Dinosaur supertree unveils evolution secrets
The supertree shows how dinosaurs evolved
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Wednesday, 23, Jul 2008 12:01
A dinosaur 'supertree' has been created that provides the most comprehensive picture ever produced of how dinosaurs evolved.
The tree shows the most likely pattern of evolution for 440 of the 600 known species of dinosaur and allows scientists to look for unusual patterns across the whole range of dinosaurs for the first time.
A study published today in the journal Proceedings of the Royal Society B claims the picture challenges opinions on how quickly dinosaurs expanded during the last 50 million years of their existence.
It has long been debated whether dinosaurs were part of the 'terrestrial revolution' that occurred some 100 million years ago during the Cretaceous period when birds, mammals, flowering plants, insects and reptiles underwent a rapid expansion.
But the supertree now suggests that dinosaurs were not expanding as actively as thought and that the apparent explosion of dinosaur diversity may be largely explained by a process known as 'sampling bias'.
The results show that all the bursts of diversification happened in the first 50 million years of the evolution of dinosaurs.
Later expansions were not distinguishable from normal rates. This suggests dinosaurs did not take advantage of the new food supplies available during the Cretaceous terrestrial revolution - such as flowering plants, lizards, snakes, birds and mammals.
Commenting on the supertree, Professor Mike Benton from Bristol University said: "It's not complete, but it's the most detailed and comprehensive single evolutionary tree produced for dinosaurs, and indeed for almost any other group.
"Up until now, most studies of the evolution of dinosaurs were not tested numerically against an accurate and comprehensive database. We hope our study will mark the first of a new wave of such thorough, quantitative studies in palaeontology."