Splendid and Seldom Isolated: The Paleobiogeography of Patagonia

Abstract

The idea that South America was an island continent over most of the Cenozoic, during which its unusual mammalian faunas evolved in isolation, is outstandingly influential in biogeography. Although large numbers of recent fossil discoveries and related advances require that the original isolation concept be significantly modified, it is still repeated in much current literature. The persistence of the idea inspired us to present here an integrated paleobiogeographic account of mammals, reptiles, and plants from the Jurassic to the Paleogene of Patagonia, which has by far the richest fossil record on the continent. All three groups show distribution patterns that are broadly consistent with South America's long separation history, first from Laurasia by the Late Jurassic, then from Africa and India-Madagascar during the late Early Cretaceous, and finally from Antarctica and Australia during the early-middle Eocene, after which “isolation” finally commenced. We highlight areas of promising future research and provide an updated view of South American isolation.

The last Patagonian cycad,Austrozamiastockeyigen. et sp. nov., early Eocene of Laguna del Hunco, Chubut, Argentina

“…This inference is similar to recent interpretations of numerous other genera now known as Paleogene fossils from Patagonia, southern Australia, and occasionally Antarctica (Hill and Brodribb 1999;Wilf et al 2009Wilf et al , 2013Carpenter et al 2014;Kooyman et al 2014). For the Encephalarteae, as for so many other examples (R.S.…”

“…The outstandingly preserved and extremely diverse Laguna del Hunco biota from Chubut, Argentina, currently stands as the most informative paleofloral record for the entire South American continent during the global warmth of the early Eocene (Berry 1925;Wilf et al 2003Wilf et al , 2013. The assemblage represents the early Eocene climatic optimum, the terminal phase of Gondwana, and the western end of an extinct, trans-Antarctic rainforest biome; thus, the Laguna del Hunco flora is uniquely relevant to studies of Gondwanan paleobiogeography and evolutionary timing, among many other topics (Romero 1978;Wilf et al 2013;Kooyman et al 2014;Merkhofer et al 2015;Wilf and Escapa 2015 Knight and Wilf 2013); and the eudicots Akania (Akaniaceae), Eucalyptus (Myrtaceae), and Gymnostoma (Casuarinaceae; Romero and Hickey 1976;Gandolfo et al 1988Gandolfo et al , 2011Zamaloa et al 2006;Hermsen et al 2012).…”

Evolução dos Toxodontia da América do Sul durante o Cenozoico: aspectos dentários, paleoclimáticos e paleoambientais

“…Os notoungulados reportados foram provavelmente herbívoros ramoneadores lofodontes, adaptados a clima quente e úmido em ambientes tropicais florestados, caracterizados por grande diversidade florística (Wilf et al 2013). …”

Structure and Alpha Biodiversity of Major Plant Communities in Chile, a Distant Gondwanan Relation

“…Although without an exact modern equivalent the vegetation is considered closest to that of the Andes in southern Chile and Argentina (Bowman et al 2014). Further north, in southern Argentina, well preserved fossils occur in Paleocene and early Eocene sediments of Gondwanan elements; these include araucarian (Agathis, Araucaria sect.Eutacta), podocarp (Dacrycarpus, Acmopyle, Retrophyllum), and cupressoid (Papuacedrus) taxa together with the angiosperms Eucalyptus, Gymnostoma, Akania, and Ripogonum that today are restricted to Australasia and regions north (Gandolfo et al2011;Wilf et al 2013;Carpenter et al 2013). Thus, by the early Eocene there was strong similarity between mesic floras of southern South America and southern Australia (Kooyman et al 2014).…”