February 24, 2014
Image Caption: Skeleton of the paravian dinosaur Microraptor, from the Early Cretaceous (125 million years ago) of NE China. This dinosaur was experimenting with flight, but its unique kind of flight – gliding using all four feathered limbs – did not lead to anything. Credit: Institute of Vertebrate Paleontology & Paleoanthropology (IVPP), Beijing / Wikipedia (CC BY 2.5)
The key characteristics of birds which allow them to fly – their wings and their small size – arose much earlier than previously thought, according to new research from the Universities of Bristol and Sheffield into the Paraves, the first birds and their closest dinosaurian relatives which lived 160 to 120 million years ago.
Mark Puttick and colleagues investigated the rates of evolution of the two key characteristics that preceded flight: body size and forelimb length. In order to fly, hulking meat-eating dinosaurs had to shrink in size and grow much longer arms to support their feathered wings.
“We were really surprised to discover that the key size shifts happened at the same time, at the origin of Paraves,” said Mr Puttick of Bristol’s School of Earth Sciences. “This was at least 20 million years before the first bird, the famous Archaeopteryx, and it shows that flight in birds arose through several evolutionary steps.”