New occurrences of tetrapod ichnotaxa from the Permian Orobic Basin (Northern Italy) and critical discussion of the age of the ichnoassociation

Abstract

Abstract:The late Cisuralian (Artinskian-Kungurian) is a key time interval for Permian tetrapod evolution. In all the main low-latitude Pangean sites, the fossil footprint record clearly shows a diversification and dispersal of non-synapsid amniote tracks compared to the early Cisuralian (AsselianSakmarian). However, data on latest Cisuralian (i.e. late Kungurian) sites are quite fragmentary. A new ichnotaxonomic study was carried out in the central part of the Orobic Basin, where the highly-fossiliferous Pizzo del Diavolo formation crops out and can potentially cover this gap in knowledge. The following tetrapod ichnogenera were identified: Amphisauropus, Batrachichnus, cf. Dimetropus, Dromopus, Erpetopus, Hyloidichnus, Limnopus, cf. Merifontichnus and Varanopus; they can be attributed to seymouriamorph and temnospondyl amphibians; pelycosaur synapsids; and diapsid, parareptile and captorhinid reptiles. Dimetropus and Merifontichnus are identified for the first time in the Permian of Italy. The ichnoassociation, in agreement with the radiometric dating of the underlying Cabianca formation, suggests a late Kungurian (latest Cisuralian) age for the Pizzo del Diavolo formation. It includes the youngest and most diverse non-synapsid amniote ichnofauna of the Cisuralian with five different ichnogenera and possibly six ichnospecies, and thus constitutes a key area for the study of eureptile and parareptile dispersal at low latitudes of Pangaea in the time span that immediately pre-dates the first therapsid synapsid radiation.

Integrated multi-stratigraphic study of the Coll de Terrers late Permian–Early Triassic continental succession from the Catalan Pyrenees (NE Iberian Peninsula): A geologic reference record for equatorial Pangaea

“…Dromopus is mostly recognized in Lower Permian deposits (Marchetti, 2016), whereas Rhynchosauroides is identified in the Upper Permian record (Valentini et al, 2007(Valentini et al, , 2009. Similar footprints from the late Permian of the Nigerian Moradi formation were attributed to Dromopus by Smith et al (2015) although further detailed studies are necessary for a confident ichnotaxonomy.…”

“…Nevertheless, these tracks most probably correspond to a single trackway, thus such morphological variations are related to locomotion and substrate rheology. Two ichnogenera present the characters described above: 1) the Dicynodontipus tracks from the Cistecephalus Assemblage Zone (late Permian) at the South African Karoo Basin (de Klerk, 2002), and 2) the Merifontichnus tracks from the La Lieude formation (middle Permian) at the French Lodève Basin (Gand et al, 2000;Gand and Durand, 2006) and possibly from the late early Permian of the Italian Orobic Basin (Marchetti, 2016). With the available data, ichnotaxonomy should remain open, although considering the age of the succession (see discussion in Section 5 below), Merifontichuns is the favoured ichnogenus for these ichnites.…”

An unusual Amphisauropus trackway and its implication for understanding seymouriamorph locomotion

“…), while the tetrapod ichnoassociation, recently revised by Marchetti et al . (, ) and Marchetti (), is most probably Late Cisuralian (Kungurian) in age. The environment related to this stratigraphic level was interpreted as a distal fan to sandflat in a semi‐arid setting (arenitic–pelitic facies association sensu Marchetti et al .…”

Aridification across the Carboniferous–Permian transition in central equatorial Pangea: The Catalan Pyrenean succession (NE Iberian Peninsula)

“…Recent studies on Permian tetrapod ichnostratigraphy (Marchetti, 2016;Voigt and Lucas, 2016) found that: (1) Hyloidichnus, a well-represented ichnogenus of the Lower Red Unit, is only found in Artinskian and younger strata; (2) Erpetopus, an index ichnotaxon for the Kungurian, has not been so far reported for the Lower Red Unit; (3) Ichniotherium, possibly found in the Lower Red Unit (cf. Ichniotherium of Mujal et al, 2016a), is not found in strata younger than Artinskian.…”