First occurrence of a Tylosaurinae mosasaur from the Turonian of the Central Apennines, Italy

Abstract During the Late Cretaceous mosasaurs experienced a very rapid diversification, and inhabited almost the whole globe, especially in ancient coastal marine environments and subtropical epicontinental seas. Occurrences of mosasaurs as both complete and fragmentary material are known from all continents, ranging from the Canadian Arctic to Antarctica and from northern Europe to southern Africa. Despite their frequent occurrence in Europe, mosasaur remains from Italy are quite rare. Considering the central position of the Italian peninsula in the Tethyan realm during the Late Cretaceous, and the extensive outcrop of shallow-marine carbonates deposited in that period, the extreme rarity of mosasaur material is really puzzling. Occurrences of mosasaurs in Italy are essentially limited to historical findings from the second half of the 19th century, with specimens from the Vittorio Veneto area in Northern Italy, Reggio Emilia (Castellarano municipality) and from the Argille Scagliose Complex of Northern Italy. In this contribution we present and describe the first evidence for a mosasaur from the Turonian of the Apennine Carbonate Platform, represented by an isolated tooth found within the Cretaceous limestones outcropping on the eastern slopes of Mt. Cima la Torre (Prossedi, Latina, Central Italy). The absence of evident granulae in the proximal portion of the crown, the just slightly posteriorly recurved tooth crown, the sub-oval cross section moderately compressed labiolingually, the different order of striae vanishing to disappear towards the upper part of the crown, and the presence of dense tertiary striae (especially at the base of the crown) allow us to refer the isolated tooth to the subfamily Tylosaurinae. The new specimen represents the first Tylosaurinae mosasaur from Italy; in addition, assuming a paleolatitude of 25°N for the Apennine Carbonate Platform, the new finding also represents the southernmost occurrence of a Tylosaurinae mosasaur in the northern margin of the Mediterranean Tethys, throwing new light on the dispersal pattern of this crucial clade of mosasaurs in the Late Cretaceous.