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Lateral trends in carbon isotope ratios reveal a Miocene vegetation gradient in the Siwaliks of Pakistan

Michele E. Morgan, Anna K. Behrensmeyer, Catherine Badgley, John C. Barry, Sherry Nelson and David Pilbeam
Lateral trends in carbon isotope ratios reveal a Miocene vegetation gradient in the Siwaliks of Pakistan
Geology (Boulder) (February 2009) 37 (2): 103-106

Abstract

Isotopic analyses of mammalian tooth enamel from a well-defined, laterally extensive 150 k.y. interval (9.15-9.30 Ma) reveal an ecological gradient in vegetation on the late Miocene sub-Himalayan alluvial plain. Two contemporaneous river systems deposited the sediments of this interval, with a mountain-sourced system (herein, Blue-gray) to the southwest interfingering with a foothill-sourced system (Buff) to the northeast. Fossil mammal teeth collected from a 32 km transect across this fluvial gradient are significantly more depleted in (super 13) C from northeastern localities than from southwestern localities. This trend occurs in equids, giraffids, suids, sivapithecine hominoids, and anthracotheres. We propose that the Buff fluvial system provided more equably moist substrate conditions and supported more closed-canopy vegetation than the Blue-gray fluvial system. Herbivores living along the paleovegetation gradient thus acquired different carbon isotopic signatures during the period of tooth enamel formation, resulting from higher delta (super 13) C values in the forage supported by the Blue-gray fluvial system compared with forage associated with the Buff system. The data also imply that many Siwalik mammalian herbivores displayed marked fidelity in juvenile home ranges and habitats.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 37
Serial Issue: 2
Title: Lateral trends in carbon isotope ratios reveal a Miocene vegetation gradient in the Siwaliks of Pakistan
Affiliation: Harvard University, Peabody Museum, Cambridge, MA, United States
Pages: 103-106
Published: 200902
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 29
Accession Number: 2009-031174
Categories: StratigraphyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2009030
Illustration Description: illus. incl. 1 table, sketch map
N32°00'00" - N35°00'00", E72°00'00" - E74°00'00"
Secondary Affiliation: Smithsonian Institution, USA, United StatesUniversity of Michigan, USA, United StatesUniversity of New Mexico, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200917
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