Earliest gibbon fossil discovered in China

A team of researchers led by the Kunming Institute of Zoology (KIZ) in China has recently discovered and described the earliest gibbon fossil in the Yuanmou area of the Yunnan Province in southwestern China. This finding could help scientists fill a long-elusive evolutionary gap in the history of apes.

The study focused on hylobatids – a family of apes also including 20 species of living gibbons found throughout tropical Asia, from the northeastern part of India to Indonesia. “Hylobatids fossil remains are very rare, and most specimens are isolated teeth and fragmentary jaw bones found in cave sites in southern China and southeast Asia dating back no more than two million years ago,” said study co-author Terry Harrison, a professor of Anthropology at the New York University.

“This new find extends the fossil record of hylobatids back to seven to eight million years ago and, more specifically, enhances our understanding of the evolution of this family of apes.”

This specific fossil belongs to a species of small ape called Yuanmoupithecus xiaoyuan. By analyzing the teeth and cranial specimens discovered in Youanmou, the researchers estimated that Yuanmoupithecus was similar in size to today’s gibbons, with a body weight of approximately six kilograms.

“The teeth and the lower face of Yuanmoupithecus are very similar to those of modern-day gibbons, but in a few features the fossil species was more primitive and points to it being the ancestor of all the living species,” Professor Harrison reported.

The scientists also found that Kapi ramnagarensis – an ape claimed to be an earlier species of hylobatid, based on a single isolated fossil molar discovered in India, is in fact not a hylobatid, but a member of a more primitive group of primates which are not closely related to modern apes.

“Genetic studies indicate that the hylobatids diverged from the lineage leading to the great apes and humans about 17 to 22 million years ago, so there is still a 10-million-year gap in the fossil record that needs to be filled. With continued exploration of promising fossil sites in China and elsewhere in Asia, it is hoped that additional discoveries will help fill these critical gaps in the evolutionary history of hylobatids,” Professor Harrison concluded.

The study is published in the Journal of Human Evolution. 

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By Andrei Ionescu, Earth.com Staff Writer