Proterochersis
{{Short description|Extinct genus of turtles}}
{{Automatic taxobox
| fossil_range = Late Triassic
| image = Proterochersis robusta 1.JPG
| image_caption = Fossil remains of Proterochersis shell
| taxon = Proterochersis
| authority = Fraas, 1913
| subdivision_ranks = Species
| subdivision =
- {{extinct}}Proterochersis intermedia? Fraas, 1913
- {{extinct}}Proterochersis limendorsa Szczygielski & Sulej, 2016
- {{extinct}}Proterochersis porebensis Szczygielski & Sulej, 2016
- {{extinct}}Proterochersis robusta Fraas, 1913
| synonyms =
- Chelytherium obscurum Meyer, 1865Meyer H (1865). "Reptilien aus dem Stubensandstein des oberen Keupers (Dritte Folge)". Palaeontographica 14(3): p. 99–124
- Proterochersis robustum Fraas, 1913 [sic]
}}
Proterochersis is an extinct genus of turtle from the Late Triassic period (Norian stage) of Europe. It is known from a large number of fossils uncovered in Germany and Poland.Fraas E (1913). [https://core.ac.uk/download/pdf/14513165.pdf "Proterochersis, eine pleurodire Schildkröte aus dem Keuper"]. Jahreshefte des Vereins für Vaterländische Naturkunde in Württemberg 69: p. 13–30Szczygielski T & Sulej T (2016). "Revision of the Triassic European turtles Proterochersis and Murrhardtia (Reptilia, Testudinata, Proterochersidae), with the description of new taxa from Poland and Germany". Zoological Journal of the Linnean Society 177(2): pp. 395–427. {{doi|10.1111/zoj.12374}}Szczygielski1 T, Słowiak J & Dróżdż1 D (2018). "Shell variability in the stem turtles Proterochersis spp". PeerJ 6: {{doi|10.7717/peerj.6134}} The genus was named from fossil remains from Germany in 1913 by Fraas, who recognized two species: P. robusta (type species) and P. intermedia. Since then, Szczygielski and Sulej have found that the differences described by Fraas could be the result of intraspecific variation, meaning that P. intermedia are synonymous with P. robusta. They also decided to classify more recent fossil findings from Poland as two new species, P. limendorsa and P. porebensis. A study from 2021 concluded that fossil turtle remains described in 1865 as Chelytherium obscurum are probably synonymous with Proterochersis.Szczygielski T. (2021). "Obscure by name: solving the enigma of Chelytherium obscurum, the first described Triassic turtle". Zoological Journal of the Linnean Society 192(4): pp. 1111–1122. {{doi|10.1093/zoolinnean/zlaa139}} Generally, the rules of nomenclature advocate that the oldest taxonomic name should replace more recent ones, but Szczygielski choose to keep the name Proterochersis.
Description
File:Proterochersis in riverbed.png
Together with Proganochelys, Proterochersis is one of the earliest known Testudinata with a fully formed shell. Fossils show that Proterochersis was a turtle of moderate size, with a domed shell similar to modern tortoises. The shell reached a length of about {{cvt|38.5|-|40|cm|in}} in the largest known specimens.{{cite book|author=Hans-Dieter Sues|url=https://books.google.com/books?id=qGycDwAAQBAJ&dq=Proterochersis&pg=PA51|title=The Rise of Reptiles. 320 Million Years of Evolution|publisher=Johns Hopkins University Press|date=August 6, 2019|pages=50–51|isbn=9781421428680}} The shell also possesses a well developed caudal notch in the back end, indicating that Proterochesis might have possessed a fairly well developed tail, similar to modern snapping turtles.
Phylogeny
File:Proterochersis Deep Time.jpg
Proterochersis belongs to the Proterochersidae, which represent the oldest and most basal of all known shelled turtles (testudinatans). Some studies in the 2010s suggested that they belong to the crown-group of turtles, as Proterochersis possess several anatomical features in common with modern side-necked turtles (pleurodires). If Proterochersis were indeed a pleurodiran, this would mean that the crown-group of turtles originated in the Late Triassic period. More detailed research, however, concludes that the similarities with modern turtles are the result of convergent evolution and that the crown group of turtles dates back no further than to Middle Jurassic.Joyce W.G., Schoch R.R. & Lyson T.R. (2013). "The girdles of the oldest fossil turtle, Proterochersis robusta, and the age of the turtle crown". BMC Evolutionary Biology 13: 266. {{doi|10.1186/1471-2148-13-266}} Szczygielski and Sulej found Proterochersis to be more primitive than Proganochelys.
Paleoecology
There are disagreement about the lifestyle of Proterochersis. while histological data have indicated a terrestrial lifestyle,Scheyer T.M. & Sander P.M. (2007). “Shell bone histology indicates terrestrial palaeoecology of basal turtles”. Proceedings of the Royal Society B 274(1620): p. 1885–1893: {{doi|10.1098/rspb.2007.0499}} other evidence suggest that it was aquatic.Bajdek P et.al. (2019). "Bromalites from a turtle-dominated fossil assemblage from the Triassic of Poland". Palaeogeography, Palaeoclimatology, Palaeoecology 520: p. 214–228. {{doi|10.1016/j.palaeo.2019.02.002}}
References
External links
- [https://paleobiodb.org/classic/displayReference?reference_no=44570&is_real_user=1 Proterochersis] at the Paleobiology Database.
- [https://ars.els-cdn.com/content/image/1-s2.0-S0031018219300306-ga1.jpg Life restoration of Proterochersis from bajdek et.al. 2019].
{{Portal|Paleontology}}
{{Pantestudines}}
{{Taxonbar|from=Q21941971}}
Category:Late Triassic reptiles of Europe
Category:Prehistoric reptile genera