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 that examined closely the Paraves, the first birds, and their closest dinosaurian relatives which lived 160 to 120 million years ago. Researchers 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...
Fuente : http://feeds.sciencedaily.com/~r/sciencedaily/~3/X...
Fuente : http://feeds.sciencedaily.com/~r/sciencedaily/~3/X...