Bats are the only group of mammals to have achieved powered flight (as opposed to gliding), and represent one of only four known instances of the evolution of true flight, along with insects, birds and pterosaurs. Here, the bone structure of the wings is highlighted in the brown long-eared bat, Plecotus auritus. The majority of support for the wing is provided by the metacarpals, the first bones of the fingers – in humans, these bones form the fleshy part of the hand (see here). These, and the phalanges (more distal bones of the fingers) are more flexible than in other mammals so that they can withstand the powerful forces generated during flight: they are oval in cross-section and are less mineralised. Compared to birds, the wings of the bat contain more bones and may therefore be able to be manipulated more dextrously to perform complex manoeuvres during hunting.

Image courtesy of Chris Thorn.