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
(unranked):	Hallucicrania
Superfamily:	†Pareiasauroidea Lydekker, 1889
(unranked):	†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

The Pareiasaurs - Family Pareiasauridae - are a clade of medium-sized to large herbivorous anapsid reptiles that flourished during the Permian period.

Their build was quite stocky, often with rather short tails and small heads. These ungainly-looking animals had very large bodies, ranging from 60 to 300 centimetres (2.0 to 9.8 ft) long, and weights of 600 kilograms (1,300 lb) would not have been unusual. They also had strong limbs, broad feet, and short tails. They were protected with bony scutes (osteoderms) set in the skin, as a defense against predators. 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 capacious body, which could have housed an extensive digestive tract, indicate that these fearsome-looking animals were herbivores.

Michael Lee has argued that pareiasaurs include the direct ancestors of modern turtles. They had turtle-like skull features, and in several genera the scutes had developed into bony plates, possibly the precursors of a turtle shell. Jalil and Janvier, in a large analysis of pareiasaur relationships, also found turtles to be close relatives of the "dwarf" pareiasaurs, such as Pumiliopareia. However, the exact relationships of turtles remains controversial, and critics have argued that pareiasaur scutes are not homologous with the turtle shell.

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