC 34914, librigena, from 84/3031/2; P, stereo pair, x8.0.; Q, lateral view, x16.0. S, CPC 34924, stereo pair, pygidium, from float, Ellery Creek, x10.0.


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84/3031/1; CPC 34924-34925 from float in Ellery Creek; CPC 34926 from Hen4. Diagnosis. Carolinites with fairly wide fixigenae, relatively large bacculae, long, curved, advanced genal spines; lacking well developed subocular band and lacking pygidial axial spine. Description. Small, strongly convex, smooth. Cranidium strongly convex, about 71% as long as wide, with maximum width at about midlength, usually across widest part (tr.) of palpebral lobes. Glabella rounded subquadrate, about 86% as wide as long, occupying about 91% of cranidial length, with maximum width usually across the occipital ring, but occasionally immediately in front of bacculae. Anterior margin of glabella ranging from broadly rounded to straight or with a slight indentation; anterolateral corners broadly rounded; lateral margins slightly convex in anterior part, with bacculae occupying variably developed concavities in posterior part immediately in front of the occipital furrow. Occipital furrow always well developed, deep and relatively narrow (sag., exsag.). S1 furrows occasionally developed as short, narrow transverse depressions immediately in front of occipital furrow, about level with midlength of bacculae, a short distance from axial furrow. S2 furrows occasionally developed as short, narrow, longitudinal depressions a short distance in front of bacculae, very near axial furrow. S3 furrows rarely developed as weak indentations in glabellar margin just behind anterolateral corners of glabella. Bacculae elongate (exsag.), subovate, clearly defined adaxially, usually poorly defined abaxially. Fixigenae relatively wide (tr.) for genus, subtriangular, laterally bounded between anterior border furrow and posterior boder furrow by long, narrow palpebral lobe. The adaxial edge of the palpebral furrow is defined along most of its length by a narrow (tr.), arcuate to sigmoidal ridge. Near its anterior extremity this ridge is interrupted in some specimens by the eye ridge, which is developed as an anterolaterally directed low ridge or shallow depression. Anterior border, narrow (sag., exsag.), roll-like, separated from remainder of cranidium by clearly defined, narrow border furrow. In anterior view, border is arcuate. Posterior border clearly defined, directed posterolaterally, separated from remainder of cranidium by well defined border furrows which are deepest abaxially. Librigena semicircular with a large reniform eye surmounting a low socle which is separated from the librigenal border by a deep furrow. Anteriorly the librigenal border is narrow and the border furrow deep and narrow. Laterally, the

AAP Memoir 32 (2006) border widens and becomes less clearly defined, while the border furrow becomes shallower and wider. Posteriorly the border narrows and the border furrow narrows and deepens. At the midlength of the lateral margin there arises a long arcuate genal spine which probably extended almost as far back as the pygidium. Hypostome and thorax unknown. Pygidium small, subquadrate to subpentagonal, about 70% as long as wide. Axis strongly convex, broad, sharply tapering, bounded by deep, broad axial furrow, occupying about 95% of pygidial length. Axial rings, three in number, well developed, with the anterior two separated from adjacent rings be deep ring furrows which are slightly shallower medially. Third axial ring separated from short, rounded terminal piece by weak ring furrow which is only clearly impressed laterally. Each axial ring is surmounted by a weakly developed rounded median tubercle. Pleural lobe strongly convex (tr.) so that abaxial portion is nearly vertical; posterior portion truncate and very steeply inclined to vertical. Pleural field with three ribs, each separated from the adjacent rib by a deep, broad pleural furrow, the posteriormost pair of ribs anteriorly bounding the near vertical portion of the pleural lobe. Remarks. In his original discussion of Carolinites genacinaca nevadensis, Hintze (1952, p. 146) noted that his subspecies differed from C. genacinaca genacinaca in having smaller bacculae, more posteriorly located and less strongly curved genal spine and a more deeply impressed marginal pygidial furrow. Fortey (1975, p. 116), in his seminal work on the species of Carolinites from Spitsbergen, distinguished C. g. nevadensis from C. g. genacinaca by its having more rounded anterolateral corners to the glabella, smaller bacculae, librigenae more variable in width, palpebral lobes narrowing more rapidly posteriorly and a less strongly curved and more narrowly based genal spine which arises further back on the librigena. However, Fortey considered the presence of a subocular band to be the “most diagnostic of all characters”. He also stated that the pygidium of C. g. nevadensis had only two axial rings clearly defined with the third separated from the terminal piece by an incomplete furrow and intimated that it lacked median tubercles on the pygidial axial rings. When Jell & Stait (1985b) redescribed the type species, C. tasmaniensis, and interpreted it as a senior subjective synonym of C. g. nevadensis Hintze, they agreed with Fortey’s (1975) analysis of the distinctions between C. g. genacinaca and C. tasmaniensis. The material illustrated by Jell & Stait (1985b) certainly does show most, if not


