Latest Articles from Zitteliana Latest 16 Articles from Zitteliana https://zitteliana.pensoft.net/ Fri, 29 Mar 2024 08:59:30 +0200 Pensoft FeedCreator https://zitteliana.pensoft.net/i/logo.jpg Latest Articles from Zitteliana https://zitteliana.pensoft.net/ Middle Cenomanian coral fauna from the Roßsteinalmen (Northern Calcareous Alps, Bavaria, Southern Germany) – a revised and extended version https://zitteliana.pensoft.net/article/113796/ Zitteliana 97: 89-147

DOI: 10.3897/zitteliana.97.113796

Authors: Hannes Löser, Winfried Werner, Robert Darga

Abstract: In the Northern Calcareous Alps, relics of a formerly widely distributed shallow marine facies belonging to the Branderfleck Formation (upper Albian to lower Turonian) crop out and contain locally abundant corals. The fauna described here derives from Middle Cenomanian sediments. This study complements a former revision. In total, the fauna includes 98 species in 46 genera, belonging to 16 scleractinian superfamilies and two octocorallian families. One species – Enallhelia octasepta – is described as new. The fauna that was formerly located at the northern part of the Apulian plate (Austroalpine unit), south of the Penninic Ocean, shows palaeobiogeographic relationships to Cenomanian faunas from the Basque-Cantabrian Basin, the Prebetic zone, the Pelagonium, and the Quillan Basin, indicating stronger connections to Tethyan rather than Boreal faunas. The fauna also shares species with Aptian and Albian, but also with Late Cretaceous faunas of the Gosau Basin. Eight genera experienced a range extension; five genera have their last occurrence in the Middle Cenomanian fauna, and three genera have their first occurrence. Although the fauna presents numerous genera that became widespread in the Late Cretaceous, its generic composition is more closely related to late Early Cretaceous corals than to post-Cenomanian corals. The faunal turnover at the Cenomanian/Turonian boundary was not marked by the sudden appearance of new faunal elements, but rather by the disappearance of taxa. Some faunal elements that constitute post-Cenomanian faunas already existed in the Cenomanian, but they were very rare. The increase of taxa after the Cenomanian/Turonian boundary took place during the Coniacian and Santonian.

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Research Article Wed, 20 Dec 2023 14:54:17 +0200
The Early Pleistocene freshwater mollusks of the Denizli Basin (Turkey): a new long-lived lake fauna at the crossroads of Pontocaspian and Aegean-Anatolian realms https://zitteliana.pensoft.net/article/115682/ Zitteliana 97: 53-88

DOI: 10.3897/zitteliana.97.115682

Authors: Thomas A. Neubauer, Frank P. Wesselingh

Abstract: We describe here a newly discovered, diverse fossil fauna of freshwater gastropods and bivalves from the Denizli Basin in SW Turkey. The material was collected from the Kolankaya Formation, for which latest chronostratigraphic and magnetostratigraphic data indicate an Early Pleistocene age, which is much younger than previously assumed for the fossil-bearing strata of the Denizli Basin. The fauna consists of at least 27 species (25 gastropods, 2 bivalves) and includes a new genus, Harzhauseria gen. nov., and 6 new species within the Hydrobiidae: Falsipyrgula ? coronata sp. nov., Graecoanatolica ? alcicekorum sp. nov., Harzhauseria schizopleura gen. et sp. nov., Iraklimelania minutissima sp. nov., Iraklimelania submediocarinata sp. nov., and Xestopyrguloides ? sagitta sp. nov. Additionally, we define lectotypes for Staja orientalis (Bukowski, 1896) and Valvata orientalis Fischer, 1866, as well as a neotype for Theodoxus percarinatus (Oppenheim, 1919). Nine of the recovered species (33.3%) are only known from the Denizli Basin. Almost half of the fauna (44.7%) is endemic to the Aegean–Anatolian region, with biogeographical affinities to the Pliocene–Early Pleistocene faunas of Rhodes, Kos, and mainland Greece, as well as the Çameli and Eşen Basin in Turkey. On the genus level, the fauna also contains several typical Pontocaspian elements. The composition points toward a typical long-lived lake environment with oligohaline conditions.

