Giant tortoises are characteristic of certain reptilian tropical island wildlife. They occur (some species are now extinct) in such places as Madagascar, the Seychelles, Mauritius, Réunion, the Galápagos Islands, Sulawesi, Timor, Flores and Java, often reaching enormous size. However, giant tortoises also once lived on the mainland of Asia, as follows from fossil finds in the Siwalik Hills in India.
These animals belong to the most ancient group of reptiles, appearing about 250 million years ago. In the Upper Cretaceous, 70 or 80 million years ago some already became gigantic and about 1 million years ago these reptiles reached the Galápagos Islands. Until 100,000 years ago most of the gigantic species began to disappear for unknown causes and only 250 years ago there were at least 20 species and subspecies in islands of the Indian Ocean and 14 or 15 species in the Galapagos Islands. From those, only one of the species of the Indian Ocean survives and 11 in Galápagos.
They are commonly known as the world’s longest living animals, with an average lifespan of 177 years.