PALEOECOLOGY OF THE FRASNIAN/FAMENNIAN BOUNDARY INTERVAL (LATE DEVONIAN), TIOGA, PENNSYLVANIA

Late Frasnian and early Famennian strata are exposed in long stratigraphic sections near Tioga, north-central Pennsylvania. Although currently described sections may not include the Frasnian/Famennian boundary itself, they are quite fossiliferous, allowing comparisons of the fauna before and after the F/F extinction in this region. These strata represent paleoenvironments closer to the shoreline than are represented at many localities in New York. Bulk samples were collected from two measured sections, each more than 50 meters in length. The fauna includes typical Devonian benthic fossils such as brachiopods, bivalves, crinoids, and bryozoans. Fossils were counted and analyzed using paleoecological ordination (e.g., non-metric multidimensional scaling) to study faunal changes through the sections, compare faunal and lithologic changes, and better understand the Frasnian/Famennian extinction. The Famennian section (US Hwy 15) is marine at its base but fully terrestrial at its top, with a transitional zone of interfingering facies in between. In this transitional zone, disarticulated fish elements are common. The ichnofossil Bergaueria (attributed to burrowing sea anemones) is also found. In some specimens, these burrows are arranged in chains, perhaps reflecting asexual reproduction.