Insular India
This allowed its local biota to follow the typical patterns seen in islands and diversify in unique ways, much as in modern Madagascar, its sister landmass.
Faunal interchanges with other landmasses, like Africa and Europe (then an archipelago of islands across the Tethys) occurred during this period, and a considerable Asian influence can already been seen long before contact was made.
This rendered India rather peculiar as not just an isolated continent but also a "stepping stone" in the dispersal of many animal and plant clades across Africa, Europe, Madagascar, Asia and possibly even Oceania.
Generally speaking, the local dinosaurian and crocodilian fauna is almost identical to that of Madagascar, with clades like abelisaurids, titanosaurs, noasaurids and notosuchians being well represented here.
The most diverse mammals in the Maastrichtian of India are eutherians, a clade normally associated with northern continents and also found in Madagascar in this epoch, which combined with their ambiguous phylogenetic positions renders them extremely important in the understanding of placental evolution.
Some like Deccanolestes have been variously interpreted as euarchontans,[19] adapisoriculids,[20] or stem-afrotherians,[21] though the general consensus appears to be that they are non-placental eutherians and that there are non known Cretaceous placentals.
[26] Non-gondwanathere multituberculates and meridiolestidans can probably also be inferred as having lived in India during this epoch, due to the former's presence in all landmasses including Madagascar[27] and the latter being the dominant mammals in other known Gondwannan sites.
Neobatrachians are an indigenous clade and locally well represented as they are in Madagascar in the form of ranids, hylids, leptodactylids, pelobatids and discoglossids, as are madtsoiid snakes like Sanajeh and possibly Indophis and iguanian lizards, while anguids are from Laurasia.
[30][4] Several fish taxa are known from estuarine locales; most are marine species, but there are also forms like lepisosteids, which do also occur in Africa but are otherwise rare in Gondwanan landmasses.
[4] The Parreysiinae, a subfamily of the freshwater mussel family Unionidae, are thought to have originated in East Gondwana during the Jurassic, and survived on both Africa and Insular India throughout the Cretaceous.
[32] Similarly, numerous lineages of mantises (clade Cernomantodea) are thought to have originated on the Antarctic-Indian landmass after the breakup of Gondwana, and persisted on Insular India after it broke away.
[4] It was previously thought that several major families of Neobatrachia (Ranidae, Dicroglossidae, Rhacophoridae) originated in India from an ancestor that colonized the continent from Africa during the Cretaceous.
It is known for certain that Deccanolestes and Bharattherium survived the K-Pg event,[31] though for how further long did non-placental eutherians and gondwanatheres live in India is unknown, and by the time the landmass makes contact with Asia they are most likely extinct.
[6] For a while it was theorised that ostriches evolved in India during this epoch, under the assumption that European ratites like Palaeotis represented recent Asiatic migrations.
Still, India probably had a thriving paleognath fauna; the volant ancestors of kiwis and elephant birds presumably flew from there to Oceania and Madagascar respectively,[36] while the mysterious Hypselornis may represent an indigenous clade.
By this time India already has an extensive placental fauna (as well as metatherians like Indodelphis), but in its isolation there are still high degrees of endemism, with some clades like anthracobunids not being found elsewhere.
