The humble beginnings of a king

Earliest tyrannosauroid (re)discovered

Tyrannosaurus rex and related large carnivorous dinosaurs together form the family Tyrannosauridae. A long forgotten fossil skull in the collections of the Natural History Museum in London has now provided crucial clues to the early stages of the lengthy evolutionary history of these fearsome predators. Almost a century after its discovery, the specimen, named Proceratosaurus, has now been recognized as the oldest known relative of the Tyrannosauridae. With the help of an ultramodern imaging technique, a team of researchers led by Dr. Oliver Rauhut from LMU Munich and Dr. Angela Milner from the Natural History Museum London, have been able to show that Proceratosaurus resembled its approximately 100-million-years younger descendant T. rex in a number of ways. The teeth, the jaws, and the structure of the cranial cavity of the two species have many features in common. Proceratosaurus weighed only about 40 kg, says Rauhut. Nevertheless, like the later tyrannosauroids, the animal obviously depended on its powerful biting apparatus. Later modifications of the jaw muscles and the overall structure of the cranium then gave rise to the perfect hunting weapon wielded by T. rex. (Zoological Journal of the Linnean Society online, 4 November 2009).

Among the dinosaur specimen housed in the collections of the Natural History Museum in London is an almost complete skull that was found in the West of England about 100 years ago. The fossil was initially misclassified, but was later recognized as representing an otherwise unknown genus, which was named Proceratosaurus. The skull has only recently been subject to detailed study by a team led by the palaeontologist Dr. Oliver Rauhut, who holds dual appointments in the Department of Geological and Environmental Sciences at Ludwig-Maximilians-Universität (LMU) in Munich and the Bavarian State Collection for Paleontology and Geology, and Dr Angela Milner, Associate Keeper of Palaeontology at the Natural History Museum in London.

This skull, which had been overlooked for so long, turns out to be a spectacular find. Proceratosaurus is the earliest known ancestor of the family Tyrannosauridae (named after its most famous representative Tyrannosaurus rex). Proceratosaurus and T. rex were both bipedal carnivores and each had a massive body, short and stubby forelimbs, a powerful tail, and sharp teeth set in a bulky skull. The best known members of the family, T. rex, lived during the late cretaceous period, although smaller species are known from the earlier Jurassic era.