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La Ornitofauna De La Formación Bahía Inglesa, Caldera, Chile

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La Ornitofauna De La Formación Bahía Inglesa, Caldera, Chile Universidad Austral de Chile Facultad de Ciencias Escuela de Ciencias PROFESOR PATROCINANTE: ROBERTO SCHLATTER V. INSTITUTO DE ZOOLOGIA FACULTAD DE CIENCIAS PROFESOR CO-PATROCINANTE: MARIO PINO Q. INSTITUTO DE GEOCIENCIAS FACULTAD DE CIENCIAS LA ORNITOFAUNA DE LA FORMACIÓN BAHÍA INGLESA, CALDERA, CHILE. Tesis de Grado presentada como parte de los requisitos para optar al Grado de Licenciado en Ciencias Biológicas. MARTÍN FELIPE CHÁVEZ HOFFMEISTER VALDIVIA – CHILE 2008 A mi familia y amigos por acompañarme estos años, y a todos quienes vieron desaparecer una parte de sus vidas junto al Edificio Emilio Pugín. AGRADECIMIENTOS Quiero agradecer en primer lugar a mi familia y amigos quienes siempre han estado ahí, acompañándome en los momentos felices y también en los más difíciles de mi vida. Gracias por su paciencia infinita y su apoyo constante. A Marcelo Stucchi, José Apolín, Mario Suárez, Karen Moreno, Carolina Acosta Hospitaleche, Claudia Tambussi, Roberto Schlatter, Mario Pino, Rosario Ulbrich, Jean Noël Martinez, Pablo Quilodrán, Maria Inés Figueroa y a todos quienes de una u otra forma ayudaron en mi formación profesional. Muchos de ellos colaboraron activamente en la elaboración de esta tesis. Gracias por creer en mí. A la Sociedad Paleontológica de Chile SPACH por su respaldo constante y por ayudarme a crecer como científico y persona. Al Instituto de Zoología “Ernst F. Kilian” de la Universidad Austral de Chile por acogerme y respaldarme. A Rodolfo Salas del Museo de Historia Natural de la Universidad de San Marcos (Lima, Perú), Eduardo Ruigómez del Museo Paleontológico “Egidio Feruglio” (Trelew, Argentina), Marcelo Reguero del Museo de La Plata (La Plata, Argentina), Alejandro Kramarz del Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (Buenos Aires, Argentina), Mario Suárez del Museo Paleontológico de Caldera (Caldera, Chile), David Rubilar del Museo Nacional de Historia Natural (Santiago, Chile), Michel Sallaverry y Roberto Yury del Departamento de Zoología de Vertebrados de la Universidad de Chile (Santiago, Chile) y a los funcionarios de la Aduana Metropolitana (Santiago, Chile) por facilitarme el acceso a los especimenes necesarios para la elaboración de esta tesis. Finalmente a Guillermo Navalón, quien fue capaz de convertir mis resultados en una ilustración excepcional (Fig. 28). Gracias por tu desinteresada ayuda. INDICE I. RESUMEN………………………………………………………………………………............1 II. INTRODUCCIÓN 1. LAS AVES EN AMBIENTES MARINOS a. Definiciones generales …………………………………………………………...........3 b. Las aves marinas en Chile y su zoogeografía …………………………………..……..5 2. ANTECEDENTES GEOLOGICOS Y PALEONTOLOGICOS a. La Formación Bahía Inglesa (FBI) ...………………………………………..………...7 b. Locálidades fosilíferas ...………………………………………………….……….…10 c. Conocimiento actual de la Ornitofauna Neógena del Pacífico Sudeste y Atlántico Suroeste ………………………………………………………………………….…..11 3. HIPOTESIS Y OBJETIVOS a. Hipótesis………………………………………………………………………...........15 b. Objetivos……………………………………………………………………..……….16 III. MATERIALES Y MÉTODOS 1. ACRONIMOS ...……………………………………………………………………...........17 2. MATERIALES a. Materiales de estudio ...……………………………….……...………………………18 b. Materiales de comparación ...…………………..…………………………………….18 3. METODOS a. Determinaciones taxonómicas y nomenclatura ………………………………...........19 b. Determinación de diversidad ………………………………………………………...20 c. Análisis tafonómico ……………………………………..………….………………..21 IV. RESULTADOS CATALOGO CRÍTICO DE LAS AVES DE LA FBI Diomedeidae ……………………………………………………………............………….23 Procellariidae ………………………………………………………………………………31 Spheniscidae ……………………………………………………………………………….40 Sulidae ……………………………………………………………………………………..60 Phalacrocoracidae ………………………………………………………………………….66 Odontopterygiformes ………………………………………………………………………69 Charadriiformes ……………………………………………………………………………71 V. DISCUSIÓN 1. COMPOSICIÓN Y RELACIONES DE LA ORNITOFAUNA DE LA FBI a. Riqueza y rangos estratigráficos de las aves de la FBI ………………………………73 b. Las faunas de aves marinas en el Pacífico Sudeste ………………………………….75 2. TAFONOMÍA GENERAL DE LA ORNITOFAUNA DEL MIEMBRO BONEBED a. Interpretación de los Spheniscidae …………………………………………………..81 b. Las Aves voladoras y el sesgo muestreal ……………………………………………84 3. RESULTADOS Y PROYECCIONES …………………………………………………….85 VI. LITERATURA CITADA ……………………………………………………………………88 FIGURAS TABLAS ANEXOS I. RESUMEN El presente estudio tiene por objetivo realizar una revisión crítica de la taxonomía de la ornitofauna registrada en la Formación Bahía Inglesa (FBI) (Mioceno Medio-Plioceno Tardío), Región de Atacama, Chile. Con este fin se elaboró un catalogo crítico, en el cual se comentan y rectifican las asignaciones taxonómicas previas. Mediante el