Zulma Brandoni de Gasparini

Academic paper

Palaeontology

Palaeontological Association

40, Part 1

135--147

A new pliosaur with a spatulate symphysis is described as Maresaurus coccai gen. et. sp. nov.. The holotype is from the upper levels of the Los Molles Formation (Lower Bajocian, Middle Jurassic) of the southern Neuquén Basin, central-western Argentina. Maresaurus coccai shares with Simolestes such synapomorphies as the absence of a dorso-medial foramen, lack of anterior interpterygoid vaccuity and fewer than 26 alveoli in the dentary. The autapomorphies of M.coccai are the strong flanges formed by the premaxilliary and maxilliary, the expanded and elevated ptreygoid wings, a disteme between the eights and ninth mandibular alveoli and the hypertrophied teeth (canniniforms) which are densely striated and without carinae or smooth faces. The record of Bajocian plesiosaurs is limited to Simolestes keleini from the Upper Bajocian of France and M.coccai from the Lower Bajocian of the Neuquén Basin. The latter is associated with other marine reptiles, mainly ichthyosaurs, coeval with a greater diversity in the invertebrate fauna, in an offshore deposit dominated by pelagic sedimentation.

English