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First Major Appearance of Brachiopod-Dominated Benthic Shelly Communities in the Reef Ecosystem During the Early Silurian Cale A.C

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Western University Scholarship@Western Electronic Thesis and Dissertation Repository August 2016 First Major Appearance of Brachiopod-Dominated Benthic Shelly Communities in the Reef Ecosystem during the Early Silurian Cale A.C. Gushulak The University of Western Ontario Supervisor Dr. Jisuo Jin The University of Western Ontario Joint Supervisor Dr. Rong-yu Li The University of Western Ontario Graduate Program in Geology A thesis submitted in partial fulfillment of the requirements for the degree in Master of Science © Cale A.C. Gushulak 2016 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Evolution Commons, Other Ecology and Evolutionary Biology Commons, Paleobiology Commons, and the Paleontology Commons Recommended Citation Gushulak, Cale A.C., "First Major Appearance of Brachiopod-Dominated Benthic Shelly Communities in the Reef Ecosystem during the Early Silurian" (2016). Electronic Thesis and Dissertation Repository. 3972. https://ir.lib.uwo.ca/etd/3972 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected], [email protected]. Abstract The early Silurian reefs of the Attawapiskat Formation in the Hudson Bay Basin preserved the oldest record of major invasion of the coral-stromatoporoid skeletal reefs by brachiopods and other marine shelly benthos, providing an excellent opportunity for studying the early evolution, functional morphology, and community organization of the rich and diverse reef-dwelling brachiopods. Biometric and multivariate analysis demonstrate that the reef-dwelling Pentameroides septentrionalis evolved from the level- bottom-dwelling Pentameroides subrectus to develop a larger and more globular shell. The reef-dwelling brachiopods in the paleoequatorial Hudson Bay Basin were more diverse than contemporaneous higher latitude reef-dwelling brachiopod faunas, with ten distinct community associations recognized in the Attawapiskat Formation. The absence or paucity of hurricane-grade storms in the paleoequatorial Hudson Bay Basin is interpreted as a major factor in the evolutionary success of the reef-dwelling brachiopods in the Attawapiskat Formation. Keywords Reef-dwelling brachiopods, early Silurian, paleoecology, evolution, Laurentia Co-Authorship Statement A more succinct version of Chapter 3 “The Paleolatiudinal morpho-gradient of Pentameroides in Telychian Laurentia” has been published by Gushulak, C.A.C., Jin, J., and Rudkin, D.M. in the Canadian Journal of Earth Sciences under the title “Paleolatitudinal morpho-gradient of the early Silurian brachiopod Pentameroides in Laurentia.” J. Jin provided assistance with the interpretation of results and editing of the manuscript while D.M. Rudkin provided additional information on the geology of the Attawapiskat Formation and editing the manuscript. ii Acknowledgments I would not have been able to finish this thesis without the support and encouragement from many people. First, I would like to thank my supervisors Dr. Jisuo Jin and Dr. Rong-yu Li. Dr. Jin’s advice and support over these last two years have been an immense help to me. Although not in London, I always appreciated Dr. Li’s support from Manitoba and friendly meetings when I was back home. I would like to thank Dr. Paul Copper for kindly making his fossil collections from Manitoulin and Anticosti islands freely available during this project. I also thank Mr. David Rudkin and Mr. Peter Fenton from the Royal Ontario Museum for their guidance and assistance in field work on Akimiski Island and the James Bay lowlands. Mr. Rudkin is thanked again for his input on Chapter 3 of this thesis and the subsequent publication. I also thank the territorial government of Nunavut for allowing access to Akimiski Island. Logistics and funding support for the Hudson Bay lowlands fieldwork were provided by the Ontario Ministry and Natural Resources and the Natural Sciences and Engineering Research Council of Canada. I would like to thank my lab-mates Nikole Bingham-Koslowski, Shuo Sun, and Colin Sproat. It has been great working with you over the past two years. Special thanks to Colin for dealing with my rants and explaining how cameras work. I thank the Western Taekwondo Club for accepting me into their family with open arms and being great friends during my time at Western. Apologies are given if I have kicked any of you too hard, graduate work can be stressful. iii Finally, I need to thank my family for their continuing and unwavering support of academic goals. Without your encouragement I would not have had the courage to move across the country and complete this degree. Research is impossible without funding. Funding for this project was provided by a University of Western Ontario entrance scholarship, teaching assistanceships in the Department of Earth Sciences, and a Western Graduate Research Sholarship from the Univeristy of Western Ontario; an Ontario Graduate Scholarship to Cale A.C. Gushulak from the Ontario provincial government; and an NSERC discovery grant to J. Jin. iv Table of Contents Abstract ............................................................................................................................... i Co-Authorship Statement ............................................................................................... ii Acknowledgments ........................................................................................................... iii Table of Contents ............................................................................................................. vi List of Tables .................................................................................................................... x List of Figures .................................................................................................................. xi List of Equations .......................................................................................................... xxii List of Appendices ......................................................................................................... xiii 1 Chapter 1 – Introduction ............................................................................................ 1 1.1 Introduction ............................................................................................................. 1 1.2 The Silurian World .................................................................................................. 3 1.2.1 Paleogeography and Tectonism ..................................................................... 3 1.2.2 Climate and Sea Level ................................................................................... 6 1.2.3 Ocean Circulation and Chemistry .................................................................. 9 1.2.4 Silurian Recovery Fauna .............................................................................. 10 1.3 Brachiopods and their Importance as Paleoecological Indicators.......................... 13 1.3.1 Pentameride Brachiopods in the Silurian ..................................................... 15 1.4 Silurian Level-Bottom Brachiopod Communities ................................................. 16 1.5 The Reef Environment ........................................................................................... 19 1.6 The Cause of Tropical Biodiversity ....................................................................... 21 1.7 Overall Objectives of Thesis Projects .................................................................... 22 1.8 Organization of the Thesis ..................................................................................... 23 References ................................................................................................................... 25 v 2 Chapter 2 – Geological Settings ............................................................................... 42 2.1 Tectonic Arrangement of Laurentia ....................................................................... 42 2.2 Coral-Stromatoporoid Reefs in the Llandovery ..................................................... 45 2.3 The Attawapiskat Formation, Hudson Platform .................................................... 48 2.3.1 Materials ...................................................................................................... 53 2.4 Anticosti Island ...................................................................................................... 56 2.4.1 Laframboise Member, Ellis Bay Formation ................................................ 57 2.4.2 East Point Member, Meniér Formation ....................................................... 59 2.4.3 Pavillon Member, Jupiter Formation ........................................................... 61 2.4.4 Chicotte Formation ...................................................................................... 63 2.5 Michigan Basin ...................................................................................................... 63 2.5.1 Fossil Hill Formation, Manitoulin Island..................................................... 64 2.5.2 Racine Formation, Wisconsin ...................................................................... 65 2.6 Högklint Formation, Gotland, Sweden (Baltica) ................................................... 66 2.7 Biostratigraphic correlations
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