Tuesday, 4 October 2011

The Largest Toothed Pterosaur In The World

The fossil of 'ugly.' The white circles mark out the tooth sockets
During the 19th century workers, digging for phosphate fertilisers in an area of Cambridge greensand, discovered a strange fossil. The fossil was handed over to Sir Henry Owen, the curator of the Natural History Museum London, creator of the word 'dinosaur' and one of the most prominent naturalists in the world. He classified the fragment of bone as belonging to a pterosaur; and that was that. It sat on a dusty storeroom shelf for  over 100 years.

It did not receive proper analysis and because it was an incomplete and poorly preserved fossil discovered before scientists were able to accurately date the Earth's rocks and draw up the geological time scale, it received very little attention from palaeontologists; until now. Many great discoveries are not always made in a remote corner of the Gobi desert or the Rocky Mountains. Thousands of specimens were collected during the 19th century when palaeontology was considered a fashionable science or past time.

Some palaeontologists spend their days searching through drawers and drawers of museum specimens and occasionally, their work is rewarded with a revolutionary new find. Dr David Martill from the University of Portsmouth and David Unwin from the University of Leicester rediscovered the mysterious fossil and studied it in depth. Their results showed that this fossil is indeed a rare find.

The fossil in question, nicknamed 'ugly' due to its poorly preserved condition, was the lower tip of the beak known as the premaxilla which displayed several tooth sockets and, luckily, a single tooth. 'Although the crown has broken off the tooth, the diameter is 13mm. This is huge for a pterosaur. Once you do the calculations you realise that the scrap in your hand is a very exciting discovery,' said Dr Martill. By using this data and comparing it with similar specimens, the team were able to build up a model of the specimen and were subsequently able to name a new species.

Coloborhynchus capito, with a wingspan of around five metres and a 75 centimetre skull, is now the largest known species of toothed pterosaur. Most species that topped five metres were all toothless and occasionally flightless giants. The fossil also sheds light upon the evolutionary history of pterosaurs. This group of flying reptiles appeared 215 million years ago. Coloborhynchus capito, at 100 million years old , shows that large pterosaurs did indeed evolve during the early Cretaceous. There was little evidence to suggest this previously. Indeed Martill described the study and the fossil record of pterosaurs as scrappy but tantalising.