upper ordovician conodonts from the bowan park ... - ScienceDirect

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lineage defined by the series Taoqupognathus phi- lipi - T blandus ...... qupognathus. Savage 1990. Epsilon. P? Delta. M? Sb? Alpha. ---. Gamma. ---. Beta. Zeta.

UPPER ORDOVICIAN CONODONTS F R O M THE BOWAN PARK S U C C E S S I O N , CENTRAI, NEW S O U T H WALES, A U S T R A I , I A YONG-YI ZHEN, BARRY D. WEBBY & CHRISTOPHERR. B A R N E S ZHEN Y.Y., WEBBY B.D. & BARNES C.R. 1999. Upper Ordovician conodonts from the Bowan Park succession, central New South Wales, Australia. [Les conodontes de l'Ordovicien supgrieur de la succession de Bowan Park, Nouvelle Galles du Sud, Australie]. GEOBIOS, 32, 1: 73-104. Villeurbanne, le 28.02.1999. Manuscrit d~pos6 le 31.10.1997; accept~ d~finitivement le 13.02.1998. ABSTRACT - Some 2379 conodont specimens have been recovered from 50 samples through the 560 m thick Bowan Park Group and the basal part of the Malachi's Hill Beds of Late Ordovician age, from the western side of the Molong high, in central New South Wales. These have been assigned to 32 species including three new species, Panderodus nodus nov. sp., Paroistodus? nowlani nov. sp. and Yaoxianognathus ani nov. sp., and a revised multielement apparatus of the species, Yaoxianognathus? tunguskaensis (MoSKALENKO).Two stratigraphically distinct conodont assemblages characterised by the first appearances of T blandus and T tumidus, respectively, are recognised. They are correlated with similar faunas in the mid-upper part of the Cliefden Caves Limestone Group and the lower Malongulli Formation of the eastern Molong High in central New South Wales. The Bowan Park fauna as a whole is dominated by Panderodus gracilis (BRANSON& MEHL),Yaoxianognathus ani nov. sp., Belodina confluens SWEET, Protopanderodus liripipus KENNEDY,BARNES& UYENOand Drepanoistodus suberectus (BRANSON& MEHL)(72% of total fauna), and shows a mixture of North American Midcontinent and North China affinities. However, influx of some species of North Atlantic Realm aspect mainly occurs in the T tumidus assemblage which, exhibiting a significant increase in diversity, is preserved in a relatively deeper water facies. KEYWORDS: CONODONTS,UPPER ORDOVICIAN,BIOSTRATIGRAPHY,BIOFACIES, NEW SOUTH WALES,AUSTRALIE. RI~SUMI~ - Environ 2379 conodontes ont ~t~ recueillis dans 50 ~chantillons pr~lev4s dans le Groupe de Bowan Park (560 m de puissance) et dans la pattie basale des couches de Malachi's Hill, h l'ouest des hauteurs de Molong, dans la partie centrale de la Nouvelle Galles du Sud. Dans ce matgriel d'fige ordovicien sup~rieur on distingue 32 espgces, dont trois nouvelles, Panderodus nodus nov. sp., Paroistodus? nowlani nov. sp., Yaoxianognathus ani nov. sp. et un appareil multi~ldments de Yaoxianognathus? tunguskaensis (MoSKALENKO)qui est r~vis~. Deux assemblages de conodontes, caract4ris~s respectivement par l'apparition de T. blandus et de T. tumidus, ont gt4 distingu~s. Ils sont mis en corr4lation avec une faune similaire provenant de la moiti4 sup~rieure du Groupe du Calcaire de Cliefden Caves et de la partie inf~rieure de la Formation de Malongulli, h l'est des hauteurs de Molong, dans la partie centrale de la Nouvelle Galles du Sud. La faune de Bowan Park, dans son ensemble, est domin~e par Panderodus gracilis (BRANSON • MEHL), Yaoxianognathus ani nov. sp., Belodina confluens SWEET,Protopanderodus liripipus KENNEDY, BARNES& UYENOet Drepanoistodus suberectus (BRANSON& MEHL)(72% de la faune totale). Elle montre un m~lange d'affinit~s nord-am~ricaines (Midcontinent) et nord-chinoises. Cependant, on note aussi l'influence de quelques esp~ces/t cachet nord-atlantique, surtout sensible dans l'assemblage h T. tumidus. Celui ci, provenant de facies assez profonds, montre un accroissement de diversitg significatif. MOTS-CLI~S: CONODONTES, ORDOVICIEN SUPI~RIEUR, BIOSTRATIGRAPHIE, BIOFACI]~S,NOUVELLE GALLES DU SUD, AUSTRALIE.

INTRODUCTION This p a p e r provides t h e first description of conodont f a u n a s from the B o w a n P a r k Group, from w h a t r e p r e s e n t s p r o b a b l y t h e t h i c k e s t (560 m thick), u n i n t e r r u p t e d , U p p e r Ordovician carbonate succession ( S e m e n i u k 1971, 1973a) p r e s e r v e d in c e n t r a l N e w S o u t h Wales (Fig. 1). The succession is n o w located on t h e w e s t e r n side of the Molong H i g h (Webby 1992). S a m p l i n g a n d processing of c o n o d o n t f a u n a s from carefully m e a s u r e d sections, at i n t e r v a l s of u p to 15 m a p a r t t h r o u g h o u t t h e e n t i r e succession, was carried out by

C.R. Barnes, B.D. W e b b y & I.G. Percival in t h e 1980s. S u p p l e m e n t a r y detailed s a m p l i n g (spaced from 0.5 to 1.5 m a p a r t ) of t h e h i g h e s t - y i e l d i n g p a r t of the sequence, t h e u p p e r m o s t c a l c a r e n i t e unit, t h e D o w n d e r r y L i m e s t o n e M e m b e r of t h e Ballingoole L i m e s t o n e , w a s u n d e r t a k e n b y Y.Y. Zhen a n d B.D. W e b b y d u r i n g 1996. A l t o g e t h e r 2379 conodont s p e c i m e n s h a v e b e e n r e c o v e r e d from t h e succession (Fig. 4), a n d t h e s e h a v e been a s s i g n e d h e r e i n to some 32 species (19 genera). The paper represents the third in a series of contributions on the U p p e r Ordovician conodont f a u n a l

74 FIGURE 1 - Locality and geological maps, a n d legend i l l u s t r a t i n g generalized stratigraphic sequence in the Bowan Park area. A, Map of eastern Australia showing location of central New South Wales. B, Map showing study area at Bowan Park. C, Outline geological map of Bowan P a r k area illustrating the m a i n stratigraphic subdivisions and the locations of the three m e a s u r e d sections in the Upper Ordovician succession at the Ranch, Quondong and Malachi's Hill (after S e m e n i u k 1973a). Carte g~ologique de localisation et [email protected] illustrant la succession stratigraphique de la r#gion de Bowan Park. ,4, carte de ['Anticline orientale s i t u a n t le centre de New South Wales. B, localisation de la rdgion d'dtude. C, schdma stratigraphic de la rdgion de Bowan Park et localisation des 3 coupes dtudi#es dans la succession ordovicienne.

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successions of central New South Wales. In particular, these aim to provide the basis for establishing a more complete biostratigraphic framework for Ordovician correlation, and to elucidate the pattern of biofacies distribution in this uniquely well preserved, offshore volcanic island shelf to carbonate platform complex. The earlier papers include Zhen & Webby (1995) which dealt with the conodont faunas of the Cliefden Caves Limestone Group, from a comparatively similar island shelf and carbonate succession, now geotectonically placed to the eastern side of the Molong High (Webby 1992), and Trotter & Webby (1994), that focused on faunas from the allochthonous, slope-derived, limes'tone breccia deposits of the overlying Malongulli Formation. The conodont-bearing clasts had been reworked from the outer margins of the platform to a basinal setting, where they had come to be associated in a graptolitic shale and siltstone succession. All these conodont assemblages accumulated in the vicinity of one or more offshore volcanic highs,

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either in habitats ranging from fringing island shelf though outer shelf to flanking the upper slope, or on an extensive carbonate platform. These sites lay in low latitudes, with near-shore assemblages occupying warm waters, and apparently the sites were well away from the continental margins of Gondwana. The conodont faunas provide the basis for establishing that all these mantling carbonates were laid down during Eastonian time, t h a t is, in E u r o p e a n terminology, mid-late Caradoc-earliest Ashgill, or North American parlance, "Trentonian" (now Chatfieldian, see Leslie & Bergstr~m 1995) - Maysvillian in age. The Bowan Park fauna as a whole is dominated by five species: Panderodus gracilis (25% of the total), Yaoxianognathus ani nov. sp. (19%), Belodina confluens (16%), Protopanderodus liripipus (7%) and Drepanoistodus suberectus (4.5%), making 72% of. the total fauna. Additionally, four species are represented as subdominants: Paroistodus? nowlani nov. sp. (3.5%), Y.? tunguskaensis

75 (2.7%), Protopanderodus insculptus (2.5%), and Taoqupognathus tumidus (2.4%). Overall, the nine species of dominants and subdominants comprise 83% of the total fauna. CONODONT DISTRIBUTION AND BIOFACIES

The Bowan Park Group is subdivided into three formations, the 250 m thick Daylesford Limestone subdivided by Semeniuk into six mappable members, succeeded by the distinctive, comparatively thin-bedded, fossiliferous, 34 m thick Quondong Limestone, and this unit, in turn, overlain by the relatively massively-bedded, 280 m thick Ballingoole Limestone (Semeniuk 1973a). Acidetched residues have been dissolved and processed from three sections representing the entire Bowan Park succession in the area, in the Ranch, Quondong and Malachi's Hill sections, respectively (Figs 1-2), with supplementary detailed sampling of the Downderry to basal Malachi's Hill QUONDONG

interval (MH numbers, see Fig.2) in the Malachi's Hill section. Average sample size was 5 kg (Samples producing less than 10 conodont specimens, as shown in Fig. 3, were leached with acetic acid solution for two weeks, and samples with higher yields were leached to completion). DAYLESFORD LIMESTONE The Daylesford Limestone is subdivided into six members, in ascending order, t h e Ranch, Bourimbla, Manooka, Gerybong, Glenrae and Davy's Plains limestone members, and best represented in the Ranch and lower p a r t of the Quondong sections (Fig. 2). The most productive conodont samples in the Daylesford Limestone are from the middle-upper part of the Ranch Member (up to 59 elements/sample), and from the topmost part of the Gerybong Limestone Member (up to 31 elements/sample). Ranch Member

Semeniuk (1973a) recorded a moderately diverse macrofauna of algae, corals, stromatoporoids, bryozoans, brachiopods, molluscs, trilobites and ostracodes from the Ranch Member. The thin-bedded marl and lithic mudstone and sandstone succession is up to 34 m thick, and rests disconformably on the underlying Cargo Volcanics. Thin localised beds of skeletal and lithoclastic grainstones and packstones also occur, and contain much of the better preserved faunas. The significant terrigenous influx testifies to a close association with an adjacent island. Nevertheless in this association, with its moderately diverse fauna (not the characteristic near-shore, "intertidal", lingulide biofacies, like that identified in the basal part of the Cliefden Caves succession - see Webby 1992; Zhen & Webby 1995) it is probably representing a mid-shelf rather than inner shelf habitat. The conodont assemblages (especially samples B7-1 and B7-2) support this interpretation because there are no characteristic representatives of the shallower Aphelognathus biofacies. Occurrences of Chirognathus? cliefdenensis, Phragmodus undatus and Spinodus sp. are indicative of a slightly deeper subtidal setting. Bonrimbla Limestone Member

FIGURE 2 - Measured stratigraphic sections in the Bowan Park Group (Daylesford, Quondong and Ballingoole formations) and basal Malachi's Hill Beds of the the Bowan Park area. Showing the horizons sampled for conodonts through the measured sections at the Ranch, Quondong and Malachi's Hill. Conodont data are presented in Fig. 3. Coupes mesurges dans le Group de Bowan Park indiquent la position des dchantillons gt conodonts. Les rdsultats sont prdsent~s dans la Fig. 3

The most distinctive feature of the skeletal wackestone and lime m u d s t o n e sequence of the Bourimbla Limestone Member is the in situ shell beds composed largely of the large inarticulate brachiopod Eodinobolus, and associated occurrences of cylindrical to branching stromatoporoid Alleynodictyon and coral Tetradium. The depositional environments suggested by these shell-bed occurrences were inferred by Webby & Percival (1983) to be localised between the inner shelf

76 FIGURE3 - Chart showing the distribution of Upper Ordovician conodont species in samples from the Ranch, Quondong and Malachi's Hill sections, Bowan Park area. Distribution des conodonts dans les gchantillons proviennent des 3 coupes ~tudi~es..

lagoon and the outer bar r i er rim of an offshore, low-relief, carbonate platform setting. Semeniuk (1973b) considered the Bourimbla environments to range from tidal to supratidal mud flats and shallow subtidal wackestones, with phases of subaerial emergence, emphasising again the restricted n a t u r e of these habitats. This explains why the conodont yields of two the Bourimbla samples are so poor, and the diversity is so low (Fig. 3).

Manooka, Gerybong, and Oakley l i m e s t o n e members The succeeding Manooka and Gerybong limestone memb er s are p r e d o m i n a n t l y burrowed lime mudstones, skeletal wackestones and more localised grainstones, with scattered, f r a g m e n t a r y biotas, the large dasycladacean alga I s c h a d i t e s characteristic of the Manooka, and the coral T e t r a d i u m an d a v a r i e t y of gastropods typical of t he

Gerybong. To the east, there is a lateral equivalent, the Oakley Limestone Member of Semeniuk (1973b), composed of skeletal and lithoclast grainstones and, locally, pellet and skeletal packstones, probably representing more active settings nearer to the barrier rim. Again the conodont samples have limited yields, though at one level (sample B7-14), close to the top of the Gerybong Limestone Member, a more diverse assemblage occurs with a total of seven species. This biofacies assemblage includes Aphelognathus webbyi and Y a o x i a n o g n a t h u s w r i g h t i suggesting a rather shallow, inner shelf or platform environment.

