Australian scientists have abandoned hopes of resurrecting the extinct Tasmanian tiger through cloning technology.
The project made headlines worldwide when it was announced six years ago, igniting hopes that other long-dead animals such as the woolly mammoth might be brought back to life.
Scientists at the Australian Museum in Sydney hoped to recreate the Tasmanian tiger, also known as a thylacine, by extracting DNA from a number of specimens, including a 139-year-old tiger pup preserved in pure alcohol.
But the museum has been forced to abandon the ambitious project after finding the supply of tiger DNA too poor.
"The thylacine DNA is far too degraded to even construct a DNA library," said museum director Frank Howarth. "The project cannot proceed to the next stage."
The Tasmanian tiger, a wolf-like marsupial with stripes across its back, was driven to extinction by sheepfarmers who blamed it for killing their stock.
The last of the species died at Hobart Zoo in 1936.
The museum's previous director, Professor Mike Archer, who had championed the cloning bid, said he was disappointed with the decision.
"Many of us still hope that it might be possible to bring back this magnificent animal to life," Archer said. "The technology to make it happen is improving all the time.
"It was Australia's top marsupial predator and it was wiped out within living memory by people ignorant or careless of its unique place in the animal world."
The Tasmanian tiger once ranged across the whole of Australia but is believed to have been pushed out of its former territory by the dingo about 2000 years ago.
Tasmania's rolling uplands and dense forests were its last stronghold before extinction.