« "Three quarters of mammal species are Bats and Rats. Maybe the future belongs to them..." »
— Helen Cutter[src]

Bats, of the order Chiroptera, are a type of mammal whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. Bats along with Rodents, made up three quarters of all mammal species living on Earth in the present day.

DNA analysis indicated that the Future Predator was descended from a sort of bat, which had become big, hairless and wingless, although retaining echolocation. (Episode 1.6)