One of the world’s smallest dinosaurs had large, fang-like teeth

Press release - 29 October 2008

A tiny dinosaur skull with a full set of strangely-shaped teeth has been identified by a scientist at London’s Natural History Museum.

One of the smallest dinosaur skulls ever discovered has been identified by a team of scientists from London, Cambridge and Chicago, led by Natural History Museum palaeontologist Dr Richard Butler. The 45 millimetre-long skull – not even as long as a teabag – belonged to a baby Heterodontosaurus. Its unusual, fang-like teeth show for the first time how one of the first dinosaurs on Earth developed into an adult.

Dr Butler said ‘This discovery is important because for the first time we can examine how Heterodontosaurus changed as it grew. The juvenile dinosaurs of this type had relatively large eyes and a short snout when compared to an adult – similar to the differences we see between puppies and fully grown dogs.’

The dinosaur skull has an unusual combination of teeth, with large fang-like canines at the front of the jaw and worn, molar-like grinding teeth at the back. Heterodontosaurus’ unusual combination of teeth has sparked debate among experts about whether they ate plants or insects and small animals. In contrast, most reptiles have teeth that are about the same size all the way along the length of their jaws. Using X-ray technology and CT scanning, Dr Butler and his colleagues were able to solve the mystery.

The baby Heterodontosaurus weighed less than 200 grams – only slightly heavier than a classic iPod. Researchers previously thought that only males developed the fearsome canine teeth, and that they used them in fights for territory or females. However, the discovery of canine teeth in a young Heterodontosaurus suggests the teeth had other functions.

Dr Richard Butler commented ‘The fact the skull of such a young Heterodontosaurus has a fully developed set of canines suggests that they were not restricted to males and used for fighting for territory or females, but instead were probably present in both sexes and may have just been used for eating and defence.’

Heterodontosaurus was one of the earliest-known dinosaurs to have roamed Earth. Few fossilised specimens have been discovered, so relatively little is known about Heterodontosaurus and its relatives. The name means different toothed lizards, and they lived in present-day South Africa during the Early Jurassic Period, around 190 million years ago.

Dr Butler’s co-author, Laura Porro, a post-doctoral student at the University of Chicago completing her doctoral dissertation on feeding in Heterodontosaurus, under the supervision of Dr David Norman, lecturer at the University of Cambridge, commented; ‘I didn’t recognize it as a dinosaur at first, but when I turned it over and saw the eye looking straight at me, I knew exactly what it was. There were only two known fossils of Heterodontosaurus, both in South Africa and both adults. There were rumours of a juvenile heterodontosaur skull in the collection of the Iziko South African Museum, but no one had ever described it.’

The research is published in the latest issue of the Journal of Vertebrate Paleontology

Ends

Notes for editors

• Dr Butler worked in collaboration with colleagues Laura Porro of the University of Chicago and formerly of the University of Cambridge, and Dr David Norman at the University of Cambridge
• The juvenile Heterodontosaurus skull is held in the collections of the Iziko South
African Museum
• Adult Heterodontosaurus were turkey-sized animals, reaching just over one metre in length and weighing around two kilograms
• The research was funded by the Royal Society, Cambridge University and the Gates Cambridge Trust
• Selected by Time Out in 2007 as one of the Seven Wonders of London, the Natural History Museum is also a world-leading science research centre. Through its collections and scientific expertise, the Museum is helping to conserve the extraordinary richness and diversity of the natural world with groundbreaking projects in 68 countries