In 2003, southwest Wyoming USA, a research team uncovered what could be the ‘missing link’ in bat evolution. The nearly complete fossilised remains of a 52-million-year-old bat species, Onychonycteris finneyi, has forelimb anatomy that indicated the species was capable of flight, however it lacks the ear morphology for echolocation. This supports the theory that flight in bats came first and echolocation evolved later.
Other features of Onychonycteris finneyi include:
- Their wing shape suggests that an undulating gliding or fluttering flight style may be primitive for bats
- A long calcar indicates that a broad tail membrane evolved early in Chiroptera, probably functioning as an additional aerofoil rather than as a prey-capture device.
- Limb proportions and retention of claws on all digits, as opposed to two or three in all other known species, indicate that the new bat may have been an agile climber that employed quadrupedal locomotion and under-branch hanging behaviour.
(Simmons, NB, Seymour, KL Habersetzer, J and Gunnell, GF. 2008. Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation. Nature, 451, 818-821.)
Oldest in Australia
Australonycteris clarkae, from the Eocene of Queensland, is the oldest bat from the Southern Hemisphere and one of the oldest in the world. It is similar to other archaic Eocene bats from the Northern Hemisphere, and could probably navigate using echolocation, like most bats do today. Until its discovery, palaeontologists thought that bats colonised Australia much later, perhaps during the Oligocene.
Photo: Aboriginal cave art of bats, Les Hall