Evolutionary pressures of aerial insectivory reflected in anurognathid pterosaurs.

Across the evolution of powered flight, the ecological niche of aerial insectivore has been occupied by members of the three volant vertebrate clades-Aves and Chiroptera, and the first known volant vertebrates, pterosaurs. However, morphological and quantitative evidence to support pterosaurs exhibiting this ecology remains scant. Anurognathids are an unusual group of pterosaurs in which the skull exhibits the unique morphology of being mediolaterally expanded, so much so that their skulls may be wider than rostrocaudally long. Here, we conduct quantitative comparative cranial measurements and dental morphology in anurognathids against extant avian and chiropteran taxa, respectively, with ecologies and behaviors that are similar to predicted putative behaviors of anurognathids. Comparative analyses of both skull and dental morphology suggest anurognathid specimens in similar morphospaces as insectivorous crepuscular and nocturnal extant volant taxa. Our results support that this unique group of pterosaurs likely occupied a niche of mid-flight insectivorous capture in low-light conditions.