Glenrae and Davy's Plains limestone members The burrow mottled skeletal grainstones, wackestones and limestone mudstones of the Glenrae

77 BIOSTRATIGRAPHY LITHOSTRATIGRAPHY Bowan Park area :liefden Caves area CoraVstrom. Brachiopods Conodonts Fauna IV Malachi's Hill Angullong Tuff Beds _ o Do,,~na~,,-,' El_

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FIGURE 4 - Lithostratigraphic subdivisions, biostratigraphic correlations and age ranges of the Upper Ordovician successions in the Bowan Park and Cliefden Caves areas (western and eastern sides of the Molong High, respectively), central New South Wales. Note also the relationship between the conodont, brachiopod a n d coral/stromatoporoid f a u n a l schemes. Lithosstratigraphie, corrdlations biostratigraphiques et g~ges des successions de l'Ordovicien supdrieur des rdgions de Bowan Park, et Cliefden Caves. Noter les sdlections entre les schdrnas de [email protected] des eonodontes, des brachiopodes et des eoraux / stromatoporoides.

sented in the layered sequence of beds. Semeniuk (1973a) recognised that these biotas were mainly reworked into distinctive gravel-sized layers. The formation reflects a widespread deepening phase, with associated development of the richly fossiliferous, subtidal, level-bottom strophomenide biofacies, also recorded from a correlative thin-bedded unit in the Cargo Creek Limestone, to the south of Bowan Park (Webby & Semeniuk 1971), as well as from the Vandon Limestone (Zhen & Webby 1995) and upper part of the Regan's Limestone (McLean 1974) to the eastern side of the Molong High. Additionally, this particular transgressional event can be identified, with the same associated biofacies, in the Billabong Creek Limestone of the Parkes Platform (Webby & Morris 1976). This may have represented a separate, isolated, offshore carbonate platform occurrence. The conodont assemblages recovered from the Quondong Limestone have comparatively low yields and low diversities (yield of up to 32 elements/sample, and a maximum diversity of 10 species), possibly the result of limited sampling. Nevertheless, the presence of Phragmodus undatus and Drepanoistodus suberectus in sample B722 indicates a slightly deeper and oxygenated (Sweet 1988) platform phase, with some mixing of shallower biofacies suggested by the co-occurrences of Aphelognathus webbyi and Yaoxianogna-

thus wrighti. Limestone Member have not produced recognisable conodonts. The overlying Davy's Plains Limestone Member is dominantly composed of i n t e r b e d d e d lithoclastic, skeletal and pellet g r a i n s t o n e s and packstones, and S e m e n i u k (1973b) again has identified a number of breaks in the succession suggesting phases of subaerial emergence. The macrofaunas and macrofloras are quite diverse, with a range of algae, corals, stromatoporoids, bryozoans, brachiopods and a variety of molluscs (Semeniuk 1973a), but the sampling for conodonts has been far from productive, with only a few undiagnostic elements found in two samples. In terms of depositional environm e n t s it would seem t h a t the Davy's Plain Limestone Member occupied a comparatively active zone in very shallow (probably intertidal) waters towards the barrier rim.

The Ballingoole Limestone is composed of three members, the Corner, Clearview and Downderry limestone members that are best developed in the upper part of the Quondong section and through the Malachi's Hill section (Fig. 2). By far the most productive part of the succession in terms of conodont yield is the succession of beds extending from the topmost Clearview Limestone Member, through the Downderry Limestone Member up into the basal part of the Malachi's Hill Beds, specifically into the individual limestone clasts of the predominantly silty basal unit. Comparatively high yields, up to 263 and up to 271 elements/ sample, were obtained from the middle part of the Downderry succession and the limestone clasts in the breccias of the basal Malachi's Hill Beds, respectively.

QUONDONG LIMESTONE

Corner and Clearview limestone members

This thin-bedded succession has been subdivided by Semeniuk (1973a) into a lower, predominantly skeletal and lithoclast grainstone unit, and an uppor, marly lime mudstone and pellet packstone unit. It contains a most abundant and diverse macrofauna (Semeniuk 1970), with distinctive assemblages of corals, stromatoporoids, gastropods, brachiopods, bryozoans, echinoderms and algae repre-

The Corner Limestone Member is composed of mainly massive skeletal grainstones, and it is rather sparsely fossiliferous (mainly fragmentary helio]itine corals, molluscan and echinoderm debris, with some algae, most notably, occurrences of Vermiporella). Semeniuk (1973a) interpreted the member as having common erosional breaks, possibly reflecting phases of subaerial emergence,

BALLINGOOLE LIMESTONE

78 and this perhaps helps to explain the virtual absence of conodonts, with only an undiagnostic and extremely low diversity fauna. The succeeding Clearview Limestone Member is lithologically similar to the Corner Limestone Member, but there are important faunal differences: the occurrence of a streptelasmatid-like species referred to Palaeophylum? patulum by McLean & Webby (1976), the first appearances in the sequence of halysitine and favositid corals (Webby & Semeniuk 1969), as well as other corals and stromatoporoids (Semeniuk 1973a). Conodonts have a restricted occurrence, except in the topmost beds of the member, close to the contact with the overlying Downderry Limestone Member. The assemblage at this level (sample B47) has a comparatively high diversity (16 species) and a moderately high yield (102 elements/sample). The occurrences in this assemblage of a number of forms of North Atlantic Realm aspect, such as Periodon grandis, Protopanderodus insculptus, P. liripipus, Scabbardella sp. cf. S. altipes B, and Walliserodus amplissimus may be taken to imply the first indication in the Bowan Park succession of a biofacies characterizing cooler and deeper waters and heralding a major drowning event into the succeeding Downderry Limestone Member. D o w n d e r r y L i m e s t o n e Member This 10 m thick, thin-bedded, calcarenitic unit is mainly composed of fragmentary shelly material, especially trilobites, ostracodes, inarticulate brachiopods and echinoderms. The trilobite Illaenus (Parillaenus)? incertus is an especially common elemerit of the fauna (Webby 1973). Other trilobites are too fragmentary to determine to species level but include Remopleurides, an asaphid, a proetid, a trinucleid and an encrinurid. The close-spaced sampling of this unit demonstrates how varied is the conodont diversity and yield on a sample-by-sample basis (Figs 2,3). Samples with highest diversities and yields include MHll with a diversity of 17 species, and B4-10 and MH12 with yields of 231 elements/sample and 263 elements/sample, respectively. The dominant species of this conodont fauna are

Belodina confluens, Panderodus gracilis, Protopanderodus liripipus, and Yaoxianognathus ani. Less dominant are Drepanoistodus suberectus, Paroistodus? nowlani, Protopanderodus insculptus, Scabbardella sp. cf. S. altipes B, Taoqupognathus tumidus, Walliserodus amplissimus, and Yaoxianognathus? tunguskaensis. Additionally, there are important, though minor, components such as Phragmodus undatus and Periodon grandis. Overall, this represents a mixed assemblage of North Atlantic (Protopanderodus liripipus, P. insculptus, Scabbardella sp. cf. S. altipes B, Walli~

serodus amplissimus, Periodon grandis), North American Midcontinent (B. confluens, P. gracilis, Paroistodus? nowlani), and Chinese (with representation of species of Yaoxianognathus and Taoqupognathus ) affinities. Like the diverse fauna described from the approximately contemporaneous, reworked, spicule-rich, limestone clasts of the Malongulli Formation (Trotter & Webby 1994), the assemblages are dominated by an admixture of provincial elements reflecting derivation from deeper, cooler waters of North Atlantic aspect, and the warmer, shallower, more restricted waters of North American Midcontinent type. It seems, therefore, that these carbonate sands accumulated in comparatively open environmental conditions at the carbonate platform margin during the episode of major submergence of the platform. This was immediately prior to the commencement of a second major phase of Ordovician volcanic activity, represented by the large pile of volcanic products comprising the overlying Malachi's Hill Beds (Semeniuk 1971). MALACHI'S HILL BEDS The Malachi's Hill Beds have been described by Semeniuk (1971) as 350 m thick, and composed of a lower succession of volcanic-derived laminated siltstones (with graptolites in some layers) and sandstones, as well as some minor effusives, and an upper sequence of volcanic breccias and effusives, including, near the top, a bed with coral-bearing limestone clasts. In the measured sections on Malachi's Hill (Fig. 2), a sharp contact separates the calcarenites of the Downderry Limestone Member from an overlying 13 m thick, basal unit of the Malachi's Hill Beds, comprising a sequence of graptolitic, lithic siltstones and fine sandstones succeeded by breccias with limestone clasts and a thin limestone band. In addition to the conodonts, fossils from the clasts include radiolarians and sponge spicules, like the Malongulli clast associations (Trotter & Webby 1994). Of the nine samples processed from the Malachi's Hill limestone breccias, three have particularly rich and diverse assemblages. These are B4-12 (271 elements/sample, including 24 species), MH21A (132 elements/sample, including 19 species) and MH-23 (168 elements/sample, including 21 species). Though these represent the most diverse assemblages known from the Bowan Park area, they have rather similar compositions (and relative abundances) to those found in the underlying Downderry Limestone Member (Figs 2,3). Only 4 species (Ansella sp. A, Belodina sp. D, B. sp. E and Pseudobelodina sp.) are restricted to the basal Malachi's Hill breccias, out of a total of 25 species recorded. Consequently it seems likely that these clasts were mainly derived directly from the

79 underlying unit, possibly locally eroded from an adjoining area. Overall, the in situ assemblages from the Downderry Limestone Member and the reworked occurrences in the basal Malachi's Hill Beds have a composition that includes: (1) species such as Drepa-

noistodus suberectus, Protopanderodus liripipus and Periodon grandis that are widespread elements of the North Atlantic Realm, although other elements such as Dapsilodus mutatus and Amorphognathus ordovicicus are absent; (2) Walliserodus amplissimus and Scabbardella altipes that are prominent components of the Mediterranean Province of the North Atlantic Realm; and (3) some species of the North American Midcontinent Realm such as Belodina confluens, Panderodus gracilis and

Phragrnodus undatus. This p a t t e r n is closely matched by the faunas of the Malongulli Formation (Trotter & Webby 1994) except for the addition of the cosmopolite D. mutatus. The explanation of this difference is not entirely clear. Similar to most of the faunas in the Malongulli breccias, the Downderry/Malachi's Hill associations lack the shallow water Aphelognathus and Plectodina biofacies of the North American Midcontinent Realm, as well as the deepest water Amorphognathus biofacies of the North Atlantic Realm. This latter has only been recorded in an association with graptolites in Tasmania (Burrett et al. 1983). The changing p a t t e r n of biofacies at the top of the respective Bowan Park and Cliefden Caves carbonate successions seems to highlight a significant drowning of the offshore carbonate platform, and appears to be correlative on both sides of the Molong High. These biofacies patterns are r a t h e r more complex t h a n m a n y faunas elsewhere with more indication of a mixing of biofacies and realm components. This is likely due to the relatively small size of the carbonate platform bearing a domin a n t l y North American Midcontinent fauna, but affected by periods of drowning with incursions of North Atlantic Realm faunas, and a redistribution downslope in some of the breccia units. This Downderry-Malachi's Hill assemblage only has a limited degree of similarity to the counterparts in the intergradational biofacies of Sweet and Bergstr~m (1984), about equally close relationships to both the low-latitude North American Midcontinent, and the mid-high latitude North Atlantic provinces of the Late Ordovician. In addition, this low-latitude, east Australian assemblage has important endemic elements t h a t in part are shared with faunas in North China (e.g. Yaoxianognathus, Taoqupognathus). Nowlan et al. (1977) have recently proposed an Australasian Province based on these faunas.

CONODONT BIOSTRATIGRAPHY Previously, an evolving lineage derived from the Taoqupognathus philipi SAVAGE, 1990 to T blandus AN (in An et a]. 1985b) succession was proposed as a basis for recognition of the biostratigraphically distinct conodont assemblages of the Cliefden Caves Limestone Group (Zhen & Webby 1995). In addition, a third species, T tumidus TROTTER & WEBBY, 1994, occurring in the limestone breccias of the succeeding Malongulli Formation, was proposed, but because it came from allochthonous limestones, its stratigraphical context remained unclear. This latter species has now been precisely located in the autochthonous sequence at Bowan Park, from the top of the Clearview Limestone Member to the top of the Downderry Limestone Member, as well as in the allochthonous, basal p a r t of the overlying Malachi's Hill Beds (Figs 2, 4). This species forms the basis for the Taoqupognathus tumidus assemblage, defined in the Ballingoole Limestone (Bowan Park Group) by first occurrence of T tumidus in the Malachi's Hill section, from the top of the Clearview Limestone Member (topmost bed of unit - sample B4-7; see Figs 2, 3), to the last (in situ) occurrence towards the top of the Downderry Limestone Member (9.3m above the base - sample MH-15). The other important associated conodont is Yaoxianognathus ani with its first appearance at the same level (sample B4-7) in the Clearview Limestone Member to the last occurrence in sample MH-18, some 11 m above the base of the Downderry Limestone Member. Other associated conodonts that appear to be restricted to within this interval in the New South Wales Late Ordovician succession include Besselodus sp., Panderodus nodus, Paroistodus? nowlani,

Protopanderodus insculptus, P. liripipus, Scabbardella sp. cf. S. altipes B, and Spinodus sp. In terms of other fossils, the equivalent faunule or assemb]age is as follows: Coral/Stromatoporoid Fauna III (characterised by first appearances of Favistina, halysitines and favositids - see Webby 1975; Webby et al. 1981; Nicoll & Webby 1996); Brachiopod fauna D - see Percival (1992); Trilobite Illaenus (Parillaenus)? incertus faunule - see Webby (1974). At the present time it is not possible to formally establish zonal indices for the intervals characterised by the three successive species of Taoqupognathus, because precise details of their first and last appearances in the Cliefden Caves and Bowan Park successions remain to be elucidated. LOCAL CORRELATION WITHIN CENTRAL NEW SOUTH WALES Webby & Packham (1982, fig. 6) and Webby & Percival (1983, fig. 2) have previously based their

80 correlations of respective basal parts of the Bowan Park and Cliefden Caves limestone groups on the sharp lithological change from terrigenous to terrigenous-free carbonates in the respective successions. This represents the changeover from fringing volcanic island to terrigenous-free carbonate platform. Hence, the lowest part of the Bowan Park Group, with its dominantly terrigenous Ranch Member of the Daylesford Limestone, has been regarded as essentially coeval with the topmost part of the Fossil Hill Limestone (lower Cliefden Caves Limestone Group), i.e., with the lithic sandstone at the top of the Transmission Limestone Member, Fig. 4). Of the ten conodont species identified from the Ranch Member, one, Taoqupognathus blandus, is particularly useful for biostratigraphic work as it is a member of the T philipi - T blandus - T tumidus lineage. It was first reported in the Cliefden Caves succession some 105 m above the base of the Belubula Limestone (Fig. 4), while the underlying T philipi makes its last appearance near the top of the Dunhill Bluff Limestone Member of the underlying Fossil Hill Limestone (Zhen & Webby 1995). Thus, the Ranch Member is either younger than the Dunhill Bluff Limestone Member, i.e., within the overlying Transmission Limestone Member, or correlates to a higher stratigraphic level, within the lower Belubula Limestone. This adds support to the previously suggested lithological correlation of the Ranch Member with the uppermost lithic part of the Transmission Limestone Member. The earliest assemblage with T philipi and some species of Aphelognathus (e.g., A. packhami, A. percivali) in the lower-middle parts of the Fossil Hill Limestone at Cliefden Caves (Zhen & Webby 1995) has not yet been recorded from other places in New South Wales or elsewhere. The conodonts recovered from the upper part of the Daylesford Limestone and the Quondong Limestone are not particularly age diagnostic, except for occurrences of Aphelognathus webbyi and Yaoxianognathus wrighti which do not have ranges extending upwards into the overlying Taoqupognathus tumidus assemblage. The Quondong Limestone has long been correlated with the Vandon Limestone towards the top of Cliefden Caves Limestone Group, the thinly-bedded unit in the lower Cargo Creek Limestone, and with the Billabong Creek Limestone of the Parkes Platform (Zhen & Webby 1995). Significantly, Taoqupognathus blandus and A. webbyi have also been recovered from the Billabong Creek Limestone. This widely recognised level is depicted as part of a significant transgressional event (Webby & Packham 1988), a comparatively shortlived period of sea level rise across the entire com-

plex of offshore, Late Ordovician, carbonate platforms in central New South Wales. The Taoqupognathus tumidus assemblage in the Malachi's Hill section comprises up to 29 species of conodonts. These are closely correlated with the fauna previously described by Trotter & Webby (1994) from limestone clasts in the lower part of the Malongulli Formation. It seems likely that the drowning of the carbonate platform in the Bowan Park area and the establishment ofbasinal depositional conditions in the Cliefden Caves area with periodic slumps (and inclusion of limestone clasts) in the lower part of the Malongulli Formation were related, possibly synchronous, events. CORRELATION WITH THE ORDOS BASIN OF NORTH CHINA The New South Wales assemblages, particularly those at the levels of the Taoqupognathus blandus and T tumidus lineages, show close faunal links with equivalent parts of the Late Ordovician succession of North China, particularly from the Taoqupo and Beignoshan formations in the Ordos Basin of Shaanxi Province (An et al. 1985b; An & Zheng 1990). More than a dozen taxa have been recorded in common with these equivalent Chinese units, for example: Belodina confluens, B. baiyan-

huaensis, Panderodus gracilis, P. nodus, Phragmodus undatus, Protopanderodus insculptus, P. liripipus, T blandus, T tumidus?, T yaoxianensis?, Yaoxianognathus? tunguskaensis and Y. wrighti?. At Taoqupo Village, 10 km NW of the Yaoxian County Town, the type section of the Yaoxian Formation consists of a 15-m thick succession of thick-bedded limestones overlain by about 300 m of thin-bedded limestones and shales of the Taoqupo Formation. T blandus is recorded by An et al. (1985b) as first appearing towards the top of the Yaoxian Formation, and ranges up to within 70 m of the top of the Taoqupo Formation. This compares with the range of T blandus in New South Wales, from lower to middle parts of the Bowan Park Group (or equivalents), that is, from the Ranch Member and equivalents of the Quondong Limestone (the latter based on the records from other localities). In China, the type species of Yaoxianognathus, Y. yaoxianensis is associated with T blandus in the lower to middle parts of the Taoqupo Formation, but this species has not been recovered from the equivalent New South Wales succession. It is less easy to establish precise correlations with North China at lower stratigraphic levels. The Yaoxian Formation is characterised by various species of Tasmanognathus, but this taxon is not well represented in central New South Wales with only one element identified and left in open nomenclature (Zhen & Webby 1995). It mainly occurs

