Scientists have found bat fossils dating back 55 million years ago, but they still do not know the genesis of their evolution. As time passed since those early bats, the animals found little competition during the night and proliferated.
Bats currently comprise 20 percent of all mammals. There are many types of bats, from the insect-eating to the fruit-eating to the blood-sucking vampire bats. These creatures are also the only mammals with powered flight or a sophisticated echolocation system.