Palaeoenvironmental and faunal inferences based on the avian fossil record of Patagonia and Pampa: what works and what does not

Analysing the effect of climatic/environmental changes on bird communities during the South American Cenozoic is quite complicated. Taking into consideration the extremely complex evolution of such environmental conditions and the incomplete and episodic fossil bird record in this part of the continent, any generalization should be considered with caution. However, some aspects may be noted: (1) certain typically South American bird groups evolved in total isolation, i.e. terrestrial or poorly flying birds, incapable of crossing important water barriers (Rheiformes, Tinamiformes, Phorusrhacidae, Brontornithidae, Anhimidae); (2) other good flyers did not cross until immediately before the definitive connection between both Americas (Teratornithidae, Passeriformes Suboscines); (3) most of the families established important intercontinental relationships (Anhingidae, Pelecanidae, Ciconiidae, Anatidae, Presbyornithidae, Rallidae, Falconidae and Accipitridae); (4) several taxa that are presently important members of the rich South American bird fauna are unknown for certain geological time periods (Throchilidae); and (5) there is a high prevalence of carnivorous birds over all other trophic habits, regardless of the association or age analysed. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society , 2011, 103 , 458–474. Analizar el efecto que los cambios climáticos y ambientales tuvieron en las comunidades de aves durante el Cenozoico sudamericano es complicado y cualquier generalización debe tomarse con cautela. Sin embargo pueden señalarse algunos aspectos: (1) algunos grupos de aves típicamente sudamericanas evolucionaron en total aislamiento (Rheiformes, Tinamiformes, Phorusrhacidae, Brontornithidae, Anhimidae); (2) otros grupos buenos voladores no cruzaron a América del Norte hasta establecido el puente Panameño entre las dos Américas (Teratornithidae, Passeriformes Suboscines); (3) la mayoría de las familias establecieron importantes relaciones intercontinentales (Anhingidae, Pelecanidae, Ciconiidae, Anatidae, Presbyornithidae, Rallidae, Falconidae, Accipitridae); (4) importantes miembros de la avifauna sudamericana actual son desconocidos en el registro fósil (Throchilidae); (5) hay una prevalencia de aves carnívoras en todas las asociaciones cualquiera fuere su antigüedad.