Adult phyllostomid (bat) enamel by scanning electron microscopy--with a note on dermopteran enamel

This study assesses the enamel of five phyllostomids of differing feeding habits; only one example of the microchiropteran super-family Phyllostomoidae having previously been studied by SEM. A dermopteran was also examined to ascertain whether the enamel might reveal insectivore, chiropteran or primate characteristics. The five phyllostomids were found to display the additional crystallite discontinuity feature (minor boundary plane or seam) which is a major characteristic of all the bats we have so far examined - with the exception of two megachiropterans. The enamel of the four fruit and nectar feeders (Phyllostomus, Carollia, Glossophaga and Artibeus) is essentially similar and different to that of the blood feeder (Desmodus). The differentiating factor for the two groups is the poor degree of prism development in Desmodus; the prisms being restricted to the inner two thirds of the enamel over the cusps or sectorial ridge, and lacking in the greater part of the axial and the sulcular enamel. The poor prism development in the vampire bat raises interesting questions from both an ontological and a phylogenetic point of view. The dermopteran (Cynocephalus sp.) displays horse-shoe shaped prisms with associated minor boundary planes (seams); an appearance entirely similar to those microchiroptera we have examined. This finding could be advanced as evidence for a close phylogenetic relationship between the Dermoptera and Chiroptera as these features are not found to the same extent in insectivores or in primates; the other two orders to which dermopterans are assigned. The evolutionary significance of the seam feature is being studied further; it is very likely to be of importance in unravelling the history of mammalian enamel.