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Research Article Tue, 12 Dec 2023 15:40:57 +0200
On Paleozoic platycerate gastropods https://zitteliana.pensoft.net/article/115688/ Zitteliana 97: 29-51

DOI: 10.3897/zitteliana.97.115688

Authors: Alexander Nützel, Jan Ove Ebbestad, Barbara Seuss, Axel Munnecke, Royal H. Mapes, Alex G. Cook

Abstract: The platycerate gastropods Orthonychia yutaroi Ebbestad, sp. nov. (Ordovician, Boda Limestone, Sweden), O. enorme (Silurian, Sweden, Gotland), O. parva (Pennsylvanian, Finis Shale Member, USA), and Orthonychia sp. (Mississippian, Imo Formation, USA) are studied including their protoconch morphology. Orthonychia yutaroi is the oldest known species in Orthonychia. Platycerates contain species with both, openly and tightly coiled protoconchs. This is the first report that tightly coiled protoconchs occur in Orthonychia. This and previously published observations blur the diagnostic difference between orders Cyrtoneritimorpha (openly coiled protoconch) and Cycloneritimorpha (tightly coiled protoconch). We suggest to treat Cyrtoneritimorpha and Cycloneritimorpha as synonyms of Neritimorpha. The monotypic Devonian genus Pragoserpulina is morphological so close to the Orthonychia species reported herein that synonymy of both genera seems to be possible (and thus of the families Pragoserpulinidae and Orthonychiidae). Protoconch morphology and dimensions suggest that the studied platycerate species had planktotrophic larval development. By contrast, two studied Carboniferous euomphaloid species (one with an openly and the other with tightly coiled protoconch) have paucispiral, large protoconchs indicating non-planktotrophic larval development. We assume that openly and tightly coiled protoconchs were present in various Paleozoic gastropod clades and that selection acted against the openly coiled protoconch morphology. It has previously been proposed that increasing predation pressure in the plankton was the reason for the demise of openly coiled protoconchs (Paleozoic plankton revolution). The presence of larval planktotrophy in platycerates excludes the possibility that they belong to extant basal gastropod clades such as Patellogastropoda, Cocculiniformia, and Vetigastropoda. However, a previously proposed close relationship to Neritimorpha is corroborated.

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Research Article Tue, 12 Dec 2023 15:40:25 +0200
Biostratigraphy and sedimentary sequences of the Toarcian Hainberg section (Northwestern Harz foreland, Northern Germany) https://zitteliana.pensoft.net/article/110677/ Zitteliana 97: 1-27

DOI: 10.3897/zitteliana.97.110677

Authors: Gernot Arp, Yagmur Balmuk, Stephan Seppelt, Andreas Reimer

Abstract: A temporary outcrop in southern Lower Saxony permitted the sedimentological, geochemical and palaeontological investigation of a 40.8 m thick Toarcian section, from the top of the Amaltheenton Formation, through the Posidonienschiefer and Jurensismergel Formations, to lower parts of the Opalinuston Formation. Bed by bed collected ammonites and belemnites, bivalve associations, as well as data from neighbouring sections indicate a largely complete sequence of ammonite zones and subzones for the Lower Toarcian. A prominent stratigraphic gap at the Posidonienschiefer/Jurensismergel Formation boundary probably comprises the Semipolitum Subzone as well as the Variabilis and Thouarsense Zones. Above a condensed Dispansum Zone follows the higher Upper Toarcian with a presumably largely complete sequence of zones and subzones, although direct evidence for this is only sporadic. However, a thin condensed bed with stromatolite crusts is recognisable at the boundary Pseudoradiosa to Mactra/Aalensis Subzone. The Toarcian/Aalenian boundary can only be drawn on basis of belemnite finds at another thin condensed bed. Only a few metres above, the Opalinum Zone is evident by ammonite findings. Based on discontinuities, lithofacies, biofacies and correlations with neighbouring sections, a subdivision into alloformations, which largely correspond to formations, is applied. Based on that, a sequence stratigraphic interpretation with respect to third order transgression-regression cycles (T-R sequences) can be inferred: Above the regressive upper parts alloformation 1 (Amaltheenton Formation) with a maximum regression surface (mrs) near its top, the T-R sequence of the alloformation 2 (Posidonienschiefer Formation) is developed, with a maximum flooding surface (mfs) at the transition Falciferum/Commune Subzone and the regressive phase within the later Bifrons Zone. For the Commune Subzone, belemnite alignment indicates a seawater bottom current from SSE. The following maximum regression surface (mrs) lies near the Bifrons/Variabilis Zone boundary. The next sequence is not preserved at the studied location, but is preserved further East as well as further West, represented by the transgressive Dörnten Member (Variabilis and Thouarsense Zone). However, the regressive phase (Fallaciosum Subzone) is also missing there, indicated by a prominent sequence boundary with erosional relief at the base of the Dispansum Zone. The following alloformation 3 (Jurensismergel Formation and lowermost parts Opalinuston Formation) represents another T-R sequence with a maximum transgressive surface (base Mactra/Aalensis subzone) and a slightly thicker regressive Aalensis Subzone. The following maximum regression surface represents the boundary to alloformation 4 (major parts of Opalinuston Formation), followed again by a short transgressive phase (Pseudolotharingicum Subzone), condensation horizon and a longer regressive phase (Opalinum Zone). These sequence stratigraphic interpretations are largely consistent with previous investigations in Northern and Southern Germany. Minor deviations in the timely position of maximum flooding and regression surfaces likely reflect effects of a higher subsidence at variable sedimentation rate in the North German Basin. With respect to the, at the site of investigation, incompletely exposed Opalinuston Formation, further studies on complete drill core sections are required.

