Anisodontosaurus

Anisodontosaurus is an extinct genus of trilophosaurid allokotosaur known from the Middle Triassic Moenkopi Formation of Arizona. The type species, A. greeri, was named and described by Samuel [Paul Welles] in 1947.

Discovery and naming

The holotype, a jaw catalogued as UCMP V3922, was discovered in 1940 and was described seven years later.
Apart from the type specimen, Anisodontosaurus is known from the referred specimen UCMP 37815, a right ilium.

Classification

Its taxonomic placement was largely unknown until the holotype was reassessed in 1998, when it was recovered as a lepidosauromorph or a trilophosaurid.
A 2023 redescription of available fossils supported its identification as a trilophosaurid, specifically as the sister taxon to Variodens, from the Late Triassic of the United Kingdom. The clade containing Anisodontosaurus and Variodens is the longest-lasting subset of Trilophosauridae, as Anisodontosaurus is one of the oldest known members of the family while Variodens is among the youngest.