Primate Fossils In China Tell Story Of Ancient Climate Change

The bone fragments of six ancient primate species reveal that anthropoid primates sought warmer Asian climates for survival.

AsianScientist (May 10, 2016) – Researchers have unearthed what has been described as a “mother lode” of a half-dozen fossil primate species in southern China. Their paper, published in Science, is the product of years of fieldwork at a site in southern China, where the primates likely sought warmer temperatures.

The team from the Chinese Academy of Sciences’ Institute of Vertebrate Paleontology and Paleoanthropology, together with colleagues in the US, describe the six new species from jaw and tooth fragments, which survived the ages due to their tough enamel surfaces. These bone fragments serve as “fingerprints” to identify ancient animals.

These primates eked out an existence just after the Eocene-Oligocene transition some 34 million years ago. It was a time when drastic cooling made much of Asia inhospitable to primates, slashing their populations and rendering discoveries of such fossils especially rare.

“At the Eocene-Oligocene boundary, because of the rearrangement of Earth’s major tectonic plates, you had a rapid drop in temperature and humidity,” said co-author, senior curator Mr. K. Christopher Beard at the University of Kansas’ Biodiversity Institute.

“Primates like it warm and wet, so they faced hard times around the world—to the extent that they went extinct in North America and Europe. Of course, primates somehow survived in Africa and Southern Asia, because we’re still around to talk about it.”

Because anthropoid primates—the forerunners of living monkeys, apes and humans—first appeared in Asia, understanding their fate on that continent is key to grasping the arc of early primate and human evolution.

“This has always been an enigma,” Beard said. “We had a lot of evidence previously that the earliest anthropoids originated in Asia. At some point, later in the Eocene, these Asian anthropoids got to Africa and started to diversify there.

“At some point, the geographic focal point of anthropoid evolution—monkeys, apes and humans—shifted from Asia to Africa. But we never understood when and why. Now, we know.

“The Eocene-Oligocene climate crisis virtually wiped out Asian anthropoids, so the only place they could evolve to become later monkeys, apes and humans was Africa.”

According to Beard, many primates from the Oligocene were present at this particular site because it was located far enough to the south that it remained warm enough during that cold, dry time, so primates could still survive there. They crowded into the limited space that remained available to them.

Beard said that if not for the intense global cooling of the Eocene-Oligocene transition, the main stage of primate evolution may have continued to be in Asia, rather than transitioning to Africa where Homo sapiens eventually emerged. Indeed, the team’s findings underscore a vulnerability to climate change shared by all primates.

“This is the flip side of what people are worried about now,” he said. “The Eocene-Oligocene transition was the opposite of global warming—the whole world was already warm, then it cooled off. It’s kind of a mirror image. The point is that primates then, just like primates today, are more sensitive to a changing climate than other mammals.”

The article can be found at: Ni et al. (2016) Oligocene Primates from China Reveal Divergence Between African and Asian Primate Evolution.


Source: University of Kansas.
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