London, Dec 3 (IANS): The discovery of a skull of the oldest tiger ever found has indicated that the beasts never changed much in two million years except turning bigger in size.

The tiger skull, unearthed in Longdan region in northwestern China, is estimated to be between 2.16 and 2.55 million years old. It's the oldest complete skull ever discovered of a 'pantherine' big cat - the big cats we know today - and may help to understand how today's animals evolved, Daily Mail said in a report.

The skull is a little smaller than the head of today's tigers - about the size of a jaguar - but it's very recognisable as the same species we know today.

The researchers, comparing the skull, observed that it has given indication that tigers may have originally evolved in China.

The skull had well-developed upper fangs, and appears to be of a male. It pre-dates all other known tiger fossils by nearly half a million years.

The researchers compared the skull with 207 other tiger skulls, 66 jaguar skulls and 100 leopard skulls.

"Expectedly, the Longdan tiger emerged as the most primitive tiger separated by a long distance from all other tiger subspecies. It is as an early branch of the tiger lineage," said the researchers.

The slightly smaller size of the 'Longdan' tiger hints that the creatures may have evolved to become bigger as they pursued bigger prey. The beast would have eaten deer and cow-like creatures.

"The discovery of the identity of this fossil is vitally important for understanding the fossil history of big cats and the relationship between them," said Andrew Kitchener, curator of vertebrate biology at the National Museum of Scotland in Edinburgh, speaking to Livescience.