Sunday, June 17, 2012

NEW FOSSIL IN MYANMAR MAYBE BE EALRIEST ANCESTOR OF HUMANS, APES AND MONKEYS

The ancestors of humans, apes and monkeys evolved first in Asia before moving on to Africa, suggests a new fossil find from Myanmar. Remains of a newly found primate, Afrasia djijidae, show this monkey-like animal lived 37 million years ago and was a likely ancestor of anthropoids -- the group including humans, apes and monkeys.

Christopher Beard, a Carnegie Museum of Natural History vertebrate paleontologist who co-authored a study about the fossil find in the latest Proceedings of the National Academy of Sciences says "Our paper is the logical precursor to that, because we are showing how the anthropoid ancestors of humans made their way 'Into Africa."

Beard, project leader Jean-Jacques Jaeger of the University of Poitiers, and their colleagues analyzed the tooth remains of Afrasia. They found that it is very similar to, but more primitive than, another early anthropoid, Afrotarsius libycus, recently discovered at a site of similar age in the Sahara Desert of Libya. (The term "anthropoid" is used instead of "primate" because all anthropoids are primates, but not all primates are anthropoids. Lemurs, for example, fall into that latter group.)

The tooth size of Afrasia and Afrotarsius indicates that in life, both animals only weighed around 3.5 ounces. They likely fed mostly on insects and probably resembled small monkeys, Beard said. It remains a mystery as to how the small Asian animals came to Africa. "What we do know is that they had to cross a much larger version of the Mediterranean Sea (the ancient body of water was called the Tethys Sea) in order to go from Asia to Africa," Beard said. "At that time, Africa was an island continent like Australia is today."

He and his colleagues suspect that this branch eventually went extinct. It is likely that multiple Asian anthropoid species were able to colonize Africa 38-37 million years ago, with one species evolving many years later into Homo sapiens.

Scientists have long wondered why anthropoids just seemed to suddenly appear in Africa, with no apparent ancestry there. Afrasia's discovery helps to solve that mystery by opening up a new pre-chapter set in Asia.

"For years, we thought the African fossil record was simply bad," Jaeger
said. "The fact that similar anthropoids lived at the same time in Myanmar
and Libya suggests that the gap in early African anthropoid evolution is
actually real. Anthropoids didn't arrive in Africa until right before we
find their fossils in Libya."

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