This electronic thesis or dissertation has been downloaded from Explore Bristol Research, http://research-information.bristol.ac.uk Author: Herrera Flores, Jorge Alfredo A Title: The macroevolution and macroecology of Mesozoic lepidosaurs General rights Access to the thesis is subject to the Creative Commons Attribution - NonCommercial-No Derivatives 4.0 International Public License. A copy of this may be found at https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode This license sets out your rights and the restrictions that apply to your access to the thesis so it is important you read this before proceeding. Take down policy Some pages of this thesis may have been removed for copyright restrictions prior to having it been deposited in Explore Bristol Research. 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This electronic thesis or dissertation has been downloaded from Explore Bristol Research, http://research-information.bristol.ac.uk Author: Herrera Flores, Jorge Alfredo A Title: The macroevolution and macroecology of Mesozoic lepidosaurs General rights Access to the thesis is subject to the Creative Commons Attribution - NonCommercial-No Derivatives 4.0 International Public License. A copy of this may be found at https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode This license sets out your rights and the restrictions that apply to your access to the thesis so it is important you read this before proceeding. Take down policy Some pages of this thesis may have been removed for copyright restrictions prior to having it been deposited in Explore Bristol Research. However, if you have discovered material within the thesis that you consider to be unlawful e.g. breaches of copyright (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please contact [email protected] and include the following information in your message: •Your contact details •Bibliographic details for the item, including a URL •An outline nature of the complaint Your claim will be investigated and, where appropriate, the item in question will be removed from public view as soon as possible. The macroevolution and macroecology of Mesozoic lepidosaurs Jorge Alfredo Herrera Flores A dissertation submitted to the University of Bristol in accordance with the requirements for award of the degree of Doctor of Philosophy in the Faculty of Science. University of Bristol, School of Earth Sciences September 2018 Word count: 30,394 Abstract I studied with the aid of geometric morphometrics and novel phylogenetic comparative methods patterns of macroevolution in Mesozoic lepidosaurs in order to answer some of the intriguing aspects of their early evolution. The results presented here show that: A) The Late Triassic rhynchocephalian Clevosaurus latidens was not related to the genus Clevosaurus as was previously suggested, and indeed it represents a new genus of an early diverging opisthodontian renamed here as Fraserosphenodon latidens. Additionally, parsimony and Bayesian phylogenetic analysis recovered very similar topologies for the phylogeny of Rhynchocephalia, allowing to formally name two higher clades of derived rhynchocephalians: Eusphenodontia and Neosphenodontia. B) Geometric morphometric analysis of rhynchocephalians confirms the high morphological disparity of the group, while evolutionary rates analysis suggests that rhynchocephalian evolution was driven by heterogenous rates. Both, evolutionary rates analysis and geometric morphometrics shows that the modern “Tuatara” has rather low rates and is morphologically average if compared with other rhynchocephalians, which suggests that it is a morphologically conservative species. C) Dental disparity, body size analysis and geometric morphometrics of Mesozoic squamates suggest that small body size, low diversity and low dental disparity seem to have been the ancestral state of the earliest squamates. However, changes in the biota during the Cretaceous Terrestrial Revolution in the Middle/Late Cretaceous triggered changes in the ecosystem that influenced ecological and morphological adaptations in squamates that resulted in their radiation at the end of the Cretaceous. D) Early lepidosaur evolution was driven by heterogeneous rates; nevertheless, when comparing evolutionary rates of rhynchocephalians, squamates and all Lepidosauria, it is possible to appreciate that rhynchocephalian rates of body size evolution were outstandingly high and sustained over a long period of time, which suggests that rhynchocephalian decline may unexpectedly be linked to their high rates of evolution sustained over time. This fits with Simpson’s tachytelic evolution theory that suggests that a lineage with high evolutionary rates is prone to extinction. The thesis shows how modern computational methods can provide answers to long-running debates in comparative macroevolution. 1 Author’s declaration I declare that the work in this dissertation was carried out in accordance with the requirements of the University's Regulations and Code of Practice for Research Degree Programmes and that it has not been submitted for any other academic award. Except where indicated by specific reference in the text, the work is the candidate's own work. Work done in collaboration with, or with the assistance of, others, is indicated as such. Any views expressed in the dissertation are those of the author. Jorge Alfredo Herrera Flores 21th of September 2018 2 Acknowledgments I would like to express my sincere gratitude to the Consejo Nacional de Ciencia y Tecnología (CONACYT), for the financial support provided with the PhD scholarship number 224636/384587. I would like to express my deepest thanks to my PhD supervisors Professor Michael J. Benton and Dr. Thomas L. Stubbs for their encouragement, support and comprehensive advice until the end of this work. I am very grateful to the Paleobiology Research Group of the University of Bristol for the Bob Savage Memorial Fund and the Paleontological Society for the Arthur J. Boucot Award. I would like to thank Bristol Museum and Art Gallery, University of Aberdeen, Oxford University Museum of Natural History, Cambridge University Museum of Zoology, National Museum Cardiff, Dorset County Museum, Teylers Museum, Muséum National d'Histoire Naturelle, Université Claude Bernard Lyon 1, Musée des Confluences, Virginia Museum of Natural History, Smithsonian National Museum of Natural History, Naturkunde-Museum Bamberg and Bayerische Staatssammlung für Paläontologie und Geologie for the access provided to their collections. I especially thank Armin Elsler and Max Stockdale for their patience, guidance, opinion and ideas shared that considerably improved my PhD. Many thanks to my friends and colleagues of the University of Bristol Paleobiology Research Group. In particular I thank Armin Elsler, Max Stockdale, Tom Stubbs, Ben Moon, Guillermo Navalón, Arnau Bolet and Susana Gutarra for their friendship, encouragement and support. My sincere thanks to my examiners, Prof. Emily Rayfield and Prof. Susan Evans for their valuable comments and suggestions that helped me to improve my work. 3 Dedication A mis padres Rosa María Flores y Lázaro Herrera, de quienes sin su amor y apoyo no me hubiese sido posible llegar hasta aquí. A ustedes les debo todo lo que soy en la vida. A mí tía Evelia, por su amor, comprensión y cariño. A mí hermana Soledad, por su apoyo y por cuidar de mis padres en mi ausencia. A mí querido Gary, por tu apego a la vida y porque pese a tu cansancio y enfermedad esperaste pacientemente mi regreso a casa. A todas aquellas personas a las que ya no tuve oportunidad de volver a ver. “El esfuerzo mismo para llegar a las cimas basta para llenar un corazón de hombre. Hay que imaginarse a Sísifo dichoso” Albert Camus 4 Table of contents Abstract .............................................................................................................................. 1 Author declaration ............................................................................................................ 2 Acknowledgements ............................................................................................................ 3 Dedication ........................................................................................................................... 4 Table of contents ................................................................................................................ 5 List of figures ..................................................................................................................... 8 List of tables ....................................................................................................................... 8 Chapter 1 Macroevolution and an overview of Mesozoic lepidosaurs. .........................................