A partial skull and jawbone excavated from the 2,300-year-old tomb of a Chinese noblewoman belonged to an unknown but now extinct gibbon, scientists say.
In a nod to its royal heritage, they dubbed the gibbon Junzi imperalis.
The bones of the little animal are the first documented evidence of an ape that became extinct since the Ice Age, the international team reports today in the journal Science.
They say the disappearance of the ape was likely caused by human activity and suggests past human-caused losses of primates have been underestimated.
“It was thought that apes and most other primates have been relatively resilient to past human pressures on biodiversity,” said Samuel Turvey from the Zoological Society of London.
“But this assumption reflects the fact that primate remains are rarely preserved in the archaeological record or recent fossil record across most of the tropics.
The discovery of Junzi imperialis suggests more effort is needed to conserve surviving gibbons in China, including what may be the world’s most endangered primate, he added.
Dr Turvey came across the fossil in archaeological collections in Xi’an, Shaanxi Province in northwest China.
The bones had been excavated in 2004 from the royal tomb, which is believed to hold Lady Xia, grandmother of China’s first emperor Qin Shihuang â€” who ordered the construction of the Great Wall and the terracotta warriors.
The tomb also contained the remains of a menagerie of animals from the local area including a leopard, lynx, Asiatic black bear, crane, domestic animals and birds.
Gibbons have featured in Chinese culture for thousands of years, where they were venerated as symbols of scholar officials â€” Junzi â€” and were kept as high-status pets.
Today, the small apes are found in pockets of forests in south-western China, 1,200 km away from the site of the tomb.
But historic accounts indicate gibbons lived in the Shaanxi region up until the 18th century.
There are around 20 species of the apes spread out over four genera in the world today.
To understand where Junzi imperialis fitted into the picture, Dr Turvey and his colleagues reconstructed the skull and jawbone of Lady Xi’s gibbon and compared it to those of living gibbons.
“The Xi’an gibbon is distinct from all living gibbons,” Dr Turvey said.
Compared to the other gibbons, Lady Xia’s gibbon had a much steeper forehead, larger eye sockets and unique dental patterns such as large wisdom teeth.
They also compared the jawbone to extinct species that lived sometime during the Middle Pleistocene period up until 126,000 years ago during the Ice Age
The fact that it didn’t match any living or extinct ape meant not only was it a new species, but a new genus.
But, he added, it is impossible to tell where it may fit in the family tree without using more destructive techniques to sample DNA.
Dr Turvey said the disappearance of Junzi imperialis was most likely due to human factors rather than other factors such as climate changes.
“No vertebrate species extinction events can definitively be associated with natural climate change during the Holocene,” he said.
“We are increasingly realising that human activities, hunting and habitat destruction, have driven large numbers of species extinctions throughout the historical period and recent prehistory.”
Zoologist Kristofer Helgen, who was not involved in the current research, said the discovery of a new species of gibbon was significant.
“These small apes are absolutely beautiful, elegant animals.”
“Some of these are very endangered species today, but we didn’t have any clear evidence that there had been recent extinctions,” said Professor Helgen, who is the deputy director of the Centre for Applied Conservation Science at the University of Adelaide.
While extinctions of primates such as lemurs and monkeys have been documented on islands since the Ice Age, this is the first extinction of a primate on a continent.
“People have lived in China for an enormous length of time.
“The past two millennia in China has been one of major growth in human population, major transformation of the environment from more natural landscapes to more human-dominated landscapes.”
“It’s exactly across this timeframe that we now realise this gibbon has disappeared.”
Dr Turvey said the disappearance of Junzi imperialis emphasises the need to focus more conservation efforts on today’s surviving gibbons.
Two species of gibbon have recently become extinct in China leaving just four remaining species â€” all of which are listed as critically endangered
According to research published last year, the expansion of rubber plantations in south-west China has caused the near extinction of both the Hainan gibbon and the northern white cheeked crested gibbon.
But it’s not all bad news. Last year Dr Turvey, Professor Helgen and colleagues announced the discovery of a new species of gibbon â€” Hoolock tianxing, dubbed the Skywalker gibbon.
“That was exciting. Even though it is endangered, now is the time to understand this gibbon, understand what it means to be protected and survive,” Professor Helgen said.
In contrast, he said the new discovery was sobering.
“If we’ve lost this gibbon in the more northern part of China, and many of the living gibbons today â€¦ just live in one particular area, this is a clue that maybe we’ve lost even more.