Scientists have found in the Tibetan Himalayas the fossil skull of the oldest known big cat, the precursor to all modern lions, tigers and leopards, pushing back the fossil record of these animals by at least 2m years and lending weight to the idea that they evolved in Asia, rather than Africa, where the previous oldest fossil was found.

The species, named Panthera blytheae, would have lived between 4-6m years ago in cold regions of the Himalayas.

"In terms of the overall size it would be a little bit smaller than a snow leopard– the size of a clouded leopard and those living cats grow up to around 20kg [44lb]," said Jack Tseng, a postdoctoral fellow at the American Museum of Natural History in New York, who led the team that discovered the fossil. "You would most likely recognise it as a big cat."

Based on the wear of the teeth in the skull, the animal probably hunted like modern snow leopards do, said Tseng. "They used their front teeth to pick at a hide or hunt in very gritty areas where they get heavy wear on the front teeth. They used their back teeth, which remain very sharp, to cut through soft tissue. You can imagine [them] hunting among the cliffs of the Himalayas, ambushing the sheep or antelopes or smaller mammals."

Tseng's team found the fossilised skull under a mound of bones, which included antelope and horse limbs, in the summer of 2010 when driving in a remote area near the China-Pakistan border.

He said the cat would have had a broad forehead, associated with an expanded sinus cavity in the head, an adaptation suiting cold environments since it helped the animal warm up the air it breathed in.

The fossil is described in detail in Wednesday's edition of the Proceedings of the Royal Society B: Biological Sciences.

Studies of the genomes of modern big cats suggest they diverged from a common ancestor about 6.37m years ago, but till now the oldest known fossil from this group of animals amounted to some teeth found in Tanzania, dated to 3.6m years ago. Tseng dated Panthera blytheae to 4.10m-5.95m years.

Anjali Goswami, a palaeobiologist at University College London, who was not involved in the research, said: "This age has the result of pushing back the origin and evolution of Pantherinae by several million years, which is more consistent with molecular estimates.

"Divergence estimates for pantherines have been based in large part on very fragmentary material, so having a beautifully preserved specimen to accurately place in the big cat family tree means that we can have a lot more confidence in the result.

"This is also potentially the biggest weakness with the study, as the locality is not very well constrained in terms of age, meaning that there is a nearly 2 million year window on when this organism lived. Any part of this window still places it as the oldest pantherine, but constraining that to a more specific date between 4-6m years ago will be essential to furthering our understanding of pantherine evolution and indeed the evolution of this new species."

The new fossil suggests central Asia, rather than Africa, was where the panthera sub family, including lions, jaguars, tigers, leopards, snow leopards, and clouded leopards, diverged from the rest of the cat family tree, felinae, which includes cougars, lynxes, and domestic cats.

Goswami said that the geographic origin of pantherines was perplexing, because the distribution of living species suggested an Asian origin for the group, but the oldest fossils were from Africa, suggesting an African origin.

"This beautiful fossil supports the Asian origin for the group, bringing together molecular, living and fossil data into a unified view of pantherine evolution.

"It also supports the idea that the Tibetan plateau was, and remains, an important biogeographic region for large mammals and is the centre of origin for many important groups. Nailing down the place of origin for pantherines also means that we can better understand the environmental and ecological context in which this group evolved."