A new lowermost middle Cambrian - Springer Link

4 downloads 7 Views 5MB Size Report
Aug 10, 2013 - from Saxony (Germany) and its bearing ... Saxo-Thuringian Zone 4 Germany ... inarticulate brachiopods, and hyoliths (Schmidt 1944;.

Pala¨ontol Z (2014) 88:239–262 DOI 10.1007/s12542-013-0195-z

RESEARCH PAPER

A new lowermost middle Cambrian (Series 3, Stage 5) faunule from Saxony (Germany) and its bearing on the tectonostratigraphic history of the Saxothuringian domain Gerd Geyer • Bernd Buschmann • Olaf Elicki

Received: 11 February 2013 / Accepted: 18 July 2013 / Published online: 10 August 2013 Ó Springer-Verlag Berlin Heidelberg 2013

Abstract The core of borehole 1209/78 west of Doberlug–Kirchhain and south of Herzberg in the Torgau– Doberlug Syncline records an atypical lower part of the Tro¨bitz Formation with thin limestone horizons. These limestone layers include the remains of a low to moderately diverse fauna with the trilobites Protolenus (Hupeolenus) bergstroemi n. sp., Cambrunicornia saxonica n. sp., Ornamentaspis? aff. todraensis Geyer 1990a, Calodiscus? n. sp., the remains of two undetermined olenelloid? and paradoxidid? species, at least two brachiopods (Trematobolus, undetermined acrotretoid), and one hyolith. The fauna clearly suggests a position in the lower Agdzian stage of the West Gondwana chronostratigraphic scheme and correlation with the lowermost to lower Middle Cambrian strata in regions such as the Moroccan Atlas ranges and northern Spain, so the assemblages represent the oldest G. Geyer (&) Institut fu¨r Geographie und Geologie, Lehrstuhl fu¨r Geodynamik und Geomaterialforschung, Bayerische Julius-MaximiliansUniversita¨t Wu¨rzburg, Am Hubland, 97074 Wu¨rzburg, Germany e-mail: [email protected] G. Geyer Department of Earth Sciences (Palaeobiology), Uppsala University, Villava¨gen 16, 752 36 Uppsala, Sweden B. Buschmann  O. Elicki Institut fu¨r Geologie, TU Bergakademie Freiberg, Bernhard-von-Cotta-Straße 2, 09599 Freiberg, Germany e-mail: [email protected] O. Elicki e-mail: [email protected] B. Buschmann Erz & Stein GbR, Hof am Alten Fernweg, Talstraße 29, 09627 Bobritzsch, Germany

Middle Cambrian fauna known from the Saxothuringian domain and reconfirm the palaeogeographic position in the Perigondwanan segment. The lithological differences of the fossiliferous cores from those of the typical Tro¨bitz Formation and the recorded high-energy conditions indicate high-frequency sea-level changes suggesting that this part of the succession may be a late stage of the subglobally recognizable eustatic sea-level fluctuations at the traditional Lower–Middle Cambrian boundary interval. Keywords Cambrian  Trilobita  Brachiopoda  Biostratigraphy  Sea-level fluctuations  Saxo-Thuringian Zone  Germany Kurzfassung Bohrkerne der westlich von Doberlug–Kirchhain und su¨dlich von Herzberg in der Torgau–Doberlug– Synkline niedergebrachten Bohrung 1209/78 zeigen einen atypisch ausgebildeten unteren Teil der Tro¨bitz-Formation mit du¨nnen Kalkstein-Horizonten. Diese Kalkstein-Lagen beinhalten eine gering bis mittelstark diverse Fauna mit den Trilobiten Protolenus (Hupeolenus) bergstroemi n. sp., Cambrunicornia saxonica n. sp., Ornamentaspis? aff. todraensis Geyer 1990, Calodiscus? n. sp., Resten von zwei unbestimmbaren Arten vermutlich olenelloider und paradoxidider Trilobiten, mindestens zwei Brachiopoden (Trematobolus, ein nicht pra¨zise bestimmbarer Acrotretide) sowie einem Hyolithen-Operculum. Die Fauna belegt eine stratigraphische Position im unteren Agdzium der fu¨r WestGondwana gu¨ltigen chronostratigraphischen Gliederung und korreliert mit Schichten des untersten bis unteren Mittelkambrium in Regionen wie den marokkanischen AtlasKetten und Nord-Spanien. Damit repra¨sentieren die Vergesellschaftungen die a¨ltesten mittelkambrischen Faunen, die aus dem Saxothuringikum bekannt geworden sind. Sie besta¨tigen ebenso die pala¨ogeographische Position

123

240

im Perigondwana-Segment. Die lithologischen Unterschiede der fossilfu¨hrenden Schichten zur typischen Ausbildung der Tro¨bitz-Formation und die dokumentierten hochenergetischen Ablagerungsbedingungen lassen hochfrequente Meeresspiegelschwankungen in diesem Teil des Profils vermuten und scheinen eine spa¨te Phase der subglobal nachweisbaren eustatischen Meeresspiegelschwankungen im traditionellen ¨ bergangsbereich Unter-/Mittelkambrium abzubilden. U Schlu¨sselwo¨rter Kambrium  Trilobita  Brachiopoda  Biostratigraphie  Meeresspiegelschwankungen  Saxothuringikum  Deutschland

Introduction Fossiliferous Cambrian rocks are rare in Central Europe but fairly well preserved in Lusatia and northern Saxony, Germany. Although the mode of preservation is quite different between the two regions, the lithologies suggest a common depositional domain that also indicates a common faunal province with distinct signatures of the West Gondwanan faunal realm. The Cambrian subsurface rocks of the Delitzsch–Torgau–Doberlug Synclinorium in northern Saxony and adjacent areas do not represent a continuous succession, because of subsequent tectonic displacement. Deposition during the Cambrian sedimentation starts after a stratigraphic and structural gap (Cadomian unconformity) with local conglomeratic debris flow deposits, followed by the Lower Cambrian composed mainly of shallow marine carbonates and minor siliciclastics with common calcimicrobial biogenic carbonates. The Middle Cambrian generally comprises siliciclastics with scarce carbonate intercalations. The Tro¨bitz Formation, dominated by quartzitic sandstones and alternating with micaceous claystones is early but not earliest Middle Cambrian (Cambrian Series 3 and Stage 5) in age as indicated by comparatively rich fossil assemblages with trilobites, inarticulate brachiopods, and hyoliths (Schmidt 1944; Sdzuy 1957a, b, 1970). The trilobites indicate a stratigraphic level corresponding to the middle to upper Agdzian sensu Geyer and Landing (2004) (=Leonian in the Iberian regional scheme; Sdzuy et al. 1999). The overlying Delitzsch Formation consists of quartzarenitic sandstones alternating with claystones. As in the Tro¨bitz Formation, the faunas are dominated by trilobites, inarticulate brachiopods, and hyoliths. Two different stratigraphic levels can be distinguished. The older level has an early Middle Cambrian age equivalent to the younger fauna of the Tro¨bitz Formation. A younger fauna with trilobites, brachiopods, and helcionelloid molluscs characterizes a

123

G. Geyer et al.

relatively narrow stratigraphic interval of mid Middle Cambrian age (early Caesaraugustan) (Geyer et al. 2008; Elicki and Geyer 2010). Unfortunately, the transition from Lower to Middle Cambrian strata is unknown. This led to the assumption that a significant stratigraphic gap between the strata of the two series is present in this area, which leaves space for the assumption of a major hiatus synchronized with subglobally recognizable eustatic sea-level fall commonly summarized as the ‘‘Hawke Bay regression’’ (Palmer and James 1980). The supposition of a major break in deposition starting well within the Early Cambrian would have suggested a late transgression so that part of the lower Middle Cambrian would not be recorded by strata. However, a newly identified faunal assemblage from the Tro¨bitz Formation in a drill core from west of Doberlug–Kirchhain and south of Herzberg (drill core 1209/78; Fig. 1), briefly reported in 2006 (Geyer and Buschmann 2006) and described in detail below, reduces this supposed hiatus considerably. This fauna represents the lowermost Middle Cambrian lower Agdzian as recorded in areas with a nearly complete record of the Lower–Middle Cambrian boundary interval (for example northern Spain and southern Morocco). Consequently, the presently recognized gap may indeed be created by incomplete biostratigraphic data rather than physical absence of strata.

Fig. 1 Distribution of Hercynian Massifs and selected structural units in present-day central and western Europe (modified from Franke 1989 and Buschmann et al. 2006). Abbreviations of structural units: AF Alpine front, AM Armorican Massif, BM Bohemian Massif, MGCH mid-German Crystalline High, RH Rheno-Hercynian Zone, ST Saxo-Thuringian Zone, TB Tepla´–Barrandian Zone, TDS Torgau– Doberlug Syncline, TESZ Teiseyre-Tornquist Line forming the northern border of the Trans-European Suture Zone

A new lowermost middle Cambrian

Geology and Cambrian stratigraphy of the Delitzsch–Torgau–Doberlug Synclinorium The Delitzsch–Torgau–Doberlug Synclinorium consists of two synclines, known as the Torgau–Doberlug Syncline (TDS) and the Delitzsch Syncline (Figs. 1, 2). The TDS is a subsurface structural unit of Ediacaran and Palaeozoic rocks in the Saxo-Thuringian Zone covered by up to 200 m of Cenozoic strata. The pre-Cenozoic rocks have been explored by use of drill holes reaching depths of up to 1,200 m. This pre-Cenozoic succession comprises Ediacaran, Lower and Middle Cambrian strata. In central parts of the TDS Vise´an rocks are present (Buschmann et al. 1995, 2006). They overlie the Cambrian strata with angular unconformity (Brause 1969; No¨ldeke 1976). The very low-grade Ediacaran rocks in the TDS are more intensely folded and cleaved than the Cambrian strata, which do not record a notable regional metamorphic overprint (Buschmann 1995). In Central Europe, a comparable succession is known only from core sections around a Variscan plutonite complex in the small Delitzsch Syncline approximately 40 km to the west (Elicki 1992; Buschmann 1995). Relationships between the Ediacaran of the TDS and the adjoining tectonostratigraphic units to the south are unclear because contacts between the structural units are buried. The Cambrian strata of the Torgau–Doberlug Syncline are lithostratigraphically subdivided into the Lower Cambrian Zwethau Formation and the Middle Cambrian Tro¨bitz and Delitzsch formations (Fig. 3) (Freyer and Suhr 1987; Brause and Elicki 1997; Elicki 1999). The substantial stratigraphic gap between the Lower and Middle

241

Cambrian formations known thus far can be interpreted either as because of a gap in the drilled rocks or as a true hiatus because the studied core profiles provided either exclusively Lower Cambrian or Middle Cambrian strata. Some authors suggested ‘‘Sardic’’ tectonic deformation (Brause 1969); this can be rejected on the basis of current information. Apparent gaps between the Middle Cambrian units are most likely to be because of the contemporary exposure situation. The total thickness of Cambrian strata in the TDS is estimated at up to 1,500? m. Deposition during the Cambrian started after a stratigraphic and structural gap termed the Cadomian unconformity (Buschmann et al. 2006; Linnemann et al. 2008). The succession commences with local conglomeratic debris flow deposits, followed by Lower Cambrian represented by shallow marine carbonates and minor siliciclastics with common calcimicrobial biogenic carbonates that contain archaeocyaths (Freyer and Suhr 1987, 1992; Elicki and Debrenne 1993; Elicki 1999), which seem to indicate an Issendalenian age sensu Geyer and Landing (2004). Bilaterian skeletal fossils are rare and do not indicate a precise stratigraphic position of the strata (Elicki 1994; Elicki and Wotte 2003). The endemic trilobite Dolerolichia pretiosa Sdzuy 1962 is best regarded as a late Early Cambrian (early Banian) fossil (Elicki and Geyer 2010). The Middle Cambrian consists of units summarized as the Arenzhain Group (composed of the Tro¨bitz and Delitzsch formations) and is represented by siliciclastics with minor carbonate intercalations (Brause 1969, 1970; Elicki 1997). The Tro¨bitz Formation is dominated by quartzitic sandstones alternating with micaceous claystones. Comparatively rich fossil associations with trilobites,

