Gandolfo, Maria , Gonzalez, Cynthia , Zamaloa, Maria , Cuneo, Nestor , Wilf, Peter .
Eucalytus (Myrtaceae) macrofossils from the early Eocene of Patagonia, Argentina.
TODAY, Eucalyptus comprises approximately 700 species distributed essentially in Australia, although a few taxa occur in some southeastern Asia islands and in Papua New Guinea. They occupy a diverse range of habitats, from high altitude meadows to the coast and from rainforest margins to watercourses in Australian deserts. Though the macrofossil record is meager and controversial, leaves were recorded from the middle Eocene to Miocene of New Zealand and the Miocene and Pliocene of Australia and fruits were recorded from the Miocene of Australia and New Zealand. For South America, Eucalyptus fossil fruits are known from a single report from ?Miocene sediments of Patagonia. Recently, numerous fossil leaves and infructescences assignable to Eucalyptus were collected from the early Eocene Tufolitas Laguna del Hunco (~52 my), in Patagonia. Although the leaves and fruits are not in organic connection, they were found intimately associated in the same locality and stratigraphic level. The leaves are characterized by their linear-lanceolate falcate shape, a prominent middle vein, an intramarginal vein developed from the base, and laminar glands. Fossil fruits are impressions or compressions of 5-valvate woody capsules grouped in triads forming panicles. The capsules are hemispherical and show the remains of the calyptra and the staminal ring. Even though assignation of fossil remains to a modern –and controversial- genus such as Eucalyptus might be arguable, foliar and fruit morphological characters do not leave much room for including these fossils within any genus other than the modern Eucalyptus. This constitutes the first report of fossil leaves in South America and one of the oldest worldwide records of infructescences with definite Eucalyptus affinities. These fossils are of particular interest because Eucalyptus is now extinct in South America, strengthening biogeographical links between Paleogene floras of Patagonia and Australasia. [c.e.:srb]
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1 - Cornell University, LH Bailey Hortorium, Dept. Plant Biology, 228 Plant Science Building, Ithaca, New York, 14853, USA
2 - Museo Paleontológico Egidio Feruglio-CONICET, Av. Fontana 140, Trelew, Chubut, CP9100, Argentina
3 - Universidad de Buenos Aires, Depto. Ecología, Genética y Evolución, Int. Güiraldes 2620, Buenos Aires, Buenos Aires, C1428EHA, Argentina
4 - Pennsylvanian State University, Department of Geosciences, Deike 403, University Park, Pennsylvania, 16802, USA
Laguna del Hunco
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 4:15 PM