Washington, March 4 : A paleontologist has discovered fossils of a 55-million-year-old ape on the Gulf Coastal Plain of Mississippi, which makes it North America's oldest known primate.
Discovered by Christopher Beard, a paleontologist at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, the fossil is of an animal named "Teilhardina magnoliana."
According to a report in National Geographic News, the animal is related to similarly aged fossils from China, Europe, and Wyoming's Big Horn Basin.
"They are very, very primitive relatives of living primates called tarsiers, which live today in Southeast Asia," said Beard.
But the layer of rock in which the new fossils were found raises the controversial possibility that primates appeared in North America before their close relatives showed up in Europe, as previous studies had suggested, added Beard.
According to Beard, the discovery suggests that Teilhardina primates migrated to North America across the Bering land bridge from Asia. Then, the creatures proceeded to Europe across an Atlantic land bridge that emerged thousands of years later.
Previous research had suggested the primates reached the Americas via a westward route instead, from Asia through Europe.
"But that path was submerged at the time the primates show up in ancient Mississippi," said Beard.
At that time, the world was undergoing an ancient global warming event known as the Paleocene-Eocene Thermal Maximum, or PETM.
"T. magnoliana dates to a time before sea levels had fallen enough for primates to cross over to North America from Europe," said Beard.
"We know the sea level was high when our fossil primates lived in Mississippi, because the actual bed that yielded our fossils is a marine bed," he added.
The same sea-level imprints are found in the rock section where Teilhardina was found in Europe. This indicates that Teilhardina arrived there after the sea level had dropped.
"So we know the Teilhardina fossils we're finding in Mississippi are older than the ones that have been found in Europe and along with that they are anatomically more primitive," said Beard.
If T. magnoliana indeed predates the Teilhardina find in Wyoming, it would also indicate the primates stuck to the coasts for tens of thousands of years before the climate changed enough for them to migrate inland.
"It took time for the North American ecosystems, especially in the interior part of the continent, to kind of adapt to this big warming event," said Beard.