Revision of a classic site for Permian tetrapod ichnology (Collio Formation, Trompia and Caffaro Valleys, N. Italy), new evidences for the radiation of captorhinomorph footprints

The recent studies on Permian captorhinomorph (non-diapsid eureptile) footprints from North America, North
Africa, and Europe raised the interest on their taxonomic and biostratigraphic significance. They seem to radiate
in the late Early Permian, but the scarcity of absolute dating in the classic sections bearing these trace fossils is not
helpful in order to unravel their distribution. The continental Collio Formation cropping out extensively in the
central Southern Alps of Italy can cover this gap of knowledge, since it preserves a rich testimony of these
trace fossils (Erpetopus, Hyloidichnus, Varanopus) and it is well-constrained from radiometric datings and fossil
content. For this and because of the huge amount of stored but unanalyzed material, a revision was necessary,
through careful taxonomic assignations. These taxa are here confirmed and/or identified as being: Amphisauropus
kablikae, cf. Batrachichnus isp., Dromopus lacertoides, Erpetopus cassinisi, Hyloidichnus bifurcatus, Limnopus
heterodactylus and Varanopus isp. The occurrence of Erpetopus at the base of the Collio Formation (Kungurian
base) suggests its minimum age of first appearance in a global context: this is a very important presence in
order to build a reliable tetrapod footprint biostratigraphy during the Permian. The quantity of material yielded
in the different facies of the Collio and Dosso dei Galli Formations also permit new insights on the
paleoenvironments and climatic settings.