''Psephochelys (meaning "pebbly turtle")'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

placodont Placodonts (" Tablet teeth") are an extinct order of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. They were part of Sauropterygia, the group that includes plesiosaurs. Placodonts were genera ...

reptile from the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...

of China. It is represented by a single species, ''Psephochelys polyosteoderma'', named in 2002 on the basis of a single partial skeleton found in an outcrop of the

Carnian The Carnian (less commonly, Karnian) is the lowermost stage of the Upper Triassic Series (or earliest age of the Late Triassic Epoch). It lasted from 237 to 227 million years ago (Ma). The Carnian is preceded by the Ladinian and is followed by t ...

-age Falong Formation in

Guizhou Province Guizhou (; formerly Kweichow) is a landlocked province in the southwest region of the People's Republic of China. Its capital and largest city is Guiyang, in the center of the province. Guizhou borders the autonomous region of Guangxi to the ...

. ''Psephochelys'' is classified as a member of the family

Placochelyidae Placochelyidae is an extinct family of placodonts belonging to the superfamily Cyamodontoidea. Genus *''Glyphoderma'' *''Placochelys'' *''Psephosauriscus'' *''Psephochelys ''Psephochelys (meaning "pebbly turtle")'' is an extinct genus of pla ...

, which is within the larger placodont superfamily

Cyamodontoidea Cyamodontoidea is an extinct superfamily of placodont marine reptiles from the Triassic period. It is one of the two main groups of placodonts, the other being Placodontoidea. Cyamodontoids are distinguished from placodontoids by their large shel ...

. Like other cyamodontoids, ''Psephochelys'' has a wide shell covering its body, similar to that of a turtle. However, unlike those of other cyamodontoids, the shell of ''Psephochelys'' only covers its back. The plastron, which covers the underside of other cyamodontoids, is absent, and in its place are rib-like

gastralia Gastralia (singular gastralium) are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods. They are found between the sternum and pelvis, and do not articulate with the vertebrae. In these ...

surrounded by loosely connecting

osteoderm Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amp ...

s or bony plates.

References

Placodonts Prehistoric animals of China Sauropterygian genera {{triassic-reptile-stub