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The Middle Triassic Marine Reptile Biodiversity in the Germanic Basin,In the Centre of the Pangaean World

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The Middle Triassic Marine Reptile Biodiversity in the Germanic Basin,In the Centre of the Pangaean World Cent. Eur. J. Geosci. • 4(1) • 2012 • 9-46 DOI: 10.2478/s13533-011-0060-0 Central European Journal of Geosciences The Middle Triassic marine reptile biodiversity in the Germanic Basin,in the centre of the Pangaean world Research article Cajus G. Diedrich1∗, 1 PaleoLogic, Private Research Institute Halle/Westph., GERMANY Received 12 September 2011; accepted 16 December 2011 Abstract: The Middle Triassic fossil reptile localities near Bayreuth (Bavaria, southern Germany) consist of shallow marine autochthonous glauconitic marls and terebratulid-rich tempestite carbonates of the newly defined Bindlach and Hegnabrunn formations. Single bones and incomplete skeletons of marine reptiles have been recorded in bone beds within in the Illyrian and Fassanian stages. These include the remains of the sauropterygians Neusticosaurus sp., Lariosaurus cf. buzzii [1], Nothosaurus mirabilis [2], Paranothosaurus giganteus [2], Placodus gigas [3], Cyamodus rostratus [4], Cyamodus münsteri [5], Pistosaurus longaevus [6], and ichthyosaurs Omphalosaurus sp., and Shastasaurus sp. or proterosaur Tanystrophaeus conspicuus [7]. New skeletal reconstructions are based on the osteological analysis of three dimensionally preserved bones and skeletal remains. The large number of marine endemic placodont macroalgae feeders (P. gigas) in the Bayreuth sites coincides with the presence of invertebrate palaeocommunities that are characteristic of macroalgae meadow paleoenvironments. Most of the reptile species and genera from the Bayreuth localities also occur in beds of similar ages from the Monte San Giorgio (Switzerland/Italy) or Perledo (Italy) lagoonal areas. Ichthyosaurs and pistosaurs were adapted for open marine conditions, and may have migrated from the Panthalassa Oceans into the shallow marine Germanic Basin to reproduce, whereas placodonts and many other sauropterygians seem to have lived permanently in those shallow marine habitats, with large squamates and thecodont or smaller archosaurs in coastal areas. Keywords: Reptile biodiversity, skeletal reconstructions, Illyrian/Fassanian (Middle Triassic), palaeobiology, palaeobiogeog- raphy, reproduction zones, Germanic Basin, global faunal interchange © Versita Sp. z o.o. 1. Introduction Muschelkalk” limestone, which outcrops in the vicinity of Bayreuth, in Bavaria (southern Germany) - see Figure 1B-C; [5,7, 12, 13]. These localities occur near Heg- nabrunn, Bindlach (Bindlacher Berg), and Laineck (Os- chersberg). Four of these exposures remain accessible Several important Middle Triassic (Illyrian to Fassanian) Fig. 1C and are valuable for the recovery of missing or marine vertebrate fossil localities are known from Pan- lost information relating to historically collected material. gaea Fig.1A; [7–11]. One such area with several bone- These small quarries were already famous at the begin- rich sites is situated in the intracratonic Germanic Basin, ning of the 19th century, with the first Placodus tooth in the world famous and historically important “Upper finds reported in 1800 by Graf zu Münster [5, 14]. Inten- sive collecting during the 19th century, mainly by manual ∗E-mail: [email protected] workers in quarries on six outcrops, resulted in the col- 9 The Middle Triassic marine reptile biodiversity in the Germanic Basin,in the centre of the Pangaean world Figure 1. The investigated historical and recent Upper Muschelkalk (Middle Triassic) outcrops along the Lainecker Höhenzug, near Bayreuth (Bavaria, southern Germany), and vertebrate bone-rich or skeleton localities discussed in the text (Middle Triassic Globe after [26]; intertidals and Germanic Basin palaeogeography from [28]; Middle Triassic localities after [1, 7, 8, 22, 23, 30, 31, 42, 101, 113, 122, 158, 159, 161]). 10 Cajus G. Diedrich, Figure 2. Stratigraphy of the Lainecker Höhenzug Upper Muschelkalk (Middle Triassic) carbonates (about 70 metres thick), with the new formation subdivision, compiled from the three main localities at Laineck, Hegnabrunn and Bindlach (Bavaria). A-D. Main facies and sediment types of the Lainecker Höhenzug Upper Muschelkalk carbonates: A. Glauconitic nodular marls with infauna (here two Pleuromya) and terebratulid-dominated tempestite shell beds of the Bindlach Formation at Bindlach 1. B. Boundary between the platy limestone (Tonplatten) facies and the glauconite marl/tempestite beds at Bindlach 1. C. Variable glauconitic nodular marls and terebratulid-rich tempestites of the Hegnabrunn Formation, at Hegnabrunn. D. Variable dolomites and dark bone beds at top of the Meißner Formation / base of the Warburg Formation, in the Laineck road cutting. 