Early Miocene Paleobiology in Patagonia: High-Latitude Paleocommunities of the Santa Cruz Formation Edited by Sergio F
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Cambridge University Press 978-0-521-19461-7 - Early Miocene Paleobiology in Patagonia: High-Latitude Paleocommunities of the Santa Cruz Formation Edited by Sergio F. Vizcaíno, Richard F. Kay and M. Susana Bargo Excerpt More information 1 Background for a paleoecological study of the Santa Cruz Formation (late Early Miocene) on the Atlantic Coast of Patagonia Sergio F. Vizcaı´no, Richard F. Kay, and M. Susana Bargo Abstract Carlos fueron descriptos por su hermano Florentino, quien For more than 120 years, the coastal exposures of the pensaba que muchas de las especies eran ma´s antiguas que Santa Cruz Formation have been fertile ground for recov- lo hoy se entiende y representaban los ancestros de muchos ery of vertebrates from the late Early Miocene (~18 to o´rdenes de mamı´feros hola´rticos. Las novedosas propues- 16 million years ago, Ma). As long ago as the 1840s, tas de Ameghino estimularon a William B. Scott a organi- Captain Bartholomew Sulivan collected fossils from this zar expediciones lideradas por John B. Hatcher para region and sent them to Charles Darwin, who passed them colectar fo´siles en los niveles santacrucenses. Los fo´siles to Richard Owen. Carlos Ameghino undertook several fueron descriptos en una serie de monografı´as exhaustivas, explorations of the region starting in the late 1880s. concluyendo que las faunas eran mucho ma´sjo´venes que lo Carlos’ specimens were described by his brother Floren- que pensaba Ameghino. Varias expediciones breves lide- tino, who believed that many of the species were more radas por investigadores de diferentes instituciones ancient than now understood and represented the ances- tuvieron lugar durante el siglo XX. Desde 2003, hemos tors of many Holarctic mammalian orders. Ameghino’s recolectado ma´s de 1600 especı´menes, incluyendo numer- novel claims prompted William B. Scott to organize fossil osos esqueletos relativamente completos. En este volumen, collecting expeditions in the Santa Cruz beds led by John hemos reunido un grupo de investigadores para estudiar la B. Hatcher. The fossils were described in a series of Formacio´n Santa Cruz de la costa, su flora y fauna aso- exhaustive monographs with the conclusion that the fauna ciada, para realizar una reconstruccio´n paleobiolo´gica de la was much younger than Ameghino thought. Several brief comunidad de vertebrados santacrucenses y ubicarla en su expeditions took place during the twentieth century, led contexto bio´tico y ambiental. by researchers from different institutions. Since 2003, we have undertaken the collection of over 1600 specimens, 1.1 Introduction including large series of relatively complete skeletons. In this edited volume we have gathered together a group of Exposures on the Atlantic coast of southern continental Pata- researchers to study the coastal Santa Cruz Formation and gonia (Figs. 1.1 and 1.2) have been fertile ground for the its associated flora and fauna to provide a paleobiological recovery of fossil vertebrates of the Santa Cruz Formation for reconstruction of the Santacrucian vertebrate community more than 120 years. The fossils come from the late Early and to place it in its biotic and physical environment. Miocene, about 18 to 16 Ma, called the Santacrucian Land Mammal Age (Marshall et al., 1983,Perkinset al., Chapter 2). Through much of the Cenozoic, South American mammals Resumen underwent diversification and ecological specialization in isol- Por ma´s de 120 an˜os, las exposiciones costeras de la For- macio´n Santa Cruz han sido campo fe´rtil para la recupera- ation from other continents (Simpson, 1980). That isolation was cio´n de vertebrados del Mioceno Temprano tardı´o(~18 to interrupted by two major upheavals, one marked by the arrival 16 Ma). En la de´cada de 1840, el Capita´n Bartholomew of rodents and primates from Africa sometime in the Middle to Sulivan recolecto´ fo´siles que envı´o a Charles Darwin, Late Eocene and the other by the interchange of faunas begin- quien se los paso´ a Richard Owen. Carlos Ameghino llevo´ ning in the Late Miocene when South America began to estab- a cabo varias exploraciones de la regio´n, comenzando a lish contact with Central and North America. The Santacrucian fines de la de´cada de 1880. Los especı´menes colectados por marks the peak of known diversification achieved by mammals after the arrival of primates and rodents but before the arrival of North American immigrants (Marshall and Cifelli, 1990). Early Miocene Paleobiology in Patagonia: High-Latitude Paleocommunities of the Santa Cruz Formation, ed. Sergio F. Between 1887 and 1906, the famous Argentine paleontologist Vizcaı´no, Richard F. Kay and M. Susana Bargo. Published by Florentino Ameghino (1853/54 to 1911; Fig. 1.3a) described a Cambridge University Press. # Cambridge University Press 