Homology of the chiropteran “dactylopatagium” brevis

Bats possess a series of patagial tracts that together act as an aerofoil for powered flight. Here we discuss the homology of a small portion of the patagium, the brevis section, traditionally assigned as a part of the handwing (dactilopatagium). Using dissected specimens and literature references we show that the muscle occipitopollicalis, a morphological marker of the propatagium, extends into the brevis section in a variety of bats. This led us to conclude that the brevis section is in fact a part of the propatagium, which is also supported by developmental evidence.