Time for some mammalian bragging. It appears, following the discovery of a unique fossil in Inner Mongolia, China, that mammals might have taken to the air before birds.
The fossil contains the remains of a small, squirrel-like mammal that was able to glide with the help of a fur-covered membrane like those of modern-day flying squirrels (pictured). At 125 million years old, the fossil is 70 million years older than the most ancient existing fossil of a flying mammal, and roughly the same age as fossils of the first birds.
About the size of a rat, the animal, named Volaticotherium antiquus, had a membrane connecting each flank of its torso to its hands and feet, forming a sail for gliding. A study of the animal's teeth reveals it ate insects, and its hand bones are suited to climbing trees (Nature, vol 444, p 889).
The find challenges assumptions that almost all early mammals were short-legged creatures that foraged in undergrowth. "It shows how diverse the early mammals were in their lifestyles and morphology," says team leader Jin Meng of the American Museum of Natural History in New York. He says the team was lucky to spot the imprint of the fur membrane in the rock containing the fossil, and that other ancient flying mammals may have been missed.
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