Late Pleistocene Climate and Proboscidean Paleoecology in North America: Insights from Stable Isotope Compositions of Skeletal Remains
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Western University Scholarship@Western Electronic Thesis and Dissertation Repository 4-16-2011 12:00 AM Late Pleistocene climate and proboscidean paleoecology in North America: Insights from stable isotope compositions of skeletal remains Jessica Z. Metcalfe The University of Western Ontario Supervisor Fred Longstaffe The University of Western Ontario Graduate Program in Geology A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Jessica Z. Metcalfe 2011 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Biogeochemistry Commons Recommended Citation Metcalfe, Jessica Z., "Late Pleistocene climate and proboscidean paleoecology in North America: Insights from stable isotope compositions of skeletal remains" (2011). Electronic Thesis and Dissertation Repository. 194. https://ir.lib.uwo.ca/etd/194 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. LATE PLEISTOCENE CLIMATE AND PROBOSCIDEAN PALEOECOLOGY IN NORTH AMERICA: INSIGHTS FROM STABLE ISOTOPE COMPOSITIONS OF SKELETAL REMAINS (Spine title: Late Pleistocene climate and proboscidean paleoecology) (Thesis format: Integrated Article) by Jessica Z. Metcalfe Graduate Program in Geology & Environmental Science A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy The School of Graduate and Postdoctoral Studies The University of Western Ontario London, Ontario, Canada © Jessica Z. Metcalfe 2011 THE UNIVERSITY OF WESTERN ONTARIO School of Graduate and Postdoctoral Studies CERTIFICATE OF EXAMINATION Supervisor Examiners ______________________________ ______________________________ Dr. Fred Longstaffe Dr. Jisuo Jin ______________________________ Supervisory Committee Dr. Burns Cheadle ______________________________ ______________________________ Dr. Elizabeth Webb Dr. Lisa Hodgetts ______________________________ ______________________________ Dr. Chris Ellis Dr. Henry Schwarcz The thesis by Jessica Zoe Metcalfe entitled: Late Pleistocene climate and proboscidean paleoecology in North America: Insights from stable isotope compositions of skeletal remains is accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy ______________________ _______________________________ Date Chair of the Thesis Examination Board ii Abstract This thesis uses the carbon, nitrogen, and oxygen isotope compositions of mammoth (Mammuthus) and mastodon (Mammut) skeletal remains to reconstruct paleoclimate and paleoecology in Late Pleistocene North America. Analytical methods, sampling strategies, environmental adaptations and seasonal behaviors of proboscideans were investigated. Reliable and reproducible results are crucial for a study of this nature. A persistent methodological problem in the isotope analysis of structural carbonate in bioapatite was solved by reacting bioapatite under “sealed vessel” conditions. Growth rate determinations are critical for designing sampling strategies and interpreting results. Histological and isotopic measurements demonstrated variations in enamel growth rates within and among teeth. Sequentially sampling through the enamel thickness can resolve shorter-term (weekly) isotopic variations, and sampling along the tooth height (especially on the inner enamel surface) can resolve longer-term (monthly or yearly) variations. Proboscideans adapted to the conditions of their local environments. Clovis-age mammoths in Arizona sought out C4 grasslands that “greened up” as a result of summer rainfall. In C3-dominated environments (Great Lakes and Western Canada), seasonal variations were larger in mastodons than mammoths, possibly because the latter exploited a greater number of microhabitats, averaging plant and drinking water isotopic compositions. Mammoths and mastodons occupied different environmental niches, but both consumed a wide range of resources and regional differences were evident. Woolly mammoths in Old Crow delayed the initiation of weaning relative to modern elephants, perhaps as a defensive adaptation to the increased predation risk and decreased food quality/quantity during long hours of winter darkness at this high latitude location. Potential consequences of delayed weaning, such as longer inter-birth intervals and greater maternal energy investments, may have increased the population’s vulnerability to climatic stress or human hunting. Isotope results for Clovis mammoths in the San Pedro Valley are consistent with a relatively warm and dry climate, but do not indicate severe drought. Regional differences iii 13 in δ C values of proboscideans from C3-dominated