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3D study shows forelimb enlargement key to evolution of dinosaurs into birds

Wednesday, Apr 24, 2013 - 02:39

April 24 - British scientists say they have found new evolutionary evidence linking dinosaurs to birds. A series of 3D reconstructions illustrate what the scientists say is the gradual evolution of small forelimbs into wings which led two-legged dinosaurs to stand and move like birds. Jim Drury reports.

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The world's third largest bird, the emu, has much in common with the dinosaurs. SOUNDBITE (English) PROFESSOR JOHN HUTCHINSON, OF THE ROYAL VETERINARY COLLEGE'S STRUCTURE & MOTION LAB, SAYING: "They still have features that the earliest dinosaurs had, like a three-toed foot, long muscular legs, they even have little tiny claws on their forelimbs, their wing stubs." Professor John Hutchinson, of Britain's Royal Veterinary College, believes the emu is living proof of how dinosaurs evolved. He is studying the evolution of archosaurs - prehistoric land animals whose modern descendants are crododiles and birds. He and colleague Dr Vivian Allen created 3D models of 17 archosaurs to help uncover their incremental evolution. SOUNDBITE (English) PROFESSOR JOHN HUTCHINSON, OF THE ROYAL VETERINARY COLLEGE'S STRUCTURE & MOTION LAB, SAYING: "We are able to reconstruct how the body shape of the whole evolutionary lineage changed over time and how we got from an ancestor that was kind of crocodile-ish to a modern-day bird that's so drastically transformed....and that's what we did in our study was use computer models of living archosaurs and extinct ones." Allen used scanning technology to create the 3D images before digitally adding flesh. SOUNDBITE (English) DR. VIVIAN ALLEN, OF THE ROYAL VETERINARY COLLEGE'S STRUCTURE & MOTION LAB, SAYING: "We started with a laser scan of as intact a skeleton as we could find and once we had this laser scan we had it as a computer model of the skeleton and from then we used very simple outline hoops, so we took cross sections of the skeleton at regular intervals and put a kind of a minimal, very tightly fitted shape around the skeleton... you can then - it's called lofting - you can extend each hoop into a full 3D shape." Received wisdom says the shortening and lightening of two-legged dinosaurs' tails caused their posture to become crouched, like their avian descendants. But the scans suggest the gradual enlargement of forelimbs were the more likely cause. SOUNDBITE (English) PROFESSOR JOHN HUTCHINSON, OF THE ROYAL VETERINARY COLLEGE'S STRUCTURE & MOTION LAB, SAYING: "It was just a few carnivorous dinosaurs that started shifting their centre of mass forward towards their head as their body changed and what changed, that changed their centre of body mass so drastically moving it forwards was not so much shrinking the tail, actually, but expanding the forelimbs which ultimately became wings but those changes began before animals were flying." Working with colleagues from Beijing and the University of Liverpool, Hutchinson and Allen's study sheds new light on the links between dinosaurs and birds, using modern technology to reveal new insights into the past.

3D study shows forelimb enlargement key to evolution of dinosaurs into birds

Wednesday, Apr 24, 2013 - 02:39

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