Of the seven species of giant tortoises known to science (although at the discovery of the islands there were probably fifteen) all are indigenous, and each is confined to its own islet.
The land tortoises chiefly belong to the genus Cynyxis.
No remains, and of course no living species, of these tortoises are known to exist or have existed on the mainland.
Past elevations of land, however (and doubtless equally great subsidences) have taken place in South America since the Eocene, and the conclusion that extensive areas of land have subsided in the Indian Ocean has long been based on a somewhat similar distribution of giant tortoises in the Mascarene region.
As for reptiles, Australia has a few tortoises, all of one family, and not of great size.