Abstract
Neotropical Ghost-Faced bats of the genus Mormoops (Order Chiroptera, Family Mormoopidae) have a radically upturned rostrum, or snout, while the other mormoopid genus, Pteronotus, has only a slight upturning of the rostrum. This type of difference in morphology between closely related taxa is likely to be the result of some sort of specialization. Observation of Mormoops blainvillei, the Antillean Ghost-Faced bat, reveals that they can open their mouths very wide relative to the size of their heads. Mormoopid bats are insectivorous with Mormoops blainvillei having a prey preference of large moths, but related species, such as Pteronotus quadridens, the Sooty Mustached bat, have a more varied diet with a large component of smaller hard-bodied beetles. While there have been many studies on feeding ecology of phyllostomid bats, available research on mormoopids is limited and functional relationships between craniorostral shape and feeding mechanics have not been established. The objectives of this study were to quantify structural and functional differences in craniomandibular function between Mormoops blainvillei and Pteronotus quadridens by analyzing maximum gape, bite force, and masticatory muscle configuration and relate this to prey preference previously described in the literature. Results showed that Mormoops blainvillei had a much wider maximum active gape and reduced normalized maximum bite force than Pteronotus quadridens which corresponded to the size and hardness of their respective diets. Mormoops blainvillei had a greater percentage of masticatory musculature allocated to wide gape than Pteronotus quadridens where the narrow gape chewing muscles were favored. Upturning of the rostrum reduces range of motion limitations at the craniomandibular joint which could have resulted in the ability to achieve wider gapes in Mormoops blainvillei.