Fig. 2 Geological sketch map of the Torgau–Doberlug Syncline with distribution of rock complexes at the preCenozoic surface (according to geophysical mapping and results from drill cores) plus location of drill hole 1209/78, LS 1/63, and the adjacent old drillings ‘‘Dobrilugk’’ and D I. Values indicate UTM coordinates. Modified from Buschmann et al. (2006, Fig. 2)

123

242

Fig. 3 Cambrian stratigraphy in the Torgau–Doberlug Syncline. The Lower Cambrian succession is based on numerous core profiles whereas the Middle Cambrian column is drawn from reference profiles (boreholes D I, LS 1/63, D IV). Gaps not to scale. Modified from Elicki (2007, Fig. 3)

inarticulate brachiopods, and hyoliths indicate early, but not earliest, Middle Cambrian age. The trilobites indicate a stratigraphic level equivalent to the Iberian Eccaparadoxides sdzuyi biozone, corresponding to the middle to upper Agdzian and Celtiberian sensu Geyer and Landing (2004), i.e. Cambrian Series 3 and Stage 5 (=middle Leonian in the Iberian regional scheme; Sdzuy et al. 1999). Fossils from the drill cores were first studied by Schmidt (1944) (drill cores ‘‘Dobrilugk’’, D I and D IV; Fig. 2). This material and the material from the drill cores of the 1950s and 1960s were studied in detail by Sdzuy (1957a, b, 1958, 1970, 1972). The oldest well-documented Middle Cambrian assemblages are known from drill core LS 1/63 (close to Doberlug–Kirchhain Fig. 2) (Brause 1970). The oldest remains in this drill core were only very large fragments of thoracic segments of Paradoxides sensu lato, which Sdzuy (1970) determined as ‘‘Paradoxides’’? aff. enormis Sdzuy 1968, because tentatively determinable large sclerites were discovered in younger levels of the core. Fairly well documented assemblages were discovered in the core between the depths of 848.4 and 756.7 m. They yielded the trilobites Acadoparadoxides? sp., Kingaspidoides? incultus

123

G. Geyer et al.

(Sdzuy 1970), and Parasolenopleura lusatica Sdzuy 1970, the brachiopod ‘‘Lingulella’’ sp., and the hyoliths ‘‘Tulenicornis’’ cf. oelandicus (Holm 1893), Decoritheca? aff. affinis (Holm 1893), and ‘‘Orthotheca’’ sp. indet. (nomenclature partly emended herein). From a second stratigraphic level between the depths of 486.8 m and 385.6 m, Sdzuy (1970) described assemblages with the trilobites Acadoparadoxides cf. insularis (Westerga˚rd 1936), Paradoxides? aff. enormis Sdzuy 1968, and Kingaspidoides? incultus (Sdzuy 1970), the brachiopod ‘‘Lingulella’’ sp., and the hyoliths ‘‘Tulenicornis’’ cf. oelandicus (Holm 1893) and Decoritheca? aff. affinis (Holm 1893). The faunas from the drill cores described by Schmidt (1944) are much more diverse. However, the assemblages are difficult to characterize because of lack of precise information about some depth intervals. Nevertheless, it should be emphasized that the trilobites of the oldest assemblage include Kingaspidoides annulatus (Schmidt 1944) (not 1942 as commonly cited!) which seems to be most closely related to Kingaspidoides frankenwaldensis (Wurm 1925) from the Galgenberg Formation of the Franconian Forest (Frankenwald) area in northern Bavaria. The faunas of the Galgenberg Formation, however, can be correlated with sufficient precision with the Morocconus notabilis Zone of the Atlas ranges in Morocco, which are early Agdzian in age. This zone (earlier termed the Cephalopyge notabilis Zone and renamed because of the junior homonyme of its eponymous index species, marks a generally amply fossiliferous interval which is well recognisable in West Gondwana and other regions (Geyer and Peel 2011, Elicki and Geyer 2013). The overlying Delitzsch Formation consists of dominating quartzarenitic sandstones alternating with claystones. As in the Tro¨bitz Formation, the faunas are dominated by trilobites, inarticulate brachiopods, and hyoliths. Two different stratigraphic levels can be distinguished. The older level has an early Middle Cambrian age, equivalent to the younger faunal assemblage of the Tro¨bitz Formation. It is represented by the youngest assemblages in drill core LS 1/63 (mentioned above) between the depths of 241.4 and 197.9 m and includes the richest fauna from which Sdzuy (1970) described the trilobites Condylopyge cf. regia (Sjo¨gren 1872), Peronopsis sp., Acadoparadoxides brausei (Sdzuy 1970), Acadoparadoxides sp. indet., Parasolenopleura lusatica Sdzuy 1970, and Bailiella cf. emarginata (Linnarsson 1877), the hyoliths ‘‘Tulenicornis’’ cf. oelandicus (Holm 1893) and ‘‘Orthotheca’’ sp. indet., and the problematic fossil Oxyprymna schloppensis (Wurm 1925) (nomenclature partly emended here). The material originally described as Condylopyge cf. regia has at least partly been assigned to Condylopyge cruzensis Lin˜an and Gozalo 1986 by Sdzuy et al. (1999) and Dies & Gozalo (2004). All assemblages from the LS 1/63 drill core

A new lowermost middle Cambrian

indicate that—despite the enormous thicknesses suggested by the distances between the sample levels—the stratigraphic differences are relatively minor and all faunas belong to the lower part of the Middle Cambrian. It should be noted that Sdzuy (1970) described two new species of Acadoparadoxides from the drill cores, Acadoparadoxides brausei (Sdzuy 1970) and A. saxonicus (Sdzuy 1970) (from drill core De 8/63 near Grebehna), both of which were based on material without pygidia so that the most characteristic features are unknown. A younger fauna in the Delitzsch Formation includes also trilobites, brachiopods, and helcionelloid molluscs. Most trilobites in these assemblages, for example Badulesia tenera (Hartt in Dawson 1868), represent a relatively narrow stratigraphic interval of mid Middle Cambrian age (early Caesaraugustan).

243

calcite input or even mild dolomitization in accordance with an anchimetamorphic overprint. The general lithology of this part of the core indicates a facies that differs to some extent from that of the typical Tro¨bitz Formation. Consequently, it may be interpreted as a lithostratigraphic unit in stratigraphical contact with the Tro¨bitz Formation with its slightly younger which has not yet been identified from other parts of the Torgau–Doberlug Syncline. However, the original definition of the Tro¨bitz Formation was based solely on data from one single drill core (Brause 1970) so that the lithological variation of the formation is imperfectly known. As a result, interpretation and identification of this unit from drill cores only has led to increasing uncertainty with increasing distance from the type locality.

Preservation of the fossils Properties and characters of drill core 1209/78 The holes drilled in the 1950s, 1960s, and 1970s were intended to serve as major information in the search for mineral resources in the German Democratic Republic. A number of drill cores from the TDS had never been studied scientifically and had been deposited in a central repository. Most material of the cores has been discarded for economic reasons during reorganization in 1994, after German reunification. Among the small amount of material rescued for scientific research by staff of the TU Bergakademie Freiberg were small amounts of rocks from a core (drill core 1209/78), obtained in 1978, which penetrated Middle Cambrian rocks west of Doberlug–Kirchhain and south of Herzberg (UTM coordinates r5719848 h4581980) (Fig. 2). The Middle Cambrian rocks of this core are approximately 350 m thick up to the final depth of the core at the depth of 477 m (Fig. 4). The material included thin limestone layers with small flakes of light coloured mica intercalated with thin-bedded alternations of mudstones, siltstones, and sandstones with rapidly vacillating lithology. Also noted are layered to nodular limestones with partly conspicuous amounts of shell fragments. These calcareous horizons occur between ca. 305–435 m of the core depth (Figs. 4, 5). They more or less postdate layers with black phosphorite and glauconite grains (between ca. 430 and 450 m). Determinable faunal remains occur in the thin light colored, mostly light grayish limestone beds (up to ca. 6 cm thick) with mica flakes between ca. 305 and 345 m depth. Layers with determinable fossil remains are listed in Table 1. Mild to conspicuous recrystallization is observed for single particles within the thin beds, and the preservation is generally indicative of a notably high magnesium

The fossils from the studied horizons between ca. 300 and 345 m depth of the core include remains of three six trilobite and at least two brachiopod species. Despite the relative paucity of the fauna, because of the limited amount of material from the core, the preservation is remarkably good with only faint distortion of the specimens and partial shell preservation. The fossils are preserved as fragments of disarticulated sclerites of very different sizes and with sharp angular broken edges. They are not well sorted and sometimes of surprisingly different sizes and frequently embedded with the ventral face upward or even oblique to the bedding plane so that the remains suggest rapid deposition under high-energy conditions and limited transport. A few fossil shells are crushed, because of compaction. As noted above, the fossil shells are generally slightly recrystallized. Nevertheless, the calcite of the shells is finegrained and almost never sparry and has fairly high magnesium content. Remarkably, the surfaces show details, but often the fine sculptures appear somewhat blurry. They tend to break not exactly at the original external surface of the fossil, so exact preservation has often been difficult and the specimens tend to appear slightly out of focus on some of the photographs.

Systematic descriptions The material from this study is housed in the palaeontological collection of the TU Bergakademie Freiberg under suite number FG 625 and the additional numbers provided below. The specimens have been blackened with graphite suspension or diluted china ink before coating with magnesium oxide or ammonium chloride.

123

244

G. Geyer et al.

Fig. 4 Generalized lithological column of the core of borehole 1209/78 with the fossiliferous limestone layers studied here shown in red. Core loss and core gain are summarized for intervals with similar lithologies from cored sections. The positions of the samples are consistent with the position within the cored section

Phylum Arthropoda Latreille 1829 Class Trilobita Walch 1771 Order Agnostida Kobayashi 1935 Superfamily Eodiscoidea Richter 1932 Family Calodiscidae Kobayashi 1943 Genus Calodiscus Howell 1935 Type species. Agnostus lobatus Hall 1847. Calodiscus? n. sp. A (Fig. 9.1, 5) Material. Single partial cranidium, under FG 625/146e. Locality and horizon. Drill core 1209/78, west of Doberlug–Kirchhain and south of Herzberg, horizon at depth of 309.3 m. Description. Incomplete cranidium with a length/width ratio of presumably ca. 0.7–0.75. Glabella presumably with subparallel sides, its frontal lobe probably reaching the anterior border furrow. Dorsal furrow deeply incised, confluent with anterior border furrow. Gena subsemicircular in outline, strongly convex, greatest height exsagittally midlength, transversely ca. one-third from dorsal

123

furrows. Eyes, palpebral lobes, eye ridges and suture absent. Lateral border convex, of more-or-less equal breadth throughout. Posterior border convex, triangular in outline, developing from minimum breadth at dorsal furrow to substantial width near genal corner, probably developing into lateral border with a distinct angle of ca. 110°. Lateral border furrow distinct, groove-like, moderately broad, less well defined from border. Posterior border furrow decreasing in breadth and depth from genal angle toward dorsal furrow. Surface of exfoliated gena coarsely granulate, test on border apparently with minute granules. Discussion. The single specimen has characters typical of the species assigned to the genus Calodiscus, particularly Calodiscus schucherti (Matthew 1896) and C. ibericus (Sdzuy 1962) (originally introduced as Calodiscus schucherti ibericus Sdzuy 1962, from the Sierra Morena, southern Spain). Both share the apparently long glabella, the front of which reaches to the anterior border furrow and thus without a preglabellar field. However, the glabella in the specimen from the Herzberg core is slightly shorter than in the Iberian specimens. The similar C. agnostoides (Kobayashi1943) from Laurentian eastern North America also has fine granules on the test, but has a slightly clavate glabella (with the resulting curved dorsal furrow) (Rasetti 1952).