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Fig. 33. Prosopiscus tatei sp. nov. A, CPC 34927, stereo pair, cranidium, from Rodinga No. 6, 44.73-44.80 m, x4.0. B-C, CPC 34928, holotype cranidium, from Rodinga No. 6, 44.73-44.80 m, x4.0; B, latex replica of external mould; C, stereo pair, internal mould. D, CPC 34929, stereo pair, pygidium, from Rodinga No. 6, 44.73-44.80 m, x4.0.

all of the features mentioned by Fortey (1975) as characteristic of C. g. nevadensis. Fortey (1975) also maintained that there was a gradation in morphology between C. genacinaca and C. tasmaniensis, such that stratigraphically low C. genacinaca possessed a remnant of the subocular band and lacked the tubercles on the pygidial axial rings. The material constituting C. genacinaca from the Horn Valley Siltstone is uncommon except for low in the formation where, unfortunately, it is poorly preserved, having been dolomitised. Examination of available material from throughout the formation shows that no librigenae have a subocular band, and all have a long, curved genal spine, the base of which is fairly advanced. Pygidia all have two strongly developed axial ring furrows and a third which is either complete or only developed laterally. The larger the pygidium the greater the tendency to have the third ring furrow strongly developed. Most of the pygidia from low in the formation appear not to have tubercles on the axial rings, but whether this is simply a consequence of the poor preservation cannot be determined. Cranidia from the Horn Valley Siltstone all seem to have well developed, relatively large bacculae, but vary considerably in the shape of the glabella and consequently the roundness of the anterolateral corners. Dean (1989) described C. genacinaca and C. aff. tasmaniensis from western Canada based on only a couple of illustrated specimens from each of several localities. Based on current understanding of the differences between these two species, it is difficult to completely support Dean’s (1989) assignments. A librigena from the Outram Formation (loc. 92293), assigned to C. genacinaca by Dean (1989, p. 29, pl. 19, figs 7-8), has a well developed subocular band, but also has an anteriorly placed genal spine which,

contrarily, is relatively short and straight. In most respects it is like the librigenae of C. killaryensis utahensis as illustrated by Young (1973, pl. 1, fig. 23) and may belong to that subspecies. Unfortunately, Dean (1989) does not illustrate any pygidia from this horizon. However, a pygidium and two partial cranidia are illustrated from a lower horizon (92275), and assigned to C. aff. tasmaniensis (Dean 1989, pl. 18, figs. 4, 8-9, 1112). In discussing this pygidium, Dean (1989) largely confines his comments to the development of ring furrows, stating that the anterior two ring furrows are well developed while the third is only partially developed. In my opinion, the third ring of this specimen seems to bend backwards and amalgamate with the fourth ring to support the base of an axial spine. The presence of a spine on the pygidial axis excludes the specimens from C. tasmaniensis and indicates that an assignment to C. killaryensis utahensis or a closely related form is more likely. Order PHACOPIDA Salter, 1864 Suborder PHACOPINA Struve, 1959 Superfamily DALMANITOIDEA Vogdes, 1890 Family PROSOPISCIDAE Fortey & Shergold, 1984 Prosopiscus Salter, 1865 Type species. Prosopiscus mimus Salter, 1865. Prosopiscus tatei sp. nov. (Fig. 33) Etymology. After Professor Ralph Tate, Inaugural Professor of Natural Science, University of Adelaide, who described some of the collections obtained by the 1894 Horn Expedition to central Australia.

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Holotype. Cranidium, CPC 34928, from Rodinga No. 6, depth 44.73-44.80 m (Fig. 33B-C). Other Material. Paratype cranidium, CPC 34927; Paratype pygidium CPC 34929, both from the basal Stairway Sandstone, Rodinga No. 6, depth 44.73-44.80 m. Diagnosis. Prosopiscus with semiovate glabella, clearly defined eye ridges, narrow lateral cephalic border and four pygidial axial rings. Description. Cranidium approximately semicircular, strongly convex, about 45% as long (sag.) as wide, with maximum width near posterior margin. Glabella elongate, semiovate, 82% as wide as long, occupying about 86% of cranidial length (sag.), with maximum width across L1 glabellar lobes; width across subpentagonal anterior glabellar lobe approximately 70% maximum glabellar width. Axial furrow well developed except around anterior margin of glabella. Occipital furrow well developed, deepest laterally, middle third bowed forward and shallower than remainder. S1 furrows straight or slightly convex forwards, directed slightly posteriorly from axial furrow, near medial extremity curving sharply forwards for a short distance. S2 furrows straight, directed slightly posteriorly from axial furrow, parallel to S1 furrows. S3 furrows straight, diverging anteriorly from each other at about 110°, intersecting the axial furrow at the same point as the eye ridge. Inner extremities of S1 to S3 furrows on each side are connected to one another and the occipital furrow by weak longitudinal (exsag.) depressions. Fixigenae strongly convex (tr., exsag.), with genal field posterior to eye ridges evenly and finely pitted except for narrow strip adjacent to posterior border furrow. This strip has no pits, but is anteriorly bounded by a row of pits which seem more clearly defined than those over remainder of genal field. Eye ridges extend anterolaterally from axial furrow, widening abaxially; clearly defined, bounded anteriorly by broad, shallow furrow and posteriorly by deep, narrow furrow which distally is confluent with the border furrow. Area in front of eye ridges smooth, arched upwards (tr.) and is anteriorly bounded by a fairly broad, weakly defined roll-like border, the anterior margin of which is slightly convex or has a broad median indentation. Lateral border fairly narrow, rounded; border furrow developed as an abrupt change in slope, containing a line of pits similar in size to those on the remainder of the genal field. Posterior border defined by deep, narrow border furrow; border widens laterally to rounded genal angle. Hypostome and thorax unknown.