81 through the Wyoming to DunhiU Bluff limestone members of the Fossil Hill Limestone. Another species, described as Yaoxianognathus sp. A, from the middle and upper parts of the Yaoxian Formation shows a close resemblance to the common Y. wrighti of the Fossil Hill Limestone, but this latter species, though not abundant, has an extended upward range in the Bowan Park area, into the middle part of the Bowan Park Group (Quondong Limestone; see Fig. 4). Correlation problems also exist at higher stratigraphic levels. The upper part of the Taoqupo Formation does not have confirmed conodont ties with the New South Wales Taoqupognathus tumidus assemblage, but the species described by Yu & Wang (1986) as T. beiguoshanensis from the Beiguoshan Formation in the Longxian region, also in Shaanxi Province bears close resemblances (Zhen & Webby 1995, p. 287).

T. blandus has also been recorded from the Sanjushan Formation in Jiangxi Province (An 1987), and T tumidus from Hongze Formation in northern J i a n g s u Province (Duan 1990) of sout h e a s t China. CORRELATION WITH THE NORTH AMERICAN MIDCONTINENT Zhen & Webby (1995) have previously outlined the best possible correlation with the North American Midcontinent comparing the ranges of common occurrences and the cited composite standard section (CSS) values of Sweet (1984). Though there were m a n y individual differences between the patterns of North American and New South Wales occurrences, especially the apparently very different ranges (and abundances) of the key North American Midcontinent species such as Belodina confluens, Panderodus gracilis, and Phragmodus undatus, an overall consensus was reached, namely, t h a t the three biostratigraphically distinct New South Wales levels extended through an interval, equating with the succession of three or four North American Midcontinent zones, from the Phragmodus undatus, or Plectodina tenuis, through Belodina confluens, to the lower Oulodus velicupsis zones, inclusive. But there is limited precision in establishing this correlation due to a number of factors. First, that P. undatus, though a key zonal index in the North American Midcontinent, has a wider range in deeper biofacies outside the North American Midcontinent, and is found in all three levels of the central New South Wales succession. The earliest New South Wales assemblage, based on the first known species in the Taoqupognathus lineage, T. phillipi, may be better correlated with the Plectodina tenuis Zone, given the common occurrences of P.: tenuis and a number of other species (Zhen & Webby 1995).

Secondly, Belodina confluens is overwhelmingly abundant in all the biostratigraphically distinct assemblages of the New South Wales succession, so it cannot be used as a zonal species. From its broad temporal distribution, it is clear t h a t its first appearance on the North American Midcontinent is later than in many other parts of the world. A number of closely related forms have, over the past fifteen years or so, been given separate status, but our present taxonomic studies demonstrate that a wide range of variability exists in the species, for example, in the number of denticles on the posterior margin and carina, as well as in the nature of grooves formed on lateral faces. It is therefore suggested that mostly these closely related species be placed in synonomy, either assigned to B. confluens, or to B. baiyanhuaensis. Thirdly, the common North American genus Oulodus has not been recognised in the New South Wales faunas. Some elements of Chirognathus? cliefdenensis show some resemblances to counterparts in the Oulodus apparatus but this does not establish the presence of the genus, again making direct application of the scheme of North American Midcontinent zones difficult to apply in New South Wales. However, the recognition of occurrences of species of Yaoxianognathus in North America m a y allow better links to be established. R.L. Ethington (pers. comm. 1996) has indicated t h a t Yaoxianognathus is a common, through not dominant, constitutent of North American platform faunas. Significantly, Ozarkodina sesquipedalis NOWL~'~& MCCRACKEN (in Nowlan et al. 1988) is recognised herein as a species of Yaoxianognathus. It seems allied to Y. ani, but first appears at a slightly higher s t r a t i g r a p h i c a l level in the North American succession t h a n t h a t of the youngest New South Wales Late Ordovician assemblage described herein. CONCLUDING REMARKS It was previously recognised t h a t the evolving lineage defined by the series Taoqupognathus philipi - T blandus - T tumidus represented biostratigraphically significant changes in the Taoqupognathus apparatus, the changes coinciding with the interval from early to late Eastonian time (Zhen & Webby 1995). In terms of British regional series nomenclature (Webby 1998) this equals the mid Caradoc to earliest Ashgill interval. The present work establishes these relationships more precisely, especially based on the record of in situ deposits containing T. tumidus, i.e., m a i n l y through the Downderry Limestone Member and basal Malachi's Hill Beds in the upper part of the Bowan Park succession.

82 The New South Wales and North China successions may be correlated using, in particular, the Taoqupognathus lineage with its three distinct species as the biostratigraphically based indicators. The oldest species, T philipi, characterises the first assemblage in this New South Wales succession and occurs in the Fossil Hill Limestone at Cliefden Caves, but cannot be used directly for precise cotrelation with North China. Instead, a few associated species of Tasmanognathus, and Yaoxianognathus (E. wrighti) can be used indirectly, and seem to suggest a correlation with the lower to middle Yaoxian Formation. T blandus is the key index species of the second assemblage and is represented in the Daylesford and Quondong limestones of the Bowan Park Group, and the upper Belubula to Vandon limestones of the Cliefden Caves Limestone Group. In North China, it occurs in the topmost Yaoxian Formation, and the succeeding lower-middle Taoqupo Formation. The youngest species, T tumidus, identifies the third New South Wales assemblage and is present in the upper part of the Ballingoole Formation and basal Malachi's Hill Beds at Bowan Park. A species closely resembling T tumidus occurs in associations within the Beiguoshan Formation of North China. SYSTEMATIC D E S C R I P T I O N S

All photographic illustrations shown in Figures 510,14,15 are SEM photomicrographs. Figured specimens bearing the prefix CPC are deposited in the Commonwealth Palaeontological Collection of the Australian Geological Survey Organisation (AGSO), Canberra. Except for two illustrated specimens (CPC 34531 and CPC 34537, pl. 7, Figs 10, 16) which are from the Billabong Creek Limestone, Billabong (or Goobang) Creek, 22 km west of Parks (Grid reference: 907268-910271; Bogan Gate 1:50,000 topographic map 8431-I & IV, first edition, 1981), central New South Wales, all the other figured specimens are from the Bowan Park Group and basal Malachi's Hill Beds. Details of the localities and measured sections of the Bowan Park successions are summarised in Figures 1, 2 (also see Cudal 1:50,000 topographic map 8631-II & III for details of the localities).

Genus Ansella FAHRAEUS& HUNTER,1985 T y p e - s p e c i e s - Belodellaflmtlandica LOFGREN, 1978.

Ansella sp. A Fig. 5.1-3 1994 Ansella sp. TROTTER & WEBBY,p. 481, pl. 1, figs 1-5; pl. 2, figs 5, 6; ?pl. 5, fig. 32. R e m a r k s - Two morphotypes are recognised among the present four specimens from the limestone breccias near the base of the Malachi's Hill Beds. They are both thin, blade-like denticulated elements, one symmetrical and the other asymmetrical. The symmetrical element is straight, with a t h i n keel on each lateral face along the latero-anterior margin. The asymmetrical element is curved with a keel on the concave inner lateral face along the latero-anterior margin.

Ansella sp. B Figs 5.4-6 1995

Serraculodus? sp. ZHEN & WEBBY,p. 286, pl. 5, partim, only fig. 2.

R e m a r k s -The two specimens, one from the top of the Gerybong Limestone Member and the other from the Downderry Limestone Member, are straight, symmetrical, undenticulated and conical. They are ornamented with coarse striation on the surface with a broad carina on each lateral face, and sharp anterior and posterior margins. Two specimens previously referred to Serraculodus? sp. (one illustrated, Zhen & Webby 1995, pl. 5, fig. 2) are conspecific. They are from the middle part of the Belubuta Limestone of the Cliefden Caves Limestone Group, and stratigraphically correlative with the Gerybong specimen. Genus

Aphelo~nathus

BRANSON, MEHL B~RANSON, 1 9 5 1

T y p e - s p e c i e s - Aphelognathus grandis BRANSON, MEHL & BRANSON, 1951.

Aphelognathus webbyi

SAVAGE,

1990

Figs 5.10,11 1990 Aphelognathus webbyi SAVAGE,p. 824, fig. 4.1-4.12.

1990 Aphelognathus stevensi SAVAGE,p. 825, fig. 5.1-5.8. 1995 Aphelognathus webbyi SAVAGE:Zhen & Webby, p. 278, 279, pl. 1, figs 9-12. R e m a r k s - This species is rare in the Bowan P a r k Group, and only occurs in the middle p a r t of the group. Only the Pa elem e n t has been recovered. In the type locality of the Cliefden Caves area, it is a b u n d a n t in the Fossil Hill Limestone, and diagnostic of the shallower, near-shore biofacies. It also occurs rarely in the Vandon Limestone (Zhen &Webby 1995).

Genus Belodina ETHINGTON, 1959 T y p e - s p e c i e s - Belodus compressus BRANSON & MEHL, 1933.

Phylum CONODONTAPander, 1856 Class CONODONTAPander, 1856

Belodina confluens SWEET, 1979 Figs 5.7-9

FIGURE 5 - 1-3. Ansella sp. A. 1, asymmetrical element, CPC 34423 (MH-2]A), x 140.2, asymmetrical element, CPC 34424 (MH21A), x 140.3, symmetrical element, CPC 34425 (MH-21A), x 105.4-6. Ansella sp. B. CPC 34426 (B7-14); 4, x 400; 5, x 190; 6, x 155.7-9. Belodina confluens SWEET. 7, compressiform, CPC 34427 (B7-2), x 75.8, grandiform, CPC 34428 (B4-12), x 45.9, eobelodiniform, CPC 34429 (MH-12), x 95.10,11.Aphelognathus webbyi SAVAGE,Pa elements. 10, CPC 34430 (B7-22), x 60.11, CPC 34431 (B7-22), x 85.12-14. Belodina baiyanhuaensis QIu. 12, eobelodiniform, CPC 34432 (B7-22), x 80.13, grandiform, CPC 34433 (B47), x 110. 14, compressiform, CPC 34434 (MH-21A), x 115. 15. Belodina sp. D TROTTER • TERRY, compressiform, CPC 34435 (B412), x 55.16. Belodina sp. E TROTTER& WEBBY,compressiform, CPC 34436 (MH-21A), x 85.17,18. Belodina sp. G TROTTER & TERRY, grandiniform?. 17: CPC 34437 (B4-12), x 105.18: CPC 34438 (B4-12), x 85.

83

84 ? 19'90 Belodina hongzeensis DUAN, p. 31, pl. 4, figs 4-8, text-fg. 3. 1990 Belodina confluens SWEET: An & Zheng, pl. 10, fig. 13. 1993 Belodina stonei SWEET: Fu et al., p. 78, pl. 2, fig. 17. ? 1993 Belodina hongzeensis DUAN: Ding et al., in Wang, p. 165, pl. 38, figs 13-15. 1995 Belodina confluens SWEET:Zhen & Webby, p. 279, pl. 1, figs 16-18 (cure syn.). - Some of our specimens are comparable with the type material of Belodina hongzeensis DUAN from the Upper Ordovician (Hongze Formation) of northern Jiangsu Province, SE China, which is characterised by four denticles in compressiform and grandiform elements. It seems t h a t B. hongzeensis is intermediate between B. baiyanhuaensis QIu with 1-3 denticles and the typical B. confluens. In the original description (Duan 1990), B. hongzeensis was differentiated from B. confluens and B. cornpressa by its smaller heel in the eobelodiniform element, denticles nearly normal to the posterior margin, and outwardly curved cusp tip. All these features are shown in our material referred to B. confluens. However the type material of the compressiform element orB. hongzeensis has a shorter cusp, which is nearly erect at its half length and then curves sharply posteriorly. Our specimens show a smooth, and gentle curvature of the cusp, but specimens referred to as B. confluens? from Trilobite Hill (Zhen & Webby 1995, pl. 1, fig. 19) and as B. confluens from the Malongulli Formation (Trotter & Webby 1994, pl. 2, figs 18-20, 24, 25) are identical to B. hongzeensis. Therefore, B. hongzeensis is tentatively regarded as conspecific with B. confluens. The compressiform elements of B. hongzeensis also resemble the corresponding element of stratigraphically slightly older B. monitorensis ETHINGTON8~ SCHUMACHER,1969, but the grandiform element of the latter has a prominent antero-lateral costa on each side of the anterior margin. Remarks

Belodina [email protected] QIu in Lin, Qiu & Xu, 1984 Figs 5.12-14 ? 1978 Belodina sp. D PALMIERI,p. 15, pl. 3, figs 16, 17. 1984 Belodina baiyanhuaensis Qm in Lin, Qiu & Xu, p. 101, pl.2, figs 6-8. 1984 Belodina longxianensis WANG &LUO, p. 254, pl. 7, figs 17-20. ? 1984 Belodina heiyingsiensis WANG & LUO, p. 254, pl. 7, fig. 21. ? 1984 Eobelodina occidentalis ETHINaTON & SCHUMAC~E~: Wang & LuG, p. 259, partita, only pl. 7, figs 12, 14. 1990 Belodina hillae SAVAGE,p. 829, fig. 10.1-10.6. 1990 Culumbodina longxianensis (WANG & LUG): An & Zheng, pl. 7, fig.9. 1990 Belodina [email protected] QIu: An & Zheng, pl. 10, figs 12, 14. 1994 Belodina confluens? SWEET: Trotter & Webby, partim; only pl. 2, fig. 7. 1994 Belodina sp. C TROTTER & WEBBY,partita; only pl. 2, fig. 15. 1995 Belodina hillae SAVAGE:Zhen & Webby, p. 280, pl. 1, figs 22-24. 1995 Belodina Sp cf. B. hillae SAVAGE:Zhen & Webby, p. 280, pl:2;:~lg~ 1-4.