A new lowermost middle Cambrian

245

Mountains under the name Calodiscus n. sp. A (Geyer 1988, p. 94ff., text Figs. 22–26). As for this specimen, pygidia are unknown from the material from the approximately coeval Moroccan Morocconus notabilis Zone so sufficient diagnosis could not be provided for the Moroccan form, but we believe the current specimen belongs to the same species. The generic assignment has to remain tentative as long as a consequent taxonomic characterization of the generic concept is not established, as in the case of Calodiscus. The distinctly older, late early Cambrian species Calodiscus lobatus (Hall 1847), as the prime example and epitome of the genus (Lochman 1956; Ahlberg and Bergstro¨m 1993; Cederstro¨m et al. 2005, 2009), has a morphology which reflects a state in the ontogenetic development known from other, closely related species, the adult morphology of which would be able to accommodate them in other genera so that Calodiscus must be regarded as demonstrating a morphological blueprint within the lineage (see Lochman 1956, for an early discussion of the problem). Order Redlichiida Richter 1932 Superfamily Ellipsocephalacea Matthew 1887 Family Ellipsocephalidae Matthew 1887 Subfamily Protoleninae Richter and Richter 1948 Genus Protolenus Matthew 1892 Type species. Protolenus elegans Matthew 1892. Subgenus Hupeolenus Geyer 1990a Type species. Protolenus (Hupeolenus) hupei Geyer 1990a (by original designation). Protolenus (Hupeolenus) bergstroemi n. sp. (Figs. 6.1–18, 9.4?) Derivatio nominis. Named after the late Jan Bergstro¨m, for his eminent contribution to the knowledge on Palaeozoic arthropods.

Fig. 5 Fossiliferous limestone layers in high frequency shale–sandstone alternations of borehole 1209/78. 1 Thin lumachellic-bioclastic limestone layer (trilobite coquina); polished vertical section of drill core. 2 Relatively thick limestone layer as a result of high-energy deposition after storm events with indication of polyphase deposition and diagenetic overprint; polished vertical section of drill core with 3 cm scale. 3 Detail of 1, showing partly well-preserved transverse sections of trilobite cranidia (probably of Cambrunicornia saxonica n. sp.) and numerous transported fragments of trilobite sclerites and shell hash

Material which perfectly matches the specimen from the Herzberg drill core has been described from the Jbel Wawrmast Formation of the Moroccan High Atlas

Holotype. Incomplete cranidium, FG 625/151a. Paratypes. Twelve incomplete cranidia and cranidial fragments under FG 625/142a, 142c, 145a, 150a, 150c, 151b, 151e, 151f, 151 g, 151 h, 152a, and 153c; three incomplete thoracic segments under FG 625/141a, 145b, and 146b; one fragment of a librigenal spine assigned to P. (H.) bergstroemi under FG 625/145c. All locotypic. Type locality and horizon. Drill core 1209/78, west of Doberlug–Kirchhain and south of Herzberg, horizon at depth of 303.5 m. Diagnosis. Species of Hupeolenus with relatively broad glabella; a weakly developed diagonal depression on the fixigena; a sagittally narrow preglabellar field of less than or approximately two-thirds anterior border width (sag.) in

123

G. Geyer et al.

x

x x

x

x

x

x

x x

x

x x

x

x

x x

3.5 1209-135

342.9

0.2 1209-141

342.9

0.5 1209-143

334.8

1 1209-142

334.8

4 1209-144

328.7

2.5 1209-146

309.3

0.5 1209-145

309.3

5 1209-147

309.3

3 1209-148

309.3

10 1209-149

309.3

4 1209-150

309.3

4 1209-151

303.5

2 1209-152

303.5

1 1209-153

303.5

x

x

x

x

x

x

x

x x

x

x

Ornamentaspis? aff. todraensis Cambrunicornia saxonica n. sp. Protolenus (Hupeolenus) bergstroemi n. sp. Calodiscus? n. sp. A Depth (m) Thickness (cm)

123

Fig. 6 Protolenus (Hupeolenus) bergstroemi n. sp. All specimens c from drill core 1209/78. Scale bars equal 1 mm. 1, 6, 9, 11, FG 625/151a, holotype, incomplete cranidium, partly exfoliated, with conspicuous caeca on preglabellar field and preocular areas; longitudinal fracture created by compaction; 1 dorsal view, 6 anterior view, 9 right lateral view, 11 detail of anterior cranidium, note caeca developing from well developed parafrontal lobe. 2, 4 FG 625/153c, paratype, incomplete immature cranidium, partly exfoliated, with approximately subparallel glabellar sides, 2 dorsal view, 4 right lateral view, 3, 5, 8 FG 625/151b, paratype, immature cranidium, partly exfoliated; note dense granulation of preglabellar field and preocular areas and long palpebral lobes reaching level of posterior border furrow, 3 dorsal view, 5 anterior view, 8 left lateral view, 7 FG 625/151e, paratype, incomplete immature cranidium, latex cast of partly exfoliated internal mould; dorsal view has convex preocular areas and separation of eye ridges from palpebral lobes, 10 FG 625/150a, paratype, fragment of large cranidium, partly exfoliated; note dense granulation. 12 FG 625/151 h, paratype, cranidial fragment, latex cast of external mould. 13 FG 625/145a, paratype, incomplete cranidium, detail showing prosopon with slightly transverse elongated granules on preglabellar field and pattern of terrace ridges on anterior border, 14 FG 625/146b, paratype, incomplete thoracic segment, partly exfoliated, with large granules on axial ring and small granules on pleura and porous pattern on internal mould, and smooth surface of sagittal broad articulating half-ring, 15 FG 625/151f, paratype, cranidial fragment, latex cast of partly exfoliated anterior portion showing distinct, branched caeca on preglabellar field and preocular areas and delicate terrace ridges on anterior half of anterior border, 16 FG 625/142a, paratype, cranidial fragment, detail showing different sizes of granules on fixigena, 17 FG 625/145b, paratype, incomplete axial ring of thoracic segment with slight median transverse swelling in axial furrow, 18 FG 625/141a, paratype, incomplete axial ring of anterior thoracic segment, partly exfoliated, shows slightly forward swing of smooth articulating halfring and corresponding curvature of transverse furrow

adult individuals; a low, broad and uniform anterior border with almost flat dorsal face; and conspicuous caeca in large individuals.

Sample no.

Table 1 Size and depth of the studied fossiliferous samples in the core of drill hole 1209/78

Trilobite genus and species undet. A

x

Trilobite genus and species undet. B

x

Acrotretoid genus and species undet. A

Trematobolus sp. A

Hyolith genus and species undet. A

246

Description. Cephalon subsemicircular in adult individuals, cranidial length/width ratio in large individuals ca. 0.85; normal sized cephala with anterior margin moderately curved. Posterior margin s-shaped laterally of occipital ring and adaxially of cephalic suture, in general directed normal to axis. Glabella moderately convex in transverse section, length ca. 85 % cephalic length and occipital ring width ca. 40 % maximum cranidial width across centre of palpebral lobes in large individuals; glabella slightly tapering forward, slightly constricted at glabellar furrows, maximum width across occipital ring in large individuals approximately 1.5 times width across frontal lobe (except parafrontal lobe). Frontal lobe distinctly convex in transverse profile, glabellar front with relatively narrow curvature compared with total size of the glabella, framed by a usually well recognizable and comparatively thick parafrontal band of subequal thickness throughout, separated from frontal lobe by only a shallow furrow (Fig. 6.11). S1 well impressed, commences at axial furrows, distinctly curved backward,

A new lowermost middle Cambrian

247

123

248

clearly disconnected medially. S2 similar, but directed slightly less strongly backward; S3 shallower than S1 and S2, shorter and only slightly backward directed. Occipital furrow consists of well impressed, relatively sharp lateral sections which are only slightly backward directed, and a much shallower, broad median section with a slight forward curvature, which tends to be obscure in some specimens. Occipital ring distinctly convex in transverse section, with thick and low median tubercle at subterminal position. Posterior margin of occipital ring with moderate overall curvature, projects well beyond posterior border. Axial furrows shallow and fairly narrow, generally defined from fixigenae by rapid slope to the groove-like depression, deepest close to L3 and S3. Fixigena trapezoidal, in normal-sized to large individuals approximately 19–23 % maximum cranidial width across palpebral lobes, slightly convex in total, but with faint diagonal depression; continues into short and narrow posterolateral projection that extends transversely beyond the level of the visual surface at the posterior end of the palpebral lobe. Low, broad swelling present at posteroproximal corner of fixigena adjacent to occipital furrow. Palpebral lobe moderately long, slightly oblique to exsagittal axis, varies in exsagittal length between ca. 25 and 30 % cephalic length in adult specimens, up to slightly more than 40 % cephalic length in juvenile specimens; moderately wide, approximately 5–8 % maximum cranidial width in adult individuals, up to 13 % in juveniles, faintly growing in width from anterior tips toward maximum breath near posterior ends, sausage-shaped, more or less uniformly convex in transverse section and not divided into internal and external lobes. Palpebral furrow readily visible although fairly shallow, more or less uniform in width throughout, but with broadest portion at midlength; proceeds with clear angular bend into a narrow and shallow furrow that separates palpebral lobe from eye ridge. Eye ridge a low but distinct, straight lobe slightly oblique to axis, slightly lower than palpebral lobe and separated by a small angle as well, moderately long, clearly separated by the axial furrow from the glabella, but projects as very shallow ocular line across axial furrow to connect with the parafrontal band. Anterior border well developed, slightly convex or barlike and nearly flat in transverse section, fairly wide, ca. 9–11 % cephalic length in large specimens, up to 12 % cephalic length in juveniles, more or less equal in width up to the facial suture. Posterior margin of anterior border slopes rapidly to preglabellar field, but without a distinctly incised anterior border furrow in adult individuals. Preglabellar field narrow (sag.), ca. 5–7 % cephalic length. Preocular field subtrapezoidal, slightly convex in small individuals, almost flat in large specimens, sloping toward anterior. Posterior border relatively narrow to moderately broad (exsag.), growing in width from the axial furrows to a

123

G. Geyer et al. Fig. 7 Cambrunicornia saxonica n. sp. All specimens from drill core c 1209/78. Scale bars equal 1 mm. 1, 4, 7, FG 625/148a, paratype, incomplete cranidium, partly exfoliated; 1 dorsal view, 4 anterior view, 7 slightly oblique lateral view, 2 FG 625/146d, paratype, latex cast of partial immature cranidium, external mould with small remains of the test, 3 FG 625/148d, paratype, latex cast of partial cranidium, external mould, 5 FG 625/144b, paratype, latex cast of partial cranidium, internal mould, 6 FG 625/151c, paratype, incomplete thoracic segment; note different density of granules on axial ring and pleura, lenticular shape of articulating half-ring, and prominent fulcral thorn, 8, 10, 11 FG 625/146a, holotype, incomplete cranidium, partly exfoliated, 8 slightly oblique anterior view, 10 lateral view, 11 dorsal view, 9, 12 FG 625/142e, paratype, latex cast of partial cranidium, external mould with test fragments, 9 dorsal view, 12 lateral view, 13 FG 625/142b, paratype, cranidial fragment, internal mould; detail shows fine punctuation of anterior border, left preocular area and preglabellar field. 14, FG 625/146c, paratype, incomplete librigena with preserved test, 15 FG 625/148b, paratype, latex cast of cranidial fragment, external mould, showing well preserved palpebral lobe, palpebral furrow and adjacent distal part of fixigena; note fine granulation grading into smooth surface of palpebral lobe, 16 FG 625/144a, paratype, cranidial fragment, largely exfoliated

slight node-like swelling posterior to the end of the palpebral furrows, strongly convex, markedly curves forward and ventrally from swelling; posterior margin is s-shaped. Posterior border furrow moderately deep, normal to axis or directed slightly forward, expands distally from axial furrows. Facial suture with strongly diverging anterior branches, strongly curved toward axis when reaching anterior border. Anterolateral corner of cranidium projects to approximately the distal margin of palpebral lobe. Posterior braches of suture ventrally directed, slightly diverging in ventral view, with gentle convex curvature. Thorax known only from fragments of disarticulated segments. Axial ring moderately convex in transverse section, with well impressed or even deep transverse furrow; postannulus with weak sagittal convexity, but relatively steep anterior face; weak median axial node present in some segments at least. Articulating half-ring moderately broad, and gently and equally convex in sagittal section in anterior segments, approximately two-thirds sagittal breadth of postannulus (Fig. 6.18), enables moderately strong inflexion of adjacent segments; broader at posterior segments and with distinctly curved anterior margin (Fig. 6.14). Pleura with straight anterior margin more or less perpendicular to the length axis up to a distinct fulcral point approximately midlength of the transverse distance, directed slightly rearward from this point and finally swinging into a narrow, moderately long pleural spine. Posterior margin straight or faintly curved, swings forward to define a small indention at the base of the pleural spine. Pleural furrow fairly broad, moderately deep, with slightly shallower slope at posterior part and steeper slope anteriorly, commences close to anterior margin at axial furrow

