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| The skull of an ape buried by a volcano 13 million years ago has preserved intriguing clues about the ancestor humans shared with apes including a likely African origin, scientists said.
A previously unknown creature that shared an extended family with the
human forefather, had a flat face like that of our far-flung cousin the gibbon,
but did not move like one, its discoverers wrote in the journal Nature.
They named it Nyanzapithecus alesi after "ales" the word for
"ancestor" in the Turkana language of Kenya, where the lemon-sized
skull was unearthed.
The sole specimen is that of an infant that would have grown to weigh
about 11 kilograms (24 pounds) in adulthood. It had a brain much larger than
monkeys from the same epoch, the researchers said.
"If you compare to all living things, it looks most like a
gibbon," study co-author Isaiah Nengo of the Stony Brook University in New
York told AFP.
This does not mean the direct ancestor of living apes necessarily looked
like a gibbon, just that a member of its family did at the time.
Assuming a gibbon-like appearance for our ancestor would be similar to
scientists from the future unearthing a gorilla skull and concluding that all
hominins the group that also includes
chimps and humans looked like a gorilla.
The location of the extraordinary fossil find, said the team, supported
the idea that the ape-human ancestor lived in Africa and not in Asia as some
have speculated.
"With this we... put the root of the hominoidea in Africa more
firmly," said Nengo.
Hominoidea, or hominoids, is the name for the family of apes.
The group is divided in two, with humans, bonobos, chimps, gorillas and
orangutans on the one side (hominids), and agile, tree-swinging gibbons
(hylobatids) alone on the other.
The new species belonged to a much older, ancestral group that included
the forefather of hominoids, the researchers concluded.
- Out of Africa -
That group, which has no official name yet, lived and died millions of
years ago.
"The majority of that group, and the oldest members of that group,
are African but we would not have been able to resolve all of that without
Alesi," said Nengo.
"Alesi is the one that has allowed us to... know who is in that
group... and when we take a close look we see that most of the group are found
in Africa."
Alesi's is the most complete ape skull from the entire Miocene period,
which ranged from about 24 million to five million years ago.
"It may be younger (than some other fossil pieces) but it is the
only one where you have a face, you have the base of a skull, you have the
inside of the skull, so you can see what a representative of them might have
looked like," said Nengo.
Hi-tech scans of the skull showed that Alesi had teeth similar to some
gibbon species.
While its baby teeth had been knocked out, Alesi's adult teeth lay
unerupted inside its jaw, and their age could be determined with great
precision the ape was one year and four months old when it died.
The team also established that the balance organs in Alesi's ear were
unlike those of the gibbon, meaning it probably had a different, slower, way of
moving.
While a lot is known about human evolution since we split from chimps
about seven million years ago, little was known about common ancestors from
before 10 million years ago.
Commenting on the study, anthropologist Brenda Benefit of the New Mexico
State University described this as a fossil find "that I never thought
would be made during my lifetime".
"This discovery will help to fill in missing information regarding
adaptations that influence ape and human evolutionary histories," she said
in comments published by the journal.
"This is an exceptional discovery,"
agreed Paul Tafforeau of the European Synchrotron Radiation Facility in
Grenoble, France, who helped examine the skull.
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