11 The Middle Triassic marine reptile biodiversity in the Germanic Basin,in the centre of the Pangaean world lection of thousands of, mainly marine, reptilian teeth and bioherm colonies [31]. The Muschelkalkmuseum at In- bones, as well as the remains of two skeletons (the first gelfingen houses an overview selection of these world- Nothosaurus:[7]; and the first Pistosaurus:[14]). The famous Muschelkalk fossils, and is also famous for its late most famous “Triassic bone monograph”, which compiled Upper Muschelkalk reptile skeletons of the thecodont ar- material mainly from the Bayreuth sites, was published chosaur Batrachotomus kupferzellensis, as well as many by Meyer [7] including illustrated skeletons, skulls, and skeletal remains of amphibians from southern Germany individual postcranial bones. Most of these specimens [31]. were forgotten for a long time, but fortunately only a few Of worldwide importance are the holotypes and originals appear to have been lost during the two world wars. of fish from Bayreuth [32, 33] and, in particular, the rep- The material illustrated by Meyer [7], as well as other tile remains such as the placodont holotype and origi- previously undescribed material, is revised herein in a nal skulls of Placodus and Cyamodus [3, 4, 6, 7, 10, 12, new overview monograph, using multidisciplinary methods 13, 20, 34–43]. Cyamodus remains from Germany have including stratigraphic studies, facies analyses, osteol- recently been revised, including a full osteological and ogy, actuopalaeontology, and palaeoecology. This review palaeoecological review [44], and the main Placodus gi- has included all of the “forgotten” collections, which are gas material from Germany has also now been revised spread across several German museums. These collections in a separate monograph [17]. Not only have individual even include skeletons and mounted skeletal casts from a skulls, teeth and bones been collected from the Bayreuth number of Middle Triassic marine reptiles of the Germanic area, but also articulated skeletons of the first described Basin. Amongst these skeletons is the holotype skeleton nothosaur Nothosaurus mirabilis in the world, and the of the world’s only known placodont Placodus gigas [15], only known skeleton of the pistosaur Pistosaurus longae- the original being in the Senckenbergmuseum in Frank- vus [6, 7, 21, 45, 46]. Several bones from the famous “long- furt [15–17], with casts exhibited in the Urwelt-Museum necked lizard“ squamate Tanystrophaeus conspicuus [7] of Oberfranken at Bayreuth and at the University of Tuebin- the Germanic Basin (mainly from Bayreuth sites), have gen [18]. Also included in these collections is the holo- also been re-examined [47]. type skeleton of the placodont Henodus chelydrops [19], the paratype skeleton of Pistosaurus longaevus [20, 21], The German Middle Triassic fossil collections cover a skeletal casts of Simosaurus gaillardoti (cf. [22]), several longer history and stratigraphic range than the Monte original skeletons of the pachypleurosaur Neusticosaurus San Giorgio Swiss/Italian collections and have at least pusillus [23], as well as other skeletons such as holo- as much international value. Compared to the tectoni- types and originals from the amphibians Mastodonsaurus cally deformed and compressed bones of the Monte San giganteus and Gerrothorax pustuloglomeratus [24, 25]. Giorgio skeletons (for example [10, 48]), the Germanic Muschelkalk bones are mostly preserved in three dimen- Several German collections also contain many Middle Tri- sions (see [7], and the new ”bone atlas” presented herein assic reptile skeletons from the Germanic Basin that have ) and provide further information and interpretation pos- never been recorded from Monte San Giorgio (for example sibilities with regard to the precise bone osteology and Placodus gigas). However, this research focuses on the histology, skeletal reconstructions, and the locomotion of Middle Triassic marine and coastal species from the Up- these reptiles. The reconstructions of reptile skeletons per Muschelkalk of the Bayreuth area only and provides from the Germanic Basin presented in Diedrich [49] are an overview of the palaeobiodoversity of this rich reptile updated with few modifications based on combined inter- faunal assemblage. This study does not attempt a global pretations from skeletal material and individual bones. revision of all Middle Triassic reptiles, despite the need for such a revision, which was started [10]. In this con- The Bayreuth region of Germany represents an important tribution some species which were belived to be endemic part of the geological and palaeontological history of the are revised to occur with similar species in the Monte San Upper Muschelkalk in the Germanic Basin [27, 31, 50–55]. Giorgio and the Germanic Basin. It has provided information that allows palaeogeograph- ical, biogeographical, and palaeoenvironmental maps to The historical
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