| Pegomastax Temporal range:
Early Jurassic, | |
|---|---|
| |
| Lower jaws of holotype SAM-PK-K10488 | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Family: | †Heterodontosauridae |
| Subfamily: | †Heterodontosaurinae |
| Genus: | †Pegomastax Sereno, 2012[1] |
| Type species | |
| Pegomastax africana[a] Sereno, 2012[2]
| |
Pegomastax is a genus of heterodontosaurid dinosaur that lived during the Early Jurassic of South Africa. The only known specimen was discovered in a 1966–1967 expedition in Transkei District of Cape Province, but was not described until 2012 when Paul Sereno named it as the new taxon Pegomastax africana. The genus name is derived from the Greek for "strong jaw", and the species name describes the provenance of Africa; it was originally spelled africanus, was corrected to africana to align with the gender of the genus name.
The only known material of Pegomastax included a partial skull with well-preserved lower jaw and teeth, showing affinities for Heterodontosaurus and the group with a deep jaw, mobile predentary, and a large canine tooth at the front of the snout. The front of the jaws would have supported a keratinous bill, and wear on the teeth suggests that Pegomastax had a herbivorous diet, possibly of tougher plant matter than relatives that lacked the canine. The morphology of the teeth and jaw shows that Pegomastax may have been most closely related to South American taxon Manidens, instead of the other South African or Lesothan genera Heterodontosaurus or Lycorhinus.
Along with many other heterodontosaurids, Pegomastax is known from the upper Elliot Formation. Though of uncertain provenance it was probably from the middle of the section making it from the mid Sinemurian and older than all the other heterodontosaurids in the formation. It would have lived alongside an abundance of sauropodomorph taxa like Massospondylus, the ornithischian Lesothosaurus, and crocodylomorphs like Protosuchus, as well as the theropod Megapnosaurus and synapsids like Diarthrognathus and Pachygenelus. The fauna of the upper Elliot is more gracile than those of the lower Elliot, which probably reflects the drier climate at the time.
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