Oldest big cat fossil found in Tibet
Panthera blytheae was similar to modern snow leopards, palaeontologists say
The
oldest big cat fossils ever found - from a previously unknown species
"similar to a snow leopard" - have been unearthed in the Himalayas.
The skull fragments of the newly-named Panthera blytheae have been dated between 4.1 and 5.95 million years old.
Their discovery in Tibet supports the theory that big cats evolved in central Asia - not Africa - and spread outward.
The findings by US and Chinese palaeontologists are published in the Royal Society journal Proceedings B.
“This ties up a lot of questions we had on how big cats evolved and spread throughout the world”
Dr Jack Tseng University of Southern California
They used both anatomical and DNA
data to determine that the skulls belonged to an extinct big cat, whose
territory appears to overlap many of the species we know today.
"This cat is a sister of living snow leopards - it has a
broad forehead and a short face. But it's a little smaller - the size of
clouded leopards," said lead author Dr Jack Tseng of the University of
Southern California.
"This ties up a lot of questions we had on how these animals evolved and spread throughout the world.
"Biologists had hypothesised that big cats originated in
Asia. But there was a division between the DNA data and the fossil
record."
Surprising find
The so-called "big cats" - the Pantherinae subfamily -
includes lions, jaguars, tigers, leopards, snow leopards, and clouded
leopards.
DNA evidence suggests they diverged from their cousins the
Felinae - which includes cougars, lynxes, and domestic cats - about 6.37
million years ago.
But the earliest fossils previously found were just 3.6
million years old - tooth fragments uncovered at Laetoli in Tanzania,
the famous hominin site excavated by Mary Leakey in the 1970s.
It is rare for such an ancient carnivore fossil to be so well preserved
The new fossils were dug up on an expedition in 2010 in the
remote Zanda Basin in southwestern Tibet, by a team including Dr Tseng
and his wife Juan Liu - a fellow palaeontologist.
They found over 100 bones deposited by a river eroding out of
a cliff, including the crushed - but largely complete - remains of a
big cat skull.
"We were very surprised to find a cat fossil in that basin," Dr Tseng told BBC News.
"Usually we find antelopes and rhinos, but this site was special. We found multiple carnivores - badgers, weasels and foxes."
Among the bones were seven skull fragments, belonging to at least three individual cats, including one nearly complete skull.
The fragments were dated using magnetostratigraphy - which
relies on historical reversals in the Earth's magnetic field recorded in
layers of rock.
They ranged between 4.10 and 5.95 million years old, the complete skull being around 4.4 million years of age.
"This is a very significant finding - it fills a very wide
gap in the fossil record," said Dr Manabu Sakamoto of the University of
Bristol, an expert on Pantherinae evolution.
"The discovery presents strong support for the Asian origin hypothesis for the big cats.
"It gives us a great insight into what early big cats may have looked like and where they may have lived."
However, Prof William Murphy of Texas A&M University, another expert on the evolutionary relationship of big cats, questioned whether the new species was really a sister of the snow leopard.
"The authors' claim that this skull is similar to the snow
leopard is very weakly supported based on morphological characters
alone, and this morphology-based tree is inconsistent with the DNA-based
tree of living cats," he told BBC News.
"It remains equally probable that this fossil is ancestral to
the living big cats. More complete skeletons would be beneficial to
confirm their findings."
Dr Tseng and his team plan to return to the fossil site in Tibet next summer to search for more specimens.