PTEROSAUR DIVERSITY PARALLELS CHANGES IN PALEOENVIRONMENT

Pterosaurs were flying archosaurs whose fossils have been found on every continent. These fossils first appear in rocks of the Late Triassic, and they cease to appear at the Cretaceous-Paleogene boundary. The currently unpublished pterosaur database PteroTerra records the paleoenvironments and families for over 500 specimens. 463 specimens had listed paleoenvironments and were utilized for this study. These paleoenvrionments were tallied and compared for six portions of the Mesozoic: the Late Triassic, Early Jurassic, Middle Jurassic, Late Jurassic, Early Cretaceous, and Late Cretaceous. Then, pterosaur families were listed for each geologic epoch. The results of these comparisons seem to show a change from pterosaurs in marine paleoenvironments in the Early Jurassic and Middle Jurassic, to a great diversity of paleoenvironments in the Late Jurassic and Early Cretaceous. Simultaneously, the number of families present almost doubles from the Middle Jurassic to Late Jurassic, and then continues to increase into the Early Cretaceous. Thus, it appears that increasing morphological diversity in pterosaurs parallels increasing habitat diversity.