U-Pb geochronology of the Santa Cruz Formation (early Miocene) at the Río Bote and Río Santa Cruz (southernmost Patagonia, Argentina): Implications for the correlation of fossil vertebrate localities
Date
2016-10-01
Journal Title
Journal ISSN
Volume Title
Citation Stats
Attention Stats
Abstract
© 2016 Elsevier Ltd.The early Miocene Santa Cruz Formation (SCF) in southern Patagonia hosts the Santacrucian South American Land Mammal Age (SALMA), whose age is known mainly from exposures along the Atlantic coast. Zircon U-Pb ages were obtained from intercalated tuffs from four inland sections of the SCF: 17.36 ± 0.63 Ma for the westernmost Río Bote locality, and 17.04 ± 0.55 Ma-16.32 ± 0.62 Ma for central Río Santa Cruz localities. All ages agree with the bounding age of underlying marine units and with equivalent strata in coastal exposures. New ages and available sedimentation rates imply time spans for each section of ~18.2 to 17.36 Ma for Río Bote and 17.45-15.63 Ma for central Río Santa Cruz (Burdigalian). These estimates support the view that deposition of the SCF began at western localities ~1 Ma earlier than at eastern localities, and that the central Río Santa Cruz localities expose the youngest SCF in southern Santa Cruz Province. Associated vertebrate faunas are consistent with our geochronologic synthesis, showing older (Notohippidian) taxa in western localities and younger (Santacrucian) taxa in central localities. The Notohippidian fauna (19.0-18.0 Ma) of the western localities is synchronous with Pinturan faunas (19.0-18.0 Ma), but older than Santacrucian faunas of the Río Santa Cruz (17.2-15.6 Ma) and coastal localities (18.0-16.2 Ma). The Santacrucian faunas of the central Río Santa Cruz localities temporally overlap Colloncuran (15.7 Ma), Friasian (16.5 Ma), and eastern Santacrucian faunas.
Type
Department
Description
Provenance
Subjects
Citation
Permalink
Published Version (Please cite this version)
Publication Info
Cuitiño, JI, JC Fernicola, MJ Kohn, R Trayler, M Naipauer, MS Bargo, RF Kay, SF Vizcaíno, et al. (2016). U-Pb geochronology of the Santa Cruz Formation (early Miocene) at the Río Bote and Río Santa Cruz (southernmost Patagonia, Argentina): Implications for the correlation of fossil vertebrate localities. Journal of South American Earth Sciences, 70. pp. 198–210. 10.1016/j.jsames.2016.05.007 Retrieved from https://hdl.handle.net/10161/12783.
This is constructed from limited available data and may be imprecise. To cite this article, please review & use the official citation provided by the journal.
Collections
Endorsement
Review
Supplemented By
Referenced By
Scholars@Duke
Richard Frederick Kay
I have two areas of research: 1) the evolution of primates in South America; and 2) the use of primate anatomy to reconstruct the phylogenetic history and adaptations of living and extinct primates, especially monkeys and apes.
1) Evolution of primates and mammalian faunal evolution, especially in South America. For the past 30 years, I have been engaged in research in Argentina, Bolivia The Dominican Republic, Peru, and Colombia with three objectives: a) to reconstruct the evolutionary history and adaptive patterns of South America primates and other mammals; b) to establish a more precise geologic chronology for the mammalian faunas between about 36 and about 15 million years ago; and c) to use anatomy and niche structure of modern mammals as a means to reconstruct the evolution of mammalian niche structure in the Neotropics.
2) Primate Anatomy. I am working to reconstruct the phylogeny of primates based (principally) on anatomical evidence; and to infer the adaptations of extinct primates based mainly on cranial and dental evidence. Recently I published a paper tracing the evolution of the primate neocortex using brain casts of living and fossil primates. We show that vision, not frontal lobe expansion, drove the evolution of large brains in primates, including humans.
Field activities
Current fieldwork is focused on the study of terrestrial biotic change in Patagonia through the 'mid-Miocene Climate Optimum' when global climate was moderate and the subtropical zone, with primates and other typically tropical vertebrates, extended their ranges up to 55 degrees of South latitude.
In this collaborative research undertaking the geochronology of the Santa Cruz Formation at in extreme southern Argentina is being refined using radiometric dating. Stratigraphically-controlled collections have been made of vertebrates and plant macro- and microfossils. Climate change and its impact on the biota is assessed by documenting changes in mammalian community structure (richness, origination and extinction rates, and ecological morphology). This evidence is compared with continental sequences in the Northern Hemisphere and oceanic climatic records to improve our understanding of the timing and character of climatic change in continental high latitudes during this temporal interval.
A second field project is the study of the fossil vertebrates of the Amazon Basin. The hope is to recover primates from the Oligocene through Early Miocene. New material will shed light on the phylogenetic status of African Paleogene anthropoids, one of which may be the platyrrhine sister-taxon. Also, new remains of fossil primates will help to refine hypotheses about the origins of the modern families and subfamilies of platyrrhines, all of which trace back to an Early Miocene (17-21 Ma) common ancestor. Finally, new fossil primates may further constrain the time of entry of platyrrhines into South America.
Unless otherwise indicated, scholarly articles published by Duke faculty members are made available here with a CC-BY-NC (Creative Commons Attribution Non-Commercial) license, as enabled by the Duke Open Access Policy. If you wish to use the materials in ways not already permitted under CC-BY-NC, please consult the copyright owner. Other materials are made available here through the author’s grant of a non-exclusive license to make their work openly accessible.