A New Genus of Fossil Octodontine Rodent from the Early Pleistocene of Argentina

New material, including associated skulls and lower jaws and postcranial bone remains from early Pleistocene San Andresian beds of southeastern Buenos Aires Province, demonstrates that the octodontine rodent Pseudoplataeomys castellanosi differs strongly from the type and referred species of Pseudoplataeomys. P. castellanosi is proposed as the type species of a new monotypic genus. The new genus is considered as closely related to, more primitive than, and probably ancestral to extant Octodon.