MORPHOMETRIC EVOLUTION OF PALEOZOIC BRACHIOPODS - THE EFFECTS OF ENVIRONMENT AND ECOLOGICAL INTERACTIONS ON SHELL MORPHOLOGY RITUPARNA BOSE Submitted to the faculty of the University Graduate School in partial fulfillment of the requirements for the degree Doctor of Philosophy In the Department of Geological Sciences, Indiana University Dec, 2011 Accepted by the Graduate Faculty, Indiana University, in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Doctoral Committee ________________________________ P. David Polly, Ph.D. ________________________________ Erika R. Elswick, Ph.D. ________________________________ Claudia C. Johnson, Ph.D. ________________________________ Lindsey R. Leighton, Ph.D. ________________________________ Greg A. Olyphant, Ph.D. __________________________________ Chris L. Schneider, Ph.D. Date of Dissertation Defense – April 11, 2011 ii Copyright © 2011 Rituparna Bose ALL RIGHTS RESERVED iii DEDICATION This thesis is dedicated to my family. Thank you all from afar! iv ACKNOWLEDGEMENTS During the course of my graduate studies in the department of geological sciences at Indiana University, I have had the honor to meet and interact with many scholars who have made significant contributions in my doctoral research career. I wish to explicitly thank all of them here and my heartfelt apologies, if I have missed anyone’s contributions in this list. First, I would like to gratefully acknowledge my kind and patient advisor, Dr. P. David Polly, without whose guidance, this work would have never been accomplished. I am indebted to him, for all his valuable contributions towards my education on all fronts. He has always guided me both as a researcher and a teacher. I gratefully acknowledge my internal committee member, Dr. Claudia C. Johnson for her valuable suggestions on my research and for her help in various professional aspects throughout my graduate education. I sincerely acknowledge my internal committee member, Dr. Erika R. Elswick for helpful suggestions. I also sincerely thank my external committee members, Dr. Lindsey R. Leighton and Dr. Chris L. Schneider, for their invaluable advices and vital feedback on my research. Besides, I want to sincerely thank Dr. Erle Kauffman, Dr. Abhijit Basu and Dr. Greg Olyphant for their precious advices throughout my graduate career. My deepest thanks to all of you. I would also like to thank other Professors in the department - Dr. Simon Brassell, Dr. Lisa Pratt, Dr. David Millen, and Dr. Jeremy Dunning (besides Dr. Claudia C. Johnson, Dr. Abhijit Basu and Dr. P. David Polly) under whose supervision I had the privilege of gathering some great learning experience while teaching courses in the department. v I would like to thank everyone who provided useful information in locating field collections in various museum repositories. Not to mention, I am sincerely thankful to Dr. Donald Hattin at Indiana University and Dr. Carlton Brett in University of Cincinnati in this regard. Besides, my sincere thanks to all curators, museum assistants and other members of the North American museums who oversee the paleontological collections housed in these repositories. A special thanks to Dr. Susan Butts and Cope McClintock from Yale Peabody Museum, Dr. Daniel Miller from University of Michigan Museum of Paleontology, Dr. Neil H. Landman and Bushra Hussaini from American Museum of Natural History, Dr. Ed Landing and Linda Hernick from New York State Museum at Albany, and Dr. Peter Wagner, Dr. Doug Erwin, Dr. Thomas J. Dutro and Jann Thompson from National Museum of Natural History for permitting access to the collections. Besides, I am sincerely thankful to Dr. Jed Day from Illinois State University for allowing access to his enormous brachiopod collections housed in his laboratory. I would also like to extend my sincere thanks to Dr. Alex Bartholomew from State University of New York at New Paltz for providing access to his field collections and for loaning me his samples for my dissertation. I would also like to extend my thanks to Dr. Murat Maga at University of Washington, for running CT-scan on a few specimens. In addition, I was fortunate to have invaluable suggestions from my former advisor, Dr. Margaret M. Yacobucci from Bowling Green State University during my work. I sincerely thank her for her enthusiasm and encouragement in my progress that introduced me to the world of research and continued progress. A special thanks to all my Geobiology laboratory colleagues, whose cooperation and support throughout my research was indispensable. I would also like to thank former vi graduate students of Indiana University - Miriam Attenoukon and Liming Zhu for helpful suggestions. I want to specially acknowledge Geosciences staff members - Mary Iverson, Lou Malcomb, Linda Stewart, Terry Stigall, Lindsay