Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex By Karen E. Poole B.A. in Geology, May 2004, University of Pennsylvania M.A. in Earth and Planetary Sciences, August 2008, Washington University in St. Louis A Dissertation submitted to The Faculty of The Columbian College of Arts and Sciences of The George Washington University in partial fulfillment of the requirements for the degree of Doctor of Philosophy August 31, 2015 Dissertation Directed by Catherine Forster Professor of Biology The Columbian College of Arts and Sciences of The George Washington University certifies that Karen Poole has passed the Final Examination for the degree of Doctor of Philosophy as of August 10th, 2015. This is the final and approved form of the dissertation. Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex Karen E. Poole Dissertation Research Committee: Catherine A. Forster, Professor of Biology, Dissertation Director James M. Clark, Ronald Weintraub Professor of Biology, Committee Member R. Alexander Pyron, Robert F. Griggs Assistant Professor of Biology, Committee Member ii © Copyright 2015 by Karen Poole All rights reserved iii Dedication To Joseph Theis, for his unending support, and for always reminding me what matters most in life. To my parents, who have always encouraged me to pursue my dreams, even those they didn’t understand. iv Acknowledgements First, a heartfelt thank you is due to my advisor, Cathy Forster, for giving me free reign in this dissertation, but always providing valuable commentary on any piece of writing I sent her, no matter how messy. To James Clark, for teaching me systematics and taking me to do field work in China. To Alex Pyron, for his help in conducting Bayesian analyses. Thanks also to Matthew Carrano and David Weishampel for serving as external committee members. Thanks to my lab-mates, Josef Stiegler, Dominic White, and Drew Moore, for discussion, help with analyses, debugging, and general morale. Many people provided access to museum specimens, which were instrumental in completing this dissertation. I am grateful to all of them for their help: Ronan Allain, Paul Barrett, Daniel Brinkman, Ken Carpenter, Matthew Carrano, Ignacio Cerda, Sandra Chapman, Jean-Pierre Chenet, Rodolfo Coria, Billy de Klerk, Annelise Folie, Philipe Halvik, Sheena Kaal, James Kirkland, Carrie Levitt, Carl Mehling, Darrin Pagnac, David Pickering, Juan Porfiri, Thomas Rich, John Scanella, Rodney Scheetz, Thomas Schossleitner, Daniela Schwarz-Wings, Joseph Sertich, Kristin Spring, Thierry Tortosa, David Weishampel, and Xu Xing. Dan Sykes and Paul Barrett provided CT scans of specimens from the Natural History Museum in London, and Matthew Carrano and Michael Brett-Surman provided access to specimens at the Smithsonian Museum of Natural History, which were CT scanned at the GW Medical Faculty Associates Diagnostic Radiology Center. Funding for this research was provided by NSF grants DEB-1405834 and EAR 0922187, and the Cosmos Club Foundation. Funding for my graduate work was v provided by the Harlan Foundation, the Weintraub Foundation, and the Department of Biological Sciences. vi Abstract of Dissertation Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex A new phylogeny of iguanodontians is presented, based on a character matrix of 323 characters, over half of which are drawn from the postcranial skeleton. This was analyzed using both parsimony and time-calibrated Bayesian methods. These produce largely congruent results among Dryosauridae and Ankylopollexia, with two small groups among basal ankylopollexians: Iguanodontidae and an unnamed clade. The holotype of Mantellisaurus is recovered as the sister taxon to RBINS 1551, the holotype of “Dollodon”, supporting the suggestion that the latter is a junior subjective synonym of the former. In both analyses, Tenontosaurus and Muttaburrasaurus group with Rhabdodontidae, forming the new clade Rhabdodontoidea. The topology in the basal portion of the tree (pectinate in the parsimony tree and bifurcating in the Bayesian tree) indicates that there is not a strong phylogenetic signal; more work is necessary to resolve this portion of the tree. A method for incorporating juvenile specimens into a phylogeny with adult taxa is discussed. Ontogenetic sequences from taxa across the area of interest are examined, forming a phylogenetic bracket. For these taxa, juvenile specimens and adults are considered as separate OTUs, and characters that differ between juvenile and adult specimens for any taxon are considered ontogenetically sensitive characters. These characters are then coded as unknown for any OTU known only