- The type material of B. baiyanhuaensis from Inner Mongolia seems identical to B. hilIae SAVAGEexcept t h a t the compressiform element of B. hillae has the cusp more sharply curved posteriorly. The specimens also referred to B. baiyanhuaensis by An & Zheng (1990) from the same locality are close to B. sp. cf. B. hillae from Cliefden Caves (Zhen & Webby 1995), except t h a t the grandiform element of the former has a single, more prominent, denticle. Therefore, B. baiyanhuaensis becomes the senior synonym of B. hillae. Qiu (in Lin et al. 1984) invalidly designated two illustrated specimens as holotype, one eobelodiniform (Pl. 2, fig. 7) and the other grandiform (P1.2, fig. 8), and a same specimen number (Bail0-8) was also given to these two specimens. The figured grandiform element of B. baiyanhuaensis (Lin et al. 1984; pl. 2, fig. 8) is most diagnostic of the species, and is here redesignated as lectotype carrying the specimen number Bail0-8. The illustrated eobelodiniform element (Qiu in Lin et al. 1984; pl. 2, fig. 7) is here assigned as paralectotype, however a new registration nmnber should be allocated to this specimen. Only compressiform and grandiform elements were originally assigned to B. longxianensis WANG & LUG. Both elements of the species typically bear two denticles. So the species is morphologically very close to B. baiyanhuaensis and B. hillae. Similar specimens are common in the Cliefden Caves Limestone Group, and were previously referred to B. hillae (Zhen & Webby 1995). Additionally, eobelodiniform elements occur in the same sample (Lip-2) as the type material ofB. longxianensis, and were originally described as Eobelodina occidentalis ETHINGTON & SCHUMACHER,1969 (Wang & LuG 1984). E. occidentalis is now regarded as belonging to the eobelodiniform element of the B. monitorensis apparatus (Sweet in Ziegler 1981). This material from the Longmendong Formation of Shaanxi Province, North China, seems identical to the type material ofB. baiyanhuaensis and the eobelodiniform elements from the Cliefden Caves Limestone Group and Bowan Park Group now referred to B. baiyanhuaensis. However, the broad carina on the grandiform and compressiform elements of B. longxianensis is seen only in a few specimens now referred in New South Wales (e.g., Savage 1990, Fig. 10-5, 6) to B. baiyanhuaensis. Also, B. longxianensis has a slightly weaker development of denticles. This latter character however, based on the material of B. baiyanhuaensis from central New South Wales, is rather variable. Nevertheless, B. longxianensis may, when further elucidated, prove to be conspecific with B. baiyanhuaensis. B. sp. cf. B. hillae (Zhen & Webby 1995) with few denticles, and the grandiform element of B. hillae with the most abundant denticles as illustrated by Savage (1990, fig. 10.5, 6) may represent the end members within the species continuity of B. baiyanhuaensis. B. heiyingsiensis WAN~ &LUO, also present in the Longmendong Formation of Shaanxi, has been inadequately described and illustrated. The only specimen illustrated was a grandiform element which is identical to B. longxianensis except for a broad carina on each lateral face of the former. B. heiyingsiensis is regarded as a junior synonym of B. longxianensis, since this similar feature is also shown in the grandiform element of the latter (Wang & LuG 1984, pl. 7, figs 17, 18). Therefore, B. heiyingsiensis is also tentatively regarded here as a junior synonym ofB. baiyanhuaensis. Remarks

B e l o d i n a sp. D TROTTER & WEBBY, 1 9 9 4 Fig. 5.15 1994 Belodina sp. D TROTTER & WEBBY,p. 481, pl. 2, figs 1617, 22-23.

FIGURE 6 - 1-12. Besselodus sp. 1, 2, a element, CPC 34439 (MH-23), 1, x 300; 2, x l 1 5 . 3 , a element, CPC 34440 (MH-23), x 145.4, b element, CPC 34441 (B4-7)i x 155.5, b element, CPC34442 (B4-12), x 130.6, b element, CPC 34443 (B4-10), x 95.7-9, c element, CPC 34444 (MH-11), 7, x 85; 8, x 85; 9, x 270.10,11, c element, CPC 34445 (MH-11), 10, x 75; 11, x 200. 12, e element, CPC 34446 (B4-12), x 95.13-17. Chirognathus? cliefdenensis ZHEN • WEBBY. 13, Sa? element, CPC 34447 (B7-2), x 145. 14, Sb element, CPC 34448 (MH-5), x 70.15, Pb element, CPC 34449 (B7-2), x 85.16, Sb element, CPC 34450 (MH-4), x 80.17, Sc element, CPC 34451 (MH-10), x 60.18,19. Culumbodina? SP- 18, CPC 34452 (MH-22B), x 70. 19, CPC 34453 (B4-12), x 75.

85

86 - This straight and smooth compressiform element is characterised by strong curvature of the anterior margin at about one-third of its length from the lower margin, at the level between the second and third denticIes.

Remarks

B e l o d i n a s p . E TROTTER & WEBBY, 1 9 9 4 Fig. 5.16 1994 Belodina sp. E TROTTER & WEBBY,p. 481, pl. 2, fig. 21, R e m a r k s - This compressiform element resembles B. sp. D TROTTER & WEBBY,but with the curvature of the anterior margin towards the cusp tip, at about two-thirds of its length from the base, and with a more strongly posteriorly extended heel.

B e l o d i n a sp. G. TROTTER • WEBBY, 1 9 9 4 Figs 5.17,18 1994 Belodina sp. G. TROTTER & WEBBY,p. 481, pI. 2, figs 3, 4. R e m a r k s - These specimens have a long cusp, bowed slightly towards the furrowed side; they are identical to those illustrated by Trotter & Webby (1994) from the Malongulli Formation.

B e s s e l o d u s ALDRIDGE, 1 9 8 2 T y p e - s p e c i e s - Besselodus arcticus ALDRIDGE,1982. Genus

Besselodus sp.

codiform specimens (Trotter & Webby 1994, pl. 3, figs 12-13, 17) are comparable with the c element. The b element has the m a x i m u m curvature of the cusp starting at about one-third of the specimen length or less from the basal margin. The oblique striae on the anterolateral m a r g i n are relatively weaker and finer or even absent in the smaller specimens. The cusp is reclined stronger t h a n t h a t of the a element, with the curvature n e a r e r the basal m a r g i n and forming a genicute and r a t h e r strongly posteriorly extended heel. The element is laterally compressed with s h a r p anterior and posterior margins, and bowed with a costa on each lateral face. The costa on the convex side is medial or postero-medial extending from tip to basal margin, and forming a groove on the posterior side. The costa on the concave side is medial or anteromedial, with a shorter groove on the posterior side, only extending from the tip to slightly more t h a n mid length. The c element has a longer, generally t r i a n g u l a r base, with a shorter costa on the convex side and a longer, more posteriorly situated costa on the concave side. The cusp curves r a t h e r sharply, with the m a x i m u m curvature on the posterior margin at, or more t h a n mid-length. Genus

Chirognathus

T y p e - s p e c i e s - Chirognathus duodactylus BRANSON & MEHL, 1933

Chirognathus? cliefdenensis ZHEN & WEBBY~ 1 9 9 5 Figs 6.13-17

Figs 6.1-12 R e m a r k s - A q u a d r i m e m b r a t e apparatus consisting of three distacodiform elements, including a short-based-1 (a), a shortbased-2 (b), a long-based (e), and an oistediform element (e). Distacodiferm elements are characterised by having a long costa (nearly the entire length of the specimen) on one lateral face, and a shorter costa on the other. Trotter & Webby (1994) recognised the oistodiform (M) element and three distacodiform elements designated as Sa, Sb, and Sc, respectively, for the species from the Malengulli Formation, but neither definition for each individual element of the apparatus, nor illustration of the Sa element were given. In our material from the top of the Bowan Park Group (uppermost Clearview to Downderry limestone members, and the basal Malachi's Hill Beds), the specimens of the oistodiform element are comparable with those illustrated by Trotter & Webby (1994, pl. 3, figs 15, 18), but with even weaker oblique striae on the antero-lateral margins or totally absent in some specimens. The a element has a short posteriorly extended heel and a gently curved posterior margin. It is also characterised by a short costa on the convex lateral face (located immediately posterior to the element axis and reaching close to the base) and a longer costa on the concave face (at or near the basal margin and more posteriorly situated). The curvature of the posterior margin of the cusp starts at about mid-length or slightly nearer the base. Oblique striae are conspicuous with an angle of about 10 to 20 degrees to the basal anterior margin. Two specimens figured from the Malongulli Formation (Trotter & Webby 1994, pl. 3, figs 7, 16) are identical to the a element described herein, and other illustrated dista-

BRANSON & MEHL, 1 9 3 3

? 1994 Oulodus cf. oregonia (BRANSON,MEHL & BRANSON): Trotter & Webby, p. 483, pl. 4, figs 16-17. 1995 Chirognathus cliefdenensis ZHEN & WEBBY, p. 281, partim, pl. 2, figs 13-22, pl. 3, figs 1-4; non pl. 3, fig. 1. R e m a r k s - The present material is comparable with the types of this species from the Cliefden Caves Limestone Group, but lacks the fine striae concentrically surrounding the basal pit. The Sb and Sc elements of C. ? cliefdenensis are superficially similar to the Pa and Pb elements ofOulodus BRANSON& MEHL, 1933, respectively. However, Oulodus has white matter, stout, peg-like, discrete denticles, separated by distinctive U-shaped spaces. Moreover, both Pa and Pb elements of Oulodus have a more open and relatively deeper basal cavity, and a much more strongly arched basal margin in comparison with the Sb and Sc elements of Chirognathus? cliefdenensis. The apparatus of typical Chirognathus from the Middle Ordevician of North America consists of hyaline, fibrous elements with highly variable denticles in respect to their numbers and inclination. The generic assignment of the present species from the Upper Ordevician of central New South Wales is uncertain, since it shows a r a t h e r consistent morphology. It m a y represent a new genus which is closely related to Chirognathus BRANSON& MEHL. Genus

Culumbodina

MOSKALENKO, 1 9 7 3

T y p e - s p e c i e s - Culumbodina mangazeica MOSKALENKO,1973.

FIGURE 7 - 1-7. Drepanoistodus suberectus (BRANSON & MEHL).1, suberectiform, CPC 34454 (MH-4), x 60.2, drepanodiform, CPC 34455 (MH-4), x 70.3, drepanodiform, CPC 34456 (MH-12), x 50.4, drepanodiform, CPC 34457 (MH-8), x 45.5, oistodiform, CPC 34458 (MH-12), x 80.6, suberectiform, CPC 34459 (MH-23), x 70.7, suberectiform, CPC 34460 (MH-10), x 45.8-12. Panderodus gracilis (BRANSON& MEnL). 8, asimiliform, CPC 34461 (MH-11), x 70.9, tortiform, CPC 34462 (MH-12), x 115.10, graciliform, CPC 34463 (MH-12), x 70.11,12, aequaliform, CPC 34464 (MH-12), 11, x 70; 12, x 75.13-20. Panderodus nodus nov. sp. 13, short-based1, CPC 34465 (B4-12), paratype, x 85.14,15, short-based-2, CPC 34466 (MH-13), paratype; 14, x 70; 15, x 60.16, long-based, CPC 34467 (MH-11), paratype, x 110.17,18, short-based-2, CPC 34468 (B4-10), holotype; 17, x 70; 18, x 75.19, long-based, CPC 34469 (B4-12), paratype, x 85.20, long-based, CPC 34470 (B4-10), paratype, x 85.21-24. Panderodus sp. C TROTTER & WEBBY. 21, broader element, CPC 34471 (B4-12), x 110.22, broader element, CPC 34472 (B4-12), x 85.23, slender element, CPC 34473 (B4-12), x 60. 24, slender element, CPC 34474 (MH-22), x 85.

87

88

Culumbodina? sp. Figs 6.18,19 R e m a r k s - The specimens are identical to those included tentatively in Culumbodina? sp. from the Malongulli Formation (Trotter & Webby 1994, pl. 2, figs 1, 2), though the slender Malongulli form is not recognised in the present collection, The specimens show a smooth, unfurrowed surface, but commonly have a weak antero-median carina on the furrowed surface. On the posterior margin, there is a prominent node-like denticle at a position slightly more than mid length towards the cusp and, additionally, two weakly developed denticles near the heel; the latter is strongly extended posteriorly.

Genus D r e p a n o i s t o d u s LINDSTR(3M, 1971 T y p e - s p e c i e s - Oistodus forceps LINDSTROM,1955.

Drepanoistodus

s u b e r e c t u s (BRANSON & MEHL, 1933) 'Figs 6.1-7

1933 Oistodus suberectus BRANSON& MEHL, p. 111, pl. 35, figs 22-27. 1988 Drepanoistodus suberectus (BRANSON& 1VIEHL):Nowlan & McCracken in Nowlan et al., p. 16, pl. 3, figs 19-22 (cum syn.). 1995 Drepanoistodus suberectus (BRANSON& MEHL):Zhen & Webby, p. 282, pl. 3, figs 8-10 (cure syn.). R e m a r k s - Three elements (suberectiform, oistodiform and drepanodiform) have been recognised in the present material from the Bowan Park Group and basal Malachi's Hill Beds. Similar transitional series from suberectiform to drepanodiform have been observed at Cliefden Caves (Zhen & Webby 1995).

Genus P a n d e r o d u s ETHINGTON, 1959 T y p e - s p e c i e s - Paltodus unicostatus BRANSON& MEHL, 1933.

Panderodus gracilis (BRANSON& MEHL, 1933) Figs 7.8-12

1933 Paltodusgracilis B~NSON & MEKL,p. 108, pl. 8, figs 20, 21. 1988 Panderodus gracilis (BRANSON & MEHL): Nowlan & McCracken in Nowlan et al., p. 21, pl. 7, figs 1-10, 1213, 19 (cum syn.). 1994 Panderodus gracilis (BRANSON & MEHL): Trotter & Webby, p. 483, pl. 5, figs 1-4, 9-10, 12, 15. 1995 Panderodus gracilis (BRANSON & MEHL): Zhen & Webby, p. 283, pl. 3, figs 18-22 (cure syn.). R e m a r k s - The quinquimembrate skeletal apparatus of Panderodus proposed by Sweet (1979) was applied to the collection ofP. gracilis from the Cliefden Caves Limestone Group of central N e w South Wales (Savage 1990; Zhen & Webby 1995). However, an additional, truely symmetrical, element bearing a well-defined panderodont furrow on each lateral face has been recognised in the Bowan Park material, Similar symmetrical elements of Panderodus were previously reported from the Silurian of Gotland, and in the Upper Ordovician of the Midcontinent of North America (Sweet 1988). Therefore, Sweet (1988) suggested that Panderodus was probably a seximembrate form. Sansom et al. (1994) recently proposed a nonimembrate apparatus for Panderodus, and the truly symmetrical specimens were formally referred as aequaliform elements.