A new lowermost middle Cambrian

249

123

250

but more or less central to pleuron for most of the distance, fades in subcentral position close to base of the pleural spine at approximately three-fourths of the pleural length. Librigena known only from a fragment showing a ca. 9.5 mm long, slender, weakly curved genal spine assigned to the species. Rostral plate, hypostome and pygidium unknown. Dorsal surface of glabella, fixigenae, preglabellar field, and preocular areas covered by medium-sized granules (Fig. 6.13, 16). Preglabellar field and preocular areas can be covered by a conspicuous network of branched caeca in a centrifugal pattern (Fig. 6.11, 15). Caeca may also be present on the fixigenae. Anteromarginal portions of the anterior cephalic border covered by terrace ridges (Fig. 6.13, 15), its posterior portions close to the slope to the border furrow sometimes carry granules. Terrace ridges sometimes present on the anterior part of the glabella. Thoracic axial ring with moderately coarse granules, pleurae finely granulose, furrows smooth (Fig. 6.14). Discussion. Protolenus (Hupeolenus) bergstroemi n. sp. has characters typical of the subgenus Hupeolenus, for example the fairly low and sagittally broad anterior border, the nearly parallel posterior part of the glabella, and a feeble diagonal depression on the fixigena. The relatively large size, the comparatively wide glabella, and the conspicuous caeca in large individuals may be counted as rather typical of the subgenus Protolenus, but the noted Hupeolenus characters are certainly much more distinct. Protolenus (H.) bergstroemi most closely resembles Protolenus (H.) termierelloides Geyer 1990a, a species first described from the upper Hupeolenus and lower Morocconus notabilis zones of the Lemdad Syncline in the Moroccan High Atlas (Geyer 1990a, p. 186–187, Fig. 64, pl. 47, Figs. 1–8; Geyer et al. 1995, p. 79, 88, 89; and Geyer and Landing 2006, p. 79, 88, 89). Protolenus (H.) bergstroemi differs from P. (H.) termierelloides in the slightly wider glabella; a more weakly developed diagonal depression on the fixigena; the absence of a recognizable ‘‘corner furrow’’ (a furrow from the proximal ends of the eye lobes toward the anterior border furrow close to the suture); a sagittally narrower preglabellar field in adult individuals (despite notable differences during ontogenetic development); and the more pronounced network of branched caeca in the large individuals of the species, at least. It is emphasized that some of these features may be enhanced by the different types of preservation and the larger size of the adult individuals in the TDS material. Protolenus (H.) termierelloides has subsequently been reported from the Valdemiedes Formation of the Iberian Chains, northern Spain (Dies et al. 2001; Gozalo et al. 2007 and Lin˜a´n et al. 2008), but these assignments remain tentative, and the illustrations of specimens from the Iberian

123

G. Geyer et al.

Chains have characters which are also visible in Protolenus (H.) bergstroemi, for example the conspicuous network of caeca on the preocular areas (Gozalo et al. 2007, p. 367, Fig. 5G). Differences in the Spanish material, however, can be recognized in the presence of a furrow from the proximal ends of the eye lobes toward the anterior border furrow and a sagittally broader preglabellar field. Protolenus (H.) dimarginatus Geyer 1990a, a species confined to the Morocconus notabilis Zone in the Moroccan Atlas ranges and also known from the Valdemiedes Formation in the Iberian Chains, is easily distinguished by the characteristic subdivision of the very broad anterior border into two bands. The type species of Hupeolenus, P. (H.) hupei Geyer 1990a, is a smaller species with a narrower glabella; a better developed diagonal furrow on the fixigena; distinct corner furrows; a broader preglabellar field; a more prominent anterior border; and relatively indistinct caeca on the preocular areas. That species is, in fact, the index fossil for the Moroccan Hupeolenus Zone. Protolenus (Hupeolenus) mckillopi Fletcher 2003 from the Brigus Formation of Avalonian southeastern Newfoundland is characterized by wide fixigenae and a low anterior border, which is barely raised above the preglabellar field and which has small but distinct punctae (Fletcher 2003, pl. 97, pl. 3, Figs. 18–20). This species, however, has a glabella with a shape that is fairly characteristic for the subgenus Protolenus (Protolenus) and could be regarded as a morphological link between the type subgenus and Hupeolenus. Genus Cambrunicornia Geyer 1990a Type species. Cambrunicornia vanlooyi Geyer 1990a. Cambrunicornia saxonica n. sp. (Fig. 7.1–16) Derivatio nominis. Named after the state of Saxony, as a reference to its location. Holotype. Incomplete cranidium FG 625/146a (Fig. 7.8, 7.10, 7.11). Paratypes. Eleven cranidia and cranidial fragments under FG 625/142b, 142e, 144a, 144b (counterpart of 144a), 146d, 148a, 148b, 148c, 148d, 149b, 150b, and 153e; one incomplete thoracic segment under FG 625/151c; one incomplete librigena under FG 625/146c. All locotypic. Type locality and horizon. Drill core 1209/78, west of Doberlug–Kirchhain and south of Herzberg, horizon at depth 303.5 m. Diagnosis. Species of Cambrunicornia with strongly convex, distinctly and more or less equally tapering glabella; fairly distinct glabellar furrows on the shell exterior; frontal lobe with thick node or spine; occipital ring clearly convex

A new lowermost middle Cambrian

in sagittal profile, with evenly curved posterior margin; preglabellar field distinctly convex. Description. Cephalon subsemicircular in adult individuals, cranidial length/width ratio in normal sized individuals ca. 0.80; anterior margin moderately to pronouncedly curved. Posterior margin more or less straight abaxial of occipital ring, directed normal to axis. Glabella strongly convex in transverse section, distinctly and more or less equally tapering forward from S1, length ca. 80 % cephalic length and occipital ring width ca. 37–40 % maximum cranidial width across centre of palpebral lobes in adult individuals; maximum width across occipital ring in large individuals nearly 1.5 times width across frontal lobe (except parafrontal lobe). Glabella with slightly curved profile in lateral view, but frontal lobe with distinct swelling or node, glabellar front with relatively narrow curvature and with low, more or less fused and often obsolescent parafrontal band. Glabellar furrows shallow to moderately impressed on the test, well impressed on internal moulds; S1 commences at axial furrows, slightly curved and distinctly directed backward, disconnected medially. S2 similar, faintly curved and slightly less strongly backward directed; S3 similar, slightly shallower than S1 and S2, slightly backward directed, tends to proceed as a very shallow depression across the midline. Occipital furrow consists of well impressed, sharp lateral sections almost normal to axis, and a slightly shallower and slightly broader median section. Occipital ring distinctly convex in transverse and sagittal section; its posterior margin with moderate overall curvature, projects well beyond posterior border. Axial furrows fairly narrow, more or less defined by changing convexities, a low groove-like depression for short sections. Fixigena trapezoidal with slightly curved anterior and anterolateral margins, in adult individuals approximately 40 % cephalic length and approximately 22–26 % maximum cranidial width across palpebral lobes, continues into short and narrow, strongly ventrally defected posterolateral projection that extends transversely beyond the level of the visual surface at the posterior end of the palpebral lobe. Low, broad swelling present at posteroproximal corner of fixigena adjacent to occipital furrow. Palpebral lobe moderately long, slightly oblique to exsagittal axis, varies in exsagittal length between ca. 25 and 30 % cephalic length in adult specimens; moderately wide (approx. 5–8 % maximum cranidial width in adult individuals), developed as distinctly upturned surface oblique to the vertical axis, lenticular in dorsal view with moderately curved adaxial margin and more strongly curved margin at suture to the visual surface, slightly convex in longitudinal profile. Palpebral furrow shallow, on the external surface of the test marked only as change in

251

convexities between fixigena and palpebral lobe; proceeds into shallow depression that separates palpebral lobe from eye ridge. Eye ridge a low but distinct, faintly curved ridge slightly oblique to axis, describes a distinct angle to the palpebral lobe, clearly separated by the axial furrow from the glabella. Anterior border narrow (sag.), ca. 8–9 % cephalic length in adult specimens, slightly convex in transverse section, more or less equal in width up to the facial suture. Anterior border furrow a shallow indistinct groove ill-defined from the preglabellar field and preocular areas. Preglabellar field moderately broad (sag.), ca. 15 % cephalic length, slightly convex. Preocular field subtrapezoidal, slightly to moderately convex, sloping toward anterior border furrow. Posterior border moderately broad (exsag.), faintly growing in width from axial furrows to a slight node-like swelling posterior to the palpebral furrow, strongly convex, curves forward and deflected ventrally from swelling. Posterior border furrow a moderately deep, relatively broad groove normal to axis or directed slightly forward, slightly expands distally from axial furrows. Facial suture with distinctly diverging anterior branches, curved toward axis slightly posterior to anterior border furrow. Anterolateral corner of the cranidium projects to, approximately, the distal margin of the palpebral lobe. Posterior braches of suture ventrally directed, slightly diverging in ventral view, with gentle convex curvature. Librigena known only from a nearly complete small sclerite consisting of a moderately broad (tr.) librigenal platform, moderately convex lateral border, and a relatively prominent eye socle. No librigenal spine developed. The lateral border furrow is a shallow and fairly narrow trough, which fades posteriorly toward the suture. The furrow which separates the eye socle from the librigenal platform is formed only by a change in convexity. The posterior branch of the suture is nearly straight. The lateral margin curves adaxially in a narrow bent to create a sharp corner. Thorax known only from two fragments of disarticulated segments. Axial ring moderately convex in transverse section, with well impressed transverse furrow; postannulus with moderate sagittal convexity and slight median swelling. Articulating half-ring relatively broad and lenticular in dorsal view, approximately two-thirds sagittal breadth of postannulus (Fig. 7.6), with distinctly curved anterior margin so that a strong flexion of adjacent segments could be performed. Pleurae with straight anterior margin more or less perpendicular to the length axis, swinging anteriorly toward a distinct acute fulcral point at approximately two-thirds the transverse distance, directed rearward from this point to develop into an acute pleural spine. Posterior margin straight or faintly curved. Pleural furrow fairly broad, moderately deep, with shallow slope at posterior part and

123

252

somewhat steeper slope anteriorly, commences close to anterior margin at axial furrow to swing into a subcentral position in the pleuron for most of the distance and swing obliquely rearward into the base of the pleural spine. Rostral plate, hypostome and pygidium unknown. Dorsal surface of glabella, fixigenae, preglabellar field, preocular areas and librigenal platform densely covered by granules, which are relatively coarse on the glabella and smaller on the other parts of the cranidium (Fig. 7.3, 15). Internal moulds finely punctuate (Fig. 7.13). Anterior border nearly smooth or with fairly long terrace ridges parallel to the cephalic margin, lateral border with long, subparallel terrace ridges, librigenal corner with faint wrinkles, furrows with low, small granules. Terrace ridges sometimes present on the anterior part of the glabella (Fig. 7.4). Thoracic axial ring with moderately coarse granules, pleurae finely granulose, furrows smooth or finely granulose. Discussion. Cambrunicornia saxonica n. sp. is morphologically very similar to Cambrunicornia vanlooyi Geyer 1990a, the type species of the genus. This species from the Morocconus notabilis Zone of the central Anti-Atlas of Morocco has a slightly narrower glabella and occipital ring with a more acute front and a low, but relatively distinct swelling on the preglabellar field, whereas the preglabellar field in C. saxonica is of normal convexity following that in the preocular fields or is even slightly sunken. In addition, the occipital ring in C. saxonica is distinctly convex in sagittal profile (rather than low convexity as in C. vanlooyi) and tapers less toward axial furrow. The anterior border in C. vanlooyi is obsolescent in front of the glabella. All known specimens of C. vanlooyi with preserved exterior of the test appear to have been smooth, whereas the test in C. saxonica is finely granulose. Cambrunicornia agdzensis Geyer 1990a, also from the Morocconus notabilis Zone of the Jbel Wawrmast Formation in the central Anti-Atlas, is clearly differentiated by its slightly upturned anterior border and a number of additional characters that need not to be discussed herein. An additional species has been described as Cambrunicornia? jafnaensis Elicki and Geyer 2012 from the Numayri Member of the Burj Formation in Jordan, which is regarded as approximately coeval with strata of the Morocconus notabilis Zone of Morocco. The species from Jordan shares the type of distinctly tapering, highly convex glabella with a narrow frontal lobe and a protolenoid pattern of three pairs of obliquely backward directed glabellar furrows and a transverse occipital furrow, but lacks the node or spine on the glabellar frontal lobe and has a Protolenus-type of fixigenae with small bacculae on the posteroproximal portions and weakly raised distal portions separated by a shallow depression.

