October 14, 2009

Scientists Find New Flying Reptile

An international group of scientists have uncovered a new type of flying reptile, they reported on Tuesday.

Writing in the Proceedings of the Royal Society B: Biological Sciences, researchers from the University of Leicester, and the Geological Institute, Beijing documented evidence of a new type of pterosaur.

Scientists said that the discovery fills in the large evolutionary gap between two different groups of pterosaurs: primitive long-tailed forms and their descendants, advanced short-tailed pterosaurs, some of which reached gigantic size.

Named for Charles Darwin on the 200th anniversary of his birth, Darwinopterus, or Darwin's wing, represents a missing link in the evolution of pterosaurs, researchers said.

They documented more than 20 fossil skeletons of the new creature. The remains were found earlier this year in North-east China in rocks dated at around 160 million years old.

This is close to the boundary between the Middle and Late Jurassic and at least 10 million years older than the first bird, Archaeopteryx, researchers noted.

They concluded that its long jaws, rows of sharp teeth and flexible neck imply that it might have been a hawk-like creature that would catch other flying animals.

"Darwinopterus came as quite a shock to us" said David Unwin, part of the research team and based at the University of Leicester's School of Museum Studies.

"We had always expected a gap-filler with typically intermediate features such as a moderately elongate tail "“ neither long nor short "“ but the strange thing about Darwinopterus is that it has a head and neck just like that of advanced pterosaurs, while the rest of the skeleton, including a very long tail, is identical to that of primitive forms".

"The geological age of Darwinopterus and bizarre combination of advanced and primitive features reveal a great deal about the evolution of advanced pterosaurs from their primitive ancestors."

"First, it was quick, with lots of big changes concentrated into a short period of time. Second, whole groups of features (termed modules by the researchers) that form important structures such as the skull, the neck, or the tail, seem to have evolved together."

"But, as Darwinopterus shows, not all these modules changed at the same time. The head and neck evolved first, followed later by the body, tail, wings and legs. It seems that natural selection was acting on and changing entire modules and not, as would normally be expected, just on single features such as the shape of the snout, or the form of a tooth. This supports the controversial idea of a relatively rapid "Ëœmodular' form of evolution."


Image 1: This is the skull of Darwinopterus (skull 185 mm long). Credit: L Junchang

Image 2: This is a drawing of Darwinopterus hunting a small feathered dinosaur (Anchiornis). Credit: Mark Witton, University of Portsmouth


On the Net: