First record of the knifetooth sawfish Anoxypristis (Elasmobranchii: Rhinopristiformes) from the Pliocene of Tuscany (central Italy)

Sawfish are a group of cartilaginous fish characterised by a long and flat rostrum whose lateral margins bear highly derived, lancet-like scales known as rostral spines. Sawfish display a circumglobal distribution in warm marine and even freshwater habitats, and their extant biodiversity is limited to five species belonging to two genera (Pristis and Anoxypristis). We report on two fossil sawfish rostral spines discovered in Pliocene marine mudstones at Tegoliccio (Tuscany, Italy) and here identified as belonging to the extant, currently Indo-Pacific genus Anoxypristis. Calcareous nannoplankton analyses of the sediment embedding the pristid remains, coupled with biostratigraphic data from literature, allowed us to bracket the time of deposition between 3.61 Ma and 3.19 Ma. To our knowledge, the rostral spines described herein represent the first record of Anoxypristis in Italy; as such, they expand our knowledge on the late Neogene central Mediterranean biodiversity. Moreover, our finding represents the geologically youngest occurrence of Anoxypristis in the Mediterranean basin and evokes palaeoenvironmental conditions favourable to the persistence of tropical/subtropical taxa along the Pliocene coasts of Tuscany. The definitive disappearance of Anoxypristis from the Mediterranean could be attributed to the severe climate degradation which accompanied the onset of long-term Northern Hemisphere glaciation around 3 Ma.