AAP Memoir 32 (2006) Pygidium about 51% as long as wide, strongly convex (tr.) such that lateral margins are nearly vertical. Axis fairly short, moderately convex (tr.), about 97% as wide as long, occupying about 65% of pygidial length, with three clearly defined rings and a fourth partly separated from the short, semicircular terminal piece by a ring furrow which is only defined laterally. Pleural fields each with four segments, each of which is separated from the adjacent by a long narrow interpleural furrow. Each segment is divided evenly by long narrow pleural furrow into anterior and posterior bands, of which only the anterior merges with the very narrow, slightly convex border. In all but the posteriormost segment, the posterior band is separated from the border by clearly defined furrows. Posteriorly, the border arches upwards, widens and becomes less clearly defined. Remarks. This species differs from both species recorded from the Nora Formation by Fortey & Shergold (1984) in having a semiovate rather than parallel-sided glabella and in having fewer pygidial axial rings on a much more strongly tapering pygidial axis. Prosopiscus tatei sp. nov. is perhaps most similar to P. mimus Salter, which was redescribed by Reed (1912) and reconstructed by Fortey & Shergold (1984), and to P. rugosus Lu (Lu & Chang, 1974) in that it similarly has an anteriorly tapering, rather than a parallel-sided glabella. However, these latter two species (which are probably synonymous) differ from P. tatei in that the lateral margins of their glabellae are not as strongly convex outwards, their S2 furrows are clearly not parallel to the S1 furrows, their S3 furrows are shorter and concave forwards and their lateral cephalic borders are wider. Prosopiscus aff. praecox Fortey & Shergold, 1984 (Fig. 34) Material. CPC 34930, 34933 from 84/3086; CPC 34931-34932 collected by R.S. Nicoll from small quarry, Wallera-Angas Downs Road. Description. Cranidium approximately semicircular, strongly convex, about 39% as long (sag.) as wide, with maximum width near posterior margin. Glabella elongate, parallelsided, about 84% as wide as long, occupying about 81% of cranidial length (sag.), with maximum width across either L1 or L3 glabellar lobes; width across ovate anterior glabellar lobe about 86% maximum glabellar width. Axial furrow well developed except around anterior margin of glabella. Occipital furrow well developed, deepest laterally, middle third bowed forward and usually shallower than remainder.


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Fig. 34. Prosopiscus aff. praecox Fortey & Shergold, 1984. A, CPC 34931, stereo pair, large cranidium, from small roadside quarry, Wallera-Angas Downs Road, x1.5. B-C, CPC 34933, distorted cranidium, from 84/3086; B, detail of fixigena, x6.0; C, stereo pair, x3.0; D, CPC 34932, stereo pair, partial cranidium, from small roadside quarry, Wallera-Angas Downs Road, x4.0. E, CPC 34930, stereo pair, small cranidium, from 84/3086, x8.0.

S1 furrows straight or slightly convex forwards, directed slightly posteriorly from axial furrow, near medial extremity, curving sharply forwards for a short distance. S2 furrows straight, directed slightly posteriorly from axial furrow, parallel to the distal portion of S1 furrows. S3 furrows slightly sinuate, diverging anteriorly from one another at about 120-130°, intersecting the axial furrow at about the same point as the eye ridge. Fixigenae strongly convex (tr., sag.), with genal field posterior to eye ridges evenly and finely pitted except for narrow strip adjacent to posterior border furrow. This strip has no pits, but is anteriorly bounded by a row of pits which seem more clearly defined than those over remainder of genal field. Eye ridges extend anterolaterally from axial furrow, widening abaxially. Ridges poorly defined externally, on internal moulds anteriorly bounded by broad, shallow furrow and posteriorly bounded by deep, narrow furrow which distally is confluent with the border furrow. Area in front of eye ridges smooth, arched upwards (tr.) and anteriorly bounded by a very weakly defined, rounded border. Lateral border fairly narrow, flattened, separated from genal field by a broad border furrow which contains numerous pits which are not aligned. Posterior border defined by narrow border furrow which externally is deepest about midway between axial furrow and genal angle; on internal moulds the furrow does not vary in development. Posterior border widens laterally to rounded genal angle. Hypostome, thorax and pygidium unknown. Remarks. These specimens are like those assigned

