India forms a large part of the Indomalayan biogeographical zone and many of the floral and faunal forms show Malayan affinities with only a few taxa being unique to the Indian region. The unique forms includes the snake family Uropeltidae found only in the Western Ghats and Sri Lanka. Fossil taxa from the Cretaceous show links to the Seychelles and Madagascar chain of islands. The Cretaceous fauna include reptiles, amphibians and fishes and an extant species demonstrating this phylogeographical link is the purple frog. The separation of India and Madagascar is traditionally estimated to have taken place about 88 million years ago. However, there are suggestions that the links to Madagascar and Africa were present even at the time when the Indian subcontinent met Eurasia. India has been suggested as a ship for the movement of several African taxa into Asia. These taxa include five frog families (including the Myobatrachidae), three caecilian families, a lacertid lizard and freshwater snails of the family Potamiopsidae. A thirty million year old Oligocene-era fossil tooth from the Bugti Hills of central Pakistan has been identified as from a lemur-like primate, prompting controversial suggestions that the lemurs may have originated in Asia. Lemur fossils from India in the past led to theories of a lost continent called Lemuria. This theory however was dismissed when continental drift and plate tectonics became well established.