Panderodus nodus nov. sp. Figs 7.13-20

1978 Panderodus sp. aff. P. panderi (STAUFFEr): Palmieri, pI. 22, partim; only pl. 1, figs 9, 13-14, text-fig. 3 (4-5). 1985b Panderodus recurvatus (RHODES): An et al., pI. 2, figs 17, 21. 1990 Panderodus recurvatus (RHODES): An & Zheng, pl. 7, figs 7-8. 1994 Panderodus sp. D TROTTER & WEBBY, p. 484, pl. 5, figs 24-26. 1995 Panderodus sp. ZHEN & WEBBY,p. 284, pl. 4, figs 1-2. D e r i v a t i o n o f n a m e - nodus Latin, swelling or knot, alluding to the node or nodes on the posterior margin. Material - Twenty-two specimens, including holotype CPC 344 68 and paratypes CPC 34465-7, CPC34469-70 and thirteen undesignated specimens, from Downderry Limestone Member (upper Bowan Park Group) and from the basal Malachi's Hill Beds.

D i a g n o s i s - A species of Panderodus characterised by a flange developed on the distal posterior margin that may bear one to three nodes. D e s c r i p t i o n - Three elements (long-based, shortbased-1 and short-based-2) have been recognised for the species. The long-based element is more common, nearly symmetrical with a furrowed, slightly convex face. It has a rounded anterior margin and a relatively sharp posterior margin. Cusp is rather sharply curved posteriorly starting at about half the specimen length. Both lateral faces are smooth, without carina or costa, commonly with striations on the posterior-lateral and anterior-lateral faces; base relatively long, without prominent extension posteriorly. The flange on the distal posterior margin is characterised by a gentle curvature of the posterior margin towards the tip of the cusp and a sharp curve in the direction of the base. It may bear one to three weak nodes. Short-based-1 element has a curvature starting at about one-third of length from the lower margin with a shorter, posteriorly extended base (Fig. 7.13). Node on the posterior margin is situated on the distal part of the cusp, closer to the posterior curvature of the cusp, and may be defined by a single, extended, blade-like, flange, or differentiated into two or three nodes (lower denticles of Zhen & Webby 1995, pl. 4, fig. 2). Short-based-2 element is characterised by a prominent costa along the anterior-outer edge on the furrowed face; it is best developed around the curvature of the cusp, and becomes narrower and sharper before it merges into the base. Cusp is less sharply curved than that of short-based-1 elements. Nodes on the posterior marging situated typically more towards the tip of the cusp, rather than closer to the curvature of the cusp in the short-based-1 element. R e m a r k s - Specimens from North China previously ascribed to Panderodus recurvatus (RHODES, 1953) by An (in An et al. 1985b) and An & Zheng (1990) are identical to this new species from central New South Wales. The type material of Panderodus recurvatus was inadequately described from the

89 Aymestry Limestone (lower Ludlow) of Britain with only one of the paratypes illustrated (Rhodes 1953, p. 297, pl. 23, figs 219-220). This shows a prominent anticusp formed by a downwardly extended antero-basal corner. The three illustrated specimens referred as Panderodus sp, D from the Malongulli Formation (Trotter & Webby 1994, pl. 5, figs 24-26) are identical to the long-based element of the present species, except that one specimen (P1.5, fig. 26) shows two smaller nodes rather than one node on the flange of the distal posterior margin.

P a n d e r o d u s sp. C TROTTER & WEBBY, 1 9 9 4 Figs 7.21-24 1994 Panderodus sp. C TROTTER& WEBBY,p. 484, pl. 1, figs 15 & 19. - The Bowan Park specimens are straight, and show varied development of the antero-median carinae from weak to rather prominent (Figs 7.21, 23). They can be divided into two forms, one slender and the other broader. Remarks

P a n d e r o d u s sp. Figs 10.12-13 1994 Panderodus gracilis (BRANSON & MEHL): Trotter & Webby, p. 483, pl. 5, partita, only figs 13-14. 1995 Scabbardella sp. ZHEN & WEBBY,p. 286, pl. 4, figs 1823. R e m a r k s - The present material is comparable with the speci-

mens referred to Scabbardella sp. from the Cliefden Caves Limestone Group within which two elements Ca" and "b') of this species were recognised (Zhen & Webby 1995), but only "a" element with a costa on each side has been recovered from the present Bowan Park material. Based on its sharp posterior and anterior margings, Zhen & Webby (1995) ascribed this species to Scabbardella. However, the presence of the fine striation near the base suggests that it may be more closely related to Panderodus. Genus Paroistodus Type-species

LINDSTROM,1971 PANDER,1856.

- Oistodus parallelus

P a r o i s t o d u s ? n o w l a n i nov. sp. Figs 8.1-16 1988 Paroistodus? sp. A NOWLAN& McCaACKENin Nowlan et al. p. 24-26, pl. 9, figs 1-22 (cure syn.) 1989 Paroistodus? sp. A NOWLAN& McCRACKEN:MeCracken & Nowlan, p. 1889, pl. 3, fig. 1. 1994 Paroistodus? sp. A NOWLAN& McCR~CKEN: Trotter & Webby, p. 484, pl. 3, fig. 21. 1994 "Oistodus" cf. venustus STAUFFER:Trotter & Webby, p. 482, pl. 3, figs 27-28. o f n a m e - After Dr. G.S. Nowlan, who contributed to the first descriptions and illustrations of this species from the Mackenzie Mountains of Northwest Territories, Canada.

Derivation

- Eighty-four specimens, including holotype CPC 34477 and paratypes CPC 34475-6 and CPC 34478-83, and seventy-five undesignated specimens, have been recovered from 14 samples from the topmost Clearview Limestone Member and Downderry Limestone Member of the upper Bowan Park Group, and from the basal part of Malachi's Hill Beds, central New South Wales. Material

- A quadrimembrate species consisr i n g o f a c o d i f o r m (a), d i s t a c o d i f o r m (b a n d c), a n d Diagnosis

o i s t o d i f o r m (e) e l e m e n t s , c h a r a c t e r i s e d b y a s h a r p posterior edge, a sharp to rather rounded anterior edge, a posteriorly extended base, and prominent, g e n e r a l l y s h a r p c o s t a (a, b a n d e) o r c o s t a e (c) on l a t e r a l face. T h e f i r s t t r a n s i t i o n s e r i e s e l e m e n t s have a short, laterally flared base, and a long, laterally compressed, cusp. The a and b elements a r e f u r t h e r s u b d i v i d e d i n t o s l i g h t l y b o w e d a-1 (to a c o s t a t e s i d e ) a n d b-l, a n d m a r k e d l y b o w e d a-2 a n d b-2 e l e m e n t s . O i s t o d i f o r m e l e m e n t h a s a s t r o n g l y e x t e n d e d b a s e , t h a t is a b o u t t h e s a m e length as the cusp. Element curvature varies from s l i g h t l y r e c l i n e d to r e c u r r e d (a, b a n d c e l e m e n t s ) a n d g e n i c u l a t e (e e l e m e n t ) . - All elements have a broad, laterally compressed cusp and a short, posteriorly extended base. Costae are generally sharp, extend from near a p e x to a b o u t m i d - b a s e . B a s e s of a l l e l e m e n t s a r e s m o o t h , l a c k i n g w r i n k l e s or s t r i a e . F i n e o b l i q u e striae centered about costae ornament the lateral faces of the e element, but the other elements are g e n e r a l l y l a c k o f s t r i a e on t h e l a t e r a l faces. T h e a e l e m e n t is u n i c o s t a t e w i t h a s h a r p c o s t a on t h e c o n v e x side. T h e a-1 e l e m e n t h a s a b r o a d e r a n d more posteriorly reclined cusp with a prominent c o s t a on t h e s l i g h t l y c o n v e x side, a s h a r p p o s t e r i o r m a r g i n , a n d a m u c h l e s s s h a r p , or c o m m o n l y r o u n ded, a n t e r i o r m a r g i n . T h e c o s t a t e r m i n a t e s a b r u p t ly a b o u t m i d - b a s e f o r m i n g a d e p r e s s i o n or d e e p g r o o v e on t h e p o s t e r i o r side, a r o u n d t h e c u r v a t u r e of t h e cusp. S o m e of t h e s p e c i m e n s h a v e t h e c o s t a a l o n g t h e m i d d l e a n d o t h e r s s l i g h t l y c l o s e r to t h e p o s t e r i o r m a r g i n . T h e a-2 e l e m e n t is s t r o n g l y b o w e d on t h e a c o s t a t e side. T h e b e l e m e n t v a r i e s f r o m s l i g h t l y (b-l) to r a t h e r s t r o n g l y b o w e d (b-2), with sharp anterior and posterior margins, and w i t h a c o s t a on e a c h l a t e r a l f a c e a l o n g t h e m i d w i d t h to f o r m a d i a m o n d - s h a p e d c r o s s s e c t i o n . C o s t a e a r e s h a r p w i t h a d e p r e s s i o n or g r o o v e on t h e p o s t e r i o r side, w h i c h is d e e p e r a r o u n d t h e p o s t e r i o r c u r v a t u r e of t h e cusp• S o m e s p e c i m e n s of t h e b-1 e l e m e n t h a v e f a i n t o b l i q u e s t r i a e on t h e a n t e r o l a t e ral margin. The c element has an anterolateral c o s t a a n d a p o s t e r o m e d i a l c o s t a on e a c h l a t e r a l face. B o t h of t h e c o s t a e a r e t h i n a n d s h a r p , f o r m i n g a w i d e r d e p r e s s i o n or g r o o v e b e t w e e n t h e m a n d a n a r r o w e r d e p r e s s i o n or g r o o v e b e t w e e n t h e p o s t e r o m e d i a l c o s t a a n d t h e p o s t e r i o r edge. T h e c u s p a n d b a s e of t h e o i s t o d i f o r m e e l e m e n t a r e a b o u t e q u a l i n l e n g t h , w i t h a p r o m i n e n t c o s t a on e a c h l a t e r a l face. T h e b a s e of t h e e e l e m e n t is p o s t e r i o r l y , s t r o n g l y extended with a sharply curved basal margin. Description

- The species was well defined by Nowlan & MeCracken (in Nowlan et al. 1988), and their definition is basically followed herein. The four elements (a,b,c, e) as recognised by Nowlan & McCracken are all identified in specimens from Bowan Park. Based on the large collections of specimens of this species from northwestern Canada and New South Wales, a formal species status is now warranted. Remarks

90 1966 Phragmodus undatus BRANSON & MEHL: BergstrSm & Sweet, p. 369, pl. 28, figs 13-20. 1988 Phragmodus undatus BRANSON & MEHL: Nowlan & McCracken in Nowlan et al., p. 26-27, pl. 10, figs 1-3, 6, 7 (cure syn.). 1990 Phragmodus undatus BRANSON & MEHL: An • Zheng, pl. 10, figs 19-21. 1995 Phragmodus undatus BRANSON & MEHL: Leslie & BergstrSm, p. 970-973, fig.4.1-4.14. 1995 Phragmodus undatus BRANSON & MEHL: Zhen & W e b b y , p. 284, pl. 4, fig. 5. (cum syn.). 1996 Phragmodus undatus BRANSON 8~ MEHL: Wang, BergstrSm & Lane, pl. 4, figs 9, 10.

The diagnostic features of the new species as mentioned above, specifically the s h a r p costa or costae on the lateral faces and an extended base of the four elements, are common with the concept of Paroistodus. However, it is only tentatively designated to it, because P.? nowlani has a n antero-basal angle in the four elements of the a p p a r a t u s commonly less t h a n 90 degrees, and also lacks inverted basal cavity. These latter features suggest t h a t it is also close to Drepanoistodus, but the drepanodiform elements of Drepanoistodus typically have smooth lateral faces and a less extended base.

Paroistodus s p . Figs 8.17, 18 R e m a r k s - These specimens are closely comparable with the oistodiform element of P.? nowlani, but have a much shorter base. This single form species was also recorded from the lower Malongulli Formation of central New South Wales (Trotter & Webby 1994, pl. 5, figs 19-23).

R e m a r k s - Phragmodus undatus is generally rare in the material from the Bowan Park succession. It is only common in a sample (B7-22) from the middle part of the Quondong Limestone representing a significant deepening episode. Only Sc and Sb elements are recognised in the collection. The two doubtfully assigned specimens are comparable with the Pb element of P. undatus. One specimen shows a denticulated antero-lateral process and a s h a r p anterior margin, but the denticulated posterior process is broken. Another specimen has a multidenticulated posterior process, an undenticulated antero-lateral process, and a s h a r p anterior m a r g i n (Fig. 9.5).

G e n u s P e r i o d o n HADDING, 1 9 1 3 T y p e - s p e c i e s - Periodon aeuleatus HADDING, 1913.

Periodon g r a n d i s (ETHINGTON, 1 9 5 9 ) Figs 8.19-21

Genus Protopanderodus

1959 Loxognathus grandis ETHINGTON,p. 281, pl. 40, fig. 6. 1966 Periodon grandis (ETHINGTON): Bergstr6m & Sweet, p. 363-5, pl. 30, figs 1-8 (cum syn.). 1993 Periodon grandis (ETHINGTON):Ding et al., in Wang, p.190, pl.35, figs 18-21. 1995 Periodon grandis (ETHINGTON):Zhen & Webby, p.284, pl. 4, figs 3, 4 (cum syn.).

T y p e - s p e c i e s -Acontiodus rectus LINDSTROM,1955.

P r o t o p a n d e r o d u s i n s c u l p t u s (BRANSON & MEHL, 1933) Figs 9.6-9 1933 Phragmodus insculptus BRANSON 8z MEHL, p. 124, pl. 10, figs 32-34. 1978 Protopanderodus insculptus (BRANSON • ~/~EHL): Palmieri, p. 25, pl. 2, figs 26-29, text-fig. 4 (10a-10c). 1984 Protopanderodus insculptus (BRANSON & ME~L): Wang & Luo, p. 277, pl. 8, figs 4, 5. 1985a Protopanderodus insculptus (BRANSON & MEHL): An et al., pl. 11, fig. 18. 1987 Protopanderodus insculptus (BRANSON & MEHL): An, p. 172, pl. 11, figs 16, 23, pl. 15, fig. 21. 1989 Protopanderodus insculptus (BRANSON & MEHL): McCracken, p. 16, pl. 3, figs 9-14, 17, 19, Fig. 3K-P. (cure syn.). 1994 Protopanderodus insculptus (BRANSON & MEHL): Trotter & Webby, p. 485, pl. 4, figs 1, 7-12.

