Onychonycteris known species, hence "Onychonycteris" meaning "clawed bat". The specific epithet is a tribute to the fossil prospector and preparator who discovered it, Bonnie Finney. "Onychonycteris finneyi" was the strongest evidence so far in the debate on whether bats developed echolocation before or after they evolved the ability to fly. "O. finneyi" had well-developed wings, and could clearly fly, but lacked the enlarged cochlea of all extant echolocating bats, closer resembling the old world fruit bats which do not echolocate. This indicates that early bats could fly before they could echolocate. However, an independent evaluation of the "Onychonycteris" reference fossil in
Daubenton's bat also always near water. Daubenton's bat hibernates in the same type of locations from September to late March or April. Daubenton's bat is insectivorous and uses echolocation to find prey and orient itself at night. Bats emit sounds too high in frequency for humans to detect, and interpret the echoes created to build a "sound picture" of their surroundings. Daubenton's bat emits echolocation calls at frequencies between 32 and 85 kHz, though typical calls peak at 45 to 50 kHz; the calls have a duration of 3.3 ms. The bats emerge at twilight to hunt for insects over the water.