Early Cretaceous palm pollen tetrads from Patagonia,Argentina |
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| Institution: | 1. UMR CNRS 6118 Géosciences Rennes, Université Rennes 1, Campus de Beaulieu, 263 Avenue du Général Leclerc, 35042 Rennes, France;2. Department of Geography and Earth Sciences, Aberystwyth University, Penglais, Aberystwyth SY23 3DB, UK;3. School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK;1. School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia;2. Geotrack International, Pty. Ltd., 37 Melville Road, Brunswick West, Victoria 3055, Australia;3. Royal Botanic Gardens Victoria, South Yarra, Victoria 3141, Australia;1. School of Botany, The University of Melbourne, Victoria 3010, Australia;2. School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia;3. Department of Palaeobiology, The Swedish Museum of Natural History, Box 50007, S-104 05 Stockholm, Sweden;4. National Herbarium of Victoria, Royal Botanic Gardens Melbourne, South Yarra, Victoria 3141, Australia |
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| Abstract: | Pollen tetrads and monads of spiny pollen grains with close affinities to palms have been found in several localities from the Lower Cretaceous (Barremian-Albian) of the Austral Basin (Magallanes), Patagonia (Argentina). When found dispersed, spiny and zonasulcate pollen grains, are commonly referred to the fossil genus Spinizonocolpites Muller, with close affinities to the extant palm Nypa. The Patagonian specimens were compared with fossil and extant members of the Arecaceae, showing close similarities in shape and sculpture with the primitive members of the subfamily Calamoideae. Nypa produces tetragonal tetrads different from the tetrahedral tetrads of the Spinizonocolpites-type recovered from Patagonia. The specimens were studied with LM and SEM. The polarity, aperture orientation and tetrad type allow segregating the Patagonian grains from the Nypoideae and relating it to the Calamoideae subfamily. These records suggest an antique origin of monocots and a probably initial diversification of calamoid palms during the Early Cretaceous in high latitudes of Gondwana. The presence of palmae during the Early Cretaceous in southern South America suggests a warm and humid climate, similar to that found in present days at tropics. |
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| Keywords: | Gondwana Patagonia Austral Basin Early Cretaceous Monocots Palms |
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