PERMIAN-TRIASSIC GLOBAL CHANGE: THE STRONTIUM CYCLE AND BODY SIZE EVOLUTION IN MARINE CLADES A DISSERTATION SUBMITED TO THE DEPARTMENT OF GEOLOGICAL & ENVIRONMENTAL SCIENCES AND THE COMMITTEE ON GRADUATE STUDIES OF STANFORD UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Ellen Kadrmas Schaal June 2014 © 2014 by Ellen Kadrmas Schaal. All Rights Reserved. Re-distributed by Stanford University under license with the author. This dissertation is online at: http://purl.stanford.edu/st726zn9395 ii I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. Jonathan Payne, Primary Adviser I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. C. Kevin Boyce I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. George Hilley I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. Donald Lowe Approved for the Stanford University Committee on Graduate Studies. Patricia J. Gumport, Vice Provost for Graduate Education This signature page was generated electronically upon submission of this dissertation in electronic format. An original signed hard copy of the signature page is on file in University Archives. iii ABSTRACT Immediately following the most severe extinction in the history of animal life, the Early Triassic was a time of major changes in ocean chemistry and delayed biotic recovery. Many hypotheses for the cause of the end-Permian extinction invoke the environmental consequences of Siberian Traps flood basalt eruption. However, the precise relationship between volcanism, ocean chemistry, and the tempo and mode of biotic recovery remain incompletely understood. I present four studies that investigate the relationship between environmental change and biological evolution during this unique time interval, using carbonate and conodont samples from south China and literature-based fossil and geochemical data from around the globe. (1) I test strontium isotopic constraints on Permian-Triassic global change with a new high- resolution seawater 87Sr/86Sr record and a numerical model of the strontium cycle. Strontium isotope data reveal a rapid radiogenic excursion occurred during the first two million years of Early Triassic time. Model results show that the magnitude of CO2 release during Siberian Traps volcanism is sufficient to account for much of the 87 86 observed increase in seawater Sr/ Sr through CO2 enhancement of continental weathering rates. (2) The small size of Early Triassic marine organisms has important implications for the ecological and environmental pressures operating during and after the end-Permian mass extinction. I quantify Permian-Triassic body size trends in eight marine clades and find widespread size decrease after the extinction in ecologically and physiologically disparate clades. Nektonic habitat or physiological buffering capacity may explain the contrast of Early Triassic size increase and iv diversification in ammonoids versus size reduction and slow recovery in benthic clades. (3) I compare size evolution in conodonts at the end-Permian extinction to their entire evolutionary history. Quantifying size trends reveals a long-term pattern of size increase during the early Paleozoic followed by size decrease until conodonts went extinct at the end of Triassic. Conodont size change during intervals of mass extinction and rapid environmental change appears small compared to long-term trends. (4) Finally, I review the constraints on Permian-Triassic ocean redox chemistry provided by lithological and geochemical proxy records. Paleoredox records show a rapid shift from relatively well-ventilated Late Permian oceans to widespread anoxic and euxinic conditions coincident with the end-Permian extinction horizon. Earth system models and geological observations support the eruption of the Siberian Traps as a mechanism for the expansion of anoxia at the Permian-Triassic boundary. Taken together, these results suggest that the physical environment has a large impact on biological evolution during intervals of rapid environmental change, but long-term evolutionary trends may be primarily driven by ecology. v A NOTE ON AUTHORSHIP This dissertation consists of four projects that reflect a collaborative effort between Ellen Schaal and coauthors. E. Schaal collected data for each chapter, analyzed the data, and wrote the main body of text. For Chapter 1, Jonathan Payne collected carbonates in Turkey and south China. Dan Lehrmann and Meiyi Yu advised field work in south China, where E. Schaal collected conodonts. 