How Dinosaurs Shrank and Became Birds
Modern birds appeared to emerge in a snap of evolutionary time. But new research illuminates the long series of evolutionary changes that made the transformation possible.
Modern birds descended from a group of two-legged dinosaurs known as theropods, whose members include the towering Tyrannosaurus rex and the smaller velociraptors. The theropods most closely related to avians generally weighed between 100 and 500 pounds — giants compared to most modern birds — and they had large snouts, big teeth, and not much between the ears. A velociraptor, for example, had a skull like a coyote’s and a brain roughly the size of a pigeon’s.
This article brought to The Bird Watch by Robert Wall, Sangre de Cristo Audubon Society webmaster.