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Palaeontology of the Cerros Bayos section, Roca Formation (Danian), La Pampa Province, Argentina

2007; Taylor & Francis; Volume: 31; Issue: 3 Linguagem: Inglês

10.1080/03115510701484713

1752-0754

Claudia J. del Río, Sérgio Martínez, Jeffrey D. Stilwell, Andrea Concheyro,

Geological formations and processes

Abstract del Río, C.J., Martínez, S.A., Stilwell, J.D. & Concheyro, A., September, 2007. Palaeontology of the Cerros Bayos section, Roca Formation (Danian), La Pampa Province, Argentina. Alcheringa 31, 241-269. ISSN 0311-5518. New mollusc and echinoid faunas are recorded from exposures of the Roca Formation at Cerros Bayos (La Pampa Province) and assigned to the Maastrichtian – Danian (CC26 – NP3 Zones of Martini 1971 Martini, E. Standard Tertiary and Quaternary calcareous nannoplankton zonation. Proceedings 2° Planktonic Conference, Rome. pp.739–785. A. Farinacci, ed., Ed. Tecnoscienza [Google Scholar]) on the basis of the associated nannofossil assemblages. The macroinvertebrate assemblages show increased diversity and abundance of molluscs from Zones NP1 to NP3. One new Danian echinoid, the spatangoid Bolbaster argentinensis sp. nov., is described. At least 19 molluscan genera are recognized; 14 of these, together with seven species, are identified for the first time from Danian exposures of La Pampa Province. An equivocal record of Pyropsis tumida Wilckens, 1905 Wilckens, O. 1905. Die Lamellibranchiaten, Gastropoden, etc. der oberen Kriede Südpatagoniens. Berichten der Naturforschenden Gesellschaft zu Freiburg i. B, Band, 15: 91–156. [Google Scholar] may extend the range of this tudiclid gastropod from the latest Cretaceous into the Danian. The Cerros Bayos exposures substantially increase our knowledge of diversity trends and biotic recovery immediately following the Cretaceous – Paleogene boundary event, and provide clues to the composition of the little-studied earliest Paleogene faunas in southern Patagonia. Claudia J. del Río [cdelrio@macn.gov.ar], Museo Argentino de Ciencias Naturales B. Rivadavia, CONICET, A. Gallardo 470-C1405DJR Buenos Aires, Argentina; Sergio A. Martínez [smart@fcien.edu.uy], Instituto de Geología y Paleontología. Facultad de Ciencias, Iguá 4225, 11400 Montevideo, Uruguay; Jeffrey D. Stilwell [jeffrey.stilwell@sci.monash.edu.au], School of Geosciences, Monash University, Clayton VIC 3800, Australia; Andrea Concheyro [andrea@gl.fcen.uba.ar], Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II. 1428 Buenos Aires, CONICET and Instituto Antártico Argentino, Argentina; received 25.11.2005, revised 8.9.2006. Key words: PalaeontologyBiostratigraphyDanianRoca FormationJagüel FormationmolluscsechinoidsnannofossilsLa Pampa ProvinceArgentina Acknowledgements We specially wish to thank to A. Beu, one of the reviewers of this manuscript, because of his useful comments and suggestions in reference to systematic assignments. To the editors of Alcheringa (A. Wright and S. McLoughlin), and A. Beu who highly improved the English language, and to D. Butarelli for their hospitality, allowing us to work in the Cerros Bayos area. This paper was supported by an Argentinean Research Council Grant (PIP 2144, CONICET, Argentina) and an Australian Research Council Fellowship and Monash University Research Fund grants (Australia).