Family tree shows dinos missed the revolution - July 23, 2008
A new update of the dinosaur ‘supertree’ of family relationships has been produced by a European team.
It has already proven useful, with a paper published today by Proceedings of the Royal Society B explaining how the tree shows that an apparent spurt of dino-versity in the Cretaceous period actually has no basis in reality.
“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,” says Graeme Lloyd, of the University of Bristol (press release). “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.”
Looking at diversification rates Lloyd and his team conclude that what appears to be an explosion of diversity is actually just sampling bias. They also say there was no progressive decline of dinosaurs at the end of the Cretaceous and that the beasts’ evolution was unrelated to an explosion of new food sources from all the tasty mammals, birds and flowering plants that started cropping up around that time, an event known as the Cretaceous Terrestrial Revolution.
Note that the fact dinos weren’t invited to the CTR party doesn’t me they “stopped evolving”, as the Daily Mail has it. Just that they didn’t suddenly start diversifying rapidly.
And if you want evidence that science proceeds by small changes to existing knowledge (pace Kuhn) it can be found in the quotes of paper author Mike Benton.
In 2002 when the supertree was first announced he said:
It's not complete, but it's the most detailed and comprehensive single evolutionary tree produced for dinosaurs.
This time round his quote is:
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.
You can see the super-tree here and read more explanation of what the researchers did here.
Image: the supertree
