Kingdom: Animalia | Phylum: Chordata | Class: Mammalia | Order: Chiroptera
Family: Vespertilionidae | Genus: Corynorhinus | Species: Townsendii ingens
Family: Vespertilionidae | Genus: Corynorhinus | Species: Townsendii ingens
Whilst the horse has adapted the pentadactyl limb according to the ground it walks upon, the Ozark bat has adapted the limb for the insects, primarily moths, which it feeds on. It has also adapted for the protection of the caves during hibernation and delivering offspring. The bat wing which is the bats form of pentadactyl limb, is made up of a membrane that is supported by elongated bones; these are adaptations of the fingers which allow the bat to thrust for great flight power. They have a humerus and ulna which work to create the flapping motion, a wrist that gives them the ability to completely wrap themselves up within their wings, four fingers and a thumb. The thumb, unlike the fingers is exposed and has formed into a claw for climbing. The hind feet are also exposed and each have five toes which are used for grasping onto rocky surfaces and trees. They have a membrane covering the hind limbs which helps them stabilize during flight; this membrane is supported by a newly developed bone called the calcar.
The evolution of the bat wing is obscure due to a lack of found fossils; however there have been theories of how their pentadactyl limb formed. One theory has said that they adapted from gliders which leap from tree to tree and use their extended skin between the limbs to hold them up for a period of time. Gliders live in trees which allow them to reach fruit and insects as well as escape most predators on the ground. Like the bat, they have four limbs each with fingers and toes and a thumb on each limb used for grasping. They also have the stretched membrane that has the same stabilizing purpose as the bat has in between their hind limbs. During and after the ice age the forests and jungles were very little making it difficult for gliders to travel within the main areas that were hit. The gliders that were able to live in forests and jungles that had little left would have had the ability to stabilize and adjust their flight for longer periods.
This is a possible time for when the gliders could have evolved into bats; the forearm and phalanges (finger bones) would begin to elongate which would form a more defined wing whilst the membrane would have become thinner for a more sufficient flight. Their wingspan would have extended further and is now 12 to 13 inches wide. The calcar bone would then form to support the motion of the stabilising membrane that originated from the gliders, whereas the hind feet would remain exposed for grasping trees and rocks. During this formation, other adaptations such as acute hearing and well developed echo location would have evolved to support their nocturnal activity and hunting which is the purpose of their radar like ears.