Cretaceous dinosaur tracks of Periadriatic carbonate platforms and their palaeogeographic significance

The occurrence of several ichnological and skeletal dinosaur remains from the Upper Jurassic to Cretaceous deposits of Central and Southern Italy raises the question about their dispersal from Laurasia or Gondwana to the Western Tethys (i.e., Adria). The diversified terrestrial ecosystem within the Periadriatic carbonate platforms (sensu Zappaterra, 1994) during the Cretaceous led some authors (e.g., Zarcone et al., 2010) to challenge the traditional palaeogeographic scenario, according to which Adria was characterised by isolated shallowwater carbonate platforms, separated by pelagic basins and far from continental areas. New ichnological data, obtained by combining traditional methods and new tools, such as photogrammetry and Principal Component Analysis, allowed us to refine the trackmakers identification, achieving a more detailed taxonomic level. Herein, we summarise the results obtained from the ichnological analysis of four tracksites from Latium (Sezze) and Apulia (Borgo Celano, Molfetta and Altamura), ranging from the Hauterivian-Barremian to the early Campanian. The Hauterivian-Barremian to early Albian interval, documented from Borgo Celano and Molfetta, represents the first snapshot. It reveals the likely occurrence in the Apulia carbonate platform of largesized theropods, such as abelisauroids and carcharodontosaurs. Geological evidence support the hypothesis of a Gondwanan origin for the Apulian large theropods, with a dispersal route from Africa to Apulia through the Constantinois, Central Tunisian and Panormide carbonate platforms, intermittently emerged and connected from the Late Jurassic to the late Cenomanian. The second snapshot is represented by the early-middle Cenomanian of Sezze, where the ongoing studies confirm the occurrence of oviraptorosaurs, thus raising three possible hypotheses: i) their dispersal from Laurasia to the Apenninic carbonate platform; ii) their presence in North Africa, to date not documented by skeletal remains; iii) the presence in Gondwana of an unknown clade of theropods with the structure of the foot converging with that of the oviraptorosaurs. The last snapshot focuses on the early Campanian, documented from Altamura. The ichnological analysis points to the occurrence of small- to medium-sized ankylosaurs, similar to the coeval European nodosaurids, and medium-sized hadrosaurs, similar to Tethyshadros insularis, a non-hadrosaurid hadrosauroid from the lower-middle Campanian of north-eastern Italy. The dispersal of these clades and the geological-stratigraphical data suggest a palaeogeographic connection between Eurasia and the Periadriatic area at least since the Santonian.