Gallego, Julieta , Gandolfo, Maria A. , Cuneo, Nestor .
Aroid fossils from Patagonia, Argentina (Campanian-Maastrichtian):phylogenetic implications in the origin of free-floating aquatic aroids.
Araceae is a highly diverse monocot family represented by approximately 104 genera and more than 3300 species world wide distributed, although it is concentrated primarily on aquatic and terrestrial habitats in tropical regions. Its first fossil documentation goes back to the Upper Cretaceous of Canada and consists of a stipitate infructescence composed of bisexual flowers, with trilocular ovaries. Herein, we introduce a suite of fossils with affinities to the aquatic members of Araceae from the La Colonia Formation (Campanian-Maastrichtian,Upper Cretaceous) Chubut province, Patagonia, Argentina. The fossils belong to an aquatic assemblage, composed of Marsilea and Regnellidium (two members of the Marsileaceae Family), and Nelumbo (Nelumbonaceae), indicating that the environment in which these plants grew was probably permanent bodies of water with low degree of transportation. These new fossils are simple and excentric peltate megaphylls. Each leaf has an inflated base, crenate margin, and papillate crenae, and a tongue-shaped auricle. The main venation of the lamina is flabellate, while the tertiary and quaternary veins are random reticulate. Although, the Patagonian fossils share several characters with the fossil Cobbania corrugata (Upper Cretaceous, Dinosaur Park Formation) and the extant Pistia stratiotes, they also differ in others. The Patagonian fossils are unique in the lacking of marginal veins and notch, the leaf shape, the presence of papillate crenae and the auricle. Most recent phylogenetic analyses of extant Araceae have focused in the phylogenetic relationships within its extant members, and there were no inclusion of the fossil taxa. With the goal of contributing to our understanding of the relationships between extant and fossil Araceae, we explore the phylogenetic placement of the Patagonian fossil as well as previously described records. This provides the opportunity to broaden our understanding of Araceae diversity and origin of the free-floating aquatic habit for some of the members of this diverse family.
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1 - Museo Paleontologico Egidio Feruglio, Avda. Fontana 140, Trelew, Chubut, N/A, 9100, Argentina
2 - Cornell University, L. H. BAILEY HORTORIUM, 410 Mann Library Building, ITHACA, NY, 14853-4301, USA
3 - MEF AV. FONTANA 140, TRELEW-CHUBUT, N/A, 9100, Argentina
Presentation Type: Oral Paper:Papers for Sections
Location: Union A/Hyatt
Date: Monday, July 9th, 2012
Time: 2:30 PM