123

G. Geyer et al.

Additional material of Cambrucornia been described by ´ lvaro (2007, Fig. 4G–I) from the Cantabrian Mountains A as ‘‘Cambrunicornia? sp.’’ The description is based on a single specimen of probably an immature individual, which resembles Cambrunicornia agdziensis in most respects, but has a more strongly convex glabella. The specimen from the Cantabrian Mountains has been recovered from the top of the lower member of the La´ncara Formation, which is assigned to the top of the Bilbilian of the Iberian regional scheme and thus below the first Paradoxides assigned to P. mureroensis. This level corresponds again to the lower Agdzian of the West Gondwanan standard and the Hupeolenus to lowermost Morocconus notabilis zones. Subfamily Ellipsocephalinae Matthew 1887 Ornamentaspis? aff. todraensis Geyer 1990a (Fig. 8.1–3) Material. Single incomplete cranidium, partly exfoliated, under FG 625/153d. Locality and horizon. Drill core 1209/78, west of Doberlug–Kirchhain and south of Herzberg, horizon at depth of 303.5 m. Description. Cranidium with length/width ratio of ca. 0.85; anterior margin pronouncedly curved; various parts of cranidium relatively smooth, separated from each other merely by changes in convexity; distinct furrows absent; glabella and the unit of preglabellar field and anterior border approach a similar overall convexity in lateral profile. Glabella moderately convex in transverse section, distinctly and more or less equally tapering forward, length ca. 70 % cephalic length; width across L1 slightly less than 40 % maximum cranidial width across centre of palpebral lobes; glabellar maximum width ca. 1.5 times width across frontal lobe; glabellar front equally rounded. Glabellar furrows obsolescent, faintly indicated as three pairs of low broad depressions. Occipital furrow consists of shallow, poorly defined lateral furrows and a median faint to obsolescent transverse depression. Occipital ring not completely preserved, obviously moderately broad (sag.), convex in transverse and sagittal section; its posterior margin probably with moderate overall curvature, projects well beyond posterior border. Axial furrows developed as moderately broad, fairly shallow concave troughs between the glabella and the fixigenae, ill-defined from the latter. Fixigena form semicircular, convex areas with their most prominent point close to the palpebral furrows, approximately 40 % cephalic length and 20 to 25 % maximum cranidial width across palpebral lobes; posterolateral parts not preserved. Palpebral lobe moderately long, slightly oblique to

A new lowermost middle Cambrian

253

oblique to axis, meets axial furrow opposite to anterolateral corners of the glabellar front. Anterior border, preglabellar field and preocular fields fused to a sagittally and transversely convex unit of slightly less than 30 % cephalic length (tr.). Posterior border and border furrow not preserved. Facial suture with nearly subparallel, ventrally directed anterior branches; posterior braches of suture ventrally not preserved. Thorax, librigena, rostral plate, hypostome and pygidium unknown. Dorsal surface of test smooth.

Fig. 8 Ornamentaspis? aff. todraensis Geyer 1990a. FG 625/153d, incomplete cranidium, partly exfoliated. 1 dorsal view, 2 right lateral view, 3 oblique anterior view. From drill core 1209/78. Scale bars equal 1 mm

Discussion. The single incomplete cranidium has characteristics of the Ellipsocephalinae, and particularly of the morphologically smooth group with genera such as Ellipsocephalus Zenker 1833, Kingaspidoides Geyer 1990a, Ornamentaspis Geyer 1990a, and Latikingaspis Geyer 1990a. However, distinct differences exist for all of these genera, particularly in the more strongly tapering glabella with comparatively narrow (tr.) frontal lobe without distinct anterolateral ‘‘corners’’ or even ‘‘winglets.’’ The overall convexities in transverse and sagittal/exsagittal directions fit largely with those found in the species of Kingaspidoides, but the fairly distinct depression which separates the frontal lobe from the convex preglabellar field does not exist in Kingaspidoides in such quality. A morphologically similar species has been described as Ornamentaspis? todraensis Geyer 1990 from the lower Middle Cambrian of the eastern Anti-Atlas, from a horizon which probably belongs to the Morocconus notabilis Zone. This species from the Anti-Atlas shares the tapering glabella and the distinct depression in front of the glabella and the kingaspidoid type of fixigenae and palpebral lobes. Even the proportions are similar in dorsal view. Differences exist, however, in the clearly more pronounced overall convexity of the Saxothuringian cranidium in sagittal direction, and a more dorsally projecting occipital ring in Ornamentaspis? todraensis. This occipital ring even projects into a fairly long terminal spine. Such a spine may have been developed in the Saxothuringian cranidium also, but most probably of a distinctly smaller size, if present at all. Additional kingaspidoid species with a somewhat tapering glabella and similar morphologies are known from Baltica, where they are described under such names as Proampyx sularpensis Ahlberg and Bergstro¨m 1978, Proampyx grandis Ahlberg and Bergstro¨m 1978, and Strenuaeva? kullingi Ahlberg and Bergstro¨m 1978 and await revision. Order and family uncertain

exsagittal axis, ca. 30 % cephalic length; moderately wide, with low overall convexity. Palpebral furrow a very shallow groove. Eye ridge a low, indistinct, ill-defined ridge

Genus and species undetermined A (Fig. 9.6)

123

254

G. Geyer et al.

Fig. 9 Trilobites from drill core 1209/78. Scale bars equal 1 mm. 1, 5, Calodiscus? n. sp. A, FG 625/146e, partial cranidium, dorsal and oblique posterior views. 2, 3, 7, Genus and species undetermined B; 2, 7, FG 625/135a, fragment of a sclerite interpreted as hypostome, entire specimen and detail showing quasi-honeycomb pattern of

meshes; 3, FG 625/135b, counterpart of FG 625/135a. 4, Protolenus (Hupeolenus) bergstroemi n. sp.?, FG 625/145c, fragment of librigenal spine. 6, Genus and species undetermined A, FG 625/135d, sclerite fragment. 8, Hyolith genus and species indeterminate A, FG 625/143b, internal mould of operculum

Material. Single fragment under FG 625/135d.

Material. Single fragment, preserved as internal mould and counterpart with recrystallized shell, under FG 625/135a and FG 625/135b (counterpart).

Locality and horizon. Drill core 1209/78, west of Doberlug–Kirchhain and south of Herzberg, horizon at depth of 342.9 m. Description and discussion. The only available material is a single small fragment of a trilobite sclerite. The specimen has transverse width of more than 4 mm and indicates a length of probably more than at least 12 mm, with distinct transverse convexity. The only visible details are moderately coarse, fairly eroded terrace ridges (crest distance ca. 0.3 mm), in a subparallel to apparently anastomosing pattern. The distinct erosion of the terrace ridges is surprising if compared with the fairly good preservation of small details in other trilobite sclerites of the samples so that the specimen may testify a secondary deposition. The identity of the specimen is difficult to indicate, but the shell fragments resemble rostral plates known in paradoxidine trilobites. Alternatively, it may be a part of the ventral side of a large librigenal spine of a paradoxidine. However, the ornamentation of this fragment also resembles patterns seen in trilobites, for example Myopsolenites palmeri (Elicki and Geyer 2013) so that confident identification of even the higher taxon is not possible. Genus and species undetermined B (Fig. 9.2, 3, 7)

123

Locality and horizon. Drill core 1209/78, west of Doberlug–Kirchhain and south of Herzberg, horizon at depth of 342.9 m. Description and discussion. The single specimen is a large fragment of ca. 21 9 13 mm in size, the margins of it preserved only as broken edges so that the true shape is unknown. Most is a more or less uniform shield of low to moderate convexity, bound by obliquely backward directed and weakly curved shallow furrows. The sclerite is covered with delicate configuration of ridges in a quasi-honeycomb pattern with mesh of the order of ca. 0.5 mm wide. The sclerite is interpreted as the remains of a large hypostome. The morphology resulting from this interpretation does not immediately match known sclerites of trilobites occurring in this stratigraphic interval of West Gondwana. The relatively significant honeycomb pattern is known best from species attributed to the olenellid genus Wanneria Walcott 1910, which, however, would not have such a type of hypostome. A similar prosopon is known from a specimen described as Callavia hastata Raw 1936 from the Avalonian Red Callavia sandstone (Ac2 horizon) of Comley, Shropshire, a distinctly older olenelline trilobite now dealt with as Callavalonia callavei (Lapworth 1888; Lieberman 2001).

A new lowermost middle Cambrian

Phylum Brachiopoda Dume´ril 1806 Class Lingulata Goryansky and Popov 1985 Order Acrotretida Kuhn 1949 Superfamily Acrotretidae Schuchert 1893 Acrotretoid genus and species indeterminate A (Fig. 10.1–4) Material. Single ventral valve under FG 625/142d, single dorsal valve under FG 625/152b. Two poorly preserved dorsal valves under FG 625/151d and 143c. Locality and horizon. Drill core 1209/78, west of Doberlug–Kirchhain and south of Herzberg, horizons at depths of 334.8 and 303.5 m. Description and discussion. The samples include a few mostly incomplete valves of acrotretoid brachiopods. The preserved characters are insufficient to enable determination

Fig. 10 Acrotretoid genus and species indeterminate A, both specimens from drill core 1209/78. Scale bars equal 1 mm. 1, 3 FG 625/142d, ventral valve with apical region partly exfoliated; ventral

255

of even genus level. Nonetheless, it is assumed herein that the best preserved specimens (described below) represent ventral and dorsal valves of the same species. Shell material phosphatic. The best preserved ventral valve (FG 625/142d) is small (ca. 1.3 mm wide), conical, with subcircular commissural outline and its greatest transverse width slightly posterior to midlength. The postlarval shell is characterized by weakly preserved concentric fila. The poor preservation does not enable determination of its generic affinity, but the specimen has the shape and attitude of genera such as Hadrotreta Rowell 1966 or Vandalotreta Mergl 1988, which are known from approximately coeval strata in Bohemia, Sardinia, Morocco, Nevada, and Greenland (Mergl 1988; Streng 1999; Mergl and Elicki 2004). The best preserved specimen of a dorsal valve (FG 625/152b) is a small, moderately convex shell ca. 1.8 mm wide, with somewhat transversely oval commissural

and right lateral views. 2, 4 FG 625/152b, dorsal valve, shell exterior with slight abrasions; dorsal and left lateral views

123

256

outline and its greatest transverse width at or slightly anterior to midlength. Postlarval shell with weakly preserved concentric fila. Two small and probably immature dorsal valves specimens (larger valve, FG 625/143c, ca. 1.5 mm wide, smaller valve, FG 625/151d, ca. 1.1 mm wide) are tentatively assigned to the same form. They have a maximum transverse width slightly anterior to midlength; lateral margins more or less evenly curved; with conspicuous sagittal and transverse convexity; beak marginal, distinctly acuminate. Ornamentation consists of moderately coarse growth lamellae, which are preserved as typically broken edges of thin laminae; radial ornamentation absent. Class Obolellata Williams et al. 1996 Order Obolellida Rowell 1965 Family Trematobolidae Popov and Holmer 2000 Genus Trematobolus Matthew 1893 Type species. Trematobolus insignis Matthew 1893. Trematobolus sp. A (Fig. 11.1–9) Reposited material. Ten valves and fragments of valves; seven dorsal valves under FG 625/147a, 147b, 147c, 149a, 150d, 153a, and 153b (counterpart of 153a); three incomplete ventral valves under FG 625/141b, 143a, and 149c (depths are given in Table 1). Description. The preserved material of Trematobolus valves is insufficient to precisely characterize the species. However, three specimens show details of characters which exclude the assignment to most of the known species. Valves dorsi-biconvex, with slightly flattened median sector, with rectimarginal commissure. Shell relatively thick. Ventral valve subcircular, widest at midlength, with evenly curved lateral margins. Beak marginal, distinctly acuminate. Particularly instructive for the internal morphology is a fragment of a ventral valve (Fig. 11.8). It includes the pseudointerarea and adjacent parts and a small part of the visceral platform. The ventral pseudointerarea is apsacline, moderately high, broadly subtriangular in outline, relatively small, and has indistinct growth lines; median part of the pseudointerarea bears pseudodeltidium developed as distinct, narrow triangular sector; anterior border of pseudointerarea with pair of tooth-like small nodes. The visceral area seems to be weakly defined in the present specimens; paired posterior adductor muscle scars relatively small and narrow, moderately incised, oblique at an angle of ca. 40° to the length axis along posterolateral margin of the visceral area.

