BEIJING, May 15 (Xinhuanet) -- The second and almost perfect 29 million-year-old
fossilised skull of an ancient relative of humans, apes and monkeys has been
unearthed in Egypt, media reported Tuesday.
Elwyn Simons with 1966 male skull (left)
and much smaller and better preserved new female specimen. (File
The skull, from a species known as Aegyptopithecus
zeuxis -- "linking Egyptian ape" or dawn ape, was identified by Duke University
primatologist Elwyn Simons in a quarry on the outskirts of Cairo. Because of the
new specimen's remarkable wholeness, Simons and his colleagues were able to
subject it to micro CT scanning, a computerized X-ray technique that can be used
to calculate the approximate dimensions of the brain the cranium once encased.
According to Simons, the specimen is from a young
female that lived in the early Oligocene, a period of global cooling, volcanic
eruptions and seismic disturbance, driven by the collision of the Indian and
Asian continental plates.
Based on previous fossils collected at the same dig
site in a quarry outside Cairo, scientists have hypothesized that this early
monkey already would have had a relatively large brain, said Simons.
But the researchers' new report, which displays the
computer-reconstructed brain as a false-color red mass within the grey skull
case, suggests that the skull was half the size of the first dawn ape skull, a
male found in 1966, suggesting modern apes and monkeys developed larger brains
later in evolution.
The species "had a brain that might have been even
smaller than that of a modern lemur's," Simons said. "This means the big-brained
monkeys and apes developed their large brains at a later point in time."
But measurements led the scientists to believe it was
capable of forming large social troops similar to those seen in modern day
primates. The shape of the eye sockets suggest the species was active during the
daytime, like modern apes.
Aegyptopithecus fossils have been found in two
quarries separated by about a kilometer within Egypt's Fayum Depression.
Scientific evidence suggests the location, now arid, was a tropical forest 29
million years ago.