https://www.anipedia.net/murcielagos/
_the internal skeleton in addition to supporting the body serves as support for the extremities and point of insertion for the musculature, the mechanical principle of its functioning is analogous to that of the extremities of the arthropods in the most primitive groups and also in some advanced, the element main motor is the movement of the spine especially among aquatic species psteriormente appeared limbs as auxiliary elements in the fish acquire the shape of the pectoral and anal fins while the tail and dorsal fins lack direct insertion the serpentine movement of the body is the one that drives the fish in the water aided by the tail while the fins act mostly of stabilizers, between the terrestrial tetrapods the limbs develop more and besides raising the body on the ground they must propel it to advance in the birds , the forelimbs have been transformed into wings covered with feathers and used the air as a point of support to advance similar function has the mebrana that extends between the fingers of the bats ...