PRELIMINARY REPORT OF VERTEBRATE (PISCES: CHONDRICHTHYES) FOSSILS IN THE MAUCH CHUNK GROUP (MISSISSIPPIAN, CHESTERIAN) OF SOUTHERN WEST VIRGINIA

The fossils of the Mauch Chunk Group of southeastern West Virginia are mostly composed of marine invertebrates with some nonmarine invertebrates and a few plants. There are also small deposits containing fish fossils found in the Mauch Chunk. A recent find of a thin (40 cm) lacustrine limestone with fish fossils including two partial skeletons has greatly augmented the vertebrate collections to date.

The rocks of the upper Mississippian Mauch Chunk Group show a transition from shallow, open marine limestones of the Greenbrier Series, into the mixed terrestrial deposits with thin marine incursions of the Mauch Chunk Group, and then into the coal-bearing Pennsylvanian siliciclastic deposits.

Fish macrofossils were only recently discovered in abundance in a nonmarine lacustrine limestone just below a maroon mudstone marker bed. The limestone is a tan to gray, grainy, ostracodal wackestone to packstone with randomly distributed, partially reworked, bone fragments. It is poorly sorted and gastropods or possibly microconchids are infrequently seen. The fossils probably represent a parautochthonous assemblage. The bones and fragments are almost all bright white to bluish black. Two large segments of skeletons have been found, suggestion that scavenging and burrowing were not major factors in distribution of the bones.

Previous finds include teeth and scales and a spine from the Bluefield Formation and a fin, a lateral piece, and teeth and scales from the Hinton Formation. Small fish teeth and scales also have been recovered from a thin (6 cm) limestone 5 m above the new limestone. The teeth and scales are ebony black and came from an ocher brown to olive gray, fossiliferous packstone to grainstone with bivalve and ostracode shells and fragments.

Only a 100 meter wide section of the limestone has yielded fossil fish fragments. Efforts are under way to extract the bones from the limestone by dissolving the latter with dilute acetic acid. Attempts to visualize the bones in the rock with X-ray and CAT scans were unsuccessful. This latest discovery enhances the known diversity of fossil vertebrates from the Mauch Chunk Group and may provide sufficient material for specific taxonomic classification.