THE FIRST REPORTED ARTHROPOD TRACKWAYS FROM THE PENNSYLVANIAN LLEWELLYN FORMATION: BEAR VALLEY STRIP MINE, SHAMOKIN, PA

The Pennsylvania Anthracite region is noted for producing some of the world's most spectacular paleobotany specimens; the lesser known are the insect body fossils.  The newly discovered trace fossil from the Llewellyn Formation is the first reported arthropod trackway.  The trackways—Diplichnites gouldi Type A—were discovered in the lower Pennsylvanian Llewellyn Formation between the Middle split (No. 8½) and Top split (No. 9) of the Mammoth coal zone.  Analysis of the invertebrate ichnofauna revealed undertracks developed on a shale/siltstone to "clean" subgraywacke. The trackway displays multiple morphologies.  Appendage imprints are sharply defined and are best interpreted as locomotion traces.   The trackways exhibit the required digit appendage pattern of arthropods including: 1) curvatures equating to angular changes in locomotion, 2) identifiable internal and external widths repeated in a symmetrically staggered alternating pattern, 3) measurable stride distances (repeatable digit distance), and 4) appendage morphologies of digit traces—circular, ellipsoidal, elongated, and comma internal digits—in an oblique V-shaped orientation to the angle of mid-line symmetry.  This new trace fossil suggests the possible existence of a diverse inchnofossil assemblage that could lead to a greater insight into the potentially complex ecosystem developed among the Pennsylvanian coal swamps.