from juvenile specimens, as the adult state is unknown, and is likely to differ from the observed state in the vii juvenile. When this technique is used, juvenile specimens of Hypacrosaurus and Dryosaurus are recovered at the same node as their respective adult specimens. Orodromeus, however, is not, and substituting the juvenile specimen results in significant changes to the topology in that area. However, this is in the poorly resolved basal region of the tree. When there is a strong phylogenetic signal and a tree is reasonably well resolved, this method is able to accurately place juvenile specimens in a phylogeny. Doing so recovers undescribed juvenile specimens from the Early Cretaceous Kirkwood Formation of South Africa as a dryosaurid. The biomechanics of the uniquely fused carpals and first digit of basal ankylopollexians is examined using Finite Element (FE) analysis. This fusion occurred concomitantly with a shift to quadrupedality, and an enlargement of the ungual of the first digit; this study explores whether either of these factors may have served as a driver of carpal-digit I fusion. The initial elements to fuse (the radiale and metacarpal I) may have helped distribute the load from a ground reaction force through metacarpal I in Camptosaurus. In Barilium, which exhibits a higher degree of fusion, effective stresses are more evenly distributed under ungual loading than in Camptosaurus, largely due to the increased proximal-distal depth of the carpal block. Thus, there were likely multiple factors involved in the evolution of this enigmatic structure. viii Table of Contents Dedication...........................................................................................................................iv Acknowledgments................................................................................................................v Abstract of Dissertation.....................................................................................................vii List of Figures………………..............................................................................................x List of Tables……………….............................................................................................xii Chapter 1: Introduction……................................................................................................1 Chapter 2: Phylogeny and Biogeography............................................................................6 Chapter 3: The Effects of Ontogeny..................................................................................74 Chapter 4: Examining the Evolution of the Fused Carpal-Metacarpal Complex..............89 Chapter 5: Conclusions…………………………………………………………………103 References........................................................................................................................107 Appendix 1: List of morphological characters.................................................................133 Appendix 2: Character matrix..........................................................................................168 Appendix 3: Sources of morphological data....................................................................182 Appendix 4: Age ranges of taxa.......................................................................................187 Appendix 5: Ontogenetically sensitive characters...........................................................194 Appendix 6: Character matrix for Ontogenetically Sensitive character coding…….….205 ix List of Figures Figure 1.1: Overview of Ornithopods…………………………………………………….3 Figure 2.1: Generalized phylogeny of Ornithischia……..…………………………….….6 Figure 2.2: Early cladistic analyses of Ornithischia………………………………….….11 Figure 2.3: Recent phylogenetic hypothesis of Iguanodontia by McDonald..………..….15 Figure 2.4: Recent phylogenetic hypothesis of Iguanodontia by Norman……………….16 Figure 2.5: Recent phylogenetic hypothesis of Neornithischians….…………………….18 Figure 2.6: NHMUK 1831, dentary..…………………………………………………….21 Figure 2.7: Strict consensus of most parsimonious trees..……………………………….36 Figure 2.8: Time-scaled majority-rule consensus tree…………………………………..38 Figure 2.9: Maximum clade credibility tree produced from Bayesian analysis…………56 Figure 2.10: Ancestral Area Reconstruction……………………………………………..62 Figure 2.11: Ankylopollexian forearms…...……………………………………………..64 Figure 2.12: Iguanodontians sternals……...……………………………………………..66 Figure 2.13: Iguanodontian dentary teeth………………………………………………..68 Figure 2.14: MCC tree showing character changes related to quadrupedality…………..70 Figure 2.15: Strict consensus tree without