FIRST RECORDS OF FOSSIL VERTEBRATES FROM THE MARINE UPPER DEVONIAN LOCK HAVEN FORMATION IN NORTH-CENTRAL PENNSYLVANIA, USA

Upper Devonian strata of the northern Appalachian basin record the diversification of marine and continental ecosystems during a dynamic time in Earth’s history. Recent prospecting in Upper Famennian strata (Lock Haven Formation) of north central Pennsylvania produced the first records of fossil vertebrates from this formation. Vertebrate fossils include isolated plates of pachyosteomorph arthrodire placoderms, isolated teeth of ctenacanthid sharks and lungfish, and many teeth, scales, and bone fragments of unknown taxonomic affinity. Strata containing and surrounding these vertebrate fossils yield marine invertebrate body fossils (mainly disarticulated brachiopods and crinoids), marine trace fossils (25 ichnotaxa), and diverse marine acritarchs. Lithofacies include green-grey mudrock, heterolithic strata, and very fine-grained sandstone with abundant symmetrical ripples, hummocky and swaley cross-stratification, combined flow ripples, horizontal laminae, and shell lags. Collectively, these paleontological and sedimentological observations indicate deposition in shoreface environments influenced by waves, tides, and suspension settling. Vertebrate fossils show extensive abrasion and fragmentation indicative of significant transport to shoreface environments from marine and/or continental environments before ultimate burial. Regionally, pachysteomorph arthrodires have been reported from Upper Devonian offshore marine strata in eastern Ohio (Cleveland Shale) and western Pennsylvania (Chadokoin Fm.) and coastal fluvial environments in central Pennsylvania (Catskill Formation). However, fossil lungfish remains are reported only from fluvial strata (Catskill Formation) and ctenacanthids have only been reported from offshore marine strata (Cleveland Shale). Ongoing paleontological, sedimentological, and geochemical analyses will further evaluate the ecologies, environments, and paleoclimate that shaped late Famennian vertebrate evolution in the northern Appalachian basin.