Tetrapod footprint paleoecology : behavior, taphonomy and ichnofauna desentagled : a case study from the lower Permian of the Southern Alps (Italy)

Vertebrate tracks are linked to the depositional environment where they were formed. Several studies hypothesized a paleoenvironmental control on vertebrate track ichnocoenoses, although this issue was never analyzed thoroughly. A new study of the sedimentology and tetrapod ichnology of two key stratigraphic sections in the Pizzo del Diavolo Formation of the lower Permian continental Orobic Basin of Southern Alps (Italy) tested the link between tetrapod ichnocoenoses and depositional environment. Behavior, taphonomy, and ichnocoenoses of three different lithozones (P-PDV, U-PDVa, U-PDVb) were analyzed and compared, two new census methods for tetrapod tracks were tested ("track/slab'' and "weighting size'') and the first was applied to our specimen sample. The possible biostratigraphic meaning of track occurrences/relative proportions were discussed and excluded. Results indicate a predominance of the ichnogenus Erpetopus in a distal floodplain environment (P-PDV), a diverse ichnocoenosis in a proximal floodplain environment (U-PDVa), and a predominance of the ichnogenus Dromopus in a scarcely diverse ichnocoenosis in a floodplain/marginal lacustrine environment (U-PDVb). This encourages further detailed studies on tetrapod track paleoecology, in order to refine and give utility to the concept of tetrapod ichnofacies.