Dinosaur evolution tree yields diversity secrets

by Rich Bowden - Jul 23 2008, 22:27

An evolutionary family tree, known as a "supertree", has revealed that dinosaurs stopped evolving 50 million years before they became extinct. The evidence, gained through an international effort, contradicts previous scientific thought which said they continued to evolve during their later years of existence on Earth.

A new study published this week in the journal Proceedings of the Royal Society B, has found that dinosaurs did not evolve during the Cretaceous Terrestrial Revolution, a time when modern ecosystems were established on land with an explosion of living things such as flowering plants, social insects, lizards, snakes, birds and mammals.

Graeme Lloyd from the University of Bristol, who led the study, explained that: "Supertrees are very large family trees made using sophisticated computer techniques that carefully stitch together several smaller trees which were previously produced by experts on the various subgroups."

"Our supertree summarises the efforts of two decades of research by hundreds of dinosaur workers from across the globe and allows us to look for unusual patterns across the whole of dinosaurs for the first time," he said.

"It is the most comprehensive picture ever produced of how dinosaurs evolved."

The study states that: "new evidence confirms that the [Cretaceous Terrestrial Revolution] was a key in the origination of modern continental ecosystems, but that the dinosaurs were not a part of it." 

The supertree concludes the main evolutionary period for dinosaurs occurred during the Late Triassic, around 200 to 225 million years ago, with a smaller diversification during the Mid-Jurassic, around 160 to 170 million years ago. 

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