Tuesday, April 27, 2010

Aetodactylus halli Hints at Hidden Pterosaur Diversity?


A 95 million-year-old fossilized jaw discovered in Texas has been identified as a new genus and species of flying reptile, Aetodactylus halli.

Aetodactylus halli is a pterosaur, a group of flying reptiles commonly referred to as pterodactyls.

The rare pterosaur — literally a winged lizard — is also one of the youngest members in the world of the pterosaur family Ornithocheiridae, according to paleontologist Timothy S. Myers, who identified and named Aetodactylus halli. The newly identified reptile is only the second ornithocheirid ever documented in North America, says Myers, a postdoctoral fellow in the Huffington Department of Earth Sciences at Southern Methodist University in Dallas.

Aetodactylus halli would have soared over what is now the Dallas-Fort Worth area during the Cretaceous Period when much of the Lone Star state was under water, covered by a vast ancient sea.

While rare in North America, toothed pterosaurs belonging to the Ornithocheiridae are a major component of Cretaceous pterosaur faunas elsewhere in the world, Myers says. The Texas specimen — a nearly complete mandible with most of its 54 teeth missing — is definitively younger than most other ornithocheirid specimens from Brazil, England and China, he says. It is five million years younger than the only other known North American ornithocheirid.

Myers describes the new species in the latest issue of the Journal of Vertebrate Paleontology. Go to www.smuresearch.com to see illustrations of Aetodactylus halli and the Cretaceous marine environment, an image of the fossilized jaw and links to more information.


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North American pterosaurs that date from the Cretaceous are all toothless, except for Aetodactylus and Coloborhynchus, Myers says. The thinness of the jaws, the upward angle of the back half of the mandible and the lack of a pronounced expansion of the jaw tips indicate that Aetodactylus is different from other ornithocheirids and represents a new genus and species of pterosaur.

"Discovery of another ornithocheirid species in Texas hints at a diversity of pterosaurs in the Cretaceous of North America that wasn't previously realized," Myers says. "Aetodactylus also represents one of the final occurrences of ornithocheirids prior to the Late Cretaceous transition to pterosaur faunas that were dominated by the edentulous, or toothless, species."


No time! Off to a meeting!

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