Peter A. Meylan

The first cryptodiran turtle with a pitted palate, Brachyopsemystingitana gen. et sp. nov., is described on the basis of skulls and a lower jaw from the early Paleocene (Danian) of the Ouled Abdoun Basin, Morocco. The new taxon shares a number of apomorphic features with Sandowniaharrisi from the Aptian of the Isle of White, England, Angolachelysmbaxi from the Turonian of Angola, and an unnamed turtle from the Albian Glen Rose Formation in Texas. A phylogenetic analysis provides evidence that they form a monophyletic clade which we name the Sandownidae fam. nov. The phylogenetic relationships of Sandownidae are problematic. Their affinities among the Eucryptodira remain uncertain; a well-preserved shell of a member of the family may be useful in determining relationships. The family appears to be a bottom-dwelling group that occurred in near-shore marine environments along the coast of the Atlantic across the Cretaceous-Tertiary boundary. Its evolutionary history is connected to the development of the Atlantic Ocean.