Darwinopterus points to chunky evolution

Pterosaur had the legs of its ancestors and the head of its descendants

Pterodactyls evolved their heads before their haunches, new fossils suggest.

HEAD-LEG DIVIDE A newly discovered flying dinosaur dubbed Darwinopterus had a big head and pointy teeth (shown), much like its descendants. But oddly, the pterosaur had legs like its ancestors. Lü Junchang/Geological Institute, Beijing

ON THE HUNT The pterosaur probably hunted like a hawk. Here it is shown catching a small feathered dinosaur, a possible ancestor of today’s birds. Mark Witton/Univ. of Portsmouth

Fossils of the flying reptiles, also known as pterosaurs, have so far fallen into two categories: primitive, long-tailed lizards and their gigantic, short-tailed descendants. Researchers had expected to find pterosaurs with medium-length tails and medium-sized bodies to fill the gap between the two.

The new creature, dubbed Darwinopterus (for “Darwin’s wing”), falls within the time gap but looks like it was Frankensteined together from parts of both its ancestors and descendants.

“It’s as if someone said, ‘Let’s nail these two together and make a sort of chimera, that’ll really confuse everybody,’” says Dave Unwin of the University of Leicester in England, who coauthored a paper reporting the findings online October 14 in Proceedings of the Royal Society B.

Unwin and colleagues uncovered more than 20 skeletons in northeast China earlier this year. Dating to around 160 million years ago, the fossils revealed a long tail and small hindquarters just like those of pterosaurs that came before, with a head and neck identical to later versions. The long jaws, sharp teeth and flexible neck suggest that the crow-sized reptile might have hunted like a hawk, snapping other flying critters out of the sky.

The “bizarre combination” of old and new traits indicates that Darwinopterus evolved in chunks, Unwin says. The find could lend support to a controversial idea called modular evolution, which says that evolutionary forces can act on whole groups of features — an entire head, for example, rather than just one tooth — at a time.

“The great thing about Darwinopterus is that it’s an example of modular evolution. It provides hard evidence for that kind of pattern,” Unwin says. “The challenge now is to find the genetic mechanism that would allow this to happen.”

Lisa Grossman is the astronomy writer. She has a degree in astronomy from Cornell University and a graduate certificate in science writing from University of California, Santa Cruz. She lives near Boston.

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