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Research Article Fri, 24 Nov 2023 10:51:06 +0200
Late Jurassic (Upper Kimmeridgian) Heterobranchia (Gastropoda) of the coral-facies of Saal near Kelheim and the viciniy of Nattheim (Germany) https://zitteliana.pensoft.net/article/84187/ Zitteliana 96: 179-221

DOI: 10.3897/zitteliana.96.e84187

Authors: Joachim Gründel, Helmut Keupp, Fritz Lang, Alexander Nützel

Abstract: Forty gastropod species of the subclass Heterobranchia are described from the Upper Jurassic (Upper Kimmeridgian) reefal limestones of South Germany, including ten species in open nomenclature and further ten species of uncertain identity. Six species are new to science: Ceritella convexa sp. nov., Nerinea donosa sp. nov., Endoplocus acutus sp. nov., Endoplocus inflatus sp. nov., Pseudonerinea ? pseudomelaniformis sp. nov., and Itieroptygmatis cylindrata sp. nov. A lectotype is designated for Ptygmatis ? tornata (Quenstedt, 1852). With this final part of the study of the Late Jurassic gastropods from Saal and the Nattheim area, a total of 156 species have been reported. Of these species, 125 have been reported from Saal and 54 from the Nattheim area. Only 23 species occur in both Saal and the Nattheim area. The sample sizes (number of specimens) from Saal and the Nattheim area differ considerably and few species are shared. Diversity metrics suggest the same high diversity at both sites. The gastropod fauna from the Saal quarry has yielded particularly much new information – all new species are based on specimens from Saal. With 125 gastropod species from a single outcrop, the diversity at the Saal quarry is the highest from the Kimmeridgian worldwide. In total, up to 300 species of marine macro-invertebrates have been reported from this quarry, which is a very high point diversity. Gastropods are by far the most diverse group from Saal, which is a modern aspect of this fauna.

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Research Article Mon, 12 Dec 2022 16:44:51 +0200
Jurassic bivalves from the Spiti area of the Himalayas, northern India https://zitteliana.pensoft.net/article/87253/ Zitteliana 96: 153-178

DOI: 10.3897/zitteliana.96.87253

Authors: Franz T. Fürsich, Matthias Alberti, Dhirendra K. Pandey, Wagih S. Ayoub-Hannaa

Abstract: The present study describes and illustrates six bivalve taxa from the Early Bathonian to Early Callovian Ferruginous Oolite Formation and 24 taxa from the Callovian to basal-most Cretaceous Spiti Shale Formation of the Spiti and Zanskar areas in the Indian Himalayas. The Spiti Shale Formation contains a low-diversity bivalve fauna that is concentrated in few horizons, particularly in the lower member of the formation. With few exceptions, the bivalves are poorly preserved. Bivalve taxa recorded by earlier studies are revised wherever possible. Several of the taxa, most of which are from mid- to outer shelf environments, are characteristic of the south-eastern margin of the Neotethys, but some are also closely related to forms occurring in Kachchh, a rift basin situated at the western margin of the Indian Craton.

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Research Article Thu, 11 Aug 2022 08:56:50 +0300
An unusual specimen of the enigmatic fungal reproductive unit Windipila spinifera from the Lower Devonian Rhynie cherts of Scotland https://zitteliana.pensoft.net/article/86327/ Zitteliana 96: 145-152

DOI: 10.3897/zitteliana.96.e86327

Authors: Michael Krings

Abstract: Windipila spinifera from the Rhynie cherts is a spheroidal microfossil enveloped in a hyphal mantle from which extend prominent spines and otherwise shaped projections. It is believed to be a reproductive unit of a fungus in the Glomeromycota or zygomycetes, but features to determine the systematic affinities have not hitherto been documented. This study describes a new specimen of W. spinifera that contains a single spherical structure from which a hypha arises that extends outside and terminates in what appears to be a sporangium. The specimen is reminiscent of germinated zygospores of the germ-sporangial type, and thus may suggest affinities of W. spinifera to the zygomycetes. However, the interior sphere and its outgrowth could also be a part of another organism that had invaded W. spinifera.

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Research Article Mon, 8 Aug 2022 19:10:49 +0300
A possible terrestrial egg cluster in driftwood from the Lower Jurassic (Late Pliensbachian) of Buttenheim (Franconia, Germany) https://zitteliana.pensoft.net/article/84493/ Zitteliana 96: 135-143

DOI: 10.3897/zitteliana.96.84493

Authors: Franz-Josef Scharfenberg, Helmut Keupp, Johann Schobert

Abstract: Our paper shows several clusters of circular fossil egg capsules from the Franconian Amaltheenton Facies (Lower Jurassic, Upper Pliensbachian), mostly found in the clay pit south of Buttenheim. The egg capsules are scatteredly and irregularly arranged on various substrates like calcareous nodules, mollusk shells, or sunken driftwoods. Marine gastropods have been presumed as their producers spawning their eggs autochthonous. Only one specimen exhibits a regular honeycomb-like pattern of small pyritized eggs deposited seemingly within driftwood but originally lead in a small deadwood break. We interpret it as representing a possible allochthonous insect spawn drifted off from the about 70 km removed coastal region.

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Research Article Mon, 27 Jun 2022 11:55:35 +0300
Lanternfish otoliths (Myctophidae, Teleostei) from the Miocene of Japan https://zitteliana.pensoft.net/article/83571/ Zitteliana 96: 103-134

DOI: 10.3897/zitteliana.96.83571

Authors: Werner Schwarzhans, Fumio Ohe, Yuki Tsuchiya, Atsushi Ujihara

Abstract: Lanternfishes (Myctophidae) are one of the most common groups of fishes in the mesopelagic zone of the world ocean, and their otoliths have been dominant in pelagic sediments since at least Miocene times. Many species have a wide geographic distribution, with several being circumglobal. This wide distribution makes myctophid otoliths potentially useful for supraregional stratigraphic purposes. The Sea of Japan and the Northwest Pacific is an important region for investigations into the diversity and evolution of the Myctophidae. Here, we describe a large collection of myctophid otoliths from the late early to early middle Miocene (late Burdigalian to early Langhian) from six localities on western and central Honshu, which were under warm water influence during that time. A total of 22 species are recognized, of which eight are new. In the order in which they are described, the new species are Bolinichthys higashibesshoensis sp. nov., Ceratoscopelus brevis sp. nov., Lampadena exima sp. nov., Lampanyctus lenticularis sp. nov., Lampanyctus tsuyamaensis sp. nov., Stenobrachius ohashii sp. nov., Diaphus epipedus sp. nov., and Diaphus watatsumi sp. nov. At least nine species are also known from coeval sediments outside of Japan, most notably New Zealand and Europe. This distribution reflects the extraordinary geographic spread of myctophid species already in the early Miocene and indicates the potential for their future use for biostratigraphic purposes. The paleoecological and paleobiogeographical implications of the studied myctophid otolith assemblages are discussed. Furthermore, the stratigraphic ranges of the observed species are discussed and compared with data from other regions of the world in an attempt to outline the potential future application of myctophid otoliths for supraregional biostratigraphic purposes.

