The Middle Triassic marine reptile biodiversity in the Germanic Basin, in the centre of the Pangaean world

Abstract

<jats:title>Abstract</jats:title><jats:p>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 ichthyosaursOmphalosaurus 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.</jats:p>

Middle Triassic chirotherid trackways on earthquake influenced intertidal limulid reproduction flats of the European Germanic Basin coasts

“…3), in which the chirotherid trackways described here were discovered within another megatracksite that extends across the Germanic Basin (track-beds XVIII-XIX). The tracks were found in the Judicarites zoldianus cephalopod biozone (middle Anisian), which can easily be correlated throughout the entire Germanic Basin and all the way to the northern Tethys [15,72,73,75].…”

“…In Bernburg, biolaminites vary in the carbonate particle sizes up to sand size, with carbonate sand material consisting of thin, intercalated, ooid layers, demonstrating a close relationship between the tidal flats and the extensive, shallow-marine sand-bar deposits that formed in the central basin of the Lower Muschelkalk in the Berlin area [82]. This carbonate sand was transported during times of flood and was deposited on the tidal flats; however, such carbonate sand layers are absent further to the west, as this area was too far away from the shallow submarine sand bars at the time of deposition [15,75].…”

“…bernburgensis' [15]. This trackform is thought to have been produced by the largest poposauroid archosauriform Arizonasaurus [75] Fig. 14.…”

“…The shallow, fully marine 'Wellenkalke facies', typical of the eastern Osnabrücker and Jena Formations, is absent in Winterswijk, indicating a condensed section in the far western part of the basin forming thick intertidal deposits rich in tracks and bone-beds [15,75]. These layers can be correlated using stratigraphic and sedimentary sequences, including tsunamite or tempestite layers, which are composed of bone-bed layers on the coastlines (Winterswijk), and bioclastics with 5-25 cm thick bone-bearing limestone beds (e.g.…”

“…The chrono-, bio-and lithostratigraphic data and track-bed stratigraphy were additionally dated through the correlation of ceratite zones (cf. [15,75]) and by using absolute radiometric data from volcanic ash layers in the northern Tethys Ocean, south of the Alps [76,77]. The Karlstadt Formation possibly represents deposition within a Milankovitch cycle of about 400 000 years (cf.…”