R e m a r k s - The oistodiform, prioniodiniform and trichonodelliform elements of this species are recognised from Bowan Park. BergstrSm & Sweet (1966) suggested t h a t the oistodiform element of Periodon grandis can be distinguished from the same element of the stratigraphically older/~ aculeatus by its large, subtriangular base, an essentially straight basal margin, and the denticles, closely appressed to the anterior margin. However, some of the Bowan Park specimens show a r a t h e r sinuous basal margin, t h a t is inflated in the mid portion of the lateral face. They are more closely comparable to a specimen from the Craighead Limestone of Scotland (BergstrSm 1990, pI. 3, fig. 7, A. superbus Zone). The surface of the Bowan Park specimens have fine striations, and there are a varied number of denticles on the anterior margin, from 4 to 8 (most commonly 5). Genus

Phragmodus

BRANSON •

LINDSTROM, 1 9 7 1

R e m a r k s - In the upper part of the Bowan Park succession, P. insculptus occurs together with P. liripipus. Based on the dellnition given by Kennedy et al. (1979), however, it can be easily distinguished from the latter by the development of a r a t h e r prominent posterior denticle on the posterior margin of its base. Kennedy et al. (1979) and McCracken (1989) also suggested t h a t P. insculptus occurred in stratigraphically younger units (oldest occurrence is from upper A. superbus Zone) in the North American Midcontinent and in Europe, although both species overlap considerably in the Upper Ordovician and extend into

MEHL, 1 9 3 3

T y p e - s p e c i e s - Phragmodus primus BRANSON 8~ MEHL, 1933.

P h r a g m o d u s u n d a t u s BRANSON & MEHL, 1 9 3 3 Figs 9.1-5 1933 Phragmodus undatus BRANSON8z MEHL,p. 115-116, pl. 8, figs 22-26.

FIGURE 8 - 1-16. Paroistodus? nowlani nov. sp. 1,2, a-1 element, CPC 34475 (B4-12), paratype, x 130.3,4, a-2 element, CPC 34476 (B4-8), paratype, x 85.5,6, b-1 element, CPC 34477 (MH-15), holotype, x 115.7,8, b-2 element, CPC 34478 (MH-21A), paratype, x 105.9,10, b-1 element, CPC 34479 (B4-12), paratype, 9, x 95; 10, x 85.11,12, b~l element, CPC 34480 (MH-11), paratype, x 105. 13, e element, CPC 34481 (MH-15), paratype, x 105.14, c element, CFC 34482 (MH-3), paratype, x 145. 15,16, b-2 element, CPC 34483 (MH-15), paratype, x 155.17,18. Paroistodus sp. 17, e element, CPC 34484 (MH-23), x 85. 18, e element, CPC 34485 (MH4), x 70.19-21. Periodongrandis (ETmNGTON). 19, trichonodelliform, CPC 34486 (B4-7), x 110.20, prioniodiniform, CPC 34487 (MH19), x 70.21, oistodiform, CPC 34488 (MH-4), x 110. r~

91

92 the A. ordovicicus Zone. An (1981) defined the P. insculptus Zone in the upper part of the Pagoda Formation, South China, and suggested it ranged through the interval from the uppermost D. clingani Zone to the lower part of the P. linearis Zone (Wang & Chen 1992). The a b u n d a n t occurrences ofP. insculptus from the lower part of the Malongulli Formation and in the upper Bowan Park Group support the Eastonian 3 zonal age indicated by graptolites, and this roughly equates with the range of ages suggested for the upper Pagoda Formation of South China. P. insculptus was also recorded from the top Longmendong Formation of Longxian, and the Jinhe Formation of Jinyiang, Shaanxi Province of North China (Wang & Luo 1984; An & Zheng 1990), also probably correlating with the upper part of the Pagoda Formation of South China. The material from the upper part of the Bowan Park succession includes a rare asymmetrical element with a convex, smooth, outer face, a concave i n n e r face with mid-groove, and a costa along its anterior and posterior edges. The cross section of this mid-groove is "V"-shaped, when the two costae bordering the edge of the groove are more or less equally developed. More commonly, the costa m a r k i n g the anterior edge of the groove is narrower and sharper t h a n the costa marking the posterior edge of the groove. The size of the denticle on the upper margin of the base varies from a small, short, conical or node-like denticle to nearly the same thickness as the basal cusp. In most specimens, the cusp is reclined or erect-proclined near the base, and then changes to reclined or even recurved, distally. Denticles are smooth, typically more strongly reclined t h a n the cusp. The thinly flattened flange, extending from the antero-basal corner, is also common but seems to extend more sharply downward in comparision to the specimens from the Malongulli Formation (Trotter & Webby 1994, pl. 4, figs 1, 11).

R e m a r k s - Variation in the symmetrical to slightly asymmetrical element and in the asymmetrical element in respect to the development of costa and the grooves on the lateral faces was discussed in detail by Kennedy et al. (1979) based on the type material from the Tetagouche Group (mid Caradoc) of New Brunswick, Canada. McCracken (1989, p. 16) employed a different terminology for the a p p a r a t u s comprising "elements of a costae-symmetry transition series (acontiodontiform or a/b, c elements) and a scandodontiform (e) element". The specimens from the upper part of the Bowan P a r k Group show a similar degree of variation. In the collection of 174 specimens referred to P. liripipus, only eleven are recognised as asymmetrical. They are characterised by a convex, smooth outer face and a concave inner face ornamented by a mid-groove and a flanking costa on both side. In one of the specimens, the anteriorly flanked costa is narrow and sharp, with a narrower secondary groove developed along its anterior side. The costa marking the posterior edge of the m a i n groove is generally broaden In the slightly asymmetrical element (a/b element of McCracken 1989), the groove is situated slightly closer to the posterior margin, with two eostae asymmetrically disposed on each lateral face. The costa m a r k i n g the anterior edge of the groove is much more prominent, n a r r o w e r and s h a r p e r t h a n the opposite costa bordering the posterior edge of the groove. Some of the specimens also show an extended postero-basal portion, forming a p r o m i n e n t keel (Figs 9.12,13). Some of them have an extended anterior basal m a r g i n t h a t forms a promin e n t narrow flange on the antero-basal corner. This is also common in the specimens from the Malongulli Formation of central New South Wales (Trotter & Webby 1994, pl. 4, figs 3, 5). The Bowan Park specimens similarly show variation in the cusp, from slightly proclined, erect, to r a t h e r strongly reclined.

Protopanderodus liripipus

KENNEDY, BARNES ~z UYENO, 1 9 7 9 Figs 9.10-13

1979 Protopanderodus liripipus KENNEDY, BARNES & UYENO, p. 546-550, pl. 1, figs 9-19. 1984 Protopanderodus liripipus KENNEDY, BARNES & UYENO: Wang & Luo, p. 278, pl. 8, figs 6-10. 1985 Protopanderodus liripipus KENNEDY, BARNES & UYENO: An, Du & Gao, pl. 12, figs 5-9. 1987 Protopanderodus liripipus KENNEDY, BARNES & UYENO: An, p. 173, pl. 11, figs 4, 11-14. 1989 Protopanderodus liripipus KENNEDY, BARNES & UYENO: McCracken, p. 18, pl. 3, figs 15, 16, 18, 20-25, Fig. 3G-J. (cure syn.). 1990 Protopanderodus liripipus KENNEDY, BARNES & UYENO: An & Zheng, pl. 6, figs 5, 9-10. 1990 Protopanderodus liripipus KENNEDY~BARNES & UYENO: BergstrNm, pl. 2, figs 7-8. 1990 Protopandcrodus liripipus KENNEDY~BARNES & UYENO: Duan, pl. 3, figs 2, 4. 1993 Protopanderodus liripipus KENNEDY~BARNES & UYENO: Ding et al. in Wang, p. 195, pl.3 8, fig. 17. 1994 Protopanderodus liripipus KENNEDY, BARNES & UYENO: Trotter & Webby, p. 485, pl. 4, figs 2-6.

Genus

Pseudobelodina

SWEET, 1 9 7 9

T y p e - s p e c i e s - Belodina kirki STONE & FURNISH, 1959.

P s e u d o b e l o d i n a sp. Figs 9.21-22 - This single element from the breccias in the basal Malachi's Hill Beds differs markedly from the occurrences of species of Belodina in the Bowan P a r k succession, in exhibiting a strongly bowed cusp towards the furrowed side, and a sharp costa along the antero-lateral margin on the furrowed side. It is comparable with the P (Sweet 1979) or e (Nowlan et al. 1988) element of Pseudobelodina. It is close to the P elem e n t ofP. vulgaris SWEET,but may be distinguished from the latter by its five long, closely spaced denticles, and a s h a r p costa on the furrowed face t h a t is positioned more closely towards the anterior margin. Remarks

G e n u s P s e u d o o n e o t o d u s DRYGANT, 1 9 7 4 T y p e - s p e c i e s - Oneotodus? bechmanni BISCHOFF & SANNEMANN, 1958.

P s e u d o o n e o t o d u s m i t r a t u s (MoSKALENKO, 1 9 7 3 ) Figs 9.14-15

FIGURE 9 - 1-5. Phragmodus undatus BRANSON• MEHL. 1, Sb element, CPC 34489 (B7-22), x 125.2, Sc element, CPC 34490 (B722), x 125.3, Sb element, CPC 34491 (B4-12), x 70.4, Sc element, CPC 34492 (B7-22), x l 0 5 . 5 , Pb? element, CPC 34493 (B7-22), x 70.6-9. Protopanderodus insculptus (BRANSON8z MEHL). 6,7, symmetrical element, CPC 34494 (B4-10), 6, x 55; 7, x 50.8,9, asymmetrical element, CPC 34495 (B4-10), 8, x 50; 9, x 45. 10-13. Protopanderodus liripipus KENNEDY, BARNES 8z UYENO. 10,11, asymmetrical element, CPC 34496 (MH-18), 10, x 45; 11, x 40. 12,13, symmetrical element, CPC 34497 (MH-15), x 40. 14,15. Pseudooneotodus mitratus (MosKALENKO). 14, b element, CPC 34498 (MH-11), x 70.15, a element, CPC 34499 (B4-8), x 50.16-19. ScabbardeUa sp. cf. Scabbardella altipes B ORCHARD. 16,17, a element, CPC 34500 (MH-12), 16, x 60; 17, x 55.18,19, a element, CPC 34501 (MH-15), x 45.20. Spinodus sp. CPC 34502 (MH-15), x 70.21,22. Pseudobelodina sp. 21, e element, CPC 34503 (B412), x 55.22, e element, CPC 34504 (MH-23), x 45.

93

94 1973 Ambalodus mitratus mitratus MOSKALENKO,p. 86, pl. 17, figs 9-11. 1988 Pseudooneotodus mitratus (MosKALENKO):Nowlan & McCracken in Nowlan et al., p. 34, pl. 16, figs 2-6 (cum syn.). 1990 Pseudooneotodus mitratus (MosKALENKO): Pohler & Orchard, pl. 6, fig. 12. 1994 Pseudooneotodus mitratus (MoSKALENKO):Trotter & Webby, pl. 4, figs 21-22 (cum syn.). - Two forms are recognised among the Bowan Park specimens, one with a more-or-less smooth surface (a), and the other bearing a row of rounded nodes on the posterior and/or lateral ridges (b). Similar forms were also recorded from the Malongulli Formation (Trotter & Webby 1994). These two forms may be allied to the two subspecies originally proposed by Moskalenko (1973), and probably represent different elem e n t s of the same species apparatus. Remarks

Genus Type-species

Scabbardella

ORCHARD, 1 9 8 0

- Drepanodus altipes HENNINGSMDEN,1948.

S p i n o d u s sp. Fig. 9.20; Figs 10.10-11 - Only one form element h a s been recognised from the Bowan Park material. It consists of a robust, conical cusp, which is erect or slightly proclined or reclined, and posterior process represented by a single denticle, typically larger t h a n the cusp and strongly posteriorly reclined. The cusp is smooth, without striation, and oval in cross section. Basal cavity is represented by a narrow groove, extending from the axis of cusp to the axis of the denticle, and surrounded by a prominent zone of the recessive basal margin. The cusp is nearly straight or has a slightly concave inner-lateral face, and a slightly convex outer-lateral face, with a r a t h e r prominent anticusp. Rarely, a second small denticle may occur at the distal end of the posterior process. The morphol%o~] and relationships of S. spinatus are poorly understood. The holotype of S. spinatus, as illustrated by LindstrSm (1955, pl. 22, fig. 18), exhibits a long, posterior process bearing six widely spaced denticles. Although a few specimens have a posterior process with a larger denticle followed by a second, m u c h smaller dentide, most specimens of the Bowan Park species have a posterior process only bearing a single large denticle. Remarks

S c a b b a r d e l l a s p . cf. S c a b b a r d e l l a altipes B ORCHARD, 1 9 8 0 Figs 9.16-19; Figs 10.1-9, 23 1984 Drepanodus? altipes (HENNINGSMOEN):Wang & Luo, p. 257, pl. 2, figs 3-4, 15, 17. 1994 Scabbardella altipes (HENNINGSMGEN) B ORCHARD: Trotter & Webby, p. 487, pl. 3, figs 1-6, 8-11. - A long-based element (referred to as e) and three short-based elements (referred to as a, b, c) have been identified for the New South Wales species, based on the curvature of the cusp and the anterior-posterior expansion of its base. The a element is drepanodiform, characterised by its gently posteriorly curved cusp and s h a r p (thin and flatter) anterior and posterior margin. The basal part of the anterior margin is wider and thinner. This species (S. sp. cf. S. altipes B) is identical with some of the a elements ofS. altipes B from the Upper Ordovician of north-west C a n a d a illustrated by Nowlan et al. (1988, especially pl. 16, figs 11-12). However, the other specimens of the a element of the C a n a d i a n species (Nowlan et al. 1988, pl. 16, figs 7-10) show a less posteriorly curved, but more slender cusp. The b element is drepanodiform, striated, with the cusp sharply curved posteriorly at about the specimen mid-length. It shows an identical outline with the specimens referred to the b element of S. altipes B from northwest C a n a d a (Nowlan et al. 1988), but the C a n a d i a n species differs in having a s h a r p costa on the unfurrowed face. The c element is characterised by a much widened base, acostate, and a generally equilateral outline, with a thin distal part of the cusp sharply curved posteriorly. The long-based (e) element is striated, bowed towards the unfurrowed side, and commonly bears an antero-medial costa on the furrowed side. Remarks

Genus

Taoqupognathus

Type-species

AN i n A n e t al., 1 9 8 5 b

- Taoqupognathus blandus AN in An et al.,

1985b. shown in Figure 11, four elements (including 10 have b e e n recognised in t h e species of Taoqupognathus occurring in the Upper Ordovician successions of central New South Wales, but some morphotypes are only recovered from one or two of the three species. The P, M and Sb elements, being morphologically distinctive, can be easily recognised. The Sc-3 and Sc-5 seem to r e p r e s e n t two basic major morphotypes of the Sc element. Sc-1 and Sc-4 are close to Sc-3, and Sc-2 is close to Sc-5. The Sc-3 element is generally t r i a n g u l a r in outline with a n arcuate or posteriorly inclined anterior margin, while the Sc-5 element is rectangular in outline, but with an almost s t r a i g h t anterior margin. Savage (1990) recognised six elements, from a l p h a to zeta, in the T philipi a p p a r a t u s based on material from the lower p a r t of the Fossil Hill Limestone (Cliefden Caves Limestone Group), central New South Wales. Trotter & Webby (1994) preferred to apply Sweet's (in Clark et al. 1981) notational scheme for T tumidus, from the Malongulli Formation also at Cliefden Caves. This classification was adopted with modification by Zhen & Webby (1995) for the two stratigraphically older species, T philipi and T blandus, from the Cliefden Caves Limestone Group. Based on a fairly large collection o f t tumidus from the top of the Bowan Park Group and the basal part of the Malachi's Hill Beds, this notational scheme for the Taoqupognathus apparatus is further revised herein (Fig. 11). Remarks

-As

morphotypes)

T a o q u p o g n a t h u s b l a n d u s AN i n A n e t al., 1 9 8 5 b Figs 14.10-16

Genus Type-species

Spinodus

DZIK, 1 9 7 6

- Cordylodus spinatus HADDING,1913.

