| Abstract Detail
Paleobotany Wilf, Peter [1], Stevenson, Dennis Wm. [2], Cuneo, N. Ruben [3]. The Last Patagonian Cycad, an Extinct Genus of Zamiaceae (Tribe Encephalarteae) from the early Eocene Laguna del Hunco Flora, Chubut, Argentina. 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 with cuticle from Australia assigned to Lepidozamia and Macrozamia. 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. We propose that the fossils belong to a new, extinct genus of Encephalarteae that has the novel combination of an Encephalartos-type frond and Lepidozamia-type cuticle. Similarly, the Australian Lepidozamia fossils, widely used for molecular dating calibrations, have unknown frond morphology and could also represent an extinct genus. The new fossils demonstrate survival of the Encephalarteae in Patagonia and presumably across Gondwana until its terminal phase, adding a striking new component to the growing list of South American plant extinctions associated with Antarctic separation and related climate changes.
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1 - Penn State Univ., 537 Deike Bldg., UNIVERSITY PARK, PA, 16802, USA
2 - New York Botanical Garden, Bronx, New York, NY, 10458, USA
3 - MEF AV. FONTANA 140, TRELEW-CHUBUT, N/A, 9100, Argentina
Keywords:
cycads
Eocene
Encephalartos
Lepidozamia
Patagonia
Zamiaceae.
Presentation Type: Oral Paper
Session: 28, Mesozoic to Pleistocene Paleobotany
Location: 102/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 2:15 PM
Number: 28004
Abstract ID:275
Candidate for Awards:None |
