March 31, 2005

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Researchers discover new species of mammal with unique features
otherwise only known to appear 100 million years later
Dubbed "Popeye" due to its massive forearms

Pittsburgh … Scientists from Carnegie Museum of Natural History have discovered a brand new species of early mammal, dubbed "Popeye" because of its massive forearms. It shows some very unique features that would be otherwise known only in armadillos, but it is older than the armadillo lineage by 100 million years and unrelated to them.

In an article published today in Science, the team of Carnegie Museum of Natural History scientists describe a 150 million year old fossilized skeleton of Fruitafossor windscheffeli ([Fruita] - for Fruita, CO the town where it was found, [fossor] - Latin for digger; [windscheffeli] - in honor of Wally Windscheffel, the museum volunteer who discovered the fossil). Fruitafossor is the most complete mammal known from the Jurassic of North America from the age of dinosaurs.

Fruitafossor is the first known mammal that was adapted for feeding on communal insects and for digging and burrowing. Its shoulder joint is more similar to primitive egg-laying mammals (the platypus and echidna or spiny anteater) than to a mole.

The most prominent feature of Fruitafossor is its single- and open-rooted tubular molars, which suggest that the molars had a sustained and continuous growth in life, and are similar to the teeth of present-day armadillos, which feed primarily on insects, small invertebrates, and occasionally plants. Fruitafossor molars also bear some resemblance to the living aardvark that is specialized for feeding on ants and termites. Because of these similarities, Fruitafossor is thought to have had a similar diet.

"It's a brand new lineage of mammal an early example of a digger, with a specialized diet, eating communal insects, a most interesting way of life for such an ancient animal," said Dr. Zhe-Xi Luo, curator of Vertebrate Paleontology at Carnegie Museum of Natural History and the lead author of the paper.

"Its teeth showed it probably lived like an armadillo," said Dr. Luo. "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."

"Nothing like this occurs in the fossil record for almost 100 million years later when the earliest armadillos appeared in South America," said Dr. John Wible, curator of Mammals at Carnegie Museum of Natural History and co-author of the paper.

"There is a remarkable convergence in the teeth as well as in the spine, where Fruitafossor and armadillos share an extra joint between individual vertebra," Dr. Wible said. The spinal similarities are only known to exist in armadillos and their relatives, sloths and anteaters, and this creature that lived 150 million years ago. It will radically change the way we look at the evolution of this adaptation.

This animal was about 15 cm (about 6 inches) long and weighed about 30 grams or one ounce. It is slightly longer and slimmer than a hairy-tailed mouse.

It was a digger, hiding in burrows from large sauropod dinosaurs as well as Stegosaurus and Allosaurus. Mammals co-existing with Fruitafossor mostly ate insects. Other types of animals living at this time included crocodiles, turtles, lizards, sphenodonts, frogs and flying reptiles as well as the first birds.

The fossil was found in 1998 outside of Fruita, CO. Windscheffel, a field associate in Carnegie Museum of Natural History's section of Vertebrate Paleontology, found the nearly complete skeleton in a fossil-rich area in the same geological formation as Dinosaur National Monument, which provided the museum most of its world-famous dinosaur collection. The research was supported by funding from the National Science Foundation and Carnegie Museum of Natural History.

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