Diversificación y cambios de las angiospermas durante el Neogeno de Argentina

VIVIANA BARREDA*, LUISA M. ANZÓTEGUI*, ALDO R. PRIETO*, PABLO ACEÑOLAZA, M.

PUBLICACION ESPECIAL - ASOCIACION PALEONTOLOGICA ARGENTINA

Asociacion Paleontologica Argentina

Lugar: Buenos Aires; Año: 2007 p. 173 - 191

0328-347X

Abstract. ANGIOSPERM DIVERSIFICATION AND CHANGES DURING THE NEOGENE IN ARGENTINA. Climate is acceptedas being the main determinant of the dynamics of Neogene floral changes. The final uplift of theAndes in South America (Late Miocene-Pliocene) would have also been an important forcing factor. Wepresent the first updated synthesis of the main changes of the Neogene flora in Argentina based on theplant fossil record. Early-Middle Miocene floras were assembled in three well supported Paleo-phytogeographicProvinces: the Neotropical, to the north, characterized by families nowadays present in theChaco Domain (e.g. Apocinaceae, Aquifoliaceae, Cactaceae, Fabaceae, Sapotaceae, Moraceae,Anacardiaceae, Ulmaceae, Arecaceae, Amaranthaceae); the Nothofagidites, to the southwestern tip, dominatedby elements of the austral forests (e.g. Nothofagaceae, Podocarpaceae, Araucariaceae,Misodendraceae, Menianthaceae, Rosaceae, Cunoniaceae); and the Transitional, in central and south-easternArgentina, defined by a mixed of Neotropical and Austral components. By the Late Miocene-Pliocene,the area previously occupied by the Transitional Province was replaced by a new one, theProtoEspinal/Estepa (earliest Espinal/Steppe) Province characterized by a xerophytic shrubby-herbaceousvegetation (e.g. Chenopodiaceae, Ephedraceae, Convolvulaceae, Anacardiaceae, Fabaceae,Asteraceae, Ulmaceae Celtoideae). The Neotropical and Nothofagidites Provinces remain without greatvariations during this interval. Pleistocene and Holocene vegetation distributions have changed extensivelyand repeatedly in both latitudinal and/or altitudinal gradients, which were recombined markedlyin different proportions from today?s in response to the atmospheric circulation patterns, oscillations inclimate, ice extent and sea level fluctuations. Pollen records suggest a transitional stage towards the presentplant distributions after 4000 yr. BP south of 34º S latitude.