Abstract

The general shape, function and development of vertebrae tend to be highly conserved among mammals; however characteristic vertebral fusion of varying degrees is well known in turtles and birds, it is less common among mammals. The goal of this study was to document the presence or absence of fusion as it occurs in bats. As the retention of independent vertebral fusion is the ancestral state for mammals, how did the vertebral fusion become present in some species of bats and not others? This study combined novel morphological data with existing morphological and molecular data with statistically insignificant results; that is, the overall topology of the phylogenetic tree did not change. Vertebral fusion in bats may have arisen independently between four and eight different occasions. One explanation for the intra- and interspecific variation that was observed is the independent mutation of _Hox_ genes.