New Dino-Eating Pterosaur Evolved in Unusual Way
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An international team of researchers has just identified a new dinosaur-eating pterosaur that soared through the Jurassic skies 160 million years ago, according to a study released this week.
Christened Darwinopterus modularis, meaning "Darwin's wing composed of interchangeable units," the new flying reptile honors the 200th anniversary of Charles Darwin's birth by providing evidence for an unusual and controversial type of evolution.
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)."
He and colleagues David Unwin, Xingsheng Jin, Yongqing Liu and Qiang Ji studied more than 20 fossil skeletons -- some complete -- of Darwinopterus, according to a study in the latest Proceedings of the Royal Society B. The bones were unearthed in northeast China earlier this year.
Based on the fossils, the researchers determined the crow-sized flying reptile was about 1.6 feet long with a 2.3-foot wingspan.
Unwin, a University of Leicester paleobiologist, informed Discovery News that several groups of flying animals lived at the time of Darwinopterus. These included other pterosaurs, a gliding mammal and several small, feathered dinosaurs, all of which Darwinopterus likely ate.
The toothy reptile "presumably caught its prey in its jaws either in mid-air, or possibly by picking them off branches or fronds as it swept past, much as bats glean insects from trees and bushes today," he explained.
It's possible that the body changes seen in the winged reptile evolved to support this method of flight and hunting, since larger jaws would have made it easier to seize prey midair. The shorter tail probably allowed for greater airborne maneuvering.
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."
Witton suspects opportunities in the animal kingdom for rapid, modular evolution must be rare, since the new species would probably have to quickly fill a bunch of "previously empty or recently vacated (ecological) niches."
While he doesn't think humans evolved this way, the unusual process could explain how mammals quickly changed and spread right after dinosaurs became extinct.