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Research Article Fri, 10 Jun 2022 08:02:33 +0300
Ammonites and stratigraphy of the Achdorf Formation (Braunjura Group; Aalenian) at the Wochenberg hill near Schömberg-Schörzingen (W Swabian Alb, SW Germany) https://zitteliana.pensoft.net/article/82835/ Zitteliana 96: 69-101

DOI: 10.3897/zitteliana.96.82835

Authors: Volker Dietze, Andreas Hofbauer, Hans Rieber, Norbert Wannenmacher, Günter Schweigert

Abstract: In sections of the Achdorf Formation at the Wochenberg hill (western Swabian Alb, SW Germany), a succession of five ammonite biohorizons is distinguished (from bottom to top): the crassicostatum and viallii biohorizons of the Lower Aalenian (Bifidatum Subzone, Opalinum Zone) and the latiumbilicus, discoidea α and discoidea β biohorizons of the Upper Aalenian (Murchisonae Subzone, Murchisonae Zone). The herein newly introduced viallii biohorizon is the youngest hitherto identified biohorizon of the Opalinum Zone (Bifidatum Subzone). A lectotype is designated for Staufenia latiumbilicus (Quenstedt, 1886), the index ammonite of the latiumbilicus biohorizon. The succession of biohorizons of the Murchisonae Subzone reflects the evolution of the graphoceratid late Aalenian ammonite genera Staufenia and Ludwigia.

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Review Article Wed, 11 May 2022 08:36:44 +0300
Early teleost otolith morphogenesis observed in the Jurassic of Franconia, Bavaria, southern Germany https://zitteliana.pensoft.net/article/81737/ Zitteliana 96: 51-67

DOI: 10.3897/zitteliana.96.81737

Authors: Werner Schwarzhans, Helmut Keupp

Abstract: The otoliths described in this study are from the late Pliensbachian of the Buttenheim clay pit near Bamberg, Franconia, northern Bavaria, and represent one of the earliest teleost otolith assemblages known so far. A total of 351 otoliths have been recovered, many of which are well-preserved and of sizes that indicate they originated from adult specimens and can be considered morphologically mature. The assemblage contains seven species, four of them stem teleosts of the genus Leptolepis and three from the enigmatic otolith-based genus Archaeotolithus, which cannot be attributed to a firm systematic position. We describe three species as new: Leptolepis buttenheimensis sp. nov., Leptolepis steberae sp. nov. and Archaeotolithus doppelsteini sp. nov. In addition, we review 49 otoliths from the original material of Schröder’s (1956) publication that were uncovered at the University of Erlangen. This material stems from the late Toarcian/early Aalenian and early Callovian of Franconia. In this review, we accept only a few of the species described by Schröder as valid. The otolith associations from the Early and Middle Jurassic of Franconia, in combination with previously published material, allow for an assessment of the morphogenesis of early teleost otoliths. Early Jurassic teleost otoliths are represented by a few common and long-ranging species. A sudden burst in otolith diversity seems to have occurred during the Middle Jurassic and is first evident in the Bathonian.

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Research Article Tue, 12 Apr 2022 18:33:06 +0300
First population-level study of the ammonite genus Hildoglochiceras Spath, and the Lower Tithonian record of the Hildoglochiceras Horizon in the Kachchh Basin, India https://zitteliana.pensoft.net/article/73892/ Zitteliana 96: 1-49

DOI: 10.3897/zitteliana.96.73892

Authors: Dhirendra Kumar Pandey, Franz T. Fürsich, Matthias Alberti, Ranajit Das, Federico Olóriz Sáez

Abstract: A Hildoglochiceras-rich horizon is reported from a thin carbonate intercalation within the siliciclastic Upper Jurassic Jhuran Formation of the Jara Dome, western Kachchh Mainland. The Hildoglochiceras specimens have been used for the first population-level study of the genus based on a multivariate analysis. High phenotype instability in the large sample confirms the occurrence of transient forms between morphospecies. Key morphological traits for interpreting Hildoglochiceras are stated, and the morphospecies Hildoglochiceras kobelli (Oppel) and H. kobelliforme (Bonarelli) are interpreted as a dimorphic pair. The ammonite-rich level is interpreted as a Hildoglochiceras Horizon, which is related to a transgressive pulse and maximum flooding zone interrupting largely restrictive conditions for ammonites. The endemic character of Hildoglochiceras is confirmed and related to its environmental restriction to shelf areas on the palaeomargins of the Trans-Erythraean Trough. A comprehensive review of biostratigraphic interpretations of Hildoglochiceras shows the influence of natural and experimental forcing factors. The uppermost Kimmeridgian to lowermost Upper Tithonian interval is the widest biostratigraphic range assumable for Hildoglochiceras based on existing reports, but most probably it was restricted to, or at least better represented in, Lower Tithonian horizons. The Hildoglochiceras Horizon described here is correlated with a lower part of the Albertinum/Darwini Zone in the Secondary Standard Scale for ammonite-based bio-chronostratigraphy in European and West-Tethyan areas. According to the current state of knowledge, a local rather than wide regional significance is favoured for Hildoglochiceras records before its significance for precise correlation across the Trans-Erythraean Trough.

