PRELIMINARY REPORT ON DINOSAUR TRACKS AND ASSOCIATED FAUNA FROM THE LATE TRIASSIC LOCKATONG FORMATION NEAR COLLEGEVILLE, PENNSYLVANIA

A new locality in the Triassic Lockatong Formation of Southeastern Pennsylvania has yielded dinosaur tracks and other vertebrate footprints along with highly productive phytosaur and fish-bearing bone beds. The study material, awaiting preparation, should provide valuable data on a relatively unknown interval of the Late Triassic in the Newark Basin. Initial investigations at the site uncovered the dinosaur track horizon, which was limited to a 25 cm-thick fluvial sandstone bed. The tracks, which do not exceed 20 cm in length, are most likely referable to the ichnogenus Atreipus but cannot be unequivocally distinguished from the similar tridactyl form Grallator due to high track density and generally less than optimal preservation. Subsequent expeditions produced a near complete phytosaur cranium and post-cranial material. The unprepared cranium is at minimum 80 cm in length. The maxilla displays post-mortem fracturing that may be related to trampling or post-depositional compaction. Isolated teeth and bone fragments are numerous and found in a variety of facies including massive mudstones, intraformational conglomerates and fish-scale conglomerate. The fish-scale conglomerate is graded and consists of isolated vertebrae, skull fragments and most commonly scales and rare partial fish. These beds also contain Unionid bivalves. The lepidosauromorph ichnite Rhynchosauroides occurs in strata immediately above the bone beds and at numerous levels throughout the locality. Further collecting has produced additional ichnotaxa. Most notable of these are well-preserved trackways of a small quadruped that does not correspond precisely to any of the known Newark Supergroup ichnogenera. These prints appear to bear some affinity to the ichnogenus Procolophonichnium but may be distinct enough to erect a new taxon. The trackways occur in a series of layers that also contain the presumed tanystropheid track Gwyneddichnium. An isolated manus of Brachychirotherium, found in displaced rubble piles, adds another component to this fauna which so far cannot be related precisely by stratigraphic position.