The giant Galapagos Islands tortoise dubbed Lonesome George, whose failed efforts to produce offspring made him a symbol of disappearing species, was found dead on Sunday, officials at the Galapagos National Park announced.

Lonesome George was believed to be the last living member of the Pinta Island subspecies and had become an ambassador of sorts for the islands off Ecuador's coast, whose unique flora and fauna helped inspire Charles Darwin's ideas on evolution.

The tortoise's age was not known, but scientists believed it was about 100, not especially old for giant tortoises, who can live well over a century. Scientists had expected the tortoise to live another few decades at least.

Various mates had been provided for Lonesome George after it was found in 1972 in what proved unsuccessful attempts to keep the subspecies alive.

It lived at a tortoise breeding centre on the archipelago's island of Santa Cruz. It was found Sunday morning in its pen by its longtime keeper, Fausto Llerena, the park said in a statement.

Attempts were initially made to mate Lonesome George with two female tortoises from Wolf Volcano. But the eggs they produced were infertile.

Two females from Spanish Island's tortoise population, the species most closely related to Pinta tortoises, were placed with George last year.

The park said the cause of death would be investigated.

The Galapagos' giant tortoise population was decimated after the arrival of humans, but a recovery program run by the park and the Charles Darwin Foundation has increased the overall population from 3,000 in 1974 to 20,000 today.