PRELIMINARY REPORT ON A NEW FOSSIL FROM THE PENNSYLVANIAN ROCKS OF THE CUMBERLAND PLATEAU OF TENNESSEE: PLANT ROOTS OR TRACE FOSSILS?

The Study area is located on the southern Cumberland Plateau near Sewanee, Tennessee. The top of the plateau exposes Pennsylvanian sandstones and shales of the Warren Point Sandstone and overlying Signal Point Shale. It is from the contact area of these two formations that a previously undescribed series of long, branching, cylindrical fossils has been found. Branching is dichotomous in some cases and in others small tubes branch from larger ones at near right angles. The fossils all branch in the same direction and are located parallel to bedding planes. Less than 5% of the fossils found show tapering of the tubes in the direction of branching. Thin section studies show that the tubes are slightly elliptical and filled with fine to medium sand from the surrounding unit. No tube linings are evident. The fossils are at first glance reminiscent of roots because they all trend in the same direction and are characterized by dichotomous branching. However, general lack of tube tapering, filling with local sand, lack of significant flattening of the tubes, and weakly developed annular structures (backfill structures?) suggest that these may be trace fossils. To date the fossils have only been found within half of a square mile on the Cumberland Plateau. Several paleobotanists and ichnologists to whom photos of the fossils were sent reported never having seen them before.