The First Southern Hemisphere Occurrence of the Extinct Cretaceous Sclerorhynchoid Sawfish (Chondrichthyes, Batoidea), With a Review of Taxonomy.

A new extinct sclerorhynchoid sawfish, sp. nov., is presented here based on abundant isolated teeth and some dermal denticles, which were recovered from the Mata Amarilla Formation, belonging to the lower Upper Cretaceous of the Santa Cruz Province in the Austral Basin of Patagonia, Argentina. This new species is the first occurrence in the southern hemisphere, which so far only has been reported from northern hemisphere deposits (Europe, North Africa, and North America). The presence of sp. nov. in these southern high-latitude deposits of Patagonia, Argentina, extends the geographic range of considerably southwards. This distribution pattern in the "middle" Cretaceous seems to correlate with the South Atlantic opening at the end of the Albian. The presence of lateral cephalic dermal denticles and the simultaneous absence of rostral denticles in the abundant fossil material support the view that did not develop such rostral structures. A reinvestigation of all known species assigned to reveals that is a junior synonym of belongs to belongs to , and represents an unidentifiable species (? sp.). The stratigraphic distribution demonstrates that might have originated in the Albian in south-western Europe and subsequently dispersed to obtain its widest distribution during the Cenomanian. In the Coniacian, a steep diversity decline is recognizable with a subsequent distribution shift from Europe to North America.