environments were minimal, but variations in δ15N may be related to spruce abundances and/or aridity. Latitudinal variations in proboscidean δ18O values correlate well with modern meteoric water isotope compositions, which indicates their potential for reconstructing past paleoclimatic conditions. Keywords: stable isotopes, mammoth, mastodon, Mammuthus, Mammut, proboscidean, Pleistocene, enamel, bone, dentin, cementum, environmental niche, seasonality, paleoclimate, paleoecology, Arizona, San Pedro Valley, Great Lakes, Ontario, New York, Alberta, Yukon, British Columbia iv Co-Authorship Statement Chapter 2 of this thesis was co-authored by Dr. Fred Longstaffe and Dr. Christine White, who provided funding for the project, contributed valuable advice throughout the research process, and reviewed and edited the manuscript. Chapter 3 of this thesis was co-authored by Dr. Fred Longstaffe and Dr. Grant Zazula. Fred provided funding for J.Z.M. to travel to Yukon and obtain samples for this study, as well as funding for analytical costs, advice, data checking, scientific reviewing, and editing. Grant provided access to samples and background information, assisted with size measurements needed to characterize specimens, prepared a map, and participated in very helpful discussions. Chapter 5 of this thesis has been reviewed by Dr. Jesse Ballenger and Dr. C. Vance Haynes, who provided helpful comments and clarification. Chapter 7 of this thesis has been reviewed by Dr. Grant Zazula, who provided additional references and constructive criticism. v Dedication with love, to Grandma and Dziadzia, who passed away during the making of this thesis, and to Henry, who was born. vi Acknowledgements Over the last five years I have had the privilege of meeting so many wonderful people, who have helped me in many ways. To my supervisor, Fred – thank you for suggesting this project and encouraging me to make it my own. Your support – financial, personal, and professional – has made it a true pleasure to work at Western. I am constantly inspired by your dedication to your students, your incredible work ethic, and your enthusiasm for science. You are the best example I can imagine of what a mentor should be. This is not the end of our collaboration, but the start of a new chapter. To my advisory committee, Liz Webb and Chris Ellis – thanks for helping me develop this project. Liz – you were always ready with great advice and enthusiasm. Chris – you helped move my project in exciting directions, through your encyclopaedic knowledge of Paleoindian archaeology and your suggestion to contact Vance Haynes. Many thanks! To my examining committee, Henry Schwarcz, Lisa Hodgetts, Jisuo Jin, and Burns Cheadle – your careful reading of this thesis and insightful comments were much appreciated. Sample collection was a major part of this project, and I am indebted to numerous individuals and institutions for providing specimens: Great Lakes Region Steve Hicock and Aleksis Dreimanis (University of Western Ontario), Robert Pearce (Musuem of Ontario Archaeology), Kevin Seymour, David Evans, and Brian Iwama (Royal Ontario Museum), and Dick Laub (Buffalo Museum of Science) – thank you for providing access to specimens. Thanks also to Dick for inviting me to the Byron Dig (2006-2007), which allowed me to get my hands dirty. vii Western Canada Grant Zazula – thank you for access to the Yukon Government collections, and for making my visit to Whitehorse so enjoyable… even though it was November! Your enthusiasm for Pleistocene research and breadth of interests are inspiring, and I greatly value our collaboration – I hope we meet again soon. Thanks also to Grant’s family (Vicky and Roman) for putting up with my visit, and to John Bailey, Bob Bailey, and Greg Hare, who helped me get initially get in touch with Grant. Alwynne Beaudoin, Chris Jass, Peter Milot, and Jim Burns (Royal Alberta Museum) – thank you for access to your collections, which helped get my project off the ground. It was great to meet you, and I hope we will work together again some day. Grant Keddie – thank you for access to specimens from the Royal British Columbia Museum. Arizona Vance Haynes – it has been a pleasure and privilege to work with you. Thanks for trusting me with the San Pedro Valley specimens, assisting in sampling, and taking me to the Murray Springs site. Your dedication to research is inspiring. Everett Lindsay, Mike Jacobs, and Alan Ferg – thank you allowing me access to the specimens. Jesse Ballenger – you are following in the tradition of Haynes; thanks for providing samples and for many helpful discussions. Greg Hodgins – thank you for welcoming me to the AMS lab and being a truly