Bugher, Ruth Droppo, Ken DeHart, John Bogeman and John M. Day who provided invaluable assistance during the course of my graduate career. Last, but certainly not the least, a big thanks to my husband, Arnab for pitching in with his patient and invaluable feedback. It was his strong support that allowed me to hold my perseverance throughout the end. I am going to remember my PhD dissertation with fond memories and anticipation. Financial support for this research was derived mainly from the Dunbar and Schuchert Grant-in Aid funded by Yale Peabody Museum, Theodore Roosevelt Memorial Grant funded by American Museum of Natural History, BP Global Energy group, and Galloway Horowitz research funds granted by the Department of Geological Sciences, Indiana University. Additional support was made available by the Indiana University School of Arts and Sciences Dissertation Year Research fellowship which assisted in continuing my research and dissertation writing. vii Rituparna Bose MORPHOMETRIC EVOLUTION OF PALEOZOIC BRACHIOPODS - THE EFFECTS OF ENVIRONMENT AND ECOLOGICAL INTERACTIONS ON SHELL MORPHOLOGY Atrypida (Brachiopoda, Rhynchonellata) are ancient marine invertebrate fossils that are well preserved, abundant and diverse in the mid-Paleozoic (ecological evolutionary unit (EEU) P3). Atrypides thus serve as useful tools for morphological shape study. While qualitative studies have been performed for solving problems in brachiopod taxonomy, phylogeny, evolution and ecology, quantitative studies have been lacking. After qualitative taxonomic identifications, morphological shape of the Silurian- Devonian Eastern North American atrypids was analyzed using geometric morphometrics, placing the results in evolutionary and ecological perspectives. Landmark analysis was performed on dorsal valves, ventral valves, anterior and posterior regions. These data were used for comparison with morphological distances, calculated as pairwise Procrustes distances. Evolutionary divergence times were determined from atrypide phylogeny and from stratigraphic zonations in the Michigan Traverse Group. Maximum likelihood tests were performed to determine evolutionary rates and modes of morphological divergence within and between genera. Episkeletobionts on hosts were examined to determine how morphological variation affected these assemblages. Morphometric results suggest that morphological distances within each genus was as large as those observed between genera. Thus, referring individuals to a particular genus, based on shell shape alone is challenging. Diversifying selection has been acting viii on morphological divergence of these generic pairs and morphometric distances are consistent with the prior phylogenetic arrangement. Short term changes observed in individual lineages, that gets averaged out in time when compared to other genera, together with considerable morphological overlap observed between genera in P3 EEU, suggests a pattern consistent with stasis, as expected in EEUs. The Traverse Group atrypid species lineage, which represents a 5 m.y. time span, exhibited lightly constrained morphological evolution, reflecting a stasis-like pattern. Greater encrustation preferences on one of two morphotypes on the dorsal valve and posterior region, suggest greater surface area facilitated by relatively deeper profile hosts in their reclining life orientation. Overall, the integration of various paleontological datasets reveal that the seemingly homogenous group of atrypide brachiopods exhibit subtle but significant evolution in their shell shape that is correlated with several kinds of ecological differences. ix TABLE OF CONTENTS ACCEPTANCE ................................................................................................................. ii DEDICATION.................................................................................................................. iv ACKNOWLEDGEMENTS ..............................................................................................v ABSTRACT .................................................................................................................... viii TABLE OF CONTENTS ..................................................................................................x LIST OF TABLES ......................................................................................................... xiii LIST OF FIGURES ....................................................................................................... xiv CHAPTER I. A geometric morphometric approach in assessing paleontological problems in atrypid taxonomy, phylogeny, evolution and ecology .....................................1 INTRODUCTION..................................................................................................2