New ichnogenus and ichnospecies Pulsocauda ankylon igen. et isp. nov. are established for single grooved crescent-shaped locomotion trails from the Frasnian (Upper Devonian) of European Russia. Earlier described trail from the Frasnian of the Onega Lake coast is assigned to this ichnospecies, and the one from the North Timan to the same ichnogenus. The similarity of these ichnofossils suggests that these trails could have been left by fishes with similar caudal fin morphology when touching the bottom. Through the use of three-dimensional models, a series of cross-sections were reconstructed, revealing modifications in their configuration that indicate a shift in the orientation of the terminal part of the caudal lobe during swimming. It is most likely that the tracks of Pulsocauda ankylon gen. et sp. nov. were produced by arthrodire placoderm fishes, which had the tail structure particularly suited to forming such distinctive trails.
Baraboshkin et al. (Mon,) studied this question.