to P. praecox by Fortey & Shergold (1984) in most respects, but differ in having a broader lateral border and much less clearly defined eye ridges. They differ from P. sp. A of Fortey & Shergold (1984) in having finer pitting on the genal field, a narrower lateral cephalic border and an entire occipital furrow. The other known species of Prosopiscus in which the glabella is parallelsided include P. edgarensis Legg (1976), which is known only from two very small, poorly preserved cranidia; P. subparallelus Lu (in Lu & Chang, 1974) which is known from three cranidia (see also Lu 1975; Zhou et al. 1984); P. yinjiangensis Yin (in Yin & Li, 1978) which is known only from one very poorly preserved cranidium; and P. latus Lu (in Lu & Chang, 1974) which is known from one entire individual which is flattened and not particularly well preserved. Comparisons with P. edgarensis Legg are difficult because of the small size of the types of that species. The poor preservation of the single cranidium of P. yinjiangensis Yin and the flattening of the single specimen of P. latus make comparisons difficult. Prosopiscus subparallelus Lu is similar in general appearance, but seems to have a coarser pitting on the genal field, more clearly defined eye ridges, less oblique S3 glabellar furrows and a wider lateral cephalic borders. The species from the base of the overlying Stairway Sandstone, P. tatei sp. nov. (see above) is easily distinguished from P. aff. praecox by its semiovate glabella and more clearly defined eye ridges. The recently described P. lauriei Paterson, 2004, from the basal Tabita Formation of western New South Wales differs in having a much larger, subpentagonal, anterior


338

lithostratigraphic analyses; Messrs A.T. Wilson and H.M. Doyle for their assistance with photography. I also thank Drs A.T. Nielsen and D.K. Choi for their helpful and constructive reviews. REFERENCES

Fig. 35. ?Galbagnostus sp. CPC 34934, cephalon, from La51, x10.0; A, stereo pair; B, lateral view; C, anterior view.

glabellar lobe and much coarser pitting on the fixigenae. ?Class TRILOBITA Walch, 1771 Order AGNOSTIDA Salter, 1864 Suborder AGNOSTINA Salter, 1864 Superfamily AGNOSTOIDEA M‘Coy, 1849 Family METAGNOSTIDAE Jaekel, 1909 Galbagnostus Whittington, 1965 Type species. Agnostus galba Billings, 1865, p. 297-298, fig. 288. ?Galbagnostus sp. (Fig. 35) Material. CPC 34934, a cephalon, from LA51. Remarks. This species is very rare in the Horn Valley Siltstone, with only one relatively well preserved specimen having been found. It is tentatively assigned to Galbagnostus because of the anteriorly located glabellar node and similarity in cephalic shape and convexity to that of the type species of the genus, G. galba (Billings) (see Whittington 1965, p. 305). However, it differs from the type species in having a less quadrate acrolobe, a more prominent glabellar node and the F3 developed immediately anterior to the glabellar node. ACKNOWLEDGEMENTS I thank the late Dr J.H. Shergold for allowing access to photographs and replicas of the material described from the Horn Valley Siltstone by Tate and Etheridge; Dr R.S. Nicoll for many useful discussions on the conodont biostratigraphy of the unit; Dr A.T. Nielsen for many useful discussions on asaphid trilobites; Mr J.D. Gorter for his generosity with unpublished information; Ms R. Elphinstone for allowing access to her

