Pareiasaur

Pareiasaurs Temporal range: Guadalupian - Lopingian, 270–250 Ma PreЄ Є O S D C P T J K Pg N possible descendant taxon Testudines survives to present
Scutosaurus karpinskii from the Late Permian of Russia
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Stem:	†Parareptilia
Node:	†Procolophoniformes
Suborder:	†Procolophonia
clade:	†Hallucicrania
Superfamily:	†Pareiasauroidea Lydekker, 1889
clade:	†Pareiasauria Seeley, 1888
Genera
†Bradysaurus †Velosauria †Bunostegos †Deltavjatia †Embrithosaurus †Nochelesaurus †Pareiasauridae †Pumiliopareiasauria †Anthodon †Nanopareia †Provelosaurus †Pumiliopareia Testudines? †Therischia †Arganaceras †Elginia †Parasaurus †Pareiasaurus †Pareiasuchus †Sanchuansaurus †Scutosaurus †Shansisaurus †Shihtienfenia

Pareiasaurs are a group of anapsid reptiles classified in the family Pareiasauridae and the larger clade Pareiasauria. They were large herbivores that flourished during the Permian period. Pareiasaurs ranged in size from from 60 to 300 centimetres (2.0 to 9.8 ft) long, and may have weighed up to 600 kilograms (1,300 lb).^{[citation needed]} They were stocky, with short tails, small heads, robust limbs, and broad feet. Pareiasaurs were protected by bony scutes called osteoderms that set into the skin. Their heavy skulls were ornamented with multiple knobs and ridges.

Deltavjatia vjatkensis

The leaf-shaped multi-cusped teeth resemble those of iguanas, caseids, and other reptilian herbivores. This dentition, together with the deep body, which may have housed an extensive digestive tract, are evidence of an herbivorous diet.

Some paleontologists such as Michael Lee have argued that pareiasaurs include the direct ancestors of modern turtles. Pareiasaur skulls have several turtle-like features, and in some species the scutes have developed into bony plates, possibly the precursors of a turtle shell.^[1] Jalil and Janvier, in a large analysis of pareiasaur relationships, also found turtles to be close relatives of the "dwarf" pareiasaurs, such as Pumiliopareia.^[2] However, the exact relationships of turtles remains controversial, and pareiasaur scutes may not be homologous with the shells of turtles.^[3]

Phylogeny

Below is a cladogram from Jalil and Janvier (2005):^[2]

References

• Carroll, R. L., (1988), Vertebrate Paleontology and Evolution, W.H. Freeman & Co. New York, p. 205
• Kuhn, O, 1969, Cotylosauria, part 6 of Handbuch der Palaoherpetologie (Encyclopedia of Palaeoherpetology), Gustav Fischer Verlag, Stuttgart & Portland
• Laurin, M. (1996), "Introduction to Pareiasauria - An Upper Permian group of Anapsids"
• Mikko's Phylogeny Archive Hallucicrania - Pareiasauriformes
• Palaeos Anapsida: Hallucicrania