123

G. Geyer et al.

Dorsal valve widest at or slightly posterior to midlength, lateral margins evenly curved; shallow sulcus may extend from umbo. Interior of dorsal valve with relatively weakly defined visceral area; probable anterior diductor muscle scars visible as faint, longitudinally elongate to spindleshaped impressions; possible posterior adductor scars located transverse to axis near the posterolateral margin of the valve. Ornamentation consists of fine growth lamellae; radial ornamentation of weak plications or absent. Vascular canals of the dorsal valve visible in specimen FG 625/147a forming faint to moderately well impressed grooves in different density in two bands parallel to the anterior and anterolateral margins (Fig. 11.2). Remarkable is the complex mosaic-type fragmentation of valves because of dorsoventral compaction (Fig. 11.7, 9). Discussion. Unfortunately, well-preserved ventral valves with details of the pedicle groove and the anterior part of the visceral platform are absent from the specimens studied so that the specific affinity remains questionable. The species portrayed by this material differs from almost all of the well known species of Trematobolus so it may be a yet undescribed new species. The most similar species is T. borobiensis Lin˜a´n and Mergl 2001 from the Daroca Formation and the lower Valdemiedes Formation of the Iberian Chains, Spain. This species shares with the current specimens from the 1209/78 borehole the fairly smooth median sector, weak muscle impressions in the dorsal valve, and the fairly small and variable posterior adductor muscle scars in the ventral valve (which are still larger in T. borobiensis), but differs in the apsacline rather than catacline to procline pseudointerarea. Additional striking differences from, particularly, the West Gondwanan species, for example T. simplex (Vogel 1962) from Spain (Lin˜a´n and Mergl 2001), T. splendidus Geyer and Mergl 1995, T. cleidrius Geyer and Mergl 1995, and T. serotinus Geyer and Mergl 1995, all from the Moroccan Anti-Atlas, exist in the relatively narrow and weakly developed posterior adductor muscle scars in the ventral valve (Geyer and Mergl 1995). In addition, it has a weak median groove posterior to the pedicle foramen unlike most of the aforementioned species, except for T. splendidus. Only a single ventral valve is known of Trematobolus palaestinensis Richter and Richter 1941 from the Cambrian of the Dead Sea area in Jordan. This valve seems to have had a transverse outline (despite slight distortion). Otherwise it is similar to T. splendidus but differs in a differently shaped pedicle groove. Of the many species from outside West Gondwana, Trematobolus pristinus (Matthew 1895) appears similar, but the shape of its ventral pseudointerarea is unknown. Trematobolus kempanum (Matthew 1897) has a slightly

A new lowermost middle Cambrian

257

Fig. 11 Trematobolus sp. A. All specimens from drill core 1209/78. Scale bars equal 1 mm. 1, 4 FG 625/147b, dorsal valve, dorsal and lateral views; note delicate radial plications on lateral flanks. 2 FG 625/147a, dorsal valve, view of valve interior with faint impressions of vascular and muscle scars, and corrugational grooves near margin. 3 FG 625/153a, dorsal valve, internal mould of partially exposed valve with well preserved visceral platform. 5 FG 625/150d, incompletely preserved internal mould of ventral valve; note

subsemicircular arrangement of vascular canals originating from the distal ends of the vascula lateralia. 6 FG 625/153b, counterpart of FG 625/153a, internal mould of partially exposed dorsal valve. 7 FG 625/149c, ventral valve crushed by dorsoventral compaction. 8 FG 625/141b, fragment of ventral valve; detail showing posterior and apical region. 9 FG 625/147b, incomplete valve crushed by dorsoventral compaction

elongate outline and a more strongly acuminate ventral beak, but also lacks a distinct sulcus. Its posterior adductor muscle scars are long and thin in the ventral valve, and thus very much resembles the material from Doberlug–Kirchhain in that character. However, it has a low median groove posterior to the pedicle foramen (Popov and Holmer 2000, Fig. 122.1a). Trematobolus insignis Matthew 1893, the type species of the genus from New Brunswick, is again imperfectly known, but seems to differ at least in the more strongly developed ventral posterior adductor

muscle scars. According to Walcott’s original drawings, Trematobolus excelsis Walcott 1908 from the upper Lower Cambrian Saline Valley Formation of the Waucoba Springs section, Saline Valley, Inyo County, California, also has thick posterior adductor muscle scars in the ventral valve and a thick and long pedicle groove. Walcott’s figures for the dorsal valve are indicative of remarkably low convexity, and its shell interior seems to be unknown. Trematobolus bicostatus (Goryansky 1964) (originally described in Goryansky et al. 1964, as T. pristinus

123

258

bicostatus), from the Toyonian of the Siberian Platform, differs in having a less projecting beak and more conspicuous radial ornament. Its posterior adductor muscle scars differ substantially in being broadly elliptical. Phylum? Mollusca Cuvier 1798 (non 1797) Class Hyolitha Marek 1963 Order Hyolithida Matthew 1899 Family uncertain Genus and species indeterminate A (Fig. 9.8) Reposited material. Incomplete operculum under FG 625/143b. Locality and horizon. Drill core 1209/78, west of Doberlug–Kirchhain and south of Herzberg, horizon at depth of 334.8 m. Description and discussion. The single cast of a small hyolithid operculum is far too poorly preserved to enable confident assignment to a family, genus, or even species. The specimen is semicircular in dorsal view and ca. 2.5 mm wide, with slightly inflated, collar-like conical shield and equally curved posterior margin; remains of the cardinal shield form a steep platform. In the sulcus-type process toward the cardinal shield the operculum resembles an operculum described by Sdzuy (1970, pl. I, Fig. 3) from slightly younger strata of the Tro¨bitz Formation of the Doberlug borehole LS 1/63. Sdzuy (1970) assigned this specimen as ‘‘Orthotheca aff. affinis Holm 1893.’’ This assignment is based on the shape of that operculum. The current material differs not only in the semicircular shape but also the absence of distinct clavicula.

Correlation and palaeogeographic relations The fauna described herein unequivocally features the lowest Middle Cambrian upper Hupeolenus and/or lowest Morocconus Zone (lower Agdzian in the West Gondwanan standard of Geyer and Landing 2004). Most significant are the trilobite remains. Species of Protolenus (Hupeolenus) characterize the low diversity assemblages of the Hupeolenus Zone in the Moroccan Atlas regions, but range well into the overlying Morocconus notabilis Zone (Geyer 1990a, 1990b; Geyer and Landing 2004, 2006). The new species P. (H.) bergstroemi has its closest resemblance with P. (H.) termierelloides, which ranges from the upper Hupeolenus into the Morocconus notabilis Zone in the Moroccan High Atlas, but seems also to occur in the coeval lower Valdemiedes Formation (Protolenus dimarginatus

123

G. Geyer et al.

and P. jilocanus zones; Dies et al. 2004) of the Iberian Chains. Species of Cambrunicornia are known from the lower Morocconus notabilis Zone of the Anti-Atlas, but also occur in coeval strata in Jordan (Elicki and Geyer, 2013). The ellipsocephaline trilobite has its closest relatives in species which also occur in the lowermost Middle Cambrian strata of West Gondwana (lower Agdzian) and in slightly older strata of the Baltican Holy Cross Mountains _ ´ ska and Masiak 2007; Zylin _ ´ ska and Szczepanik (Zylin 2009) and Sweden (Ahlberg and Bergstro¨m 1978; Geyer et al. 2004). Calodiscus? n. sp. almost certainly represents a species which is already known from the Morocconus notabilis Zone of the High Atlas Mountains of Morocco (Geyer 1988). Trematobolus is a characteristic obolelloid brachiopod genus distributed with a number of species in a relatively short stratigraphic interval of the traditional Lower–Middle Cambrian boundary interval. It seems to have its maximum distribution in West Gondwana (Moroccan Atlas ranges, northern Iberia, Dead Sea region), but is also known from a few spot samples in the West Avalonian New Brunswick, and is possibly known from the upper Lower Cambrian of the Death Valley region, California (Walcott 1908). Trematobolus insignis (Matthew 1893) and Trematobolus pristinus (Matthew 1895) both come from the classical Hanford Brook section of New Brunswick, where it slightly predates, or co-occurs with, the Protolenus fauna that includes species of Protolenus (Protolenus) (Matthew 1895; Westrop and Landing 2000). The stratigraphic level of these species can be correlated with the Morocconus notabilis Zone of Morocco (Geyer 1990a). Trematobolus bicostatus (Goryansky 1964) comes from a number of sections in the Anabar Uplift of eastern Siberia and occurs in strata now assigned to the Toyonian (Goryansky et al. 1964). At least the upper Toyonian, however, correlates with the lower Agdzian stage of West Gondwana (Geyer and Peel 2011). It should further be emphasized that Trematobolus characterizes a particular distinctive situation in lithofacial development. The species of this genus are obviously following opportunistic live strategies as indicated by mass occurrences such as in the Moroccan Atlas ranges (Geyer and Mergl 1995), so they tend to occur in mass assemblages. Those strata with associations dominated by individuals of Trematobolus species are typical of strata of transgressive systems tracts so that the genus is particularly representative of strata overlying stratigraphic hiatuses. To summarize, the assemblages described are not only the oldest known Middle Cambrian from the Lusatian/ Saxonian segment of the Saxothuringian but also the oldest Middle Cambrian fauna known from the Saxothuringian domain in general. All of the fairly well determinable

A new lowermost middle Cambrian

species have relatives in coeval strata of the typical West Gondwanan realm, particularly in southern Morocco, from where Hupeolenus, Cambrunicornia, and Trematobolus occur relatively frequently. They reconfirm the palaeogeographic position in the Perigondwanan segment. As noted above, the lithological characters suggest differences from the typical Tro¨bitz Formation. In accordance, the numerous limestone intercalations with indication of high-energy conditions suggests high-frequency sea-level changes, and Trematobolus as a potential indicator of transgressive developments in the basin suggests, also, that this part of the section may represent a late stage of subglobally recognizable eustatic sea-level fluctuations at the traditional Lower–Middle Cambrian boundary interval.

