Dinosaurs 'ran out of steam'

Dinosaurs were running out of evolutionary steam during their last 50 million years on Earth, scientists have learned.

They were not part of the Cretaceous Terrestrial Revolution around 100 million years ago, which saw the rapid expansion of many land animals and plants.

While flowering plants, lizards, snakes, birds and mammals evolved swiftly, the dinosaurs plodded behind. A short time later, they were extinct.

Researchers made the discovery after using powerful computer programs to produce a "supertree" of dinosaur lineages.

The results showed the most likely pattern of evolution for 440 of the 600 known species of dinosaur.

Graeme Lloyd, one of the University of Bristol scientists who led the study, said: "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. It is the most comprehensive picture ever produced of how dinosaurs evolved."

The findings, published in the journal Proceedings of the Royal Society B, revealed that dinosaurs had a burst of diversification in the first 50 million years of their reign. Then their rate of evolution slowed down, and did not change.

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