Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Clementz, M. T. Articles by Domning, D. P. Search for Related Content GeoRef GeoRef Citation

Evidence of Cenozoic environmental and ecological change from stable isotope analysis of sirenian remains from the Tethys-Mediterranean region

¹ Department of Geology and Geophysics, University of Wyoming, 1000 East University Avenue, Laramie, Wyoming 82071, USA
² Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, 56126 Pisa, Italy
³ Department of Anatomy, Howard University, Washington, D.C. 20059, USA

Correspondence: *E-mail: mclemen1{at}uwyo.edu.

Sirenians (sea cows: manatees and dugongs) have been primary consumers in tropical and subtropical shallow-water marine ecosystems for more than 50 m.y. Though fossils of the earliest sirenians have been recovered from the Caribbean, sirenians are thought to have originated in the Tethys-Mediterranean region, which underwent significant climate change over the course of the Cenozoic. Application of stable isotope analysis can provide new insight into how diet and habitat preferences were affected by climate change and how these ecological changes correlate with diversity patterns for this region. Tooth enamel was sampled from 57 specimens of sirenians from the Tethys-Mediterranean and adjacent seas spanning the Eocene to Pliocene. Enamel ¹³C values across this time interval were consistently high and indicative of diets composed mostly of marine seagrasses. In contrast, enamel ¹⁸O values showed significant change over time and across the region. Sirenians from southern sites (i.e., Egypt, Libya) had significantly higher mean ¹⁸O values than specimens from most European locations, suggesting variation in salinity within the Tethys-Mediterranean. The range in enamel ¹⁸O values increased from the Paleogene through the Neogene, but enamel ¹³C values remained steady, indicating that changes in environmental conditions did not necessarily coincide with major changes in dietary preferences. Declines in sirenian taxonomic diversity in the late Miocene were likely due to the rapid climate and oceanographic changes during the latter half of the Cenozoic and their impacts on available dietary resources. Elevated ¹³C and ¹⁸O values in Mediterranean sirenians during the Messinian salinity crisis corroborate the hypothesis of ecophenotypic dwarfing in these animals.