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341 1579, 50 p. SALTER, J.W., 1849. Figures and descriptions illustrative of British organic remains. Memoir of the Geological Survey of the United Kingdom, Decade 2, 1-39. S ALTER , J.W., 1864. A monograph of the British trilobites. Palaeontographical Society Monograph, 1-80. S ALTER , J.W., 1865. A monograph of the British trilobites. Palaeontographical Society Monograph, 81-128. SARS, M., 1835. Über einige neue oder unvollständig bekannte Trilobiten. Isis (oder Encyclopedische Zeitung) 1835, 333-343. SHERGOLD, J.H., 1986. Review of the Cambrian and Ordovician palaeontology of the Amadeus Basin, central Australia. Bureau of Mineral Resources Geology and Geophysics, Report 276, 1-21. SHERGOLD, J.H., ELPHINSTONE, R., LAURIE, J.R., NICOLL, R.S., WALTER, M.R., YOUNG, G.C. & ZANG WENLONG, 1991. Late Proterozoic and Early Palaeozoic palaeontology and biostratigraphy of the Amadeus Basin. Bureau of Mineral Resources, Geology and Geophysics, Bulletin 236, 97-111. SHERGOLD, J.H., LAURIE, J.R. & NICOLL, R.S., 1995a. Biostratigraphy of the Prices Creek Group (Early Ordovician, late Lancefieldian-Bendigonian) on the Lennard Shelf, Canning Basin, Western Australia. 93-96 in Cooper, J.D., Droser, M.L. & Finney, S.C. (eds), Ordovician Odyssey: Short Papers for the Seventh International Symposium on the Ordovician System, Las Vegas, Nevada, USA. SEPM, Pacific Section. SHERGOLD, J.H., LAURIE, J.R. & NICOLL, R.S., 1995b. Correlation of selected late LancefieldianBendigonian (Early Ordovician) successions. 89-92 in Cooper, J.D., Droser, M.L. & Finney, S.C. (eds), Ordovician Odyssey: Short Papers for the Seventh International Symposium on the Ordovician System Las Vegas, Nevada, USA. SEPM, Pacific Section. SKWARKO, S.K., 1967. Some Ordovician graptolites from the Canning Basin. 1. On the structure of Didymograptus artus Elles & Wood. Bureau of Mineral Resources, Geology and Geophysics, Bulletin 92, 171-188. SPENCER, B., 1896. Report on the Work of the Horn Scientific Expedition to Central Australia. Melville, Mullen and Slade, Melbourne, Vol. 1, 220 p.; Vol. 2, 432 p.; Vol. 3, 204 p.; Vol. 4, 200 p. STAIT, K. & DRUCE, E.C., 1993. Conodonts from the Lower Ordovician Coolibah Formation, Georgina Basin, central Australia. BMR Journal of Australian Geology & Geophysics 13, 293-322. STRUVE, W., 1959. Suborder Phacopina, nov. 461-495 in Moore, R.C. (ed.), Treatise on Invertebrate Paleontology, Part O, Arthropoda 1. Geological Society of America, New York and University of Kansas Press, Lawrence. STUBBLEFIELD, C.J., 1950. A new komaspid trilobite

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AAP Memoir 32 (2006) B.A., THOMSON, M.R.A. & WEBERS, G.F., 1981. The Ordovician System in Australia, New Zealand and Antarctica. International Union of Geological Sciences Publication 6, 64 p. WELLS, A.T., FORMAN, D.J. & RANFORD, L.C., 1965. Geological reconnaissance of the north-western part of the Amadeus Basin, Northern Territory. Bureau of Mineral Resources, Geology and Geophysics, Report 85, 45 p. WELLS, A.T., R ANFORD , L.C. & C OOK , P.J., 1970. Geology of the Amadeus Basin, central Australia. Bureau of Mineral Resources, Geology and Geophysics, Bulletin 100, 222 p. WHITTINGTON, H.B., 1965. Trilobites of the Ordovician Table Head Formation, western Newfoundland. Bulletin of the Museum of Comparative Zoology 132, 275-442. W H I T T I N G T O N , H.B. & K E L LY , S.R.A., 1997. Morphological terms applied to Trilobita. 313-329 in Kaesler, R.L. (ed.), Treatise on Invertebrate Paleontology, Part O, Arthropoda 1: Trilobita, revised, Volume 1. Geological Society of America, Boulder and University of Kansas, Lawrence. WINNECKE, C., 1897. Journal of the Horn Scientific Expedition, 1894. C.E. Bristow, Adelaide, 86 p. YIN GONG-ZHENG & LI SHAN-JI, 1978. Trilobita. 385-594 in Handbook of Palaeontology of southwest China, Guizhou, Part 1. Geological Press, Beijing. YOUNG, G.E., 1973. An Ordovician (Arenigian) trilobite faunule of great diversity from the Ibex area, western Utah. Brigham Young University Geology Studies 20, 91-115. ZHEN YONG-YI & PERCIVAL, I.G., 2006. Late CambrianEarly Ordovician conodont faunas from the Koonenberry Belt of western New South Wales. Memoirs of the Association of Australasian Palaeontologists 32, 267-285. ZHEN YONG-YI, PERCIVAL, I.G. & WEBBY, B.D., 2003. Early Ordovician conodonts from far western New South Wales, Australia. Records of the Australian Museum 55, 169-220. ZHOU TIAN-MEI, LIU YI-REN, MENG XIAN-SONG & S UN Z HEN -H UA , 1977. Trilobita. 104-266 in Palaeontological atlas of central southern China, Volume 1. Geological Publishing House, Beijing. ZHOU ZHI-QIANG, LI JIN-SENG & QU XIN-GUO, 1982. Trilobita. 215-294 in Palaeontological Atlas of northwest China, Shaanxi-Gansu-Ningxia Volume 1. Geological Publishing House, Beijing. ZHOU ZHI-YI & DEAN, W.T., 1986. Ordovician trilobites from Chedao, Gansu Province, northwest China. Palaeontology 29, 743-786. ZHOU ZHI-YI & FORTEY, R.A., 1986. Ordovician trilobites from north and northeast China. Palaeontographica Abteilung A 192, 157-210. ZHOU ZHI-YI, YIN GONG-ZHENG & TRIPP, R.P., 1984. Trilobites from the Ordovician Shihtzupu Formation, Zunyi, Guizhou Province, China. Transactions of

