First, there is the time problem in that superficially bird-like dinosaurs occurred some 30 million to 80 million years after the earliest known bird, which is 150 million years old. This is absolutely the worse body plan for the evolution of bird flight. Third, he said, if one views a chicken skeleton and a dinosaur skeleton through binoculars they appear similar, but close and detailed examination reveals many differences. Theropod dinosaurs, for example, had curved, serrated teeth, but the earliest birds had straight, unserrated peg-like teeth. All dinosaurs had a major joint in the lower jaw that early birds did not.
Birds have a reversed rear toe that opposes the front three toes and allows birds to perch.
Dinosaurs had no reversed toe. Birds grow a girdle of bone in their chests quite different from dinosaur chests. The new work involved microscopic examination of early limb development in ostriches, chickens, cormorants, alligators and turtles and comparison of chick fore- and hindlimbs. The answer is that you can't. Findings from the examination of alligator and turtle embryos were consistent with those of birds, the biologist added.