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  • 31 July 2014, 22:56

Dinosaurs Evolved Into Birds By 'Shrinking'

Huge carnivorous, land-living dinosaurs evolved into birds by steadily shrinking over 50 million years, scientists have found.

They have mapped out the evolutionary transformation in a detailed family tree of dinosaurs and their bird descendants after comparing the fossils of 120 different species and 1,500 skeletal features, particularly thigh bones.

It shows the branch of the two-legged meat-eaters called the theropods - the only dinosaurs that kept getting smaller.

Scientists from the University of Southampton were part of an international team that carried out the research which has presented its findings in the journal Science.

Darren Naish, a vertebrate palaeontologist, said: "These bird ancestors also evolved new adaptations, such as feathers, wishbones and wings, four times faster than other dinosaurs."

The study's author, associate professor Michael Lee, from the University of Adelaide, described them as "shape-shifters".

He said: "Birds evolved through a unique phase of sustained miniaturisation in dinosaurs.

"Being smaller and lighter in the land of giants, with rapidly evolving anatomical adaptations, provided these bird ancestors with new ecological opportunities, such as the ability to climb trees, glide and fly.

"Ultimately, this evolutionary flexibility helped birds survive the deadly meteorite impact which killed off all their dinosaurian cousins.

"Birds out-shrank and out-evolved their dinosaurian ancestors, surviving where their larger, less evolvable relatives could not."

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