BIOGEOGRAPHY OF THE VERTEBRATE FAUNA FROM THE CATSKILL FORMATION

The vertebrate fauna recovered from the Catskill Formation in northcentral Pennsylvania reflects the nature of the aquatic ecosystems of the Catskill Delta complex, informs the global paleobiogeographic distribution of the fauna, and helps elucidate paleobiological aspects of faunal elements. Our paleontological work in the upper parts of the Catskill Formation has recognized two distinct and contemporaneous faunal assemblages. The Duncannon Member fauna (mostly from the Red Hill site) is from alluvial plain depositional settings, whereas the Sherman Creek Member fauna generally suggests delta plain depositional settings. A hypothesis of endemism in the presumed freshwater taxa of the alluvial plain setting is supported by some unique genera from the Red Hill site that belong to widespread families. Conversely, however, the Red Hill site also produces some cosmopolitan genera such as Groenlandaspis and Gyracanthus. The delta plain setting produces an abundance of cosmopolitan genera suggesting a greater marine dispersal potential for taxa such as Bothriolepis, Holoptychius, and Soederberghia. Recognizing these faunas and their sedimentological context illustrates partitioning of the Catskill Delta aquatic ecosystems. Paleogeographic reconstructions for the latest Devonian suggest potential pathways for dispersal between the northern and southern landmasses, and the patterns of dispersal within different vertebrates can provide a better understanding of paleobiological characteristics of those groups.