Wednesday March 15 2:47 PM ET
Fossils of Tiny Primates Found
By DAVID KINNEY, Associated Press Writer

Anthropologists have discovered fossils from two species of ``teeny, tiny
primates,'' thumb-sized creatures smaller than any other known primate on the
family tree leading to monkeys, apes and humans.

``This discovery reinvents our definition of what the primate order is all
about and how it arose,'' said Richard Stucky, curator at the Denver Museum
of Natural History.

The fossilized foot bones, each about the size of a grain of rice, were
sifted from tons of muddy rubbish at a limestone mine in eastern China. About
45 million years ago, the fragile primates lived in a rain forest, feeding on
insects and sap.

At one-third of an ounce - the weight of a couple of pencils - the smaller of
the two is dwarfed by the 1-ounce Madagascar mouse lemur, the smallest known
primate alive today.

Scientists from Northern Illinois, Northwestern and Beijing's Chinese Academy
of Sciences detail the species in this week's Journal of Human Evolution.

In a separate article in the journal Nature, the group reported more fossils
from a previously discovered third primate called Eosimias centennicus. They
had discovered its teeth and jaws in the mid 1990s. Now they have ankle
bones, which they say backs up their controversial claim that Eosimias is an
early ancestor of humans.

Eosimias and the two new tiny species all lived together around the time when
lower primates split from the higher primates. Lower primates include lemurs.
Higher primates include humans. The split happened 40 million to 50 million
years ago.

At 3 ounces, Eosimias was larger than the tiny species, which have not been
named.

The smaller of the two new species might have been below Eosimias on the
evolutionary branch, a common ancestor of higher primates and some lower
primates, said Chris Beard of the Carnegie Museum of Natural History.

The larger one - weighing half an ounce - appears to be a higher primate,
perhaps in the same family as Eosimias.

``Nobody would have believed that as recently as 45 million years ago, our
ancestors were about the size of a shrew,'' Beard said.

Anthropologists expected to find a smallish creature at the fork between
higher and lower primates.

Because it would have needed to eat insects voraciously to keep up with an
overheated metabolism, it would have had higher primate features: two eyes
facing forward and soft hands without claws, all the better to focus on and
grab bugs.

``That said, these are really tiny,'' said Brian Richmond, a George
Washington researcher.

Unlike modern higher primates, which are social and move about in the
daytime, these creatures' tiny size would have forced them to hide during the
day and feed at night.

The tiny species are the smallest of 12 to 16 species of little primates
found at the Chinese mine.

Eosimias is among them. Its ankle bones are further proof the creature was a
higher primate, Beard said. They show it walked on all fours. Like monkeys
that scurry atop tree branches, their feet face downward. Lower primate feet
face inward, so they can cling to tree trunks.

But the evidence of Eosimias' status as a higher primate is still not
conclusive. Richmond said it is possible Eosimias was a lower primate that
evolved a few characteristics similar to higher primates.

Also, Beard's team has not found a skull or full skeleton. They inferred the
ankle fossils to be Eosimias' based on where they were found.

Stucky is convinced, calling it ``significant, additional evidence'' that
Eosimias is a higher primate.

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On the Net: Researchers' site: http://www.niu.edu/pubaffairs/primate