New Dino-Eating Pterosaur Evolved in Unusual Way
Modular evolution theory holds that entire modules, or groups of body features, evolve together within a relatively short period of time.
Lead author Junchang Lu told Discovery News that the pterosaur fills a gap between primitive basal forms of this animal and more advanced pterodactyl types.
Older forms had "small heads, short necks, short wrists, a long tail and a long fifth toe on the foot," he said. In later, more derived types, "the skull, neck and wrist became relatively long, but the tail became short and the fifth toe dwindled to a small nub or was lost altogether."
Lu added: "Darwinopterus captures a moment in that evolution from primitive to advanced forms. But contrary to what we expected, it has the head and neck of an advanced pterodactyloid while the rest of the skeleton is like that of the primitive rhamphorhynchoids (flying reptiles)."
....
Mark Witton, who is an expert on pterosaurs and is a University of Portsmouth paleobiologist, told Discovery News that he agrees with the findings and was very surprised when he first heard about the new species.
"While we could predict that intermediate forms between basal pterosaurs and pterodactyloids had to exist at one stage, the 'cut-n-shut' mechanism of this new critter is pretty amazing," Witton said, adding that he wonders why these animals evolved in such a manner.
"What selection pressures made the head and neck change without affecting the rest of the skeleton?" he asked. "Was it something to do with feeding, locomotion or any number of other things? At the moment, I don't think we really know, but it should be pretty interesting to find out."
http://news.discovery.com/dinosaurs/pterosaur-fossils-evolution.html