CASADIO Silvio Alberto
Primer registro de Dinosauria (Ornithischia, Hadrosauridae) para la provincia de La Pampa (Argentina) y sus implicancias paleobiogeográficas
GONZÁLEZ RIGA, B.; CASADÍO, S.
ASOCIACION PALEONTOLOGICA ARGENTINA
Lugar: Buenos Aires; Año: 2000 vol. 37 p. 341 - 351
Dinosaur remains were recorded for the first time in the province of La Pampa, Argentina. They are from the lowest levels of the Allen Formation, Late Campanian-Early Maastrichtian in age. These remains are incomplete cervical, dorsal, sacral and caudal vertebrae, scapula, coracoid, femur and phalanges which may be assigned to Hadrosauridae (Ornithischia, Ornithopoda). The caudal centra are anteriorly hexagonal, condition that has been interpreted as a synapomorphy of Hadrosauridae by many authors. In addition, the presence of dorsal neural arches with diapophyses strongly upward oriented and relatively short neural spines suggests referral of these remains to Hadrosaurinae. Athough some differences with respect to Kritosaurus australis are evident, a more precise systematic assignment is difficult in view of the fragmentary state of these remains. The fossils were found in sandy facies of littoral deposits, influenced by river flow and tides, related to the first Atlantic marine event for the Neuquén Basin. From a paleogeographic standpoint, this new record of Hadrosauridae adds new evidence on the immigration of these dinosaurs from North America toward the end of the Cretaceous. The record from the Allen Formation and equivalent units of northern Patagonia suggests a physical connection between both Americas during the Campanian.