Conclusions Numerous thin limestone horizons in a succession dominated by siliciclastics yield low to moderately diverse assemblages with trilobites and brachiopods, including the new formally introduced herein species Protolenus (Hupeolenus) bergstroemi n. sp. and Cambrunicornia saxonica n. sp. These faunas are the earliest to early Middle Cambrian lower Agdzian as recorded in areas with a nearly complete record of the Lower–Middle Cambrian boundary interval (for example northern Spain and southern Morocco). Consequently, the gap currently recognized between Lower Cambrian and Middle Cambrian rock successions in the northern segment of the Saxothuringian domain seems to have arisen solely as a result of incomplete biostratigraphic and lithostratigraphic data rather than the physical absence of strata because of non-deposition, or subsequent erosion. Remarkably, the thin limestone layers which yield the macrofossils seem to indicate a transgressive development and frequent sea-level changes and thus parallel the environmental development seen in the coeval strata of the Jbel Wawrmast Formation in southern Morocco which marks the termination of the regressional events at the Lower– Middle Cambrian boundary interval. Acknowledgments Preparation of this article was made possible by research grant GE 549/21-1 of the Deutsche Forschungsgemeinschaft (DFG) to G.G. Most of the photography and of the preparation was performed in the research laboratory of J.S. Peel at Uppsala University, which is gratefully acknowledged. Sincere thanks are due to _ ´ ska, University of Warsaw, and R. Gozalo, Universitat de A. Zylin Vale`ncia, Burjassot, for thorough review and helpful remarks on the manuscript, to M. Streng, Uppsala University, for kind assistance and information on the acrotretoid specimens, and to E. Landing, New York State Museum, Albany, NY, for explanations of G.F. Matthew’s original stratigraphic concepts.

259

References Ahlberg, P., and J. Bergstro¨m. 1978. Lower Cambrian ptychopariid trilobites from Scandinavia. Sveriges Geologiska Underso¨kning, Avhandlingar och Uppsatser, I 4:o, Ser. Ca, 49. Ahlberg, P., and J. Bergstro¨m. 1993. The trilobite Calodiscus lobatus from the Lower Cambrian of Scania, Sweden. Geologiska Fo¨reningens i Stockholm Fo¨rhandlingar 115: 331–334. ´ lvaro, J.J. 2007. New ellipsocephalid trilobites from the lower A Cambrian member of the La´ncara Formation, Cantabrian Mountains, northern Spain. Memoirs of the Association of Australasian Palaeontologists 34: 343–355. Brause, H., 1969. Das verdeckte Altpala¨ozoikum der Lausitz und seine regionale Stellung. Abhandlungen der Deutschen Akademie der Wissenschaften Berlin, Klasse fu¨r Bergbau, Hu¨ttenwesen und Montangeologie 1968 (1). Brause, H. 1970. Ein neuer wichtiger Aufschluß im Kambrium von Doberlug–Kirchhain. Geologie 19: 1048–1065. Brause, H., and O. Elicki. 1997. Kambrium. In Stratigraphie von Deutschland, II. Ordovizium, Kambrium, Vendium, Ripha¨ikum, Teil I. Courier Forschungsinstitut Senckenberg 200:308–322. Buschmann, B., 1995. Tectonic facies analysis of the Rothstein Formation (Neoproterozoic, Saxothuringian Zone, E Germany). Unpublished Ph.D. Thesis, TU Bergakademie Freiberg. Buschmann, B., U. Linnemann, J. Schneider, and T. Su¨ß. 1995. Die cadomische Entwicklung im Untergrund der Torgau–Doberluger Synklinale. Zeitschrift fu¨r Geologische Wissenschaften 23: 729–749. Buschmann, B., O. Elicki, and P. Jonas. 2006. The Cadomian unconformity in the Saxo-Thuringian Zone, Germany: palaeogeographic affinities of Ediacaran (terminal Neoproterozoic) and Cambrian strata. Precambrian Research 147: 387–403. Cederstro¨m, P., P. Ahlberg, and E.N.K. Clarkson. 2005. Morphology, ontogeny, and enrollment of the Lower Cambrian eodiscoid trilobite Calodiscus lobatus from Sweden. Geologiska Fo¨reningens i Stockholm Fo¨rhandlingar 127: 46. Cederstro¨m, O., P. Ahlberg, E.N.K. Clarkson, C.H. Nilsson, and N. Axheimer. 2009. The lower Cambrian eodiscoid trilobite Calodiscus lobatus from Sweden: morphology, ontogeny and distribution. Palaeontology 52: 491–539 Cuvier, G., 1798. Tableau e´le´mentaire de l’histoire naturelle des animaux. pp. i–xvi, 1–710. Paris: Baudouin. Dawson, J.W., 1868. Acadian geology. The geological structure, organic remains and mineral resources of Nova Scotia, New Brunswick, and Prince Edward Island, etc. 2nd edn. i–XXVII, 1–694. London: MacMillan and Co. Dies, M.E., and R. Gozalo. 2004. Agnostida (Trilobita) de la Formacio´n Valdemiedes (Leoniense: Ca´mbrico Medio basal) de las Cadenas Ibe´ricas (NE de Espan˜a). Boletı´n Geolo´gico y Minero 115: 683–698. Dies, M.E., R. Gozalo, and E. Lin˜a´n. 2001. Protolenus (Hupeolenus) Geyer 1990 (Trilobita) en el Bilbiliense (Ca´mbrico Inferior) de Jarque (Zaragoza, Cadenas Ibe´ricas). In: Los Fo´siles y la Paleogeografı´a. XVII Jornadas de la Sociedad Espan˜ola de Paleontologı´a, 18–20 de octubre 2001, vol. 5.2, 301–309. Dies, M.E., R. Gozalo, and E. Lin˜a´n. 2004. Zonacio´n del lı´mite Bilbiliense–Leoniense (Formacio´n Valdemiedes, Ca´mbrico Inferior–Medio) en las Cadenas Ibe´ricas. Geo-Tema 6(2): 283–286. Dume´ril, A.M.C., 1806. Zoologie analytique, ou me´thode naturelle de classification des animaux, rendue plus facile a` l’aide de tableaux synoptiques. pp. i–xxxiii, 1–344. Paris: Allais. Elicki, O., 1992. Faziesanalyse der unterkambrischen Karbonate Deutschlands. Unpublished Ph.D. Thesis, TU Bergakademie Freiberg.

123

260 Elicki, O. 1994. Lower Cambrian carbonates from eastern Germany: palaeontology, stratigraphy and palaeogeography. Neues Jahrbuch fu¨r Geologie und Pala¨ontologie Abhandlungen 191(1): 69–93. Elicki, O. 1997. Biostratigraphic data of the German Cambrian— present state of knowledge. Pala¨ontologie, Stratigraphie, Fazies psf 4, Freiberger Forschungshefte C 466: 155–165. Elicki, O. 1999. Beitrag zur Lithofacies und zur Lithostratigraphie im Unterkambrium von Doberlug–Torgau. Pala¨ontologie, Stratigraphie, Fazies psf 7, Freiberger Forschungshefte C 481: 107–119. Elicki, O. 2007. Paleontological data from the Early Cambrian of Germany and paleobiogeographical implications for the configuration of central Perigondwana. Geological Society of America Special Paper 423: 143–152. Elicki, O., and F. Debrenne. 1993. The Archaeocyatha of Germany. Pala¨ontologie, Stratigraphie, Fazies psf 1, Freiberger Forschungshefte C 450: 3–40. Elicki, O., and G. Geyer. 2010. The faunal province of the southern margin of the Rheic Ocean. Cambrian biostratigraphy. In PreMesozoic Geology of Saxo-Thuringia—from the Cadomian active margin to the Variscan Orogen, eds. Linnemann, U. and R.L. Romer, 103–114. Stuttgart: Schweizerbart. Elicki, O., and G. Geyer. 2013. The Cambrian trilobites of Jordan— taxonomy, systematic and stratigraphic significance. Acta Geologica Polonica 63(1): 1–56. Elicki, O., and T. Wotte. 2003. Cambroclaves from the Cambrian of Sardinia (Italy) and Germany: constraints for the architecture of western Gondwana and the palaeogeographical and paleoecological potential of cambroclaves. Palaeogeography Palaeoclimatology Palaeoecology 195(1–2): 55–71. Fletcher, T.P. 2003. Ovatoryctocara granulata: the key to a global Cambrian stage boundary and the correlation of the olenellid, redlichiid and paradoxidid realms. Special Papers in Palaeontology 70: 73–102. Franke, W. 1989. Tectonostratigraphic units in the Variscan Belt of Europe. Geological Society of America, Special Papers 230: 67–90. ¨ ber Archaeocyathinen-Funde und den Freyer, G., and P. Suhr. 1987. U lithologischen Aufbau des Unterkambriums im Gebiet von Torgau. Zeitschrift fu¨r Geologische Wissenschaften 15: 655–680. ¨ ber Algengemeinschaften aus der Freyer, G., and P. Suhr, P. 1992. U unterkambrischen Zwethauer Folge des Gebietes von Torgau. Freiberger Forschungsheft, C 445, Pala¨ontologie:49–65. Geyer, G., 1988. Agnostida aus dem ho¨heren Unterkambrium und dem Mittelkambrium von Marokko. Teil 2: Eodiscina. Neues Jahrbuch fu¨r Geologie und Pala¨ontologie, Abhandlungen 177(1):93–133. Geyer, G. 1990a. Die marokkanischen Ellipsocephalidae (Trilobita: Redlichiida). Beringeria 3: 1–363. Geyer, G. 1990b. Revised Lower to lower Middle Cambrian biostratigraphy of Morocco. Newsletters on Stratigraphy 22(2/ 3): 53–70. Geyer, G., and B. Buschmann. 2006. A new earliest Middle Cambian faunule from Saxony (Germany) and its bearing on the tectonostratigraphic history of the Saxothuringian domain. In South Australia 2006. XI International Conference of the Cambrian Stage Subdivision Working Group, ed. Jago, J.B. Geological Society of Australia, Abstracts Number 84:14–15. Geyer, G., and E. Landing. 2004. A unified Lower–Middle Cambrian chronostratigraphy for west Gondwana. Acta Geologica Polonica 54: 179–218. Geyer, G., and E. Landing. 2006. Ediacaran–Cambrian depositional environments and stratigraphy of the western Atlas regions. In Morocco 2006 – Ediacaran–Cambrian depositional environments and stratigraphy of the western Atlas regions, eds. Geyer, G., and E. Landing. UCL Maghreb Petroleum Research Group, Infracambrian/Early Palaeozic Field Guide Series 1 and Beringeria Special Issue 6:47–120.