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Research Article Wed, 2 Mar 2022 19:01:48 +0200
In search for the unlikely: Leaf-mining caterpillars (Gracillariidae, Lepidoptera) from Upper Cretaceous and Eocene ambers https://zitteliana.pensoft.net/article/63317/ Zitteliana 95: 135-145

DOI: 10.3897/zitteliana.95.63317

Authors: Thilo C. Fischer

Abstract: Fossil leaf-mining caterpillars from amber are firstly described as the new species Phyllocnistis cretacea from Upper Cretaceous Myanmar amber and Phyllonorycter inopinata from Eocene Baltic amber. Both show typical traits of leaf-miners, and specifically, of later instars of caterpillars of their respective genera. The findings give further evidence for these being quite old and conservative genera of Gracillariidae. These are basal Ditrysia which retained the larval feeding and mining live mode. The findings also represent direct fossil evidence of individual stages of hypermetamorphosis known from extant Gracillariidae. The finds from the Upper Cretaceous and their putative identifications give direct evidence for a minimal geological age for the genus Phyllocnistis (Phyllocnistinae) and, by indirect conclusion based on their divergence, also for the genus Phyllonorycter in a sister clade (Lithocolletinae). It also predates mining habit closer to the time of radiation of their angiospermous host plants.

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Research Article Wed, 8 Dec 2021 07:00:18 +0200
Paleontological inventory of Paleozoic, Late Mesozoic, and Cenozoic plant, invertebrate, and vertebrate fossil species from Big Bend National Park, Texas, USA - over a century of paleontological discovery https://zitteliana.pensoft.net/article/73026/ Zitteliana 95: 95-134

DOI: 10.3897/zitteliana.95.73026

Authors: Steven L. Wick

Abstract: The extraordinary paleontological record from Big Bend National Park (BIBE), Texas chronicles nearly 120 million years of largely uninterrupted deposition through Late Cretaceous, Paleogene and Neogene time. Therefore, the park records one of the most complete and continuous fossil records of its kind in North America, if not the world. Paleontologists have collected and studied fossils from BIBE for over a century and nearly 1400 fossil species have been reported thus far. The BIBE paleontological record includes type specimens representing 44 scientifically valid species (five plants, nine invertebrates, and 30 vertebrates). Numerous other reported specimens are very likely new to science but have yet to be formally named. The present catalog presents the currently known assemblage of fossil plant, invertebrate, and vertebrate species from BIBE within a single, comprehensive record with significant references for each. This work is designed and written to be a research and resource management tool for scientists and non-scientists alike.

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Research Article Fri, 19 Nov 2021 07:42:06 +0200
Biostratigraphy and sequence stratigraphy of the Toarcian Ludwigskanal section (Franconian Alb, Southern Germany) https://zitteliana.pensoft.net/article/56222/ Zitteliana 95: 57-94

DOI: 10.3897/zitteliana.95.56222

Authors: Gernot Arp, Sebastian Gropengießer, Christian Schulbert, Dietmar Jung, Andreas Reimer

