First Record of the Knifetooth Sawfish Anoxypristis (Elasmobranchii

Home , Knifetooth sawfish, Rhinopristiformes

N. Jb. Geol. Paläont. Abh. 284/3 (2017), 289–297 Article Stuttgart, June 2017

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

Alberto Collareta, Simone Casati, Rita Catanzariti, and Andrea Di Cencio With 3 ﬁgures and 1 table

Abstract: 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 nanno- plankton 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/subtropi- cal 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.

Key words: Pristidae, Anoxypristis cuspidata, Pliocene, Tuscany, blue clays, Messinian Salinity Crisis, Mid Piacenzian Warm Period, palaeobiogeography, palaeoecology, vertebrate palaeontology.

1. Introduction and references therein). Sawfish display a circumglobal distribution in warm waters and occupy proximal Sawfish (Chondrichthyes: Batomorphii: Pristidae) are marine and even freshwater habitats (e.g., WUERINGER et a family of large shark-shaped rays characterised by al. 2009; DULVY et al. 2014). Their extant biodiversity is a long and dorsoventrally flattened rostrum whose la- limited to five largely sympatric and highly threatened teral margins bear lancet-like, highly derived dermal species belonging to the genera Pristis LINCK, 1790 and denticles (not homologous to teeth) commonly known Anoxypristis WHITE & MOY-THOMAS, 1941 (DULVY et al. as saw teeth, rostral teeth, rostral pegs, or rostral spines 2014). Among Pristidae, the currently monotypic genus (e.g., CARRILLO-BRICEÑO et al. 2015). Here we use the Anoxypristis (known as knifetooth sawfish, or narrow latter term, following LATHAM (1794). Members of the sawfish) is a nectobenthic organism which is found in family Pristidae feed on small fish and invertebrates coastal and estuarine environments of the Indian and using their saw-like rostra to uncover infaunal orga- Western Pacific oceans, ranging from the Persian Gulf nisms from the seafloor, immobilise food items, and to New Guinea and northern Australia (DULVY et al. stun or slash individual prey (WUERINGER et al. 2009, 2014).