The Ichnofossil Assemblage from the Tikhvinskoe Locality (Yaroslavl Region: Lower Triassic, Rybinskian Horizon) as Evidence of Paleoecosystem Organization

This article provides an integrated description of the paleobiota of the Tikhvinskoe locality (Rybinsk District of Yaroslavl Region, Russia; Lower Triassic) with a special focus on the most typical ichnofossils for this locality. Ichnofossils are split into several informal groups: (1) tracks of the horseshoe crab Limulitella volgensis Ponomarenko, which were identified as the ichnospecies Selenichnites eotriassicus Naugolnykh, (2) fish swim tracks of fish movement over the bottom, which was a dense but soft carbonate substrate; tracks of this type are identified as Undichna sp.; (3) traces of fish burrowing into the substrate with the formation of cocoons (supposed burrows of Dipnoi); (4) root traces of Radicites sp.; and (5) temnospondyl amphibian footprints, sometimes accompanied by tail and body drag marks of these animals. The author’s taphonomic observations and general information about the taxonomic composition of the Tikhvinskoe paleobiota and hypotheses on the general organization of the Tikhvinskoe paleoecosystem are presented.