AAP Memoir 32 (2006) the Royal Society of Edinburgh: Earth Sciences 75, 13-36. APPENDIX: DISTRIBUTION IN CORES Rodinga No. 6 44.73-44.82 m: Prosopiscus tatei 47.00-47.05 m: bivalves, brachiopods, gastropods 57.59-57.62 m: Lycophron howchini 64.81-64.84 m: Lycophron howchini? 65.41-65.45 m: Lycophron howchini? 65.70-65.71 m: Lycophron sp. 66.15-66.18 m: Rodingaia nielseni 66.20-66.24 m: Rodingaia nielseni 66.28-66.30 m: Rodingaia nielseni 66.54-66.55 m: Rodingaia nielseni, Lycophron howchini 66.89-66.90 m: Lycophron howchini?, Rodingaia nielseni, Carolinites genacinaca 66.98-67.01 m: Lycophron howchini 67.49-67.51 m: Rodingaia nielseni, Lycophron howchini 67.76-67.78 m: Rodingaia nielseni, Lycophron howchini 67.97-67.98 m: Lycophron sp. indet., Carolinites genacinaca, indet. asaphid 68.03-68.05 m: Rodingaia nielseni, Carolinites genacinaca, Lycophron howchini? 69.61-69.62 m: Lycophron sp. indet., Rodingaia nielseni 69.77-69.78 m: Lycophron howchini,, indet. asaphid 70.20-70.21 m: Lycophron howchini 70.31-70.32 m: indet. Asaphidae sp. A 70.68-70.70 m: Lycophron howchini, indet. asaphid. 70.83-70.85 m: Lycophron howchini, indet. asaphid 71.08-71.09 m: Lycophron howchini, Madiganaspis madigani?, Carolinites genacinaca 71.17-71.18 m: Carolinites genacinaca, Lycophron sp. indet., indet. asaphid 71.48-71.50 m: Lycophron howchini, indet. asaphid 72.05-72.07 m: Lycophron howchini?, indet. asaphid 72.64-72.66 m: Lycophron howchini, Madiganaspis sp. 73.47-73.49 m: Lycophron howchini? 74.04-74.06 m: Lycophron sp. indet., Carolinites genacinaca, indet. asaphid 74.11-74.13 m: Carolinites genacinaca, indet. asaphid 74.43-74.44 m: Lycophron howchini?, Carolinites genacinaca, indet. asaphid 74.74-74.75 m: Carolinites genacinaca, indet. asaphid 74.80-74.81 m: Carolinites genacinaca, indet. asaphid 75.15-75.16 m: Lycophron howchini 75.29-75.31 m: Lycophron howchini, Madiganaspis madigani? 76.37-76.39 m: Carolinites genacinaca 76.62-76.64 m: Lycophron sp.

