Trilophosauridae

Trilophosaurids Temporal range: Triassic
restoration of Trilophosaurus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	†Allokotosauria
Order:	†Trilophosauria Romer, 1956
Family:	†Trilophosauridae Gregory, 1945
Genera
?†Anisodontosaurus ?†Coelodontognathus †Doniceps †Teraterpeton †Tricuspisaurus †Trilophosaurus †Spinosuchus †Variodens ?†Vitalia
Synonyms
Teraterpetidae Sues, 2003

Trilophosaurs are lizard-like Triassic allokotosaur reptiles related to the archosaurs. The best known genus is Trilophosaurus, a herbivore up to 2.5 meters long. It had a short, unusually heavily built skull, equipped with massive, broad flattened cheek teeth with sharp shearing surfaces for cutting up tough plant material. Teeth are absent from the premaxilla and front of the lower jaw, which in life were probably equipped with a horny beak.

Trilophosaurus buettneri

The skull is also unusual in that the lower temporal opening is missing, giving the appearance of a euryapsid skull, and originally the Trilophosaurs were classified with placodonts and sauropterygia. Carroll 1988 suggests that the lower opening may have been lost to strengthen the skull.

Trilophosaurs are so far known only from the Late Triassic of North America and Europe.

Below is a cladogram showing the phylogenetic relationships of Trilophosauridae within Archosauromorpha as recovered by Nesbitt et al. (2015).^[1]

Sauria

Lepidosauromorpha  Archosauromorpha  Protorosaurus speneri  Tanystropheidae  Macrocnemus bassanii Langobardisaurus pandolfii Tanytrachelos ahynis Amotosaurus rotfeldensis Tanystropheus longobardicus  Crocopoda sensu Ezcurra (2016)   Rhynchosauria  Mesosuchus browni Rhynchosaurus articeps Teyumbaita sulcognathus Archosauriformes Prolacerta broomi  Allokotosauria  Pamelaria dolichotrachela  Azendohsauridae  Azendohsaurus laaroussii Azendohsaurus madagaskarensis  Trilophosauridae  Teraterpeton hrynewichorum Trilophosaurus buettneri  Spinosuchus caseanus  "Trilophosaurus" jacobsi Spinosuchus caseanus holotype

References

1. Nesbitt, S.J.; Flynn, J.J.; Pritchard, A.C.; Parrish, M.J.; Ranivoharimanana, L.; Wyss, A.R. (2015). "Postcranial osteology of Azendohsaurus madagaskarensis (?Middle to Upper Triassic, Isalo Group, Madagascar) and its systematic position among stem archosaur reptiles". Bulletin of the American Museum of Natural History (398): 1–126. doi:10.5531/sd.sp.15. ISSN 0003-0090.

Sources

• Benton, M. J. (2000), Vertebrate Paleontology, 2nd ed. Blackwell Science Ltd, p. 144
• Carroll, R. L. (1988), Vertebrate Paleontology and Evolution, W.H. Freeman & Co. p. 266

External links

• Archosauromorpha: Rhynchosaurs and Trilophosaurus at Palaeos