for National Geographic News
Paleontologists have unearthed a chipmunk-size creature from the late Jurassic period, and they say it could have a big impact on ideas about early mammal evolution.
The species is about 150 million years old and has the scientific name Fruitafossor windscheffeli. But noting the animal's enormous forearms, scientists nicknamed it "Popeye," after the cartoon sailor.
The small species is by far the earliest known burrowing mammal to have fed on communal insects, such as termites.
Until the new discovery, the most recent evidence of such behavior was only 50 million years olda difference of about a 100 million years.
Scientists from the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, describe the fossil in tomorrow's issue of the research journal Science.
Zhe-Xi Luo, led author of the paper, said he knew immediately that the find was unusual because of creature's distinctive teeth.
Unlike most known mammals of the period, Fruitafossor had teeth that each had a single root (a human molar has four roots), no enamel, and a wide opening at the root. So-called open-root teeth are common to animals that gnaw, such as beavers. Wide root openings allow teeth to quickly replace tooth material lost through intense chewing.
"These peculiar teeth in an otherwise very primitive Jurassic mammal were puzzling, as these teeth weren't supposed to appear until much later, when the armadillos evolved 50 million years ago, and again still later in form of the African aardvark," said Luo, who is the curator of vertebrate paleontology at the Carnegie Museum.
"Gradually we came to a startling realization that 150 million years ago, there was a separate evolutionary experiment by some Jurassic mammal in feeding on communal insects.
"Its teeth showed it probably lived like an armadillo," Luo added. "It most likely used its massive arms and claws to dig in the earth to eat colonies of termites and other invertebrates. But it was also capable of eating plants when insects weren't available. This type of adaptation occurred many times in mammalian evolution, but this is the earliest appearance."
Fruitafossor's Popeye-like forearms not only allowed the animal to burrow for insects but possibly to hide from Stegosaurus, Allosaurus, and other large dinosaurs of the day.
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