When India was an island, what kind of unique animals did it have? Was there a large amount of endemism similar to today's Australia and Madagascar?

 During the time when India was an island, which was around 100 million years ago during the Late Cretaceous period, it likely had a diverse array of unique animals, although direct evidence of these creatures is limited. India's isolation would indeed have promoted the evolution of endemic species, similar to what we observe in present-day Australia and Madagascar.

While we don't have an exhaustive record of the fauna from that era in India, we can make some educated guesses based on what we know about the geological history of the region and the types of creatures that lived during the Late Cretaceous period in neighboring areas.

Some of the unique animals that might have inhabited ancient India during its isolation as an island could include:

1. Dinosaur Fauna: During the Late Cretaceous, dinosaurs were abundant worldwide. India would have had its own diverse array of dinosaurs, including various species of theropods, sauropods, and ornithischians. However, specific species would have been unique to the Indian landmass due to its isolation.

2. Mammals: While mammals were not dominant during the Mesozoic Era, there were still small, primitive mammals. It's possible that India harbored its own unique species of early mammals, although they would have been quite different from modern mammals.

3. Reptiles: Aside from dinosaurs, India would have had its own populations of other reptiles such as crocodiles, turtles, and lizards. Some of these species may have been unique to the region.

4. Marine Life: Given that India was an island during this period, marine life would have been abundant along its shores. Ancient marine reptiles like ichthyosaurs, plesiosaurs, and mosasaurs could have populated the waters around India.

5. Invertebrates: Various species of invertebrates, including marine mollusks, crustaceans, and insects, would have existed on the island