87Sr/86Sr analyses were run by Crystal Breier and E. Schaal in Adina Paytan’s lab at UC Santa Cruz. Demír Altiner provided foraminiferal biostratigraphy for Turkey and Rachelle Kernen helped calibrate carbon and strontium isotope curves. For Chapter 2, Matthew Clapham contributed size data for brachipods, bivalves, ammonoids, and ostracods, Jonathan Payne contributed size data for gastropods, and Brianna Rego contributed size data for foraminifera. Steve Wang gave advice on statistical methods and developed the method used to measure the relative effects of the three components of size change. M. Clapham and S. Wang commented on the manuscript. For Chapter 3, Daniel Morgan measured numerous conodonts and assisted with analyses. For Chapter 4, Katja Meyer contributed writing on biomarkers and modeling, Kimberly Lau on cerium and uranium, Juan Carlos Silva-Tamayo on molybdenum, and J. Payne on lithologic evidence. J. Payne supervised all projects and commented on drafts of this dissertation. vi ACKNOWLEDGMENTS I would first like to thank my advisor, Jonathan Payne, for all his great advice and support over the course of my time at Stanford. He has been a wonderful role model, for research, mentoring, and building a lab that fosters scientific collaboration. Thank you to all of my coauthors and members of my committee, whose valuable insights contributed greatly to this work. I would also like to thank the members of the Stanford Paleobiology Lab, past and present, for fantastic discussions and comments: A. Bachan, S. Finnegan, K. Fristad, N. Goudemand, P. Harnik, N. Heim, J. Hinojosa, A. Jost, C. Keating-Bitonti, B. Kelley, M. Knope, K. Lau, K. Meyer, B. Rego, and J. C. Silva-Tamayo. Many thanks to my undergraduate research assistants, Daniel Morgan, Kathryn (Kit) Vanderboll, and Margaret Chapman, who helped with conodont picking and size data collection, and to my field assistants in south China, Fu Hongbin, Li Xiaowei, Wen Xuefeng, Xiao Long, and Xiao Wei. My work was supported by the Eugene Holman Stanford Graduate Fellowship, the Shell Foundation, and the National Science Foundation (EAR-0807377 to J. Payne). On a personal note, I am very thankful for all of the amazing friends I met at Stanford, who have made graduate school such a good experience. Special thanks go to David for cheering me on during the final stages of my dissertation. Finally, I am deeply grateful to my family for all their love and support. vii TABLE OF CONTENTS Abstract……......…………………………………………………………………..iv A Note on Authorship…………………………………..…………………………vi Acknowledgments………………………..………………………………………vii List of Figures…...……………………………………………………………..….xi List of Tables…...………………………………………………………………...xii INTRODUCTION……………………………………………………………………..1 References……………………………………………………………………….....4 CHAPTER 1: STRONTIUM ISOTOPE CONSTRAINTS ON PERMIAN-TRIASSIC GLOBAL CHANGE…………………………………………………………………..7 Introduction…………………………………………………………………….…..9 Field Setting and Methods……………………………………………………..…12 Strontium and Carbon Isotope Results……………………………………………17 Numerical Modeling…………………………………………………………...…18 Discussion………………………………………………………………………...23 Conclusions……………………………………………………………………….27 Acknowledgments…..………………………………………………………….…28 References………………………………………………………………………...29 Figure Captions…………………………………………………………………...37 Table Caption……………………………………………………………………..39 Chapter 1 Figures…………………………………………………………………40 Chapter 1 Table…………………………………………………………………...45 CHAPTER 2: COMPARATIVE SIZE EVOLUTION OF MARINE CLADES FROM THE LATE PERMIAN THOUGH MIDDLE TRIASSIC…………………………..46 Introduction……………………………………………………………………….48 Methods…………………………………………………………………………...52 Results…………………………………………………………………………….54 Discussion………………………………………………………………………...61 Conclusions…………………………………………………………………….…69 viii Acknowledgments…..………………………………………………………….…70 References………………………………………………………………………...71 Figure Captions………………………………………………………………...…82 Table Caption……………………………………………………………………..84 Chapter 2 Figures…………………………………………………………………85 Chapter 2 Table…………………………………………………………………...89 CHAPTER 3: BODY SIZE EVOLUTION IN CONODONTS FROM THE CAMBRIAN THROUGH THE TRIASSIC………………………………………….90 Introduction……………………………………………………………………….92 Data and Methods……………………………………………………………...…94 Results…………………………………………………………………………….98 Discussion…………………………………………………………………….....100 Conclusions……………………………………………………………………...103 Acknowledgments……..………………………………………………………...104 References……………………………………………………………………….105 Figure Captions………………………………………………………………….114 Table Caption……………………………………………………………………115 Chapter 3 Figures……………………………………………………………..…116 Chapter