123

G. Geyer et al. Geyer, G., and M. Mergl. 1995. Mediterranean representatives of the obolellid Trematobolus (Brachiopoda) and a review of the genus. Pala¨ontologische Zeitschrift 69(1/2): 179–209. Geyer, G., and J.S. Peel. 2011. The Henson Gletscher Formation, North Greenland, and its bearing on the global Cambrian Series 2–Series 3 boundary. Bulletin of the Czech Geological Survey 86(3): 465–534. Geyer, G., E. Landing, and W. Heldmaier. 1995. Faunas and depositional environments of the Cambrian of the Moroccan Atlas region. In MOROCCO ‘95—the Lower–Middle Cambrian standard of western Gondwana, eds. Geyer, G., and E. Landing. Beringeria Special Issue 2:47–119. Geyer, G., A. Popp, T. Weidner, and L. Fo¨rster. 2004. New Lower Cambrian trilobites from Pleistocene erratic boulders of northern Germany and Denmark and their bearing on the intercontinental correlation. Pala¨ontologische Zeitschrift 78(1): 127–135. _ ´ ska. 2008. Cambrian. In Geyer, G., O. Elicki, O. Fatka, and A. Zylin The geology of central Europe, vol. 1. Precambrian and Palaeozoic, ed. T. McCann, 155–202. London: Geological Society of London. Goryansky, V.Y., and L.E. Popov. 1985. Morfologiya, sistematicheskoe polozhenie i proiskhozhdenie bezzamkovykh brakhiopod c karbonatnoy rakovinoy [The morphology, systematic position and origin of the inarticulate brachiopods with calcareous shells]. Paleontologicheskiy Zhurnal’ 1985(3): 3–14. Goryansky, V.Yu., L.I. Egorova, and V.E. Savitsky. 1964. O faune nizhnego kembriya srednego sklona Anabarskogo shchita. Uchenie zapiskiy nauchno-issled. instituta geologii Arktiki (NIIGA), seriya Paleontologiya i biostratigrafiya 4:5–32. ´ lvarez, J.A. Ga´mez Vintaned, and Gozalo, R., E. Lin˜a´n, M.E. Dies A E. Mayoral. 2007. The Lower–Middle Cambrian boundary in the Mediterranean subprovince. In The evolution of the Rheic Ocean: from Avalonian-Cadomian active margin to Alleghenian–Variscan collision, eds. Linnemann, U., R.D. Nance, P. Kraft, and G. Zulauf. Geological Society of America Special Paper 423:359–373. doi:10.1130/2007.2423(17). Hall, J., 1847. Natural History of New York. Palaeontology, vol. 1. Containing descriptions of the organic remains of the lower division of the New-York System. Albany: C. van Benthuysen. Holm, G., 1893. Sveriges kambrisk-siluriska Hyolithidae och Conulariidae. Sveriges geologiska Underso¨kning, Afhandlingar och Uppsatser C 112. Howell, B.F. 1935. Cambrian and Ordovician Trilobites from He´rault, Southern France. Journal of Paleontology 9: 222–238. Kobayashi, T. 1935. 935c. The Cambro-Ordovician formations and faunas of South Chosen. Palaeontology. Part 3. Cambrian faunas of South Chosen with a special study on the Cambrian trilobite genera and families. Journal of the Faculty of Science, Imperial University of Tokyo, Section II, 4:49–344. Kobayashi, T. 1943. Brief notes on the eodiscids I, their classification with a description of a new species and a new variety. Proceeding of the Imperial Academy Tokyo XIX 1: 37–42. Kuhn, O., 1949. Lehrbuch der Pala¨ozoologie. Stuttgart: Schweizerbart. Lapworth, C. 1888. On the discovery of the Olenellus fauna in the Lower Cambrian rocks of Britain. Nature 39: 212–213. Latreille, P.A., 1829. Crustace´s, Arachnides et partie des Insectes. In: Le Re`gne Animal, distribue´ d’apre`s son organisation, pour servir de base a l’histoire naturelle des animaux et d’introduction a` l’anatomie compare´, ed. G. Cuvier, Nouvelle e´dition, revue et augmente´e. Tome IV: i–xxvii, 1–584. Paris. Lieberman, B.S. 2001. Phylogenetic Analysis of the Olenellina Walcott, 1890 (Trilobita, Cambrian). Journal of Paleontology 75(1): 96–115. Lin˜an, E., and R. Gozalo. 1986. Trilobites del Ca´mbrico inferior y medio de Murero (Cordillera Ibe´rica). Memorias del Museo Paleontolo´gico, Universidad de Zaragoza 2: 1–104.

A new lowermost middle Cambrian Lin˜a´n, E., and M. Mergl. 2001. Lower and Middle Cambrian brachiopods from the Iberian Chains and Sierra Morena, Spain. Revista Espan˜ola de Paleontologı´a 16(2): 317–337. Lin˜a´n, E., M.E. Dies, J.A. Ga´mez Vintaned, R. Gozalo, and E. Mayoral. 2008. ‘‘Distinguishing eustatic and epeirogenic controls on Lower–Middle Cambrian boundary successions in West Gondwana (Morocco and Iberia)’’, by Ed Landing, Gerd Geyer and Wolfram Heldmaier, published in Sedimentology (2006), 53(4), 899–918—discussion. Sedimentology 55:723–724. Linnarsson, G., 1877. Om faunan i lagren med Paradoxides œlandicus. Sveriges geologiska Underso¨kning, Ser. C, 40, Fo¨reningen i Stockholm Fo¨rhandlingar 1877, III (12):352–375 [1–24]. Linnemann, U., R. d’Lemos, K. Drost, T. Jeffries, A. Gerdes, R.L. Romer, S.D. Samson, and R.A. Strachan. 2008. Cadomian tectonics:103–154. In: The Geology of Central Europe, vol. 1. ed. T. McCann. London: The Geological Society. Lochman, C. 1956. Stratigraphy and paleogeography of the Elliptocephala asaphoides strata in Cambridge and Hoosick quadrangles, New York. Bulletin of the Geological Society of America 67(10): 1331–1396. Marek, L. 1963. New knowledge on the morphology of Hyolithes. Sbornı´k geologickych veˇd, rˇada Paleontologie 1: 53–72. Matthew, G.F. 1887. Illustrations of the fauna of the St. John Group. No. 4.—on the smaller-eyed trilobites of Division I., with a few remarks on the species of the higher divisions of the group. Canadian Record of Science 2: 357–363. Matthew, G.F. 1892. Protolenus—a new genus of Cambrian trilobites. Bulletin of the Natural History Society of New Brunswick 10: 34–37. Matthew, G.F. 1893. Trematobolus. An articulate Brachiopod of the Inarticulate Order. Canadian Record of Science 5: 276–279. Matthew, G.F., 1895. The Protolenus Fauna. Transactions of the New York Academy of Science XIV (for 1894–1895):101–153. Matthew, G.F. 1896. Notes on the Cambrian faunas—the genus Microdiscus. American Geologist XVIII: 28–31. Matthew, G.F., 1897. The oldest Siphonotreta. Geological Magazine, new series, Decade 4, IV:68–71. Matthew, G.F., 1899. The Etcheminian Fauna of Smith Sound, Newfoundland. Transactions of the Royal Society of Canada Series 2 V:97–123. Mergl, M. 1988. Inarticulate brachiopods of early Middle Cambrian age from the High Atlas, Morocco. Vesˇtnı´k u´strˇenı´ho u´stavu geologicke´ho 63(5): 291–295. Mergl, M., and O. Elicki. 2004. Cambrian lingulid and acrotretid brachiopods from the Iglesiente area (Campo Pisano Formation, southwestern Sardinia). Rivista Italiana di Paleontologia i Stratigrafia 110(3): 581–589. No¨ldeke, W., 1976. Das Obervise´ von Doberlug–Kirchhain. Jahrbuch fu¨r Geologie 5/6 (for 1969/70):589–706. Palmer, A.R., and N.P. James. 1980. The Hawke Bay event: a circumIapetus regression near the Lower–Middle Cambrian boundary. In The Caledonides in the USA. ed. D.R. Wones, 15–18. Department of Geological Sciences, Virginia Polytechnic Institute State Univ., Memoir 2. Popov, L.E., and L.E. Holmer. 2000. Family TREMATOBOLIDAE new family: 205–206. In Treatise on Invertebrate Paleontology. Part H. Brachiopoda, vol. 2. ed. Kaesler, R.L. Boulder, CO: Geological Society of America, and Lawrence, KS: University of Kansas Press. Rasetti, F. 1952. Revision of the North American trilobites of the family Eodiscidae. Journal of Paleontology 26(3): 434–451. Raw, F. 1936. Mesonacidae of Comley in Shropshire, with a discussion of classification within the family. Quarterly Journal of the geological Society, London 92(3): 236–293. Richter, R., 1932. Crustacea (Pala¨ontologie) 840–863. In Handwo¨rterbuch der Naturwissenschaften, 2nd edn. Jena: Fischer.

261 Richter, R., and E. Richter. 1941. Das Kambrium am Toten Meer und die a¨lteste Tethys. Abhandlungen der senckenbergischen naturforschenden Gesellschaft 460: 1–50. Richter, R., and E. Richter. 1948. Zur Frage des Unter-Kambriums in Nordost-Spanien. Senckenbergiana 29: 23–39. Rowell, A.J., 1965. Inarticulata. In Treatise On Invertebrate Paleontology, Part H, Brachiopoda, ed. Moore, R.C.: H260–H296. Boulder, CO: Geological Society of America, and Lawrence, KS: University of Kansas Press. Rowell, A.J., 1966. Revision of some Cambrian and Ordovician inarticulate brachiopods. University of Kansas Paleontological Contributions, Paper 7. Schmidt, E.W., 1944. Die mittelkambrische Fauna von Doberlug. Jahrbuch der Reichsstelle fu¨r Bodenforschung 62 (for 1941):344–402. Schuchert, C. 1893. A classification of the Brachiopoda. The American Geologist 11: 141–167. Sdzuy, K. 1957a. Alter und tiergeographische Stellung des Mittelkambriums von Doberlug. Geologie 6: 465–475. Sdzuy, K. 1957b. Revision der mittelkambrischen Trilobiten von Doberlug. Senckenbergiana Lethaea 38: 7–28. Sdzuy, K. 1958. Tiergeographie und Pala¨ogeographie im europa¨ischen Mittelkambrium. Geologische Rundschau 47: 450–461. Sdzuy, K. 1962. Trilobiten aus dem Unter-Kambrium der Sierra Morena (S-Spanien). Senckenbergiana Lethaea 43(3): 181–229. Sdzuy, K. 1968. Trilobites del Ca´mbrico medio de Asturias. Trabajos de Geologı´a, Facultad de Ciencias, Universidad de Oviedo 1: 77–133. Sdzuy, K. 1970. Mittelkambrische Fossilien aus neuen Bohrungen bei Doberlug und bei Delitzsch. Geologie 19: 1066–1091. Sdzuy, K., 1972. Das Kambrium der acadobaltischen Faunenprovinz—Gegenwa¨rtiger Kenntnisstand und Probleme. Zentralblatt fu¨r Geologie und Pala¨ontologie Teil II, Jg. 1972:1–91. Sdzuy, K., E. Lin˜a´n, and R. Gozalo. 1999. The Leonian Stage (early Middle Cambrian): a unit for Cambrian correlation in the Mediterranean subprovince. Geological Magazine 136: 39–48. ¨ lands kambriska lager. Sjo¨gren, A., 1872. Om na˚gra fo¨rsteningar i O Geologiska Fo¨reningen i Stockholm Fo¨rhandlingar 1 (5) (for 1872–1873):67–80. Streng, M. 1999. Early Middle Cambrian representatives of the superfamily Acrotretoidea (Brachiopoda) from Morocco. Zeitschrift der deutschen geologischen Gesellschaft 150(1): 27–87. Vogel, K., 1962. Muscheln mit Schloßza¨hnen aus dem spanischen Kambrium und ihre Bedeutung fu¨r die Evolution der Lamellibranchiaten. Akademie der Wissenschaften und der Literatur, Mainz, Abhandlungen der mathematisch- naturwissenschaftlichen Klasse, Jg. 1962. Walch, J.E.I., 1771. Die Naturgeschichte der Versteinerungen zur Erla¨uterung der Knorrischen Sammlung von Merkwu¨rdigkeiten der Natur. Dritter Theil. [1–8], 1–235. Nu¨rnberg: Felßecker. Walcott, C.D. 1908. Cambrian Geology and Paleontology, No. 3. Cambrian Brachiopoda: description of new genera and species. Smithsonian Miscellaneous Collections LIII 3: 55–137. Walcott, C.D. 1910. Olenellus and other genera of the Mesonacidae. Smithsonian Miscellaneous Collections 53(6): 231–422. ¨ land with Westerga˚rd, A.H., 1936. Paradoxides oelandicus Beds of O the Account of a Diamond Boring through the Cambrian at Mo¨ssberga. Sveriges geologiska underso¨kning, Ser. C, 394, ˚ rsb. 30 (f. 1936), 1. A Westrop, S.R., and E. Landing. 2000. Lower Cambrian (Branchian) trilobites and biostratigraphy of the Hanford Brook Formation, southern New Brunswick. Journal of Paleontology 74(5): 858–878. Williams, A., S. Carlson, C.H.C. Brunton, L.E. Holmer, and L.E. Popov. 1996. A supra-ordinal classification of the Brachiopoda. Philosophical Transactions of the Royal Society, London 351: 1117–1193.

123

262 ¨ ber ein Vorkommen von Mittelcambrium (ParaWurm, A., 1925. U doxidesschichten) im bayrischen Frankenwald bei Wildenstein su¨dlich Presseck. Neues Jahrbuch fu¨r Mineralogie etc., Beilagen-Band 52, Abt. B:71–93. _ ´ ska, A., and M. Masiak. 2007. Cambrian trilobites from Zylin Brzecho´w, Holy Cross Mountains (Poland) and their significance

123

G. Geyer et al. in stratigraphic correlation and biogeographic reconstructions. Geological Magazine 144(4): 661–686. _ ´ ska, A., and Z. Szczepanik. 2009. Trilobite and acritarch Zylin assemblages from the Lower–Middle Cambrian boundary interval in the Holy Cross Mountains (Poland). Acta Geologica Polonica 59(4): 413–458.

Suggest Documents