Plagiogmus arcuatus Roedel, 1929

Description. This trace fossil occurs as horizontal, slightly winding flat-bottom troughs, 29–32 mm wide, with perpendicular, rarely slightly oblique, straight-to-slightly arcuate ribs. Some of them, through overlap and divergence, form false branches. The ribs are 4–5 mm wide, and their midlines are 15 mm apart. A single, winding, slightly bilobate ridge of comparable width was found on the same bedding plane. It probably belongs to the same trace fossil.