Onychonycteris is the most primitive of the two oldest known monospecific genera of bat, having lived in the area that is current day Wyoming during the Eocene period, 52.5 million years ago.
Thought to have been extinct for 52 million years, there are still some that remain alive on Primeval Island. In fact, they are among the most common bat on the island, alongside Icaronycteris.