A highly diverse Pennsylvanian tetrapod ichnoassemblage from the Semily Formation (Krkonoše Piedmont Basin, Czechia)

The Krkonoše Piedmont Basin (KPB) is one of the Late Paleozoic continental basins in Bohemia, Czechia, comprising a sedimentary sequence from the Late Pennsylvanian to the early Cisuralian. The Pennsylvanian in the KPB consists of alluvial-fluvial to lacustrine deposits with a relatively rich fossil record, comprising mainly ray-finned fishes, freshwater sharks, and invertebrates. Although no skeletal remains of terrestrial vertebrates have been discovered in the Late Pennsylvanian deposits of the KPB, recent studies of tetrapod footprints provide the first direct evidence of pre-Permian terrestrial tetrapod diversity within this basin. A diverse ichnofossil assemblage is represented by six ichnogenera, Amphisauropus , Batrachichnus , Dimetropu s, Dromopus , Ichniotherium and Limnopus , including five known ichnospecies, Amphisauropus kablikae , Batrachichnus salamandroides , Dromopus lacertoides, Ichniotherium cottae , and Limnopus heterodactylus , and two unknown ichnospecies, Dimetropus isp. and Limnopus isp. This tetrapod ichnoassemblage is among the most diverse in the Pennsylvanian. Moreover, the Amphisauropus tracks from the KPB represent the first undisputed occurrence of this ichnotaxon in the Gzhelian. Furthermore, the Ichniotherium cottae tracks described here complement the still rare Pennsylvanian occurrences of this ichnospecies in the European part of Pangaea. The ichnofauna studied herein is associated with alluvial-plain to lacustrine nearshore deposits, highlighting the ecological importance of the lacustrine environment and its adjacent areas for the presence of terrestrial vertebrates and the preservation of their footprints.