A new resting trace of echiuran worms from the Paleocene turbiditic deposits of the Northern Apennines and the Polish Outer Carpathians

A new trace fossil, Cochlearichnus tumidus igen. nov. et isp. nov., is described from Paleocene deep-seadeposits of the Ropianka Formation (Magura Nappe, Polish Outer Carpathians) and the Pagliaro Formation(Northern Apennines, Italy). The trace occurs in fine-grained turbiditic sandstones and is preserved as a hypichnialconvex semi-relief with a consistent spoon-shaped outline. Comparison with the body outlines of extantechiuran worms indicates that C. tumidus igen. nov. et isp. nov. represents a resting trace, most likely producedby a deep-sea echiuran inhabiting soft, muddy substrates. The structure was formed in mud and subsequentlyscoured and cast by turbiditic sand. The deposits bearing this trace fossil are characterized by the Paleodictyonichnosubfacies within the Nereites ichnofacies, typical of distal parts of the turbiditic depositional systems.