Museum discovery
The story began in South Africa, with Dr Butler’s PhD focusing on plant-eating dinosaurs whose fossils were found in South Africa. ‘In 2004,’ says Dr Butler, ‘I visited the Iziko South African Museum in Cape Town for two weeks. I was working in their fossil collections when I spotted this tiny skull. It had no label and the curator was unsure what it was. I recognised it immediately as a juvenile of one of the dinosaurs that I was studying, Heterodontosaurus. Only two skulls of Heterodontosaurus were previously known, and both were of much larger adults.’ Dr Butler recognized that the smaller skull could give new insight into growth in this species and in 2006 his team borrowed the skull and began to study it.

Diets
The team took CT scans of the skull and discovered evidence that the Heterodontosaurus had fang-like teeth when young, and might have evolved, ‘for defense against predators and for occasional predation on insects or small animals. This would suggest that Heterodontosaurus was an omnivore rather than strictly herbivorous.’  And because early dinosaurs were meat-eaters, and later ones fed on plants, this suggests that the Heterodontosaurus might be a transitional dinosaur.

‘What Heterodontosaurus may represent’, says Dr Butler, ‘is an early stage in the evolution of the ability to feed upon plants; this ability allowed dinosaurs to diversify into a bewildering array of body sizes and shapes. Heterodontosaurus may, therefore, be key to understanding the evolution of dinosaur diets.’