Doctor of Philosophy
Dr. Fred Longstaffe
The Pleistocene mammoth steppe was a vast biome that stretched from northwestern Europe to central Canada. A diverse set of megaherbivore and megacarnivore species lived within this biome and there was significant ecosystem faunal and floral homogeneity. At the end of the Pleistocene, this biome disappeared, with the extinction or extirpation of many of the megafaunal species that inhabited it. This thesis reconstructs the ecology of the mammoth steppe using the isotopic compositions of carbon and nitrogen from megafaunal collagen. The reconstruction is done at a variety of ecological scales, beginning with individual animal- and season-specific isotopic studies of antlers, and then comparison to bones from the same species. This provides a framework to understand the habitat and diet of antlered species through the Pleistocene and into the Holocene. Non-ruminant species ecology is assessed using the carbon and nitrogen isotopic compositions of the individual amino acids that comprise their bulk collagen. The compound-specific technique allows metabolic and habitat or dietary effects to be separated and diets to be classified. These studies indicate woolly mammoths ate a distinct diet, likely comprising decayed plants, and that some horses shared this dietary niche. The Pleistocene giant beaver consumed aquatic plants, while the mastodon consumed unmodified terrestrial plant material. Finally, the bulk collagen isotopic compositions measured in this work as well as reviewed from the literature are compiled and the mathematical tool SIBER (Stable Isotope Bayesian Ellipses in R) is used to define the isotopic niche for multiple megaherbivore species at different times and sites across the mammoth steppe. This, combined with the dietary and habitat information gleaned from the antler and amino acid isotopic measurements, allows an in-depth analysis of mammoth steppe ecology. Before the LGM (Last Glacial Maximum), most species occupied consistent isotopic niches between sites across the mammoth steppe, suggesting consistent diets or habitats during the pre-LGM period. These isotopic niche patterns changed during the LGM, and the patterns were not re-established post-LGM or in the Holocene. These changes suggest that the ecosystem suffered a major disturbance during the LGM, before the extinctions that occurred at the end of the Pleistocene.
Schwartz-Narbonne, Rachel E., "Reframing the Mammoth Steppe: Examining Mammoth Steppe Ecology Using Carbon and Nitrogen Isotopic Compositions of Megafauna Collagen" (2016). Electronic Thesis and Dissertation Repository. 3495.
Available for download on Sunday, February 11, 2018