English: Life restoration of the Late Triassic turtle Proterochersis laying at the bottom of a dried up riverbed. On the river bank, a coelophysid dinosaur are lurking, while a pair of pterosaurs are flying by among the trees.

• Head: the head is mostly based on skull drawings of Proganochelys.^[1] I also chose to depict Proterochersis without visible teeth (while Odontochelys possessed teeth, Proganochelys were almost toothless (except some teeth in the vomer and pterygoid).
• Shell: the shell is mostly based on restorations from Szczygielski et.al. (2018).^[2]
• Limbs: as far as I know, remains of Proterochersis limb bones are limited. Because of this, the legs, feet and claws are speculative.
• Tail: the "long" tail is speculative: while many extant species of giant tortoise have little to no tail, snapping turtles (family Cheydridae) possess fairly long tails, as do the extinct Proganochelys and Meiolania. I have restored Proterochersis with a well-developed tail, as the upper shell (carpace) of Proterochersis have a crescent-shaped incurvation posteriorly – probably to make space for a protruding tail. Other paleoartists have also restored Proterochersis with a long tail.^[3]

• Environment: the lifestyle and diet of Proterochersis are contested: it has been suggested to have been terrestrial (based on bone histology),^[4] but also to have been aquatic (bromalites attributed to Proterochersis contain remains of fish).^[3] As a compromise, I have restored it in a dried up riverbed. The coelophysid is based on fossil remains from the same Late Triassic rocks of Poland that have unearthed Proterochersis.^[5]

References

1. ↑ Gaffney E.S. (1990). “The comparative osteology of the Triassic turtle Proganochelys”. Bulletin of the American Museum of Natural History 194: 263 pages
2. ↑ Szczygielski T et.al. (2018). "Shell variability in the stem turtles Proterochersis spp". PeerJ 6:e6134. doi.org/10.7717/peerj.6134
3. ↑ ^{a b} 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.org/10.1016/j.palaeo.2019.02.002
4. ↑ 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.org/10.1098/rspb.2007.0499
5. ↑ Sulej T et.al. (2012). “A new Late Triassic vertebrate fauna from Poland with turtles, aetosaurs, and coelophysoid dinosaurs”. Journal of Vertebrate Paleontology 32(5): p. 1033-1041. doi.org/10.1080/02724634.2012.694384