BIRDS - How birds got their wings: Fossil data show scaling of limbs altered as birds originated from dinosaurs

Birds originated from a group of small, meat-eating theropod dinosaurs called maniraptorans sometime around 150 million years ago. Recent findings from around the world show that many maniraptorans were very bird-like, with feathers, hollow bones, small body sizes and high metabolic rates ...

http://phys.org/news/2013-09-birds-wings-fossil-scaling-limbs.htm