A new Paleogene pipid frog from northwestern Patagonia

Numerous isolated and fragmentary remains of a pipid frog from Paleocene-Eocene lacustrine beds of the Vaca Mahuida Formation are described and referred to a new species of the genus Shelania Casamiquela. A cladistic analysis of fossil and extant pipoid frogs based on 47 osteological characters places the new species in a trichotomy with the South American Paleogene pipids S. pascuali and "Xenopus" romeri. These three species share a seemingly derived arrangement of perilymphatic and jugular foramina in the occipital region. The species described herein, "X" romeri and, presumably, S. pascuali lack discrete superior perilymphatic foramina as in extant African xenopodines; however, they possess several plesiomorphic conditions with respect to the latter. The presence of a pipid lineage distinct to that represented by extant taxa in South America is confirmed by this study.