title: Fossil pollen records indicate that Patagonian desertification was not solely a consequence of Andean uplift.
abstract: The Patagonian steppe-a massive rain-shadow on the lee side of the southern Andes-is assumed to have evolved ~15-12 Myr as a consequence of the southern Andean uplift. However, fossil evidence supporting this assumption is limited. Here we quantitatively estimate climatic conditions and plant richness for the interval ~10-6 Myr based on the study and bioclimatic analysis of terrestrially derived spore-pollen assemblages preserved in well-constrained Patagonian marine deposits. Our analyses indicate a mesothermal climate, with mean temperatures of the coldest quarter between 11.4 °C and 16.9 °C (presently ~3.5 °C) and annual precipitation rarely below 661 mm (presently ~200 mm). Rarefied richness reveals a significantly more diverse flora during the late Miocene than today at the same latitude but comparable with that approximately 2,000 km further northeast at mid-latitudes on the Brazilian coast. We infer that the Patagonian desertification was not solely a consequence of the Andean uplift as previously insinuated.
authors.affiliation: 1] Museo Argentino de Ciencias Naturales 'Bernardino Rivadavia', Angel Gallardo 470 (C1405DJR), Buenos Aires, Argentina [2] Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK.
authors.forename: L
authors.initials: L
authors.lastname: Palazzesi
authors.affiliation: Museo Argentino de Ciencias Naturales 'Bernardino Rivadavia', Angel Gallardo 470 (C1405DJR), Buenos Aires, Argentina.
authors.forename: V D
authors.initials: VD
authors.lastname: Barreda
authors.affiliation: Universidad de Buenos Aires, Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales. Intendente Güiraldes 2160 (C1428EHA), Buenos Aires, Argentina.
authors.forename: J I
authors.initials: JI
authors.lastname: Cuitiño
authors.affiliation: Universidad Nacional del Sur, Departamento de Geología, San Juan 670 (8000) Bahía Blanca, Buenos Aires, Argentina.
authors.forename: M V
authors.initials: MV
authors.lastname: Guler
authors.affiliation: Laboratorio de Sistemática y Biología Evolutiva (LASBE), Museo de La Plata, Paseo del Bosque s/n (1900) La Plata, Buenos Aires, Argentina.
authors.forename: M C
authors.initials: MC
authors.lastname: Tellería
authors.affiliation: Universidade de Brasília, Instituto de Geociências. Campus Universitário Darcy Ribeiro, Brasília - DF CEP 70910-900, Brazil.
authors.forename: R
authors.initials: R
authors.lastname: Ventura Santos
mesh_terms: D001118:Argentina; D002980:Climate; D003889:Desert Climate; D005580:Fossils; D010802:Phylogeny; D011058:Pollen / Q000145:classification*; D013696:Temperature