WASHINGTON (AP) - New fossil evidence of the earliest completeskeleton of an ancient primate suggests it was a hyperactive, wide-eyedcreature so small you could hold a couple of them in your hand - if onlythey would stay still long enough.
The 55-million-year-old fossildug up in central China is one of our first primate relatives and itgives scientists a better understanding of the complex evolution thateventually led to us. This tiny monkey-like creature weighed an ounce orless and wasn't a direct ancestor. Because it's so far back on thefamily tree it offers the best clues yet of what our earliest directrelatives would have been like at that time, according to a studypublished Wednesday in the journal Nature.
"It's a close cousin infact," said study author Christopher Beard, curator at the CarnegieMuseum of Natural History in Pittsburgh. He said it is "the closestthing we have to an ancestor of humans" so long ago.
Primate isthe order of life that includes humans along with apes, monkeys, andlemurs. Humans and other primates are set apart from other mammalsbecause of our grasping five fingers and toes, nails, and forward-facingeyes. And this new species called Archicebus achilles fits right in,Beard said.
Among primates there are three suborders: anthropoids,which include apes, monkeys and us; and two other suborders thatinclude lemurs and the lesser known tarsiers. This new species is in thesame grouping as tarsiers, but close to the offshoot branch in thefamily tree where humans come from. The fossil includes anthropoid-likefeatures.
"It's a cute little thing; it's ridiculously little,"Beard said. "That's one of the more important scientific aspects of thewhole story."
With a trunk only 2.8 inches long, the furrycreature was about as small as you can get and still be a mammal, Beardsaid. Just like elephants and horses, the farther back in time you getfor some of today's bigger mammals, the smaller they get, Beard said.
Because it was so small and warm-blooded, it had to eat bugs and move constantly to keep from losing internal heat, Beard said.
Thatmeans, Beard said, our earliest primate relatives were "very freneticcreatures, anxious, highly caffeinated animals running around lookingfor their next meal." They lived in a tree-lined area near a Chineselake, swinging around trees in a hotter climate, Beard said.
Outsideexperts praised the study as significant, confirming what some thoughtabout our primate ancestors. Rick Potts, director of the human originsprogram at the Smithsonian Institution, said this fossil's mix ofdifferent features illustrate the fascinating and crucial changes thatoccur around major evolutionary branch points in our family tree.
Thestudy also bolstered another theory that early primates first developedin Asia, even though humans evolved nearly 50 million years later inAfrica, Beard said.