343 77.77-77.79 m: Carolinites genacinaca, indet. asaphid 78.51-78.53 m: Carolinites genacinaca, indet. asaphid, plectambonitoidean brachiopod 81.31-81.33 m: indet. trilobites Henbury No. 4 69.90-69.93 m: Basilicus (Parabasilicus) winneckei 72.96-73.00 m: indet. trilobites 73.22-73.26 m: Carolinites genacinaca 73.37-73.40 m: Basilicus (Parabasilicus) winneckei 73.42-73.44 m: Carolinites genacinaca, Basilicus (Parabasilicus) winneckei 73.66-73.68 m: Basilicus (Parabasilicus) winneckei 74.26-74.28 m: Lycophron freemani? 75.35-75.39 m: indet. asaphid 76.30-76.32 m: indet. asaphid 77.14-77.16 m: Madiganaspis olifentensis 84.42-84.48 m: Madiganaspis olifentensis 84.73-84.74 m: Prosopiscus aff. praecox, Madiganaspis madigani?, Basilicus (Basiliella) illarensis? 90.12-90.16 m: indet plectambonitoidean brachiopods 90.71-90.73 m: Madiganaspis madigani, Carolinites sp. indet. 98.17-98.21 m: Lonchodomas sp., indet. agnostid, Lycophron sp. 98.39-98.43 m: Lycophron howchini 101.33-101.36 m: Carolinites sp. indet., indet. asaphid 101.56-101.60 m: Lycophron howchini Tempe Vale No. 1 367.45 m: lingulate brachiopod 369.30 m: lingulate brachiopod 373.65 m: lingulate brachiopod 381.10 m: orthoid brachiopod 384.65 m: ?orthoid brachiopod, ?strophomenoid brachiopod 386.05 m: strophomenoid brachiopod 393.74 m: orthoid brachiopod, Lycophron sp. 394.20 m: orthoid brachiopod, lingulate brachiopod 395.95 m: Basilicus (Parabasilicus) sp. 397.75 m: Basilicus (Parabasilicus) sp. 399.10 m: Basilicus (Parabasilicus) winneckei 399.80 m: Lycophron freemani, Basilicus (Parabasilicus) winneckei 401.10 m: Basilicus (Parabasilicus) winneckei 401.40 m: Lycophron sp. 402.40 m: Carolinites genacinaca, Madiganaspis olifentensis 403.00 m: Carolinites genacinaca, Basilicus (Parabasilicus) sp. 404.00 m: Basilicus (Parabasilicus) winneckei, Carolinites genacinaca, ostracods 404.65 m: Basilicus (Parabasilicus) sp., graptolite, ?Eisarkaspis sp. 406.05 m: Basilicus (Parabasilicus) winneckei

344 407.50 m: graptolite, indet. asaphid, Lycophron freemani 408.75 m: Madiganaspis olifentensis, ostracods 409.40 m: Lycophron sp., Madiganaspis olifentensis, Carolinites sp. 409.85 m: Eisarkaspis etheridgei, Lycophron freemani, ostracods 412.50 m: Eisarkaspis etheridgei, orthoid brachiopod Tent Hill No. 1 1145.87-1145.90 m: Eisarkaspis etheridgei, ostracods 1149.82-1149.85 m: Lycophron freemani, strophomenoid brachiopod 1151.08-1151.10 m: indet. asaphid, nautiloid 1152.05-1152.07 m: Basilicus (Parabasilicus) sp. Approx. 1155.15 m: Lycophron sp., strophomenoid brachiopod 1155.68-1155.73 m: Madiganaspis olifentensis, Lycophron sp., strophomenoid brachiopod Approx. 1157.00 m: Annamitella sp. 1157.32-1157.37 m: Lycophron sp., Madiganaspis olifentensis, ostracods 1157.80-1157.88 m: Lycophron sp., Madiganaspis sp. Approx. 1159.00 m: indet. asaphid 1160.13-1160.14 m: Madiganaspis olifentensis, graptolites 1160.40-1160.44 m: Lycophron sp., graptolites, ostracods 1160.87-1160.89 m: Madiganaspis olifentensis 1161.30-1161.32 m: ?Madiganaspis sp., indet. asaphid, strophomenoid brachiopod, ostracods 1161.62-1161.64 m: Lycophron sp. 1163.15-1163.17 m: Lycophron freemani, graptolites, ostracods 1163.55-1163.58 m: indet asaphid 1164.01-1164.03 m: Lycophron sp., indet. asaphid 1164.52-1164.54 m: Madiganapis olifentensis, Carolinites sp., ostracods 1164.80-1164.86 m: Lycophron freemani, Madiganaspis olifentensis, ostracods 1164.97-1164.99 m: Lycophron sp. ostracods 1165.85-1165.88 m: indet. asaphid, graptolites, ostracods 1166.50-1166.56 m: Madiganaspis ?olifentensis, graptolites, ostracods, lingulate brachiopods 1166.86-1166.89 m: Basilicus (Basiliella) illarensis, graptolites, ostracods 1167.11-1167.16 m: Madiganaspis ?madigani, graptolites 1168.83-1168.91 m: ?strophomenoid, Basilicus ( B a s i l i e l l a ) i l l a re n s i s , C a ro l i n i t e s s p . , raphiophoroid 1169.03-1169.07 m: Basilicus (Basiliella) illarensis 1169.20-1169.23 m: Lycophron sp., Basilicus (Basiliella) illarensis, indet. asaphid, graptolite 1169.27-1169.29 m: Basilicus (Basiliella) illarensis