1985b Taoqupognathus blandus A~ in An et al., p. 104, pl. 2, figs 18, 19.

FIGURE 10 - 1-9,23 - ScabbardeUa sp. cf. Scabbardella altipes B ORCHARD.1-3, b element, CPC 34505 (B4-8), 1, x 155; 2,3, x 55.4,5, c element, CPC 34506 (MH-11), x 90. 6,7, e element, CPC 34507 (MH-10), 6, x 145; 7, x 45.8,9, a element, CPC 34508 (MH-12), x 45.23, b element, CPC 34509 (MH-12), x 70.10,11. Spinodus sp. 19, CPC 34510 (MH-19), x 50.11, CPC 34511 (MH-15), x 55.12,13. Panderodus sp. 12, CPC 34512 (B4-11), x 125.13, CPC34513 (B7-11), x 55.14. Yaoxianognathus? tunguskaensis (MoSKALENKO). Sd element, CPC34514 (MH-4), x 125.15-22. Walliserodus amplissimus (SERPAaLI). 15, c element, CPC 34515 (B4-12), x 170.16, c element, CPC 34516 (MH-12), x 100.17,18, c element, CPC 34517 (MH-23), 17, x 130; 18, x115.19, a element, CPC 34518 (MH-4), x 70.20, c element, CPC 34519 (MH-21A), x 145.21, e element, CPC 34520 (MH-12), x 85.22, e element, CPC 34521 (B4-10), x 85.

95

96 1987 1990

Taoqupognathus blandus AN:An, p. 192, pl. 30, fig. 20. Taoqupognathus blandus AN: An & Zheng, pl. 7, figs

1995

Taoqupognathus blandus AN: Zhen & Webby, p. 287,

5,6,20. pl. 6, figs 1-13. R e m a r k s - The specimens previously referred to the Sc-6 elem e n t from the Belubula Limestone of the Cliefden Caves area (Zhen & Webby 1995) are now re-assigned to the Sb-2 element. This is characterised by a prominent, lobe-like lateral process along its postero-lateral margin. The lateral process is slightly smaller t h a n the posterior process and is situated more towards the tip of the cusp. In some specimens (Zhen &Webby 1995, pl. 6, figs 5-6), the lateral process is shorter, while in others it is longer extending downward to the heel, but turns into a low ridge in the lower h a l f of the specimen, as shown also in the type specimen (An, in An et al. 1985b, pl. 2, fig. 18). In comparision with the Sb-2 element of T. tumidus, the Sb-2 element of T. blandus has its lateral process placed more towards the tip of the cusp.

T a o q u p o g n a t h u s t u m i d u s TROTTER ~r WEBBY, 1 9 9 4 Figs 14.1-9 1990 Belodina cf. B. blandus (AN): Duan, p. 31, pl.5, fig. 7. 1994 Taoqupognathus tumidus TROTTER & WEBBY,p. 487, pl. 7, figs 10-24. R e m a r k s - Trotter & Webby (1994) recognised two morphotypes for the Sb element of the T. tumidus apparatus, characterised by a costa or process on the unfurrowed lateral (inner) face, but did not illustrate these important features. The Bowan Park material shows t h a t both Sb-1 and Sb-2 elements are distinctive and can be easily recognised. Sb-1 is numerically the dominant element in the collection (Fig. 12). This element is relatively larger and more robust t h a n the other elements of the apparatus, characterised by its upwardly extended posterior process, and a sharp, posterolateral flange-like costa on the unfurrowed side. This latter extends from tip downwards to just over half-length of the specimen on the postero-lateral margin. Also the element exhibits a prominent ridge just a short distance above the antero-basal corner, defining the lower margin of a flange-like structure at the antero-basal corner. This flange parallels the basal margin, but with slightly downward arching. It extends posteriorly about one-third of the width on the unfurrowed side, and anteriorly around the anterior margin to the furrowed side. It t h e n meets the panderodid furrow to divide the coarsely striated heel from the rest of the specimen. The Sb-

1 element is the most distinctive and common element of this species; it has not been recognised in the stratigraphically older species T. blandus and T. philipi. The Sb-2 element is represented by only one specimen in the Bowan Park material and is characterised by a lateral process on the unfurrowed side, which extends postero-laterally from near the basal margin upward to about two-thirds of the length of the specimen along the postero-lateral margin. The lateral process is elevated at mid-length and becomes lower towards the basal margin. The specimens referred to as Sc-6 in T. blandus (Zhen & Webby 1995) are comparable with the Sb-2 element of T. tumidus, except t h a t they have a much shorter lateral process at mid-length in specimens along the postero-lateral margin. This is now re-assigned as an Sb-2 element. No similar element has been recognised in the T. philipi apparatus. The M e l e m e n t s of the t h r e e A u s t r a l i a n species of Taoqupognathus do not appear to be markedly different, though the M-2 element of T. tumidus h a s yet to be identified. As discussed previously (Zhen & Webby 1995), the P elements of the three species are particularly distinctive. The Se element of Taoqupognathus shows a transitional series reflecting the degree of extension of the posterior process. Trotter & Webby (1994) recognised three morphotypes of the Sc element for T. tumidus (Fig. 11). In the Bowan P a r k collection, four morphotypes are recognised. The Sc-3 is common, while the Sc-2, Sc-4 and Sc-5 elements are relatively rare; no Sc-1 has been recovered (Fig. 11). The Sc-3 element is characterised by a lobe-like posterior process near the mid-height, and may have been derived from the Sc-3 element of the stratigraphically older T. blandus. The Sc-4 element figured by (Trotter & Webby 1994, pl. 7, figs 12-13) shows a transitional morphology between the Sc-3 element of T. tumidus and the Sc-3 element of T. blandus. The Sc-5 of T. tumidus seems to have been derived from the Sc-5 element of T. blandus (Zhen & Webby 1995). In terms of specimen n u m b e r s of each element of the apparatuses of the Taoqupognathus species in central New South Wales, the Sc-5 morphotype is overwhelmingly the dominant element of T. philipi, while the Sc-3 morphotype is the most a b u n d a n t element of T. blandus (Zhen & Webby 1995). Based on the Bowan Park m a t e r i a l of T. tumidus, the Sb-1 element is the most common morphotype and the Sc elemerit is also dominated by the Sc-3 morphotype. Genus

Walliserodus

W a l l i s e r o d u s a m p l i s s i m u s (SERPAGLI, 1 9 6 7 ) Figs 10.15-22; Figs 14.17-20

Notational systems 11 - Relationships between the notational schemes used by Savage (1990), Trotter & Webby (1994) and Zhen & Webby (1995) for the discrete elem e n t s of the Taoqupognathus apparatus. Equivalences

SERPAGLI, 1 9 6 7

T y p e - s p e c i e s -Acodus curvatus BRANSON& BRANSON, 1947.

Occurrences

FIGURE

entre les notations utilisdes par Savage (1990) Trotter & Webby (1994), et Zhen & Webby (1995)pour les dldments discrets de l'appareil de Taoqupognathus.

Savage 1990 Trotter & Webby Zhen & Webby Present Paper 1994 1995 Epsilon P? P P M1 Delta M? M1 M M M2 M2 Sb-1 Sb Sb? Sb Sc6 Sb-2 Scl Scl Alpha --Sc2 Gamma --Sc2 Sc Sc Sc?-a Sc3 Sc-3 Beta Sc-4 Sc?-b Sc4 Sc-5 Zeta Sc?-c Sc5

T. philipi

T. blandus

T. tumidus

common

common

common

common

rare

rare ---

--dominant

rare

common

rare common

rare dominant

common

rare

rare

---

rare

rare

dominant

--common

common

rare rare

97 FIGURE 12 - Distribution of the discrete elements of Taoqupognathus tumidus based on samples size 5kg from the upper Ballingoole Limestone and basal Malachi's Hill Beds, Malachi's Hill section, Bowan Park.

Distribution des dldments discrets de Taoqupognathus tumidus & partir d~chantillons de 5 kg provenant du Ballingoole Limestone supdrieur et de la base des couches de Malachi's Hill, coupe de Malachi's hill, Bowan Park.

Sb

M

Sc Total

M1

M2

Sbl

Sb2

Scl

Sc2

Sc3

Sc4

Sc5

MH-21A

2

MH-15

1

1

MH-13 MH-12

7

1

8

MH-11

5

5

MH-10

7

8

MH-9

1

1

MH-8

1

1

MH-4

2

4 3

B4-12 B4-10

21

22

1

1

B4-8 B4-7 Total

1

1 4

2

1967 Drepanodus amplissimus SERPAGLI,p. 66, pl. 15, figs la-5b. 1978 Drepanodus sp. aff. D. amplissimus SERPAaLI:Palmieri, p. 20, pl. 2, figs 15-16. 1988 Walliserodus amplissimus (SERPAGLI): Nowlan & McCracken in Nowlan et al., p. 40-41, pl. 19, figs 1-15 (cum syn.) 1989 Walliserodus amplissimus? (SERPAGLD: McCraeken & Nowlan, p. 1892, pl. 4, fig. 11. 1994 Walliserodus amplissimus (SERPAGLI): Trotter & Webby, p. 488, pl. 7, figs 1-9.

44

2

1

4

1

58

correlatives), whereas Y. ani characterises the upper part of the Bowan Park succession (Ballingoole Limestone to basal Malachi's Hill Beds). The following six species are assigned to the genus: Y. yaoxianensis An, in An et al., 1985b; Y. abruptus (BRANSON& MEHL, 1933); Y. ani nov. sp., X neimengguensis (QIu, in Lin et al., 1984); Y. sesquipedalis (NoWLAN & McCRACKEN, in Nowlan et al., 1988) and Y. wrighti SAVAGE,1990.

Yaoxianognathus ani nov. sp. Figs 15.1-16

R e m a r k s - The quinquimembrate apparatus nomenclature suggested by Nowlan & McCracken (in Nowlan et al. 1988) is tentatively adopted herein. Only three elements (referred to as a, c, e) are recognised from the Bowan Park material. The a elem e n t is larger in size with a deep basal cavity, and with fine striations on both sides. The c element is identical with the Sa element of Trotter & Webby (1994, pl. 7, figs 1, 3-4) from the Malongulli Formation. It is characterised by having a sharp antero-lateral costa on each lateral face, to form a wide anterior margin, and a second costa on one lateral face only. One specimen shows a strong antero-lateral costa, a second costa near the posterior margin of one lateral face, and a sharp antero-medial costa on the other lateral face and is therefore referred to doubtfully as a c element.

Genus Yaoxianognathus AN in AN et al., 1985b T y p e - s p e c i e s - Yaoxianognathus yaoxianensis AN in An et al., 1985b. R e m a r k s - An (in An et al. 1985b) recognised a quinquimembrate apparatus for the type species, Y. yaoxianensis, from the Taoqupo Formation (Upper Ordovician) of Shaanxi Province, North China. Savage (1990) proposed a seximembrate nomenclature for Y. wrighti from the Cliefden Caves Limestone Group of central New South Wales. The new species, Yaoxianognathus ani, consists of a seximembrate apparatus, showing a resemblance to both Y. yaoxianensis from North China, and Y. wrighti. The latter is widely distributed in central New South Wales, but is restricted to a lower stratigraphic interval, up to and including the Quondong Limestone (and

1994

Ozarkodina sesquipedalis NOWLAN A MCCRACKEN Trotter & Webby, p. 483, pl. 6, figs 13-25.

D e r i v a t i o n o f n a m e - The species is named in memory of the late Professor Taixiang An, eminent Chinese conodont worker and author of the genus Yaoxianognathus. M a t e r i a l - 449 specimens (Fig. 13), including holotype CPC 34558 and paratypes CPC 34545-57, CPC 34559-60, have been recovered from 23 samples through the uppermost part of Clearview Limestone Member and the Downderry Limestone Member of the upper Bowan Park Group, and from the basal Malachi's Hill Beds, central New South Wales.

Diagnosis A s e p t i m e m b r a t e species of Yaoxianognathus characterised by a triangularly outlined, angulate M element with a straight lower margin, a bipennate Sb element with an erected robust cusp, and a digyrate Sd element with a long, inner-lateral process. D e s c r i p t i o n - Pa element carminate, unarched, with almost straight lower margin, basal cavity of moderate size, situated immediately beneath the cusp, with basal margin laterally slightly inflated; cusp prominent, twice as thick as adjacent denticles, strongly inclined posteriorly, forming an angle of 40-50 degrees with the lower margin. Anterior process straight, approximately twice or

98

Samples MH-3 MH-4 MH-8 MH-9 MH-10 MH-11 MH-12 MH-13 MH-14 MH-15 MH-16 MH-17 MH-18 MH-19 MH-21A MH-22B MH-23 B4-7 B4-8 B4-10 B4-11 B4-12 Total

Pa

Pb

14

5 1 1 13 24 19 4

M

Sa

Sb

Sc

1

3 26 39 68 I0

2 4

1

7 4

2 2 1

2 2 1 1 4 30 37 7 1 266

7 7 5

1 1

1 2 4

4 7 1

Sd

Total

1 1

2 5 3 1

2 20 1 4 49 82 107 16

1

4 5

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II 7 1 2 5 1 2 5 54 56 8 1 449

FIGURE 13 - Distribution of discrete elements of Yaoxianognathus ani nov. sp. based on the samples (average sample size: 5kg) from the upper BallingooIe Limestone and basal Malachi's Hill Beds in the Malachi's Hill section, Bowan Park. Distribution des dldments discrets de Taoqupognathus tumidus & partir d'dchantillons de 5 kg provenant du Ballingoole Limestone supdrieur et de la base des couches de Malachi's Hill, coupe de Malachi's hill, Bowan Park.

