| Named By: | Nancy B. Simmons, Kevin L. Seymour, Jorg Habersetzer & Gregg F. Gunnell in 2008 |
| Time Period: | 52.5 Ma Early Eocene |
| Location: | USA, Wyoming - Green River Formation |
| Size: | Roughly 25 centimetres long, 52 centimetre wingspan |
| Diet: | Insectivore |
| Fossil(s): | Almost complete skull and skeleton preserved flat on a slab |
| Classification: | | Chordata | Mammalia | Chiroptera | Onychonycteridae | Onychonycteris | |
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.