The Ancient Wing
Archaeopteryx lithographica literally means the “Ancient Wing from the Printing Stone”. Seven specimens of this species have been found; the first one was discovered in London, one year after the publication of the Origin of Species! Darwin once referred to it as “that strange bird Archaeopteryx”.
“That strange bird Archaeopteryx…”
Archaeopteryx lived around 150–145 million years ago in the Jurassic period. It’s skeleton is basically reptilian; our “strange bird” had teeth, a long bony tail, abdominal ribs and grasping hands. But it also had feathers, wishbones, an opposable toe and a retroverted pubic bone. So is it a bird or a reptile?
It is my understanding that in modern birds, the teeth formation genes have been deactivated as they are no longer needed. But hey, scientists have been able to reactivate this teeth-making gene. Check out the chicken on the right.
It is a good hypothesis that feathers have been evolved for insulation first, before it is co-opted into flight. Most paleontologists now agree that birds evolved from small theropod dinosaurs. Coelurosauria are dinosaurs more related to birds. There are two proposed models regarding the evolution of wings — “trees down” and “ground up”. Gliding vertebrates such as the flying squirrels are a good example of “tree down” evolution.