sentences:  These studies have had limited success in identifying unique links between megabats and present-day primates, instead concluding that the megabat brain has characteristics that may resemble those likely to have existed in primitive primate brains.Nonetheless, modern neuroanatomical studies have repeatedly supported the existence of very significant differences between the brains of megabats and microbats, which is one of the anchors of the "flying primate" hypothesis.The implication that bats are diphyletic has been fiercely disputed by many zoologists, not only based on the unlikelihood that wings would have evolved twice in mammals, but also on biochemical studies of molecular evolution, which indicate that bats are monophyletic.