2012. plethora of species from a bizarre taxonomic assemblage – very 1 © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-0-521-19461-7 - Early Miocene Paleobiology in Patagonia: High-Latitude Paleocommunities of the Santa Cruz Formation Edited by Sergio F. Vizcaíno, Richard F. Kay and M. Susana Bargo Excerpt More information 2 Sergio F. Vizcaı´no et al. 72° 70° 68° 66° Fig. 1.1. Map of Santa Cruz Province L. Blanco DEL CHUBUT PROVINCE (southern Patagonia, Argentina) and the Santacrucian localities treated in this volume 46° 26 46° 40 3 San Jorge and listed in Appendix 1.1. Lago Buenos Aires Caleta Olivia Gulf Perito Moreno Las Heras Pico Truncado Río Deseado 40 Río Pinturas L. Pueyrredón 281 L. Posadas Río Deseado Puerto CHILE Deseado L. Belgrano 48° 48° 3 Río Belgrano Gdor. Gregores L. Cardiel Lago 40 San Martín Puerto 288 San julián Lago ViedmaTres Lagos Río Chico 40 Río Chalía o Shehuen 288 N 50° Cruz Karaiken ío sa n t a Puerto 50° R Santa Cruz L. Argentino ATLANTIC OCEAN 3 EI Calafate R Pelque Coastal localities (Fig. 1.2) Río Coyle South America ío Coyle Brazo Sur del R. Coig (Coyle) R 40 Río Turbio Río Gallegos Río Gallegos 40 3 52° Argentina 52° Santa Cruz CHILE OCEAN PACIFIC Province ío Chico ATLANTIC OCEAN R 050100 km Estrecho de Magallanes 72° 70° 68° 66° different as a consequence of the long isolation of South to be and that he had documented the ancestors of many America from other continents – of large predatory birds, as mammalian orders in South America, including those of well as a diverse array of insectivorous, carnivorous, and herb- artiodactyls, perissodactyls, and even human beings. Hith- ivorous marsupials, glyptodonts, armadillos, sloths, small and erto, the fossil record of many mammalian orders had been large herbivorous hippo-like astrapotheres, rabbit- to cow-sized restricted to northern continents, and it was supposed by notoungulates, horse-like and camel-like litopterns, small to most authorities that most or all orders originated there. medium-sized rodents, and platyrrhine monkeys. Another sin- Ameghino’s novel claims prompted W. B. Scott (1858– gular nature of these finds, known even in Ameghino’s day, is 1947; see Simpson, 1948) from Princeton University, New that the outcrops yield numerous remarkably complete speci- Jersey, USA, to organize a series of expeditions (see below) mens, including skulls with associated skeletons. to collect fossils in the Santa Cruz beds where the faunas Florentino Ameghino believed that many of the species he were best known (see Scott’s Preface to the Narrative of described were more ancient than we now understand them the Princeton University Expeditions to Patagonia by © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-0-521-19461-7 - Early Miocene Paleobiology in Patagonia: High-Latitude Paleocommunities of the Santa Cruz Formation Edited by Sergio F. Vizcaíno, Richard F. Kay and M. Susana Bargo Excerpt More information Background for paleoecological study of Santa Cruz Formation 3 Fig. 1.2. Detailed map of the study area in the coastal Santa Cruz Formation, indicated in Fig. 1.1, and the localities listed in Appendix 1.1. Asterisks indicate localities; filled circles, towns; squares, Estancia (¼ Ea.). Hatcher, 1903: vii). The fossils were described in a series of all, secrets of this fauna had been revealed. In contrast, we exhaustive monographs (1903–1928) in the Reports of the see the relative completeness of the taxonomic coverage as Princeton University Expeditions to Patagonia, edited by an opportunity, not a curse. Scott between 1903 and 1932 (see Scott, 1903–1905, 1910, George G. Simpson (1902–1984) claimed that the Santa- 1912, 1928; Sinclair, 1906, 1909; Sinclair and Farr, 1932) crucian fauna was particularly important for its wealth of with extensive anatomical descriptions and illustrations. The nearly complete skeletons of representatives of a phase in conclusion was that the fauna was much younger than Ame- South American mammal history in which the communities ghino had thought, and that most of the similarities that consisted of a complex mixture of descendants of ancient Ameghino identified between the Santa Cruz mammals and lineages of the continent (Marsupialia, Xenarthra, Litopterna, their northern counterparts were a consequence of adaptive Notoungulata, and Astrapotheria) and new forms from convergence. In some ways, the size and scope of Scott’s other continents (Rodentia and Primates) (Simpson, 1980). edited volumes led later workers to assume that most, if not Among these mammals, rather peculiar groups such © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-0-521-19461-7 - Early Miocene Paleobiology in Patagonia: High-Latitude Paleocommunities of the Santa Cruz Formation Edited by Sergio F. Vizcaíno, Richard F. Kay and M. Susana Bargo Excerpt More information 4 Sergio F. Vizcaı´no et al. Fig. 1.3. a, Florentino Ameghino (1853/54 to 1911). b, Francisco P. Moreno (1852–1919). c, Carlos Ameghino (1865–1936).