Pucapristis

Pucapristis is a prehistoric genus of sclerorhynchid ray whose fossils first appear in the fossil record in rocks dating from the Maastrichtian stage. The genus was described in 1963 by Schaeffer. Fossils of "Pucapristis" have not been found in any subsequent strata. Incidentally, the Maastrichtian is the final portion of the Cretaceous Period and its endpoint marks the advent of the Cretaceous–Paleogene extinction event. This major geological transition is famous for being the mass extinction that wiped out the dinosaurs.
Biogeography.
To date, "Pucapristis" fossils have been found only in the Maastrichtian deposits of central South America. The El Molino Formation of Bolivia produces "Pucapristis" tooth fossils in abundance. These Bolivian specimens have been recovered near the cities of Potosi and Sucre The Yacoraite Formation of Salta Province in northwestern Argentina is another locality from which "Pucapristis" remains can be excavated.