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By ALICIA CHANG
AP Science Writer
LOS ANGELES
Scientists have unearthed the oldest big cat fossil yet, suggesting the predator—similar to a snow leopard—evolved in Asia and spread out.The nearly complete skull dug up in Tibet was estimated at 4.4 million years old—older than the big cat remains recovered from Tanzania dating to about 3.7 million years ago, the team reported.
While the new specimen is not a direct ancestor to big cats like tigers, lions, jaguars, it is closely related to the snow leopard, said study leader Jack Tseng of the American Museum of Natural History in New York.
The find was detailed in Wednesday’s Proceedings of the Royal Society B: Biological Sciences.
In 2010, Tseng and colleagues drove to the Himalayas to go fossil hunting. The team split up to cover more ground. While hiking on a mountaintop, Tseng’s wife, Juan Liu, a graduate student, found a trove of scattered bones and radioed others to help collect them. As they started digging, they found a buried cat skull about the size of a large grapefruit.
By analyzing the surrounding rocks and soil, the researchers determined the skull’s age.
The fossil is “convincingly older than the current record holder,” said David Polly, a paleontologist at Indiana University who had no role in the study.
Polly said in an email that there’s also good evidence that the big cat lived in the Tibetan plateau and there could be even older big cat fossils there to uncover.
The newest fossil had a broad forehead similar to snow leopards and its front teeth were heavily worn. It was small for a big cat—probably about the size of a clouded leopard, a cat found in the rainforests of Southeast Asia that can grow to 50 pounds.
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But wait, there’s more!
National Geographic: A New Species of Wild Cat Found Prowling Brazilian Forests and Grasslands
The tigrina is actually two separate species, say researchers in a new report.
Photograph by Tadeu Oliveira
Wild cats are charismatic creatures, so you’d think we’d know them all pretty well by now. Just how little we understand—at least in some cases—is reflected in the identification of a new species of cat known as a tigrina in northeastern Brazil.
Scientists have discovered that two populations of tigrina previously thought to be one species do not, in fact, interbreed and thus are distinct, according to results published today in Current Biology.
“So much is still unknown about the natural world, even in groups that are supposed to be well-characterized, such as cats,” says the study’s lead author, Eduardo Eizirik of Pontifícia Universidade Católica do Rio Grande do Sul in Brazil.
“In fact, there are many basic aspects that we still don’t know about wild cats, from their precise geographic distribution and their diets.”
Eizirik’s results have implications for conservation efforts—particularly laws about poaching and the designation of national parkland. Such measures are often focused on individual species.
Recognizing the northeastern tigrina as distinct means that biologists will have to assess its conservation status and determine what steps need to be taken so that both species of tigrina can be adequately protected. (See “Rare Cat Captured in Camera Trap.”)
Ancient Interbreeding
Eizirik and colleagues weren’t looking to discover a new species. Instead, they were looking to understand the evolutionary history of what were thought to be three species of cat from the genus Leopardus:
The Pampas cat (Leopardus colocolo) looks like a large, heavy-set, long-haired house cat. It lives in the grasslands and scrublands of South America, from southern Argentina and Chile up through Peru and Ecuador along the western third of the continent.
Geoffroy’s cat (Leopardus geoffroyi) is roughly the same size as the Pampas cat, with a brownish-yellow or gray coat, black spots on its trunk, and dark bands across its tail and limbs. Like the Pampas cat, Geoffroy’s cat likes scrublands and lives throughout Argentina.
The tigrina (Leopardus tigrinus), also known as the oncilla or little spotted cat, lives throughout much of Central and South America. With a yellow-brown coat and black rosettes, the tigrina looks like a house cat-sized leopard. Scientists had previously identified four sub-populations of tigrina, including the southern tigrina, which lives primarily in Brazil’s mountainous forests, and the northeastern tigrina, which lives in savannahs and grasslands. The coat of the northeastern tigrina is slightly lighter, and the rosettes are sightly smaller, than those of its southern relative. (Learn about National Geographic’s big cats initiative.)
Eizirik and colleagues obtained DNA samples from a total of 216 different Leopardus cats across their ranges. Analysis of the DNA sequences found in the mitochondria, the cell’s power plant, revealed ancient interbreeding between the Pampas cat and the northeastern tigrina.
Since an individual only inherits mitochondrial DNA from its mother, researchers could peer into the ancient history of these two felines, and found that they mated together frequently before the two cats split into separate species.
Although the Geoffroy’s cat and the southern tigrina divided into separate species over a million years ago, they began to mate together in the more recent past in the areas of southern Brazil and Bolivia where their habitats overlap. While the two cats interbreed regularly at this contact zone, the mating doesn’t extend to farther areas and the two species remain distinct.
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