Publication: Emergence of Grassy Habitats during the Greenhouse-Icehouse Systems Transition in the Middle Eocene of Southern South America
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Asociación Paleontológica Argentina
Abstract
Asociaciones fitolíticas provenientes de la Formación Koluel-Kaike (Eoceno medio) en Patagonia Central, sur de América del Sur, confirman la presencia de componentes herbáceos, principalmente relacionados a ecosistemas mixto o sabanas, y comunidades arbóreas secas subordinadas. Esta nueva información paleobotánica revela una clara transición entre las comunidades previamente descriptas en las Formación Las Flores (Eoceno inferior), dominadas por componentes leñosos subtropicales/tropicales de tierras bajas, y la sección inferior de la Formación Sarmiento (Eoceno medio), caracterizada por una mayor abundancia de gramíneas. Fitolitos en silla de montar hallados en la Formación Koluel-Kaike indican la presencia de gramíneas C4 (Chloridoideae) en el Eoceno medio de la Patagonia Central. Estos fitolitos del tipo de silla de montar son los registros herbáceos más antiguos de la Patagonia Central y precede al menos ~8 Ma al propuesto por otras contribuciones. La aparición temprana de ecosistemas dominados por gramíneas en el sur de América del Sur, estaría relacionada a la transición climática global, desde sistema Greenhouse a Icehouse, iniciada a partir del Paleógeno medio.
Phytolith assemblages recovered from the middle Eocene Koluel-Kaike Formation in Central Patagonia, southern South America, confirm the presence of herbaceous components, mainly related to mixed ecosystems or savannahs, and subordinate dry forest communities. This new palaeobotanical information reveals a clear transition between previously described subtropical/tropical woodland-dominated communities from the early Eocene Las Flores Formation, and grass-rich ecosystems from the mid-Eocene Sarmiento Formation. Saddle phytoliths recorded in the Koluel-Kaike Formation would attest the presence of C4 grasses (Chloridoideae) by the middle Eocene of Central Patagonia. These saddle phytoliths is the oldest grassy habits recorded in Central Patagonia, and preceding in at least ∼8 Ma the timing proposed by previous contributions. The early appearance of grass-dominated ecosystems in southern South America, would be related to the worldwide greenhouse to icehouse systems transition initiated during the mid-Paleogene.
Phytolith assemblages recovered from the middle Eocene Koluel-Kaike Formation in Central Patagonia, southern South America, confirm the presence of herbaceous components, mainly related to mixed ecosystems or savannahs, and subordinate dry forest communities. This new palaeobotanical information reveals a clear transition between previously described subtropical/tropical woodland-dominated communities from the early Eocene Las Flores Formation, and grass-rich ecosystems from the mid-Eocene Sarmiento Formation. Saddle phytoliths recorded in the Koluel-Kaike Formation would attest the presence of C4 grasses (Chloridoideae) by the middle Eocene of Central Patagonia. These saddle phytoliths is the oldest grassy habits recorded in Central Patagonia, and preceding in at least ∼8 Ma the timing proposed by previous contributions. The early appearance of grass-dominated ecosystems in southern South America, would be related to the worldwide greenhouse to icehouse systems transition initiated during the mid-Paleogene.