Dinosaur family tree shows how birds evolved


A chicken, a Cretaceous bird, and a Velociraptor show their family resemblance.
Jason Brougham

Scientists have compiled the most comprehensive family tree of meat-eating dinosaurs (see below) and it's helping them work out how birds evolved.

All the familiar anatomical features of the birds– feathers, wings and wishbones – first evolved in the dinosaurs over tens of millions of years. But once all the parts were in place, evolution of birds was rapid, a team of researchers, led by the University of Edinburgh, found.

The researchers analysed the anatomy of more than 850 body features in 150 extinct species, and used statistical techniques to analyse their findings and assemble a detailed family tree.

The emergence of birds some 150 million years ago appears to have been a gradual process, as some dinosaurs became more and more bird-like, so much so that it is very difficult to draw a dividing line on the family tree between dinosaurs and birds.

But once the line was crossed, the birds' development was very fast indeed, as Dr Steve Brusatte, of the University of Edinburgh's School of GeoSciences, who led the study, explains.

"There was no moment in time when a dinosaur became a bird, and there is no single missing link between them. What we think of as the classic bird skeleton was pieced together gradually over tens of millions of years. Once it came together fully, it unlocked great evolutionary potential that allowed birds to evolve at a super-charged rate."

Dr Graeme Lloyd, of the University of Oxford, said: "Our study adds to a growing number of works that approach this problem from different angles, but all seem to confirm that the origin of birds was a truly special event in Earth history. It is particularly cool that it is evidence from the fossil record that shows how an oddball offshoot of the dinosaurs paved the way for the spectacular variety of bird species we see today."

The study is published in the journal Current Biology.


The most comprehensive family tree of meat-eating dinosaurs shows how they evolved into birds.
Stephen Brusatte

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