Dinosaur body shape changed the way birds stand

Scientists at the University of Liverpool and the Royal Veterinary College developed computer models of the skeletons of dinosaurs to show how body shape changed during dinosaur evolution and affected the way birds stand today. The study reveals for the first time that, contrary to popular opinion, it was the enlargement of the forelimbs over time, rather than the shortening and lightening of the tail, that led to two-legged dinosaurs gradually adopting an unusually crouched posture, with the thigh held nearly horizontally - a trait inherited by their descendants: birds. The research group used digitising technology to create 3D images of the skeletons of 17 archosaurs - land animals including living crocodiles and birds as well as extinct dinosaurs. They then digitally added 'flesh' around the skeletons to estimate the overall shape of the body as well as the individual body segments such as the head, forelimbs and tail. Evolution Dr Karl Bates, from the University's Institute of Ageing and Chronic Disease , said: "The evolution of birds from their dinosaurian ancestors is historically important not only to dinosaur research but also to the development of the theory of evolution itself. "Way back in the 1860's, Thomas Huxley used Mesozoic dinosaurs and modern birds as key evidence in promoting Darwin's theory of evolution. In this study, modern digital technologies have allowed us to quantify the 'descent with modification' observed by Huxley all those years ago.