BONE-HISTOLOGY DETERMINES IDENTIFICATION OF A NEW FOSSIL TAXON OF PTEROSAUR (REPTILIA, ARCHOSAURIA)

As small specimen of azhdarchid pterosaur (wingspan about 2.5 m) was d iscovered in the Two Medicine Formation (Late Cretaceous: Campanian) o f Montana (USA). Several gross morphological characters appear to diff erentiate it from other azhdarchids, notably the relative sizes of the ulna and metacarpus. Most known azhdarchids are quite large, so we ex amined the bone histology of this specimen to see if it showed feature s associated with immaturity, such as rapid growth. Several features s uggest that it is an adult, which on the basis of its small size would indicate that it represents a new genus and species of pterosaur.