The #1 source for news about monkeys and apes

[Josh Greenman <josh.greenman AT gmail.com>]

http://www.nytimes.com/2010/07/20/science/20obmonkey.html?src=twr

July 19, 2010

A Discovery Could Help Date Monkey-Ape Split

By SINDYA N. BHANOO

There are a few important differences between Old World monkeys and
apes. Old World monkeys, like baboons and macaques, have tails and a
great deal of agility, enabling them to jump and swing from tree
branches.

Apes, which include gorillas and chimpanzees, are tail-less and tend
to have a more upright posture. Scientists agree that Old World
monkeys and apes share a common ancestry, but at some point two
lineages diverged, one giving rise to the Old World monkeys and
another to both apes and humans. Eactly when the split happened is a
matter of debate.

A primate skull unearthed outside of Mecca in Saudi Arabia is the
closest common ancestor to apes and Old World monkeys, researchers
say, and helps date the split. Sediment records indicate that the
fossil is 25 million to 29 million years old, making 24 million to 29
million years ago the window in which the monkey-ape split may have
occurred. The ape and human lineages split later.

The research appears in the journal Nature.

“It is neither a monkey, nor an ape,” said Iyad Zalmout a
paleontologist at the University of Michigan and the study’s lead
author. “You have an intermediate primate that tells you a story about
Old World monkeys and apes.”

Based on the skull, the primate was medium-sized and weighed about 30
pounds to 40 pounds. It had broad upper molars and a long, baboonlike
snout.

A previous estimate, made with DNA samples of living primates found
that the split occurred earlier, 34.5 million to 29.2 million years
ago. There is however, no fossil evidence to support this.