Secrets revealed
Our fascination with dinosaurs is enduring, from Hollywood movies to TV reconstructions of pre-historic life, we are hungry consumers of stories about dinosaurs. It’s partly because scientists continually reveal new secrets about their evolutionary story, and now a team of scientists from London, Cambridge and Chicago, lead by dinosaur expert Dr Richard Butler of the National History Museum, have discovered new information about the Heterodontosaurus.

The teeth structure of this turkey-sized animal is unusual, having ‘enlarged fang-like canines at the front of the jaws,’ explains Dr Butler, ‘and closely packed chisel-like grinding teeth (a little like molars) in the cheek region. The chisel-like grinding teeth are well-designed for feeding on plants, and previous researchers had suggested that Heterodontosaurus were exclusively herbivorous and that the fang-like canines were sexually dimorphic (only present in males) and used for display or fighting between males.’

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.’