Abstract Detail

Paleobotany

Gandolfo, Maria A [1], Zamaloa, Maria C. [2].

Antarctic- Patagonian Plant Diversity during the Cretaceous-Tertiary.

In the Modern World the Northern Hemisphere (NH) is characterized by its continentality whereas the Southern Hemisphere (SH) is characterized by its oceanicity. This results in completely different scenarios for plant distributions, since the continentality of the north and the oceanicity of the south have considerable effects on the corresponding climates. Interestingly, the SH is more diverse than the NH, in particular Patagonia, which is considered an area of high endemism. In general, peaks in diversity started with the beginning of the fragmentation of Gondwana during the Jurassic followed by the appearance of the angiosperms during the Cretaceous and increasing dramatically in the Tertiary (mostly during the Paleogene - Miocene). The fossil record indicates 1- that equatorial peaks in species richness are typical of terrestrial plants, 2- that diversity and equatorial peaks increased during the Cenozoic, and 3- that several vicariant events that occurred during the Neogene were fundamental for the creation of high diversity centers. The main goal of this contribution is to present a comprehensive analysis of plant diversity for Patagonia and the Antarctic Peninsula from the Late Cretaceous to the Miocene. Although, the North-South America pathway is not strongly detected in the plant fossil record at this point a route from the NH is emerging as boreotropical elements (such as Ulmaceae, Juglandaceae, Azolla, Marsileaceae, and Nelumbo) were found in Cretaceous and Paleocene sediments of Patagonia while the Antarctic route allowed the movement of Gondwanan elements (such as Cunoniaceae, Myrtaceae, Nothofagaceae, Proteaceae and Casuarinaceae) during the Tertiary. As the climate changed, some elements became extinct but others survived and are now members of the extant floras. Although today 98% of Antarctica is covered by ice, during the Cretaceous - Oligocene the Antarctic Peninsula vegetation was similar to the one found today at the Valdivian Forests of the west Patagonian Andes. The eastern vegetation of Patagonia is a typical steppe or grassland. Undoubtedly, both routes influenced the composition of the extant floras and are central for explaining modern austral vegetation and the high Patagonian endemism.

1 - Cornell University, L. H. BAILEY HORTORIUM, 410 Mann Library Building, ITHACA, NY, 14853-4301, USA
2 - Universidad de Buenos Aires, Ecologí­a, Genética y Evolución IEGEBA (CONICET-UBA). , Intendente Güiraldes 2620, Buenos Aires, C1428EHA, Argentina

Keywords:
endemism
Patagonia
Cretaceous
Tertiary
Argentina.

Presentation Type: Oral Paper
Session: 23, Paleozoic and Mesozoic Paleobotany
Location: 102/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 11:00 AM
Number: 23011
Abstract ID:612
Candidate for Awards:None