British researchers have identified a gibbon found in an ancient Chinese tomb as a never-before seen, now-extinct genus and species.

Samuel Turvey, a conservationist and gibbon expert, was touring a Chinese museum in 2009 when a partial skull caught his eye. It had been found buried, along with several other animals in the tomb of Lady Xia, a grandmother of China’s first emperor Qin Shihuang, in what is now Shaanxi, China. The tomb was estimated to be 2,200 to 2,300 years old.

Dr. Turvey was struck by the shape of the head, which didn’t look like any modern animal he knew, said James Hansford, a postdoctoral student in Turvey’s lab at the Institute of Zoology, Zoological Society of London.

A new paper, published Thursday in Science, confirms that his instinct was correct. Dr. Turvey’s research team, identified the animal as a member of a new genus and species, Junzi imperialis. Gibbons were seen as a symbol of scholar-officials in ancient China, and junzi means “scholarly gentlemen.”

There are four gibbon genera alive in Asia today, including a species that is the most endangered mammal on earth.

In comparison to living gibbons, the new one has a comparatively flat, small face, Mr. Hansford said, with canines that are particularly long for the animal’s size.

The team was not able to do DNA analysis on the cranium and jaw, but, using digital scans, compared its shape to skulls from hundreds of animals across Asia and in collections in Germany and England, Dr. Hansford said. “This one sticks out as really different, something definitely separate as a genus,” he said.

No other gibbon has ever been found in a tomb, said Susan Cheyne, who was not involved in the research, but who collaborates with team members. It’s extremely rare, she said, to find such old gibbon remains anywhere because their forest habitat tends to degrade bones quickly.

The animal’s placement in the tomb suggests it was kept as a pet. Such a practice could have been devastating to the species, and may explain why it went extinct, said Dr. Cheyne, an associate lecturer in primate conservation at Oxford Brookes University.

The gibbon probably would have been captured as a youngster, she said, because they are particularly “small and cute and fluffy.” That could have meant killing its mother, “potentially impacting the social structure of entire group, which may not survive the loss of an adult,” Dr. Cheyne said. “So each live individual being kept as a pet certainly represents a bigger loss of individuals from the wild.”

Its presence in the tomb strongly suggests that humans played a role in the species’ extinction, she said.

The field of gibbon research has taken off in recent years, Cheyne said, with eight new species of living gibbons discovered since 2000 and two just in the last two years. “It goes to show how much we still have to learn about these animals,” she said.

The 20 known living species include, in China, the recently discovered Skywalker gibbon, and the Hainan, which is found only in a small part of Hainan Island, off the southern tip of China. It is considered the most endangered mammal on earth, with fewer than 30 known individuals left in the species, she said.

Dr. Cheyne said that conserving a species requires a multipronged effort, including the end of hunting and the preservation of habitat.

Jo Setchell, a professor of anthropology at Durham University and president of the Primate Society of Great Britain, who was not involved in the work, said the discovery provided new insights.

“The broader message is that we might have underestimated the number of primate extinctions caused by humans in the past,” she wrote in an email. “Understanding past extinctions will help us to predict how vulnerable current species are, and therefore help us to protect them more effectively.”