Perichelydia

Perichelydia Temporal range: Middle Jurassic–Present PreꞒ Ꞓ O S D C P T J K Pg N
Meiolania
Helochelydra skull
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Pantestudines
Clade:	Testudinata
Clade:	Mesochelydia
Clade:	Perichelydia Joyce, 2017
Subgroupings
†Helochelydridae †Meiolaniformes †Sichuanchelyidae †Kallokibotion †Spoochelys †Paracryptodira? †Angolachelonia? †Macrobaenidae? †Sinemydidae? †Xinjiangchelyidae? Testudines

Perichelydia (from Greek peri "near" and chelys "turtle") is a clade within Pantestudines (turtles and their extinct relatives) known from the Middle Jurassic to Holocene. Alongside crown group Testudines, it also contains Helochelydridae, which is known from the Cretaceous of Europe and North America, Sichuanchelyidae from the Middle Jurassic to Paleocene of Asia and Europe, Meiolaniformes, which is known from the Cretaceous to Holocene of South America, Australia and Oceania,^[1] and Spoochelys, known from the Mid-Cretaceous Griman Creek Formation of Australia. Kallokibotion from the Late Cretaceous of Europe is also considered part of this group.^[2] Several other groups, including the proposed clade Angolachelonia (containing Thalassochelydia and Sandownidae), Paracryptodira, Macrobaenidae, Sinemydidae and Xinjiangchelyidae, which are sometimes considered members of Cryptodira, have also been found outside crown Testudines in several analyses. These groups are usually considered to be closer to the crown group than the other members of Perichelydia.^[3]

The clade Perichelydia was created by W. G. Joyce in 2017.^[1] They are distinguished from other mesochelydians by two characters: the presence of processus trochlearis oticum, and a closed interpterygoid vacuity.^[4]

References

1. Hans-Dieter Sues (6 August 2019). The Rise of Reptiles. 320 Million Years of Evolution. Johns Hopkins University Press. p. 53. ISBN 9781421428680.
2. Pérez-García, Adán (30 January 2020). "Surviving the Cretaceous-Paleogene mass extinction event: A terrestrial stem turtle in the Cenozoic of Laurasia". Scientific Reports. 10 (1): 1489. doi:10.1038/s41598-020-58511-8. ISSN 2045-2322. PMC 6992736. PMID 32001765.
3. Evers, Serjoscha W.; Benson, Roger B. J. (2019). "A new phylogenetic hypothesis of turtles with implications for the timing and number of evolutionary transitions to marine lifestyles in the group". Palaeontology. 62 (1): 93–134. doi:10.1111/pala.12384. ISSN 1475-4983. S2CID 134736808.
4. Joyce, Walter G. (April 2017). "A Review of the Fossil Record of Basal Mesozoic Turtles". Bulletin of the Peabody Museum of Natural History. 58 (1): 65–113. doi:10.3374/014.058.0105. ISSN 0079-032X. S2CID 54982901.