CAMPANIAN AND MAASTRICHTIAN MOSASAURS FROM PENINSULA ANTARTICA AND PATAGONIA

FERNANDEZ, M.; GASPARINI, Z.

Paris

Simposio; Third Mosasaur Meeting; 2010

Mosasaur records from Patagonia and Antarctic Peninsula are, although scarce, the most abundant and diverse of Western Gondwana. Ameghino (1893) described the first mosasaurs from Patagonia. Based  on isolated teeth he erected the new species “Liodon argentinus”. This material could not be found for revision. Gasparini & Del Valle (1981) reported the first mosasaurs from Antarctica; and in 2008, Fernández et al., described diagnostic material from northern Patagonia. Antartic mosasaurs were found in Vega, Seymour and Ross Islands (northeast of Antarctic Peninsula) and their record comprises from the Late Campanian to the Late Maastrichtian. Campanian record is restricted to tylosaurine remains, among which the most significant specimen is the type of Taniwhasaurus antarcticus  from the Late Campanian Santa Marta Formation on James  Ross Island (Fernández & Martin, 2009). Early Maastrichtian record is represented by a juvenile T. antarcticus from the Snow Hill Island Formation on Vega Island, and tylosaurine vertebrae from the basal portion of the López de Bertodano Formation  on Seymour Island. The highest diversity has been found in the Late Maastrichtian. Tylosaurines, plioplatecarpines (Plioplatecarpus  sp)  and mosasaurines (Leiodon sp.,   Mosasaurus  sp. cf. M. lemmonieri¸  and Mosasaurus  sp.  aff. M. hoffmanni) have been recovered from Seymour and Vega islands (Martin, 2006). In the Bajos de Trapalcó, northern Patagonia, Argentina, exposures of the upper part of the Jagüel Formation (Late Maastrichtian)  yielded mosasaur remains  of three different taxa: Mosasaurus sp. aff. M. hoffmani; Mosasaurinae indet.; Plioplatecarpus sp. An isolated Prognathodon tooth has been collected by local people in the same area. Complementing Patagonian record, mosasaurine vertebrae have been found in the Jagüel Fm. (Late Maastrichthian) of Liu Malal, Mendoza, Argentina (Gasparini et al., 2001). Comparison of Patagonian and Antarctic records reveals some differences. Patagonian mosasaur record is restricted to the Late Maastrichtian (no mosasaur remains have been found in Campanian localities where plesiosaurs have been found); and no tylosaurine mosasaurs have been recovered from Patagonia to date.