[1] It was proposed in its modern form by Australian neuroscientist Jack Pettigrew in 1986[2] after he discovered that the connections between the retina and the superior colliculus (a region of the midbrain) in the megabat Pteropus were organized in the same way found in primates, and purportedly different from all other mammals.
Pettigrew suggested that flying foxes, colugos, and primates were all descendants of the same group of early arboreal mammals.
Rather, many biologists resisted the implication that megabats and microbats (or echolocating bats) formed distinct branches of mammalian evolution, with flight having evolved twice.
[4][5][6][7] Soon after Pettigrew's study, work on another genus of megabat (Rousettus) disputed the existence of an advanced pattern of connections between the retina and the superior colliculus.
[10] 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.