A New Species of Opisthodactylus Ameghino 1891 (Aves, Rheidae) from the late Miocene of Northwestern Argentina, with implications for the paleobiogeography and phylogeny of rheas

NORIEGA, J.I.; JORDAN, E.A.; VEZZOSI, R.I.; ARETA, J.I.

JOURNAL OF VERTEBRATE PALEONTOLOGY

SOC VERTEBRATE PALEONTOLOGY

Lugar: Lawrence; Año: 2017

0272-4634

A new species of rheid, Opisthodactylus kirchneri sp. nov., is erected on thebasis of associated elements of both hind limbs coming from the late Miocene innorthwestern Argentina. The new species extends the biochron of Opisthodactylus fromearly Miocene to late Miocene and its distribution from Patagonia to Northwest ofArgentina. The cladistic analysis recovered an Opisthodactylus−Pterocnemia clade as sisterto a Rhea americana clade. The Opisthodactylus−Pterocnemia clade would have inhabitedthe most southern, central and western regions of southern South America throughout theearly−middle Neogene, whereas the Rhea stock would have had a north-northeastern orBrazilian ancestral distribution in the lowlands of the continent. The similar biogeographic patterns of living and fossil rheids, cariamids and tinamids seem to roughly reflect the environmental shift from closed to open habitats that took place at the southern end of South America during the Neogene and Pleistocene, and at least in the former two families the effects of isolation produced by the ?Paranaense? sea. Closed-habitat taxa of these three families were recorded at early Miocene localities in Patagonia (O. horacioperezi, O. patagonicus, Noriegavis santacrucensis, and Crypturellus reai) whereas open-habitat taxa came from late Miocene−early Pliocene sites at Central (Pterocnemia sp. and Eudromia sp.), Northwestern (O. kirchneri, Pterocnemia cf. mesopotamica), and Northeastern (Pterocnemia mesopotamica) regions in Argentina.