Tiny, Ancient Tree-Dweller Was One Of Earth's Earliest Primates About 55 million years ago, a teacup-sized critter in China was helping to pave the way for apes and humans. This insect eater had fingernails and stereo vision, a newly published analysis of a fossil suggests. And it weighed just 1 ounce.

Tiny, Ancient Tree-Dweller Was One Of Earth's Earliest Primates

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From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.


And I'm Audie Cornish.

Scientists place the origin of the very first primates - the group that includes humans, apes and monkeys - way back in the deep past about 55 million years ago. Fossils from that period are rare. But now, there's an exciting new one.

NPR's Christopher Joyce reports on what scientists make of it.

CHRISTOPHER JOYCE, BYLINE: It's called Archicebus, roughly meaning beginning long-tailed monkey. Actually, this creature lived before the monkeys we know of today - 55 million years ago, a mere 10 million years after the dinosaurs died out. But Archicebus had some primitive features we associate with monkeys and the rest of the primates. It had big eye sockets, for example, and they are angled in a way that meant the animal had good stereo vision. It had nails instead of claws and grasping digits, and other unique traits.

Many of these would have been good for living in trees and, perhaps, capturing insects.

CHRISTOPHER BEARD: It's a fossil that shows a combination of features that we've simply never seen before in any living or fossil primate.

JOYCE: Christopher Beard is with the Carnegie Museum of Natural History, in Pittsburgh, and worked on the team.

The fossil was discovered by a farmer in China. Alive, the animal weighed an ounce and would fit in the palm of your hand. The skeleton's completeness and its great age are extraordinary. It was a special time in evolution. The first primates were emerging. Over time, they would evolve and diverge into numerous body types and behaviors; some becoming monkeys, some lemurs, and one would one would eventually evolve into us - Homo sapiens.

Beard says the lineage Archicebus was on may not have been the one we came from.

BEARD: But in any case, the take-home picture should be that here is a fossil that's very, very close to that evolutionary divergence.

JOYCE: And apparently, that divergence happened in Asia. Writing in the journal "Nature," the scientists say Archicebus may be the earliest primate skeleton ever found. Duke University anthropologist Richard Kay says, well, maybe. It's a murky field of study - some other primate fossils might qualify. But Archicebus was certainly close kin to the first primate and it could help answer some crucial questions.

RICHARD KAY: Why did this group of animals get really well-developed vision? Why did they get rid of perfectly good claws and start to have nails on their fingers? And a lot of other characteristics, they beg an answer as to why did this change occur.

JOYCE: Christopher Joyce, NPR News.

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