The Permian of the Nurra region (NW Sardinia, Italy): a unique window for the Late Palaeozoic tetrapod communities of Europe

AUSONIO RONCHI; MARTINA CARATELLI; PAOLO CITTON; EVA SACCHI; MARCO ROMANO; SIMONE MAGANUCO; UMBERTO NICOSIA

Milano

Congreso; STRATI 2019; 2019

Società Geologica Italiana

Since 2008 more than fifteen fieldworks have been conducted in the Nurra area in NW Sardinia, were a well-known thick succession of more than 600 m of post-Variscan continental deposits crops out. The fieldworks, headed by a team of the Department of Earth Sciences of Sapienza of Rome in collaboration with the University of Pavia, led to the collection of truly unique osteological material for both Italian and European Permian panorama. The first vertebrate find in 2008 was represented by both articulated and isolated postcranial material referred to a new genus and species of Caseidae Alierasaurus ronchii from the red Permian sediments of the Cala del Vino Formation, outcropping in the Torre del Porticciolo promontory (Romano & Nicosia, 2014). In 2015 a second productive site was discovered, about hundred metres from the original Alierasaurus site. Fieldworks in this locality in 2016 and 2017 led to the recovery of several isolated and fragmentary bones found both embedded in the original red bed deposit, and as loose material deriving from the erosion of the productive sedimentary body. A detailed taphonomic analysis allows us to refer all the collected material to a single individual, characterized by peculiar features typical of the non-therapsid synapsids family Sphenacodontidae (Romano et al., 2018). Thus, in addition to a big herbivorous represented by the huge caseid Alierasaurus, the new finding testifies the presence of a medium size carnivorous ?pelycosaur? in the study region, the first in Italy and one of the few described for the whole European continent, throwing new light on the occurrence and dispersal of the clade. In 2017 a third site was discovered at Cala Viola locality, which led to the discovery of both isolated and in situ tetrapod tracks (Citton et la., 2018). The new material represents the first Permian tetrapod footprints from Sardinia, adding a new crucial piece of evidence to the overall picture. Considering these elements together, the Torre del Porticciolo area results one of the very few sites in Europe where both body fossils and ichnofossils are jointly preserved. The Nurra Region in Sardinia thus shows a real great potential to throw new light on the Permian faunal diversity and ecosystem structure in this area of Pangea.