A new,richly fossiliferous member comprised of tidal deposits in the Upper Cretaceous Maevarano Formation,northwestern Madagascar |
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| Affiliation: | 1. Geology Department, Macalester College, Saint Paul, MN 55105, USA;2. Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794, USA;3. Department of Geophysical Sciences, University of Chicago, Chicago, IL 60637, USA;4. Département de Paléontologie, Université d''Antananarivo, Antananarivo (101), Madagascar;5. W.M. Keck Science Department, Claremont McKenna, Pitzer, and Scripps Colleges, Claremont, CA 91711, USA;6. Department of Earth Sciences, Denver Museum of Nature and Science, Denver, CO 80205, USA;1. Departament d''Estratigrafia, Paleontologia i Geociències marines, Facultat de Geologia, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain;2. Departamento de Ciencias de la Tierra (Paleontología), Instituto Universitario de Investigación en Ciencias Ambientales de Aragón, Universidad de Zaragoza, C/ Pedro Cerbuna 12, E-50009 Zaragoza, Spain;3. Departament de Geologia (Estratigrafia), Facultat de Ciències, Universitat Autònoma de Barcelona, Bellaterra, Barcelona E-08193, Catalonia, Spain;1. Université de Sfax, Faculté des Sciences de Sfax, CP 3000, Sfax, Tunisia;2. Department of Geodynamics and Sedimentology, University of Vienna, UZA 2, Althanstrasse 14, 1090 Vienna, Austria;3. Sam Noble Oklahoma Museum of Natural History, 2401 Chautauqua Ave., OK 73072-7029, USA;4. Mazarine Energy, Rue de la Bourse, 3 ème étage, Immeuble ZENITH, Les Berges Du Lac II, 1053 Tunis, Tunisia;5. Department of Geology, Federal University of Pernambuco (UFPE), 50.740-530, Recife, Pernambuco, Brazil;6. Entreprise Tunisienne d''Activités Pétrolières (ETAP), 54 Avenue Mohamed V- 1002 Tunis, Tunisia;7. Département de la Géologie. Office National des Mines, 24 rue de l′énergie 2035 la Charguia, BP.215, 1080 Tunis Cedex, Tunisia;8. Université de Tunis El Manar II, Faculté des Sciences de Tunis, BSGP (LR18 ES07); C.P. 2092, Tunis, Tunisia;1. School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK;2. 146 Church Hill Road, Sutton, Surrey SM3 8NF, UK;3. Earth Sciences Department, The Natural History Museum, Cromwell Road, London SW7 5BD, UK;1. CNRS (UMR 8538), Laboratoire de Géologie, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, 24 Rue Lhomond, Paris, Cedex, 05, 75231, France;2. Palaeontological Research and Education Centre, Maha Sarakham University, Maha Sarakham, Thailand;3. School of Earth Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol, BS8 1TQ, United Kingdom;1. Universidad Nacional Autónoma de México, Instituto de Geología, Estación Regional del Noroeste, Hermosillo, Sonora 83000, Mexico;2. Universidad Nacional Autónoma de México, Centro de Geociencias, Campus Juriquilla, Querétaro, Qro. 76230, Mexico;1. Programa de Pós-Graduação em Geociências (PPGGEO), Instituto de Geociências, Universidade Federal do Rio Grande do Sul (UFRGS), Brazil;2. Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul (UFRGS), 91501-970, Porto Alegre, Brazil;3. Serviço Geológico do Brasil (CPRM), Brazil |
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| Abstract: | A new member of the Upper Cretaceous (Maastrichtian) Maevarano Formation is proposed to accommodate a distinctive succession of strata exposed along the shores of Lac Kinkony in northwestern Madagascar. The new Lac Kinkony Member overlies fully terrestrial sandstones of the Anembalemba Member of the Maevarano Formation, and is capped by marine dolostones of the Berivotra Formation. In the stratotype section, the base of the Lac Kinkony Member consists of siltstone interbeds that host networks of Ophiomorpha. Siltstone facies pass up-section to distinctive white sandstones packed with dolomitic mud matrix that exhibit rhythmic clay drapes, flaser and wavy bedding, and oppositely-oriented ripples developed on the toes of larger foresets. Thin flat interbeds of microgranular dolostone and claystone comprise the uppermost facies of the Lac Kinkony Member, and a laterally traceable ravinement bed mantled by cobbles of rounded dolostone marks the contact with the superjacent Berivotra Formation. Deposits of the Lac Kinkony Member are interpreted to represent siliciclastic and carbonate tidal flats dissected by tidally-influenced rivers. Vertebrate fossils are abundantly preserved in these coastal deposits, and are locally concentrated in microfossil bonebeds that have the potential to yield thousands of small identifiable specimens. In addition to many taxa already known from the Maevarano Formation, the Lac Kinkony Member has yielded a wealth of phyllodontid albuloid fish skull elements, the distal humerus of a new frog taxon, five vertebrae representing two new snakes, a tooth of a possible dromaeosaurid, and a complete skull of a new mammal. The discovery of several new vertebrate taxa from this new member reflects the fact that it samples a previously unsampled nearshore, peritidal paleoenvironment in the Late Cretaceous of Madagascar. |
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| Keywords: | Stratigraphy Madagascar Vertebrates Dinosaurs Peritidal |
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