Dinodontosaurus

Dinodontosaurus; Temporal range: Mid-Late Triassic; ~242–229 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Mounted Dinodontosaurus skeleton
	D. tener illustration
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Clade:	Therapsida
Clade:	†Anomodontia
Clade:	†Dicynodontia
Clade:	†Kannemeyeriiformes
Genus:	†Dinodontosaurus; Romer, 1943
Type species
	†Dinodontosaurus oliveirai; Romer, 1943 [Junior synonym]
Species
	D. brevirostris Cox, 1968; D. tener (Huene, 1935); D. turpior (Huene, 1935) [nomen dubium];
Synonyms
	Genus synonymy Chanaria Cox, 1968 ; Diodontosaurus Tupí-Caldas, 1936 [nomen suppressum] ; Species synonymy Synonyms of D. brevirostris: Chanaria platyceps Cox, 1968 ; D. platygnathus Cox, 1968 ; ; Synonyms of D. tener: Diodontosaurus pedroanum Tupí-Caldas, 1936 ; D. oliveirai Romer, 1943 ; ;

Dinodontosaurus (meaning "terrible-toothed lizard") is a genus of dicynodont therapsid that lived in Brazil from the Middle Triassic to the Upper Triassic period. It was medium to large sized dicynodont with a skull up to 40 centimetres (16 in) long and had a beak corneum. There have two species that belong to this genus: D. brevirostris and D. tener. There is a third species that is a nomen dubium, D. turpior.^[1]

Taxonomy

Species

Dinodontosaurus tener is the most common species of dicynodont that existed in the Middle Triassic, and more common in the fossil layers that age in Rio Grande do Sul, in Rota Paleontológica. They are found mainly in the Paleontological Site Chiniquá in São Pedro do Sul and Candelária, where a group of ten pups were found together, demonstrating that these animals had strategies for coexistence in a group and caring for their offspring. Diodontosaurus pedroanum Tupi-Caldas, 1936 and Dinodontosaurus oliveirai, Romer 1943 are synonyms.^[2]
Dinodontosaurus brevirostris is known from skeleton remains and a coprolite animal latrine^[3] found in Argentina. Chanaria platyceps Cox, 1968 and Dinodontosaurus platygnathus are synonyms.

Phylogeny

Dinodontosaurus in a cladogram from Szczygielski & Sulej (2023):^[4]

	Shansiodon

	Vinceria

Dinodontosaurus

"Kannemeyeriidae"

Dolichuranus

Acratophorus

	Rabidosaurus

	Wadiasaurus

Sinokannemeyeria

	Parakannemeyeria

	Xiyukannemeyeria

Rhadiodromus

Shaanbeikannemeyeria

Kannemeyeria

	Rechnisaurus

	Uralokannemeyeria

Angonisaurus

	Woznikella

	Stahleckeriidae

Description

Dinodontosaurus was a medium to larger sized dicynodont. It has a skull length of up to 40 centimetres (16 in). It possessed both tusks that were notably elongated and curved and beak corneum. Specimens of Dinodontosaurus tener has a high amount of morphological variability among known specimens. While some of this variation is partially due to taphonomic alterations to the skeletons, this variation is potentially due to intraspecific or even interspecific variation.^[5]

Paleoecology

Dinodontosaurus is one of the most common tetrapod taxon that lived during the Middle Triassic being more common in fossil layers from the Rio Grande do Sul and Santa Maria Supersequence.^[2]^[5]

Coprolites (fossilized dung) from the Chañares Formation that have been attributed to Dinodontosaurus suggest that it had a broad diet of low-lying plants.^[6]