Australonycteris big
An artist's illustration of Australonycteris clarkae
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Chiroptera
Suborder: Microchiroptera
Family: Archaeonycteridae
Genus: Australonycteris
Hand et al. 1994
Species: A. webbi
Binomial name
Australonycteris clarkae
Hand et al. 1994

Australonycteris is an extinct genus of microchiropteran bat with the single species Australonycteris clarkae. The species is known from fragmentary remains found at the Murgon fossil site, in south-eastern Queensland, dating to the early Eocene, 54.6 million years ago. It is the oldest bat from the Southern Hemisphere and one of the oldest bats in the world, and inhabited forests and swampy areas, with a diet of insects and probably even small fish.

Australonycteris, one of the oldest known bats, is known from several upper and lower teeth, an edentulous lower jaw fragment, a partial periotic bone, and several postcranial fragments. It has a forearm length of 40–45 millimetres (1.6–1.8 in), making it a medium-size bat, and it could echolocate. Australonycteris displayed some differences in dental anatomy, compared to extant bats, and it is possible that it foraged for insects and small fish.