Botany The last Patagonian cycad, Austrozamia stockeyi gen. et sp. nov., early Eocene of Laguna del Hunco, Chubut, Argentina Journal: Botany Manuscript ID cjb-2016-0038.R1 Manuscript Type: Article Date Submitted by the Author: 19-May-2016 Complete List of Authors: Wilf, Peter; Pennsylvania State University, Geosciences Stevenson, Dennis; New York Botanical Garden Cuneo, N.;Draft CONICET, Museo Paleontológico Egidio Feruglio Keyword: cycads, Eocene, <i>Encephalartos</i>, <i>Lepidozamia</i>, Patagonia https://mc06.manuscriptcentral.com/botany-pubs Page 1 of 36 Botany The last Patagonian cycad, Austrozamia stockeyi gen. et sp. nov., early Eocene of Laguna del Hunco, Chubut, Argentina Peter Wilf, Dennis Wm. Stevenson, and N. Rubén Cúneo P. Wilf. Department of Geosciences, Pennsylvania State University, University Park, PA 16802, USA. D. Wm. Stevenson. New York Botanical Garden, Bronx, NY 10458, USA N.R. Cúneo. CONICET, Museo PaleontológicoDraft Egidio Feruglio, Avenida Fontana 140, 9100 Trelew, Chubut, Argentina. Corresponding author: Peter Wilf (e-mail:
[email protected]) 1 https://mc06.manuscriptcentral.com/botany-pubs Botany Page 2 of 36 Abstract: The cycads pose classic problems in evolutionary biogeography due to their far-flung extant distributions and the sparse fossil records of living genera. A noteworthy example is Tribe Encephalarteae of Family Zamiaceae, today consisting of Encephalartos (Africa) and the Australian genera Lepidozamia and Macrozamia . Numerous petrified trunks of Encephalarteae described from the Cretaceous of Patagonia, Antarctica, and India indicate far larger past distributions across Gondwana and subsequent extinctions. The only fossils close to the current range are Paleogene leaf fragments from Australia assigned to Lepidozamia and Macrozamia . Here, we report a large frond piece and several isolated leaflets of a compressed cycad, along with an associated spiny petiole, from the late-Gondwanan, 52.2 Ma Laguna del Hunco flora of Patagonia, Argentina.