AAP Memoir 32 (2006) 1171.93-1171.97 m: Basilicus (Basiliella) illarensis 1172.65-1172.67 m: Carolinites sp., Lycophron ?howchini 1173.22-1173.24 m: Basilicus (Basiliella) illarensis 1174.57-1174.60 m: Lycophron howchini Approx. 1175.00 m: Madiganaspis madigani Approx. 1175.15 m: Carolinites genacinaca, indet. asaphid 1175.25-1175.28 m: strophomenoid brachiopod, indet. asaphid, Lycophron howchini 1176.25-1176.27 m: Lycophron sp. 1177.54-1177.58 m: Madiganaspis madigani, Lycophron sp. 1177.83-1177.86 m: indet. asaphid, strophomenoid brachiopod 1177.90-1177.93 m: ?Madiganaspis sp. 1178.88-1178.92 m: ?Lycophron sp. 1180.05-1180.08 m: Lycophron sp., indet. asaphid Mt Winter No. 2A 193.50-193.55 m: orthoid brachiopods 193.90-193.95 m: ?orthoid brachiopods 197.95-197.97 m: ?Lycophron sp. 198.75-198.85 m: orthoid brachiopods, strophomenoid brachiopods 199.25-199.30 m: orthoid brachiopods, strophomenoid brachiopods 203.10 m: indet. asaphid 204.00 m: indet. asaphid 205.15 m: Basilicus (Parabasilicus) winneckei 206.20 m: indet. asaphid 206.30 m: indet. asaphid, ?Lycophron sp. 206.50 m: indet. asaphid 206.80 m: Madiganaspis sp., ostracods 206.95 m: ?orthoid brachiopod, ostracods, indet. asaphid 207.60 m: indet. trilobite 207.68 m: indet. asaphid 207.85 m: Carolinites sp., indet. asaphid 209.20 m: indet. asaphid 209.55 m: Lycophron ?freemani 209.78 m: Basilicus ?(Parabasilicus) sp. 209.85 m: Basilicus ?(Parabasilicus) sp., ostracods 210.22 m: Lycophron freemani 210.65 m: indet. asaphid 210.85 m: Basilicus ?(Parabasilicus) sp. 211.30 m: indet. asaphid 211.40 m: Lycophron sp. 211.70 m: Carolinites sp., Madiganaspis sp. 212.20 m: Basilicus ?(Parabasilicus) sp. 212.50 m: indet. asaphid, graptolites, ostracods 213.45 m: Carolinites sp., indet. asaphid, graptolites, ostracods 215.45 m: Carolinites sp., indet. asaphid, ostracods 215.60 m: Lycophron sp., Carolinites sp., indet. asaphid 215.65 m: Madiganaspis olifentensis, Carolinites sp. 215.70 m: Lycophron freemani, Madiganaspis

AAP Memoir 32 (2006) olifentensis 215.80 m: Lycophron freemani, Carolinites genacinaca, indet asaphid, ostracods 215.90 m: Carolinites genacinaca, Madiganaspis sp., Lycophron freemani 216.25 m: Lycophron ?freemani 216.30 m: Lycophron freemani 216.40 m: Madiganaspis sp. 216.50 m: Carolinites sp., Madiganaspis olifentensis, Lycophron sp. 216.65 m: Madiganaspis olifentensis, ?Carolinites sp., indet.asaphid 216.70 m: indet. asaphid 216.80 m: Lycophron freemani, indet. asaphid 217.15 m: Lycophron freemani, Basilicus (Parabasilicus) winneckei 217.45 m: Lycophron freemani, indet. asaphid 217.65 m: Carolinites genacinaca, ostracods 217.95 m: Lycophron freemani, Madiganaspis ?olifentensis, ostracods 218.05 m: Lycophron freemani, indet. asaphid, ostracods 218.50 m: Lycophron freemani, Madiganaspis olifentensis, graptolites

345 2 1 8 . 6 0 m : C a ro l i n i t e s s p . , M a d i g a n a s p i s ?olifentensis 219.25 m: indet. asaphid 220.14 m: Eisarkaspis ?etheridgei 221.25 m: Eisarkaspis etheridgei, Madiganaspis olifentensis, strophomenoid brachiopod 222.30 m: Lycophron freemani 224.00 m: indet. asaphid 224.30 m: indet. asaphid, ?orthoid brachiopod 224.55 m: indet. asaphid 225.35 m: indet. asaphid, strophomenoid brachiopod 227.30 m: indet. asaphid, ?orthoid brachiopod, strophomenoid brachiopod, ostracods 229.60 m: Basilicus (Basiliella) ?illarensis 230.00 m: ?Madiganaspis sp. 230.95 m: Madiganaspis madigani 231.00 m: Lycophron ?howchini 233.30 m: Lycophron sp., ostracods 237.85 m: Lycophron sp., indet. trilobite 238.15 m: orthoid, ?Madiganaspis sp. 242.00 m: indet. trilobite 243.50 m: indet. asaphid, strophomenoid brachiopod 244.05 m: strophomenoid brachiopod 255.40 m: lingulate brachiopods