Research With a Roar

The oldest big cat fossil ever found — which fills in a significant gap in the fossil record — has been unearthed on a paleontological dig in Tibet, scientists announced.

A skull from the new species, named Panthera blytheae, was excavated and described by a team led by Jack Tseng, a Ph.D. student at USC Dornsife at the time of the discovery and now a postdoctoral fellow at the American Museum of Natural History (AMNH) in New York.

“This find suggests that big cats have a deeper evolutionary origin than previously suspected,” Tseng said.

The announcement was made in a scientific paper published by the Proceedings of the Royal Society B: Biological Sciences.

DNA evidence suggested that the so-called “big cats” — the Pantherinae subfamily, including lions, jaguars, tigers, leopards, snow leopards and clouded leopards — diverged from their nearest evolutionary cousins, Felinae, which included cougars, lynxes and domestic cats, about 10.8 million years ago. However, the oldest fossils of big cats previously found were tooth fragments uncovered at Laetoli, the famed hominin site excavated in Tanzania by Mary Leakey in the 1970s, which dates to just 3.8 million years ago.

Using magnetostratigraphy — dating fossils based on the distinctive patterns of reversals in the Earth’s magnetic field, which are recorded in layers of rock — Tseng and his team were able to estimate the age of the skull and other fossils belonging to the new species at between 4.10 and 5.95 million years old.

The new cat takes its name from Blythe, the snow-leopard-loving daughter of Paul and Heather Haaga, who are avid supporters of the Natural History Museum of Los Angeles County.

Jack Tseng was a Ph.D. student at USC Dornsife when he led the big cat fossil expedition. Here, he catalogs fossils at the dig site in Tibet. Photo courtesy of Jack Tseng.

The find not only challenges previous suppositions about the evolution of big cats, it also helps place that evolution in a geographical context. The find occurred in a region that overlaps the majority of current big cat habitats and suggested that the group evolved in central Asia and spread outward.

In addition, recent estimates suggested that species within the genus Panthera (lions, tigers, leopards, jaguars and snow leopards) did not diversify until 3.72 million years ago – which the new find disproves.

Tseng, his wife, Juan Liu, and co-author Gary Takeuchi discovered the skull in 2010 while scouting in the remote border region between Pakistan and China, an area that takes a bumpy seven-day car ride to reach from Beijing.

Liu found more than 100 bones that were likely deposited by a river eroding out of a cliff. There, below the antelope limbs and jaws, was the crushed but largely complete remains of the skull.

“It was just lodged in the middle of all that mess,” Tseng said.

For the past three years, Tseng and his team have used both anatomical and DNA data to determine that the skull does, in fact, represent a new species.

The researchers plan to return to the site where they found the skull in the summer to search for more specimens.

“We are in the business of discovery,” said co-author Xiaoming Wang. “We go out into the world in search of new fossils to illuminate the past.”

Tseng’s co-authors included Wang, who has joint appointments at USC, the Natural History Museum, the AMNH and the Chinese Academy of Sciences (CAS); Graham Slater of the Smithsonian Institution; Takeuchi of the Natural History Museum and the Page Museum; Qiang Li of the CAS; Liu of the University of Alberta and the CAS; and Guangpu Xie of the Gansu Provincial Museum.

The research was funded by National Basic Research Program of China, the CAS, the National Science Foundation, the AMNH, the Smithsonian Institution (National Museum of Natural History) and the National Geographic Society.