Dino of the Week: Pegomastax

Type Species: Pegomastax africana

Classification: Dinosauria - Ornithischia - Heterodontosauridae

Time Period: Early Jurassic

Location: South Africa

Diet: Opportunistic Omnivore

Pegomastax lived in Early Jurassic South Africa between 200 to 190 million years ago. This creature was much smaller than other heterodontosaurs of the environment, such as Heterodontosaurus and Lesothosaurus. While the latter dinosaurs reached between four and six feet, Pegomastax measured just under two feet head-to-tail. The parrot-like Pegomastax had a robust lower jaw with a short beak and an enlarged canine-like tooth at the beginning of the lower jaw’s tooth row. This canine-like tooth may have been a defensive weapon, or it may have been used to dig for roots and shrubs. 

Pegomastax had thin, porcupine-like spikes that sprouted over its body. These could’ve been used as a defensive function, like porcupines, or to make the creature unappealing to predators. Or, perhaps, they were used to make it look bigger – it was a little squirt, after all, who weighed less than an average housecat – in order to intimidate rivals or predators. Another theory is that they were used for sexual display to attract mates. World-renowned paleontologist Paul Sereno described Pegomastax as a ‘nimble two-legged porcupine,’ adding, ‘I think the bristles would’ve made it look at least a little bigger than it was – perhaps they could poke out more strongly when excited… [Its] main defense would be the speed of escape. These were very fast long-legged critters. They could inflict a nipping bite if cornered, using the fangs much like a peccary or fanged deer.’