"Primer registro de Dinosauria (Ornithischia, Hadrosauridae) en la provincia de La Pampa (Argentina) y sus implicancias paleobiogeográficas"

Bernardo J. González Riga, Silvio Casadío

Abstract


"Dinosaur remains are recorded for the first time in La Pampa Provincc.
Argenti na. They are from the lowest levels of the Allen Forrnation, late Campanian-early Maastrichtian
in age. These remains are incomplete cervical, dorsal, sacral and caudal vertebrae, scapula, coracoid,
fernur and phalanges which may be assigned to Hadrosauridae (Omithischia, Ornithopoda). The caudal
centra are anteriorly hexagonal, condition that has been interpreted as a synapornorphy of Hadrosauridae
by Illany authors. In addition, the presence of dorsal neural arches with strongly upward oriented diapophyses
and relatively short neural spines suggests reference of these remains to Hadrosaurinae.
Although sorne differences from Kritosaurus australis Bonaparte et al. 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 irnmigration 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 phvsical
connection between both Americas during the Campanian."

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