uso de Faunas descritas para el Pacífico Norte, se realiza una comparación con el registro conocido en otras formaciones neógenas de Chile, Perú y Argentina; y mediante parámetros tafonómicos se realizan comparaciones con comunidades de aves marinas actuales. Como resultado se presenta un total de 27 registros fósiles, que representan un mínimo de 26 especies de las familias Diomedeidae, Procellariidae, Spheniscidae, Sulidae, Phalacrocoracidae, Pelagornithidae y Laridae (?). Se destaca la presentación de dos posibles nuevas especies (Eudyptula? nov. sp. y Sula? nov. sp.), la reasignación de los especimenes previamente asociados a Paraptenodytes y Palaeospheniscus y la presentación de los primeros especimenes atribuibles a Charadriiformes procedentes del Mioceno Tardío de la FBI. A partir de la correlación y comparación con las Faunas de Aves marinas establecidas para el Pacífico Norte, se reconocen diferencias significativas entre los registros de la costa Pacifica y Atlántica de Sudamérica; así como respecto al Pacífico Norte. Las principales diferencias entre las faunas neógenas y actual en el Pacífico Sudeste son: 1) la gran riqueza de especies y el posterior declive de los Spheniscidae y Sulidae; y 2) la escasez de Charadriiformes. Finalmente y con base en el análisis tafonómico, se sugiere la existencia de colonias de Spheniscidae durante la formación del Miembro Bonebed y se sugiere además, la existencia de sesgo en el muestreo, el cual puede explicar en parte la ausencia o subrepresentación de algunos taxones. ABSTRACT The present study does a critical review of the taxonomy of the Ornitofauna registered in the Bahia Inglesa Formation (FBI) (Middle Miocene-Late Pliocene), from the coast of the Atacama Region, Chile. The aims were to elaborate a critical catalogue of fossil, make the necessary comments and rectify taxonomic assignments of these with previous published research. Be means of the described faunal elements of the northern Pacific we did a comparison with the known Neogene formations from Chile, Peru and Argentina. For this we did comparisons by means of taphonomic parameters with the actual seabird communities. We present a total of 27 register as a results of the analysis which allowed us to review a minimum of 26 species of the seabird families: Diomedeidae, Procellariidae, Spheniscidae, Sulidae, Phalacrocoracidae, Pelagornithidae and Laridae (?). We underline the findings of 2 possible new species (Eudyptula? nov. sp. and Sula? nov. sp.), the reassignement of the specimens previously associated to Paraptenodytes and Palaeospheniscus and the first specimens belonging probably to Charadriiformes from the Late Miocene of the FBI. Correlation and comparisons with the seabird faunas known from the northern Pacific permitted us to recognize significant differences between the records of the Pacific and Atlantic coast of South America, and with the north Pacific. The main differences observed between the Neogene and current avifauna from the Southeast Pacific are: 1) the greater richness and later decline of the Spheniscidae and Sulidae; and 2) the reduced representation of the Charadriiformes. Finally the existence of Sphenicid colonies during the formation of the Bonebed Member is suggested based on the taphonomic analysis. The existence of bias in the sampling procedures are also suggested which can explain partly the absence or underrepresentation of some taxas. II. INTRODUCCIÓN 1. LAS AVES EN AMBIENTES MARINOS a. Definiciones generales El océano y las costas marinas brindan una amplia variedad de ambientes en los que la vida ha proliferado por millones de años, lo que ha llevado a que más del 50 % de las clases de animales actuales viva en los océanos (Nicol, 1971). Esta abundancia de potenciales presas, ha posibilitado la reconquista del medio marino por parte de diversos linajes originados en tierra firme, entre los cuales las aves han sido uno de los más exitosos. El grado de dependencia que cada familia de aves ha establecido respecto al océano, permite diferenciar dos grandes grupos asociados a estos ambientes: aves marinas y litorales. El termino “aves marinas” (seabirds) agrupa una amplia variedad de aves no directamente relacionadas, cuya principal característica es que se alimentan en agua salobre, siendo parte integral de los ciclos energéticos de los sistemás marinos (Ainley, 1980). Este único factor origina un estilo de vida común que diferencia a estas aves de aquellas que viven en ambientes continentales. Tradicionalmente, 14 familias de aves pertenecientes a cuatro ordenes reciben esta designación común: Spheniscidae (Sphenisciformes), Diomedeidae, Procellariidae, Pelecanoididae, Hydrobatidae (Procellariiformes), Phaethontidae, Fregatidae, Pelecanidae, Sulidae, Phalacrocoracidae (Pelecaniformes), Stercorariidae, Laridae, Rhynchopidae y Alcidae (Charadriiformes)
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