Abstract: Extensive construction work at the canal cutting of the Ludwigskanal near Dörlbach, Franconian Alb, provided the opportunity to re-investigate a scientific-historical and biostratigraphically important reference section of the South-German Toarcian. The 16 m thick section, described bed by bed with respect to lithology and macrofossils, starts within the Upper Pliensbachian Amaltheenton Formation, covers the Toarcian Posidonienschiefer and Jurensismergel Formation, and ends in basal parts of the Opalinuston Formation. Carbonate contents are high in the Posidonienschiefer and successively decline within the Jurensismergel to basal parts of the Opalinuston. The high carbonate contents in the Posidonienschiefer are associated with comparatively low organic carbon contents. However, organic carbon contents normalized to the silicate fraction are similarily high if compared to other regions in Germany. Only the persistence of high organic carbon levels into middle parts of the Upper Toarcian differs from those of most regions in central Europe. Ammonite biostratigraphy indicates a thickness of >9 m for the Upper Pliensbachian, 1.15–1.20 m for the Lower Toarcian, 5.04 m for the Upper Toarcian, and >0.5 m for the Lower Aalenian. Despite the low sediment thickness, all Toarcian ammonite zones and almost all subzones are present, except for major parts of the Tenuicostatum Zone and the Fallaciosum Subzone. On the basis of discontinuities, condensed beds, and correlations with neighbouring sections in Southern Germany, a sequence stratigraphic interpretation is proposed for the Toarcian of this region: (i) The Posidonienschiefer Formation corresponds to one 3rd order T-R sequence, from the top of the Hawskerense Subzone to a fucoid bed at the top of the Variabilis Subzone, with a maximum flooding surface at the top of the Falciferum Zone. (ii) The Jurensismergel Formation exhibits two 3rd order T-R sequences: The first ranges from the basis of the Illustris Subzone (i.e., the Intra-Variabilis-Discontinuity) to the top of the Thouarsense Zone, with a maximum flooding surface within the Thouarsense Zone. The “belemnite battlefield” reflects a transgressive “ravinement surface” within the first Jurensismergel Sequence, not a maximum regression surface at its basis. The second sequence extents from the erosive basis of the Dispansum Zone to the top of the Aalensis Subzone, with a maximum flooding surface at the Pseudoradiosa-Aalensis Zone boundary. Finally, the Opalinuston starts with a new sequence at the basis of the Torulosum Subzone. Transgressive system tracts of these 3rd order T-R sequences are commonly phosphoritic, while some regressive system tracts show pyrite preservation of ammonites. The maximum regression surfaces at the basis of the Toarcian and within the Variabilis Zone reflect a significant submarine erosion and relief formation by seawater currents, while this effect is less pronounced at the basis of the Dispansum Zone and basis of the Torulosum Subzone (i.e., the boundary Jurensismergel-Opalinuston Formation).

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Research Article Thu, 17 Jun 2021 17:46:46 +0300
New records of ostracods and ammonites from the Aalenian (mainly Concavum Zone) of the Zollernalb (Swabian Alb, SW Germany) https://zitteliana.pensoft.net/article/56296/ Zitteliana 95: 1-55

DOI: 10.3897/zitteliana.95.56296

Authors: Norbert Wannenmacher, Volker Dietze, Matthias Franz, Günter Schweigert

Abstract: The lithostratigraphy and ammonite/ostracod biostratigraphy and the accompanying fauna of several sections and outcrops around the Hohenzollern (Zollernalb, SW Germany), ranging from the topmost Opalinuston Formation (uppermost Lower Aalenian) to the basal Wedelsandstein Formation (lowermost Lower Bajocian) are described and analyzed. The study of ostracods from 41 samples from the Aalenian and Lower Bajocian of the Heiligenbach, Hausterberg and Roschbach sections has yielded approximately 4,100 specimens. Significant changes in the ostracod assemblage occur at the base of the Lower Aalenian “Comptum” Subzone, at the Bradfordensis/Gigantea subzonal boundary, at the Bradfordensis/Concavum zonal boundary and at the Aalenian/Bajocian boundary (Concavum/Discites zones). A minor change occurs above the Calceola-Bank within the Concavum Zone. The following new ostracod species are described: Cytheropterina crassicostata sp. nov., Eucytherura eberti sp. nov. and Eucytherura foveolata sp. nov. In addition, 15 presumably new species are briefly described; 10 ‘incertae sedis’ taxa are figured, but left in open nomenclature. The ammonite faunas of the Inopernabank and Konglomeratbank beds (Upper Aalenian, Bradfordensis Zone, Gigantea Subzone) as well as the ammonite faunas from the Calceolabank and Rostrote Kalkbank beds (Upper Aalenian, Concavum Zone, Concavum Subzone, cavatum biohorizon) are described and correlated with those of other areas.

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Research Article Thu, 17 Jun 2021 16:35:30 +0300