University of Calgary PRISM: University of Calgary's Digital Repository Graduate Studies The Vault: Electronic Theses and Dissertations 2018-12-20 An Analysis of North American Taeniolabidoid Multituberculate (Mammalia, Allotheria) Dentitions Using Mammalian Dietary Proxies Robson, Selina Viktoria Robson, S. V. (2018). An Analysis of North American Taeniolabidoid Multituberculate (Mammalia, Allotheria) Dentitions Using Mammalian Dietary Proxies (Unpublished master's thesis). University of Calgary, Calgary, AB. http://hdl.handle.net/1880/109394 master thesis University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. Downloaded from PRISM: https://prism.ucalgary.ca UNIVERSITY OF CALGARY An Analysis of North American Taeniolabidoid Multituberculate (Mammalia, Allotheria) Dentitions Using Mammalian Dietary Proxies by Selina V. Robson A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE GRADUATE PROGRAM IN BIOLOGICAL SCIENCES CALGARY, ALBERTA DECEMBER, 2018 © Selina V. Robson 2018 Abstract In this thesis, a set of dietary proxies – dental microwear analysis, cusp row ratios (CRR) (similar to shearing ratios), relief index (RFI), orientation patch count rotated (OPCR), and Dirichlet normal energy (DNE) – was used to infer diets of North American taeniolabidoid multituberculates. Based on the signals recovered by these proxies, taeniolabidoid diets did not vary consistently with body size: small-bodied and large-bodied taeniolabidoids had similar dietary signals for almost all proxies, the only difference being in microwear feature dimensions. Dental microwear signals suggest that taeniolabidoids and non-taeniolabidoid cimolodontans may have had different diets, but all other proxies have recovered equivalent signals between the two groups. Dietary classifications are inconsistent among CRR, RFI, OPCR, and DNE. This suggests that these proxies are not equally good predictors and that their generalizability to non- therian mammals may need to be re-evaluated. 2 Preface This thesis is original, unpublished, independent work by the author, S. V. Robson. 3 Acknowledgements I would like to thank C. Barrón-Ortiz and E. Townsend for teaching me microwear molding, casting, and counting methods. I would also like to thank the Instrumentation Facility for Analytical Electron Microscopy (IFFAEM) at the University of Calgary for the use of their scanning electron microscope (SEM) and specifically C. Debuhr for operating the SEM. I thank H. Christensen for discussing her thesis with me, and for providing me with some of her unpublished datasets. These data served as useful comparisons. I also thank the University of Calgary MicroCT Laboratory for the use of their computed tomography (CT) scanner, and I am particularly grateful to T. Barry, who taught me how to use the CT scanner. Furthermore, I thank J. Pampush and A. Evans for offering advice about molaR and SurferManipulator, respectively. I also thank the American Museum of Natural and Cultural History (AMNH) and the New Mexico Museum of Natural History and Science (NMMNH) for allowing me to visit their collections. In particularly, I would like to thank J. Galkin and V. Lee from the AMNH and T. Williamson from the NMMNH for all of their help during my visits. Lastly, I thank my co-supervisors, J. Theodor and C. Scott, and my committee members, S. Cote and D. Syme, for all of their assistance, advice, and support over the course of my thesis. This research was partially funded by a University of Calgary Entrance Scholarship, a University of Calgary Faculty of Graduate Studies Travel Award for International Students, a University of Calgary Graduate Performance Award, the University of Calgary Graeme Bell and Normal Key Sullivan-Bell Graduate Scholarship in Biology, a Jackson School of Geosciences Student Member Travel Grant, and an NSERC Discovery Grant. 4 Table of Contents Abstract ............................................................................................................................... ii Preface................................................................................................................................ iii Acknowledgements ............................................................................................................ iv Table of Contents .................................................................................................................v List of Tables ..................................................................................................................... ix List of Figures and Illustrations ......................................................................................... xi List of Symbols, Abbreviations and Nomenclature ...........................................................xv CHAPTER 1: INTRODUCTION ........................................................................................1 1.1 Taeniolabidoids ..........................................................................................................3 1.2 Dietary Proxies for Extinct Mammals .......................................................................6 1.3 Included Taxa ............................................................................................................7 1.4 Literature Cited ..........................................................................................................9 CHAPTER TWO: MOLAR MICROWEAR OF CIMOLODONTAN MULTITUBERCULATES .......................................................................................16 2.1 Introduction ..............................................................................................................16 2.1.1 Microwear analysis: cautions and considerations. ..........................................19 2.1.1.1 Selecting an imaging method. ................................................................19 2.1.1.2 Selecting teeth and cusps. ......................................................................21 2.1.1.3 What produces microwear? ...................................................................22 2.1.1.4 Effects of taphonomy on microwear. .....................................................25 2.1.1.5 Effects of microstructure on microwear. ...............................................26 2.1.1.6 Effects of phylogeny on microwear. ......................................................27 2.2 Methods ...................................................................................................................28 2.2.1 Molding and casting. .......................................................................................28 2.2.2 Scanning electron microscopy. ........................................................................29 2.2.3 Counting microwear. .......................................................................................30 2.2.4 Analyzing data. ................................................................................................35 2.3 Results ......................................................................................................................36 2.3.1 Scratches and pits. ...........................................................................................36 2.3.2 Feature size. .....................................................................................................40 2.4 Discussion ................................................................................................................43 2.4.1 Comparisons within this study. .......................................................................43 2.4.1.1 Scratches and pits. ..................................................................................43 2.4.1.2 Feature dimensions. ...............................................................................44 2.4.2 Comparisons to previous multituberculate microwear work. ..........................44 2.4.3 Comparisons to extant small mammals. ..........................................................45 2.4.4 Cimolodontan dental microwear and locomotor habits. ..................................47 2.5 Summary and Conclusions ......................................................................................49 2.6 Literature Cited ........................................................................................................50 CHAPTER THREE: CUSP ROW RATIOS OF CIMOLODONTAN LOWER MOLARS63 3.1 Two-Dimensional Quantifications of Tooth Shape .................................................63 3.1.1 Shearing ratios. ................................................................................................63 5 3.1.2 Shearing ratios applied to multituberculates. ..................................................65 3.2 Methods ...................................................................................................................66 3.3 Results ......................................................................................................................70 3.4 Discussion ................................................................................................................80 3.4.1 CRR of lower molars. ......................................................................................80