Unveiling trampling history through trackway interferences and track preservational features. A case study from the Bletterbach gorge (Redagno, Western Dolomites, Italy)

A slab from the Upper Permian Arenaria di Val Gardena Formation, bearing hundreds of tracks of different tetrapods, has been studied in order to reconstruct the trampling history through standard ichnological analysis and 3D photogrammetry. Analysis of crossed trackways to determine the relative timing of passages, as well as preservational features of the tracks qualitatively considered with trackmaker dimensions, has elucidated the nature of the trampled layer and the preservational mode of the tracks, especially the different conditions (i.e., sediment cohesion) that characterized the trampled layer during trackmaker crossings. Moreover, the analysis of an event timeline strongly suggests that caution should be exercised in analyzing track interferences, especially when multiple lines of evidence are lacking. As a consequence, the timeline of events may be masked, misleading and misinterpreted with obvious repercussions on general reconstructions (e.g., palaeoecological and behavioural). This study highlights the reliability of this type of analysis in untangling the preservational history of trampled surfaces; a useful investigative tool to be employed prior to traditional ichnological analyses aimed at classification of tetrapod tracks.