Fausta, thought to be the world's oldest rhino, has died aged 57

Fausta passed away on Friday from what is believed to be natural causes, according to the sanctuary where she had been living since 2016.

"Records show that Fausta lived longest than any rhino in the world and survived in the Ngorongoro, free-ranging, for more than 54 years," Freddy Manongi, conservation commissioner at the Ngorongoro Conservation Area Authority, said in a statement.

Female black rhinos typically have their first calf at around 7 years old and can reach between 40 and 50 years old, according to the WWF. Fausta did not have calves during her life.

Sana, a white rhino whose death in France at the age of 55 was reported just last month, was previously believed to be the oldest captive rhino in the world.

Fausta's sanctuary said she was discovered in the Ngorongoro crater, a conservation area in the north of the country, by a researcher in 1965, when she was aged either three or four.

"Her health begun to deteriorate in 2016, when we were forced to put the animal in captivity," it said, adding she suffered attacks from hyenas in the wild. Fausta had also lost her vision.

Black rhinos are critically endangered, but the species' numbers have risen in recent years after falling dramatically last century.

Last year, the world's last male northern white rhino, Sudan, died in Kenya.