Fossils Found In China Help Piece Together The Evolution Of Primates

A new fossil trove has been discovered in southern China, reports Maine News Online. It was announced on Thursday that scientists have discovered the remains of six formerly unknown, extinct primate species that lived in trees 34 million years ago. This discovery is expected to shed more light on the evolution of primates.

Four of the remains found are similar to the Madagascan Lemur, another to the furry, squirrel sized tarsiers of the Philippines and Indonesia, and one monkey-like primate.

Ring-tailed lemurs, one of the many species of lemur found in Madagascar with a skeleton similar to four of the new fossils discovered [AP Photo/Nati Harnik]
Ring-tailed lemurs, one of the many species of lemur found in Madagascar with a skeleton similar to four of the new fossils discovered [AP Photo/Nati Harnik]The primate lineage that led to monkeys, apes and our earliest ancestors called anthropoids, originated in Asia, said researcher, where the earliest fossils date from around 45 million years ago. It was only seven million years later that some of these anthropoids migrated to Africa.

Why then, did apes and people not surface in Asia as opposed to Africa? The answer to this question has been put forward by Palaeontologist Xijun Ni at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences. According to a joint study conducted by him and US scientists, the "Big Chill," a massive cooling event in the region some 34 million years ago that wiped out all large primates, was "a critical filtering episode during the evolutionary history of primates."

During this period, known as Eocene-Oligocene transition, most of the earth except for Africa and Southeast Asia experienced a rapid drop in temperature and humidity because of tectonic shifts. Prior to this event, anthropoids were the most prolific of Asia's primates, later to be dominated by lemur-like primates, with the monkey-like ones all but destroyed, as indicated by the fact that only one of the six new species found in China's Yunnan Province was an anthropoid. This anthropoid, named Bahinia banyueae, is said to have resembled the present day marmoset, a small South American monkey. Its teeth indicated it's diet consisted of mainly fruits and insects.

[caption id="attachment_3076002" align="aligncenter" width="670"]The Yunnan Province where the discovery was made [image via gringos4] The Yunnan Province where the discovery ewas made[image via gringos4][/caption]Because Africa was less affected by the cooling, its anthropoids evolved into larger and more varied species, with the first humans emerging around 200,000 years ago.

The study was conducted over a period of 10 years in southern China, where it is likely the primates migrated in search of warmer temperatures.

"The fossil record usually gives you a snapshot here or there of what ancient life was like. You typically don't get a movie," Chris Beard, paleontologist at University of Kansas, said. "We have so many primates from the Oligocene at this particular site because it was located far enough to the south that it remained warm enough during that cold, dry time that primates could still survive there."

The findings are consistent with all primate's low resistance to climatic change. "This is the flip side of what people are worried about now," Beard said. "The point is that primates then, just like primates today, are more sensitive to a changing climate than other mammals." He further stated that, "If early Asian anthropoids had not been able to colonize Africa prior to the [climate cooling], then we certainly would not be here to ponder such things. Likewise, if Asian anthropoids had not suffered such big evolutionary losses [after the cooling], our distant ancestors might have evolved in Asia instead of Africa."

According to retired paleoanthropologist professor Wei Qi, the study may have overestimated the impact of climate change because the cooling event 34 million years ago was a long time before the emergence of the earliest humanoids. "Some primates might still have survived in Asia after the Eocene-Oligocene transition, and we just haven't found their fossils yet. To rule out the possibility of Asian origin with a few fragments of jaws and teeth is to make a big claim with little evidence."

[Image: AP Photo/Aaron Favila]