Chinese fossils illuminate key evolutionary period

WASHINGTON // The fossils of six furry critters that inhabited the trees of southern China 34 million years ago is providing a deeper understanding of the evolution of primates, which eventually gave rise to human beings.

Scientists on Thursday announced the discovery of the remains of six previously unknown extinct primate species: four similar to Madagascar’s lemurs; one similar to the nocturnal insect and lizard-eating tarsiers of the Philippines and Indonesia; and one monkey-like primate.

Primates are among the most environmentally sensitive of all mammals.

These lived shortly ­after a dramatic spell of global climate change that brought cooler, drier conditions, triggering the extinction of all primates in North America and Europe and devastating Asia’s primates.

The primate lineage that led to monkeys, apes and people, called anthropoids, originated in Asia, with their earliest fossils dating from 45 million years ago.

Only later, about 38 million years ago, did some anthropoids migrate to Africa, where 200,000 years ago human beings arose.

But if anthropoids first appeared in Asia, why did apes and people not emerge there, too?

The big chill 34 million years ago is the reason. This juncture represented “a critical filtering episode during the evolutionary history of primates”, says palaeontologist Xijun Ni of the Chinese Academy of Sciences’ Institute of Vertebrate Palaeontology and Palaeoanthropology.

Before the temperatures fell, Asia’s primates were dominated by anthropoids. Afterwards, they were dominated by lemur-like primates. To illustrate that, just one of the six new species unearthed in China’s Yunnan Province was an anthropoid.

Africa was less affected by the climate change and its anthropoids became larger and more diverse.

“If early Asian anthropoids had not been able to colonise Africa prior to the climate cooling, then we certainly would not be here to ponder such things,” said University of Kansas palaeontologist Chris Beard.

“Likewise, if Asian anthropoids had not suffered such big evolutionary losses, our distant ancestors might have evolved in Asia instead of Africa.”

The lone anthropoid in the group, a small, monkey-like primate, probably resembled some of today’s smaller South American monkeys such as marmosets, while its teeth suggest its diet was mainly fruits and insects, Dr Beard said. The six species were represented by fossil teeth, jaws and other bones.

The research was published in the journal Science.