Thrinaxodon

Thrinaxodon
Temporal range: Early Triassic,
Fossil of T. liorhinus in National Museum of Natural History
Diagram of skull in lateral view
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Therapsida
Clade: Cynodontia
Clade: Epicynodontia
Family: Thrinaxodontidae
Watson & Romer, 1956
Genus: Thrinaxodon
Seeley, 1894
Type species
Thrinaxodon liorhinus
Seeley, 1894

Thrinaxodon is an extinct genus of cynodonts which lived in what are now South Africa and Antarctica during the Early Triassic. The genus contains a single species, T. liorhinus.

Similar to other therapsids, Thrinaxodon adopted a semi-sprawling posture, an intermediary form between the sprawling position of basal tetrapods and the more upright posture present in current mammals. Thrinaxodon is prevalent in the fossil record, and one of the specimens represent the oldest known record of burrowing behavior among cynodonts.