[asa] Any comments? Fossils belong to new great ape

From: IW <iain@secure.holuwon.com>
Date: Wed Aug 22 2007 - 18:47:45 EDT

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http://news.bbc.co.uk/2/hi/science/nature/6958313.stm

Fossils belong to new great ape
By Liz Seward

Chororapithecus abyssinicus teeth Image: Gen Suwa
The teeth have gorilla-like characteristics, say researchers
Nine fossilised teeth found in Ethiopia are from a previously unknown
species of great ape, Nature journal reports.

The 10 million-year-old fossils belong to an animal that has been named
Cororapithecus abyssinicus by the Ethiopian-Japanese team.

This new species could be a direct ancestor of living African great
apes, say the researchers.

The finds from the Afar rift, in eastern Ethiopia, raise questions on
current theories of human evolution.

The researchers say the fossils from Ethiopia probably belonged to an
ape from the gorilla family.

Evolutionary divide

Based on genetic evidence, gorillas and humans were thought to have
split away from a common ancestor about eight million years ago.

The 10 million-year age of the fossils led the research team to suggest
that the split must have happened earlier than 10.5 million years ago.

If correct, molecular and DNA studies will need to be revisited.

Sieving the Chororapithecus molar site. Dr Yonas Beyene (right
foreground) instructing the work Image: Gen Suwa The fossils were found
at a site in eastern Ethiopia's Afar rift The team's claims that the
teeth belong to a member of the gorilla family stem from similarities
with teeth of modern gorillas.

They carried out cutting-edge 3D analysis of the molar tooth's
structure and found that both gorillas and the new species had a unique
specialisation for eating fibrous foodstuffs such as stems and leaves.

"It's a subtle distinction, but we've compared it with everything we
could think of," said Dr Suwa from The University of Tokyo, and a
member of the research team.

"And it does show some telling signs of gorilla-like molar structure.
If it's not a gorilla relative, then it's something very similar to
what an early gorilla must have looked like."

Vegetarian tastes

Gorillas are unique among modern and fossil large-bodied apes in having
molars that are specialised for shredding fibrous vegetation. The
reason for this is that large-bodied gorillas depend on stems and
leaves as an important part of their diet.

Not everyone agrees with the teams conclusions, however. Professor
Peter Andrews, from London's Natural History Museum, commented: "It is
stretching the evidence to base a time scale for the evolution of the
great apes on this new fossil."

Professor Andrews believes the structures found on the teeth could be
related to the diet of the animal.

He added: "These structures appear on at least three independent
lineages of apes, including gorillas, and they could relate to a
dietary shift rather than indicating a new genetic trait."

Fossil record

What is not in doubt is that is that the find itself is impressive.

"The ancestry of humans is increasingly well known, but the fossil
evidence for the evolution of our closest living relatives, the great
apes, is almost non-existent," Professor Andrews explained.

"It is really exciting therefore to find a fossil ape from this time
period - about 10 million years ago - since there is only one other
fossil ape known from this time, the more complete Samburupithecus."

The find also supports data that suggests Africa was the origin of both
humans and modern African apes.

The teeth were discovered in a region called the Afar rift in Ethiopia,
about 170km (106 miles) east of Addis Ababa.

In an area of the Oromiya National Regional State, there are exposed
patches of sediments that are 10 to 11 million years old, from the
Miocene era, which are known as Miocene Chorora Formation.

The name of the ape is taken from the geological formation Chorora and
the former name of Ethiopia, Abyssinia.
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Received on Wed Aug 22 19:07:09 2007

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