t w o - a n d - h a l f t i m e s as long as posterior process, b e a r i n g 9-15 closely s p a c e d denticles, w h i c h i n c r e a s e in h e i g h t a n d inclination posteriorly; denticles t o w a r d s a n t e r i o r end are smallest, a n d erect to n e a r erect; posterior process s h o r t e r a n d slightly i n w a r d l y c u r v e d distally, b e a r i n g 3-6 closely s p a c e d denticles t h a t are s h o r t e r posteriorly, b u t w i t h a s i m i l a r inclination. Pb e l e m e n t a n g u l a t e , w i t h a p r o m i n e n t cusp, a b o u t twice t h e w i d t h of a d j a c e n t denticles. A n t e r i o r process s t r o n g l y d o w n c u r v e d to form a s t r o n g l y a r c h e d lower m a r g i n , b e a r i n g 5-10 closely s p a c e d denticles, w i t h posterior inclination a n d b e c o m i n g t h i n n e r a n d s h o r t e r anteriorly; a n t e r i o r a n d p o s t e r i o r processes also c u r v e d i n w a r d to

form a concave inner face and convex outer face. Posterior process is longer than anterior process, slightly downcurved, bearing up to 20 almost erect denticles; these are closely spaced and in two different sizes, alternating with each other; larger denticles are about the same size, or slightly smaller and shorter than those on the anterior process; smaller dentic]es occur in alternation to the larger denticles, about half (or less) as wide as

the a d j a c e n t l a r g e r denticles; t y p i c a l l y t h e r e is one s m a l l e r denticle b e t w e e n t h e l a r g e r ones. B a s a l cavity located b e n e a t h t h e cusp, w i t h slightly inflated b a s a l m a r g i n . M e l e m e n t a n g u l a t e , s t r a i g h t , t r i a n g u l a r in outline, w i t h a s t r a i g h t lower m a r g i n ; cusp p r o m i n e n t , a b o u t twice as wide as a d j a c e n t denticles on the posterior process, a n d inclined posteriorly, form i n g an angle of 50°-60 ° to t h e lower m a r g i n . B a s a l cavity m o d e r a t e in size, w i d e s t b e n e a t h cusp, n a r r o w i n g t o w a r d s distal ends of a n t e r i o r and posterior processes. A n t e r i o r process is shorter, w i t h 5-6 small, closely spaced, low denticles, w h i c h are p o s t e r i o r l y inclined at a s i m i l a r angle to the basal m a r g i n as the cusp. P o s t e r i o r process is twice as long as the a n t e r i o r process, b e a r i n g 812 s h a r p l y pointed, p o s t e r i o r l y inclined denticles, w h i c h are s h o r t e r t o w a r d s p o s t e r i o r end; cusp and denticles are o r n a m e n t e d b y fine striation. Sa e l e m e n t alate, w i t h a f l a t t e n e d cusp a n d two l a t e r a l processes, each b e a r i n g a b o u t 10 h i g h l y erect, closely spaced denticles. Sb e l e m e n t bipennate, w i t h a r o b u s t a n d erect cusp; long a n t e r i o r process curved d o w n w a r d a n d laterally, b e a r i n g a b o u t 18 closely spaced, a l m o s t erect denticles. Posterior process v e r y short, c o n s i s t i n g of one or two, erect, small denticles a t t a c h e d to p o s t e r i o r edge of cusp; b a s a l c a v i t y small, w i t h a long, n a r row, b a s a l groove b e n e a t h a n t e r i o r process. Sc element dolabrate, but with a single, slender denticle anterior to the cusp, which is p r o m i n e n t , almost erect, a n d about t h r e e times the w i d t h of adjacent denticles. Posterior process v e r y long, with straight lower margin, b e a r i n g closely spaced denticles of various sizes; l a r g e r denticles up to two-thirds the w i d t h of cusp, w i t h i n t e r c a l a t e d smaller ones; most specimens h a v e b r o k e n posterior processes; in one b e t t e r p r e s e r v e d Sc element, there are 14 larger denticles w i t h 2 or 3 (rarely 4

FIGURE14 - 1-9. Taoqupognathus tumidus TROTTER• WEBBY.1, Sc-3 element, CPC 34522 (B4-12), x 155.2, Sc-3 element, CPC 34523 (B4-8), x 105.3, Sb-2 element, CPC 34524 (B4-10), x 95.4, P element, CPC 34525 (B4-12), x 155.5, P element, CPC 34526 (MH15), x 155.6, Sb-1 element, CPC 34527 (B4-10), x 125.7, M-1 element, CPC 34528 (B4-7), x 125.8, Sb-1 element, CPC34529 (B410), x 95.9, Sc-3 element, CPC 34530 (B4-12), x 90.10-16. Taoqupognathus blandus AN. 10: P element, CPC 34531 (B2-1), x 130; from Billabong Creek Limestone, Billabong (or Goobang) Creek, 22km west of Parkes. 11, P element, CPC34532 (B7-4), x 175.12, Sc-2 element, CPC 34533 (B7-4), x 130.13, M-1 element, CPC 34534 (B7-4), x 145.14, M-1 element, CPC 34535 (B7-4), x 155.15: Sc-2 element, CPC 34536 (B7-4), x 115. 16, Sc-5 element, CPC 34537 (B2-1), x 95; same locality as fig. 10. 17-20. Walliserodus amplissimus (SERPAGLI).17, e element, CPC 34538 (MH-11), x 60.18, c element, CPC 34516 (MH-12), x 105.19,20, a element, CPC 34540 (MH-12), x 60. 21-23. Yaoxianognathus wrighti SAVAGE.21, Sa element, CPC 34541 (B7-14), x 155. 22, Pa element, CPC 34542 (B7-22), x 55.23, Pa element, CPC 34543 (B7-22), x 70.24. Yaoxianognathus? tunguskaensis (MOSKALENKO).Sb element, CPC 34544 (B4-8), x 75.

99

100 when near the cusp and only one near the distal end) intercalated smaller denticles between every two larger ones on the posterior process (Fig. 15.3). Sd element digyrate with an erect cusp, with diamond-shaped cross section, and sharp anterior and posterior margins. The outer-lateral process shorter, distally curved downward and slightly posteriorly, bearing about 8-12 closely spaced denticles of variable width. The inner-lateral process is twice as long as the outer lateral process, sharply curved posteriorly beyond the second denticle towards the cusp, with almost straight lower margin, and bearing up to 10 larger denticles with alternating smaller denticles between. Typically there are 1-4 smaller denticles between two larger denticles. The second denticle from the cusp is proclined and larger, only slightly smaller than the cusp. R e m a r k s - Specimens referred to Ozarkodina sesquipedalis from the limestone clasts of the lower Malongulli Formation (Trotter & Webby 1994) are considered here to be conspecific with Y. ani. Compared with Y. ani, the Y. wrighti apparatus recorded from the lower and middle parts of the Bowan Park Group, and the Cliefden Caves Limestone Group, exhibits the following differences: (1) the dolabrate M element has a shorter posterior process and complete lack of an anterior process; (2) the Sc element bears a shorter posterior process; (3) the Sb element has larger denticles, distally; and (4) the Sa element bears a larger denticle towards the distal end of each lateral process. The Pa element of Y. wrighti has a rather straight lower margin like that ofY ani, but it differs in having a stout, much less posteriorly inclined cusp, and in having a lesser number of denticles on the anterior process. Prioniodina lijiapoensis WANe & Luo, 1984 is a form species based on a Pb element which is close to the Pb element of Y. yaoxianensis except for its smaller and less common intercalated denticles on a shorter posterior process. It is here regarded as a junior synonym of Z yaoxianensis. The Pa element of type species Y. yaoxianensis has a posteriorly, rather strongly inclined, cusp, like that of Y. ani, but it has a lesser number of denticles on the anterior process and the lower margin is curved posteriorly upwards. The Pb element of Y. ani is identical to that of Y. yaoxianensis, except for a narrower posterior process, especially towards the posterior end. Y. yaoxianensis also differs in having an Sc element with smaller denticles and an Sb element with a more slender cusp. No Sa element has been recovered for Y yaoxianensis. AN & ZHENG (1990) suggested an evolutionary trend of the Pb elements, from a shorter posterior process bearing a less number of denticles (stratigraphically lower) to a longer posterior process with more denticles (stratigraphically higher), based on the species of Yaoxianognathus occuring in the Upper Ordovician successions on the west-northwest margin of North China. The Pb element of Y. ani typically has alternating smaller and larger denticles on the posterior process, and seems closer to Y yaoxianensis. The type material of Y neimengguensis was originally defined as a form species represented by five spe-

cimens of the Pa element. It is close to the Pa element of Y. wrighti, except for its more prominent basal cavity with inflated basal margins and a more concave inner face. It differs from the Pa element of Y. yaoxianensis in having an less curved lower margin. Ozarkodina sesquipedalis NOWLAN& MCCRACKEN(in Nowlan et al. 1988) from the uppermost Ordovician (about 60 m below the Ordovician/Silurian boundary) Whittaker Formation of the Mackenzie Mountains in northwest Canada also seems referrable to Yaoxianognathus. The holotype (an M element) of the Canadian O. sesquipedalis shows a general similarity to the M element of both Y. wrighti and Y ani from New South Wales. This dolabrate form is not commonly a part of the species apparatus of Ozarkodina. The Sc element of Yaoxianognathus is a distinctive element of the genus, although the Pa and Pb elements show some similarities to those of Ozarkodina. The specimen referred as an a-2 element (paratype, Nowlan et al. 1988; pl. 5, fig. 3) although poorly preserved and broken, is no doubt an Sc element of Yaoxianognathus. However, the c? element, represented by only one specimen (Nowlan et al. 1988; pl. 5, fig. 4), seems to be incorrectly assigned to the Y. sesquipedalis apparatus.

Yaoxianognathus wrighti SAVAGE,1990 Figs 14.21-23 ? 1985b Yaoxianognathus sp. A AN in An et al., pl. 2, fig. 8. 1990 Yaoxianognathus wrighti SAVAOE,p. 826, fig. 6.1-6.12. 1995 Yaoxianognathus wrighti SAVAGE:Zhen & Webby, p. 289, pl. 6, figs 14, 15. 1995 Chirognathus cliefdenensis ZHEN & WEBBY,p. 281, only pl. 3, fig. 1. - Only Pa and Sa elements of this species have been recovered, from the top of the Gerybong Limestone Member and the Quondong Limestone at Bowan Park. They are identical to the type material recorded from the Cliefden Caves Limestone Group, except that the Pa element has a slightly longer posterior process with up to six denticles. Remarks

Yaoxianognathus? tunzuskaensis (Moss,LENtO, 1973)

Fig. 10.14; Fig.14.24; Fig. 15.17-22 1973 Phragmodus ? tunguskaensis MOSKALNEKO,p. 74, pl. 12, figs 1-3. 1984 Phragmodus ? tunguskaensis (MosKALENKO):Wang & Luo, p. 273, pl. 10, figs 14-15, 17, 21. 1990 Oulodus? tunguskaensis (MOSKALENKO):An & Zheng, pl. 10, figs 10-11. 1994 Yaoxianognathus? tunguskaensis (Mos~LENKO): Trotter & Webby, pl. 4, figs 18-20 (cum syn.). 1994 Periodon? sp. TROTTER & WEBBY,p. 485, pl. 5, fig. 34. 1995 Yaoxianognathus? tungushaensis (MOSKALENKO):Zhen & Webby, p. 289-290, pl. 6, fig.22. 1995 Spinodus sp. ZHEN & WEBSY, p. 286, pl. 5, figs 5-6. R e m a r k s - This species, only recognised previously based on a dolabrate element, is widely distributed in the Upper Ordovician of the Siberian Platform, North China, eastern Australia and

FIGURE 15 - 1-16. Yaoxianognathus ani nov. sp. 1, Pa element, CPC 34545 (MH-16), paratype, x 50.2, Fa element, CPC 34546 (MH12), paratype, x 45.3, Sc element, CPC 34547 (Mh-16), paratype, x 35.4, Sc element, CPC 34548 (MH-12), paratype, x 75.5, Sd element, CPC 34549 (MH-15), paratype, x 55.6, Sd element, CPC 34550 (MH-11), paratype, x 60.7, Pb element, CPC 34551 (MH17), paratype, x 55.8, Pb element, CPC 34552 (MH-16), paratype, x 45.9, Sd element, CPC 34553 (MH-11), paratype, x 55.10, Sc element, CPC 34554 (MH-11), paratype, x 75.11, Sb element, CPC 34555 (MH-16), paratype, x 75.12, Sb element, CPC 34556 (MH12), paratype, x 70.13, Sa element, CPC 34557 (MH-11), paratype, x 80.14, M element, CPC 34558 (MH-10), holotype, x 45.15, M element, CPC 34559 (MH-12), paratype, x 55.16, Sa element, CPC 34560 (MH-11), paratype, x 90.17-22. Yaoxianognathus? tunguskaensis (Mos~ALENKO).17, Pa element, CPC 34539 (B7-18), x 80. 18, Sd element, CPC 34561 (MH-12), x 115.19, Sb element, CPC 34562 (MH-9), x 90.20, Sc element, CPC 34563 (B4-8), x 40.21,22, Sa element, CPC 34564 (MH-12), 21, x 95; 22, x 85.

I01

102

northwestern Canada. As discussed by Savage (1990), and Trotter & Webby (1994), it was previously assigned tentatively to a variety of genera. Trotter & Webby (1994) regarded it questionably as a species of Yaoxianognathus, based on the similarity of their Malongulli specimens to the Sc element of that genus. Savage (1990) suggested that other elements of the apparatus might be rare or reworked prior to burial. Y.? tunguskaensis is moderately common in the Cliefden Caves and Bowan Park successions of central New South Wales. A number of specimens have been recovered from the Bowan Park Group and basal Malachi's Hill Beds, and are assigned here to the Pa, Sa, Sb, Sc and Sd elements of Y.? tunguskaensis. Although the Pb and M elements have not be recovered, the four S elements and the Pa element are comparable with those of Yaoxianognathus. However, the elements of this species are all characterised by having long and widely spaced denticles, occasionally in alternation with smaller denticles. Therefore, it is doubtfully retained as a species of Yaoxianognathus. The Pa element has a nearly erect cusp, an anterior and a posterior processes, both processes bear 4-8, long, nearly erect, denticles. The basal margin is slightly arched downwards and inwardK The basal cavity is commonly inverted with a small basal pit and basal groove extending beneath both anterior and posterior processes. The Sa element is alate, with each lateral process bearing a very large, long denticle at its distal end, and two, much smaller denticles between the cusp and these larger denticles. Cusp is erect to slightly proclined, with a sharp anterior edge in the distal half, and relatively broader in the basal part. The larger denticles at the distal ends of the lateral processes are nearly twice as long as the cusp, erect to slightly reclined, and with a thin costa along their anterior edges. The Sb element is bipennate, with a finely striated, high and robust cusp, a long, curved anterior process, and a very short posterior process. The anterior process curves laterally and then posteriorly, typically with five widely spaced denticles. The two distal denticles are much larger. The short posterior process is lack of denticles, or rarely bearing a single denticle. The Sd element is alate with a small, proclined cusp, and a thick, robust lateral process on each side. The lateral processes curve posteriorly and bear two or three widely spaced, reclined denticles. The denticle at the distal end of the lateral process is much larger, robust and flattened, with an oval-shaped cross section; commonly more strongly reclined posteriorly than the smaller denticles near the cusp. A c k n o w l e d g e m e n t s - This study was undertaken with the support of the Australian Research Council during 1996 and 1997 (grant A39600788) and of the National Science and Engineering Research Council of Canada. We thank R. Mawson, J. Talent, G. Brock, M. Engelbretsen (Macquarie University, Sydney), I. Percival (Geological Survey of New South Wales) and J. Laurie (AGSO, Canberra) for advice and assistance in preparing this paper. We are also grateful to M. LindstrSm (Stockholm) and F. Paris (Rennes) for providing critical reviews of the manuscript, and additionally to Dr Paris for help in preparing the French translation of the abstract. The scanning electron microscope illustrations were prepared in the Electron Microscope Unit of the School of Biological Sciences, Macquarie University. This is a contribution to the global Ordovician biodiversity project, IGCP Project n ° 410.

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WEBBY B.D., VANDENBERG A.H.M., M.R., BURRETT C.F., HENDERSON

COOPER R.A., BANKS R.A., CLARKSON P.D,

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