Cuneo, Nestor , Seoane, Liliana V. , Gandolfo, Maria , Wilf, Peter .
Last ginkgoalean record in South America.
The history of ginkgoalean records in South America can be traced back to the late Carboniferous, showing a constant occurrence through time on almost every geologic period, excepting perhaps the Jurassic for not a clear reason. This record consists mostly of leaves, in many cases preserving their cuticles, with very scarce examples of attached or associated reproductive organs. The particular case of the Cenozoic record, shows that ginkgoaleans lived in South America until the middle Eocene through the species formerly assigned to Ginkgo patagonica (Berry) Traverso, which occurs in well dated ash beds from the Laguna del Hunco (52 m.a) and Río Pichileufu (47 m.a.) localities. The record of this species includes excellently preserved petiolate leaves with their cuticles almost entirely preserved allowing SEM and TEM analyses. On these grounds a revision of the taxonomy at the generic level has been performed, suggesting the inconvenience of including the Patagonian species in the genus Ginkgo. Likewise, based on the reproductive organ record, homoplasic features of vegetative organs, and character homology, the real presence in South America, and most probably in the Southern Hemisphere, of true Ginkgoaceae is argued. Finally, the disappearance of an entire clade of plants from South America is analyzed in light of the major climatic shifts that operated in the subcontinent from the end of the Eocene.
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1 - Museo Paleontológico Egidio Feruglio-CONICET, Av. Fontana 140, Trelew, Chubut, CP9100, Argentina
2 - MACN-CONICET, División Paleobotánica, Av. Angel Gallarto 470, Buenos Aires, 1425, Argentina
3 - Cornell University, LH Bailey Hortorium, 462 Mann Library, Ithaca, New York, 14853-4301, USA
4 - Pennsylvania State University, Department of Geosciences, University Park, PA, 16802, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 556A/Convention Center
Date: Wednesday, August 4th, 2010
Time: 11:00 AM