Trilophosauridae

Trilophosaurs are lizard-like Triassic allokotosaur reptiles related to the archosaurs. The best known genus is Trilophosaurus, a herbivore up to 2.5 metres (8.2 feet) 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.

Size comparison of Trilophosaurus buettneri

Trilophosauridae Temporal range: Triassic, [1]
Mounted skeleton of Trilophosaurus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	†Allokotosauria
Order:	†Trilophosauria Romer, 1956
Family:	†Trilophosauridae Gregory, 1945
Genera
†Anisodontosaurus? †Coelodontognathus? †Doniceps? †Rutiotomodon †Spinosuchus †Teraterpeton †Tricuspisaurus †Trilophosaurus †Variodens †Vitalia?
Synonyms
Teraterpetidae Sues, 2003

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.[2]

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).[3]