Primate fossils reveal these animals suffered extreme stress due to a dramatic shift in climate. This discovery could reveal secrets about our distant ancestors.

Six previously-unknown species of primates were recently discovered in southeastern China, in a find being called a treasure trove of fossils. These newly-discovered forms of extinct animals were identified from jaw and tooth fragments preserved through the ages due to a tough coating of enamel.

The animals which formed these fossils lived around 34 million years ago, soon after the Eocene-Oligocene transition. Cooling at this time transformed Asia to a climate inhospitable to primates, wiping out populations which once lived on the continent.

"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," K. Christopher Beard, from the Biodiversity Institute at the University of Kansas, said.

Anthropoid primates - the distant ancestors of monkeys, as well as apes and humans - were driven to extinction in Asia, due to the rapid climate change. This event forms a vital link in the chain of human evolutionary development.

Later in the Eocene, the descendants of Asian survivors reached Africa, where the animals began to proliferate. This led to new species, and the creatures diversified. This same movement likely drove primates in eastern Asia down to lands now encompassing southeast China, where the fossils were found.

Oligotarsius rarus, one of the newly-discovered species, was found to be "incredibly similar" to the tarsier, seen today in the Philippines and the islands of Indonesia. These animals once roamed as far as northern China. The contemporary species is sometimes referred to as a "living fossil" due to their archaic body design.

Climate change during that distant era was just the opposite of the conditions we see today, as a warmer world began to cool. Researchers state their study reinforces the notion of the great vulnerability of primates to climate change.

Investigators suggest that if this ancient cooling had not occurred, these primates may have evolved and diversified in Asia, with potentially far-different results.

Discovery of the six previously-unknown species of primate and analysis of what the artifacts can tell us about our own evolution are profiled in the journal Science.

Photo: Carlos Luna | Flickr