Trackways of Arthropleura from the Late Pennsylvanian of Graissessac (H?rault, southern France)

The Late Pennsylvanian deposits of the Graissessac Basin (southern France) are well known for their abundant and diversified plant remains. Here we report on seven trackways of giant millipede-like arthropods recently discovered from two surfaces. These traces are ascribed to Diplichnites cuithensis. The trackways are up to 200 cm long, up to 36 cm wide, straight to curved and consist of two parallel rows of numerous and elongated appendage imprints that are oriented perpendicular to the midline. Although body fossils of giant millipede-like arthropods remain unknown in sediments from this basin, the morphology and size of the trace fossils indicate that the trails were made by 0.9 to 1.6 m long individuals of Arthropleura. The depositional environment is interpreted as a regularly inundated floodplain close to a fluvial channel and dominated by lycopsids. Such a vegetation was probably an attractive and important source of food for the giant herbivorous arthropods that were roaming the riparian landscapes of the Graissessac Basin. This new occurrence of Arthropleura trackways confirms that this giant arthropod was a common member of Late Palaeozoic continental biotas.