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The Palaeontology of Ediacaran Avalonia: New Insights Using Morphometrics and Multivariate Statistical Analyses

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The Palaeontology of Ediacaran Avalonia: New Insights Using Morphometrics and Multivariate Statistical Analyses THE PALAEONTOLOGY OF EDIACARAN AVALONIA: NEW INSIGHTS USING MORPHOMETRICS AND MULTIVARIATE STATISTICAL ANALYSES by © Jessica Bernadette Hawco, B. Sc. (Honours) A thesis submitted to the School of Graduate Studies in partial fulfillment of the requirements for the degree of Master of Science Department of Earth Sciences Memorial University of Newfoundland January 2020 St. John’s, Newfoundland and Labrador Abstract The Avalonian Ediacaran fossil assemblage of Newfoundland, Canada contains abundant fossils with a wide range of morphologies and preservational styles. Quantitative morphological and statistical analysis in Ediacaran fossil assemblages has recently been used to recognize natural morphological groupings, providing evidence for variability within and between taxa. This approach is first used herein to test the grouping of the serially arranged, millimeter- scale chambered organism known as Palaeopascichnus. The combined morphometric and statistical analytical approach was applied to collected specimens from Ferryland, and demonstrates constrained, discrete growth patterns. The same technique was used to compare fossil palaeopascichnids with extant Protista, which has supported the protistan affinity for the hitherto enigmatic palaeopascichnids. This thesis also statistically investigates an Ediacaran taxonomic dispute known as the Beothukis/Culmofrons problem. The two taxa (Beothukis mistakensis and Culmofrons plumosa) were established separately, but were later synonymized. To determine the validity of this taxonomic reassignment, this thesis investigates the clustering of specimens based on their morphology and morphometrics and assesses the validity of certain taxonomic characters within the specimen dataset. These findings validate the original genus-level differentiation of Beothukis and Culmofrons, while also showing evidence for previously unrecognized variation within the genus Beothukis. Overall, this technique has led to the finding that more morphotypes may exist within the Ediacaran biota than originally thought, and proves the utility of detailed statistical and morphological analysis in determining morphological diversity and disparity. ! ""! Acknowledgments Firstly, I would like to send out my sincerest gratitude to my supervisor for this project, Dr. Duncan McIlroy. Thank you for all the support and opportunities you have given me, and for making me a better scientist. You have taught me so many valuable lessons, and have opened my eyes to the interplay between science, art and imagination – a lesson that I will take with me forward into every aspect of my life. A special thank you goes out to Dr. Suzanne Dufour, my supervisory committee member, for your contribution to this thesis, as well as to Dr. Charlotte Kenchington, who taught and explained to me (quite a few times) the morphometric and statistical technique, who spent countless days in the field and lab with me casting fossils, and for your editorial contributions to the manuscripts. I’d also like to acknowledge my fantastic Ediacaran Research group, who are truly the best group of people and the best introduction to the world of academia that I could have asked for. Kendra, Chris, Rod, Jack, Alex, Frankie, and Emily – it’s been a pleasure learning from you all and it was a joy to spend time in the field with you. Thank you for all your support. This research was financially supported by an NSERC Discovery Grant and a Discovery Accelerator Supplement awarded to Dr. McIlroy, as well as an Aldrich K. Snelgrove scholarship in Earth Sciences, and the School of Graduate Studies Fellowship awarded to myself. Funding from the Department of Earth Sciences, School of Graduate Studies, Faculty of Science, and the Graduate Students Union, in addition to student travel grants from both the PALASS and NAPC organizers, aided in allowing me to travel to present parts of my thesis at international conferences. Lastly, I’d like to thank my friends and family from the bottom of my heart for helping me through this program. You were there to cheer me on through the best parts, and to push me forward when times became rough. I owe you all a great debt. ! """! Table of Contents Abstract…………………………………………………………………………………….ii Acknowledgements………………………………………………………………………..iii Table of Contents……………………………………………………………………….....iv List of Tables………………………………………………………………………………vi List of Figures…………………………………………………………………………….vii List of Appendices……………………………………………………………………….viii Co-authorship Statement…………………………………………………………………ix Chapter 1 – Introduction and Overview…………………………….…………………...1 1.1 Introduction………………………………………………………………….……….2 1.2 Literature Review……………………………………………………….…….……...5 1.2.1 Geological Setting………………………………………………………..…...6 1.2.2 Ediacaran fossils……………………………………………………..………..9 1.2.3 Morphology of rangeomorphs……………………………………….………13 1.2.4 Previous Work…………………………………………………………..…...18 1.3 Methods…………………………………………………………………….……….21 1.3.1 Fieldwork…………………………………………………….……………....21 1.3.2 Analytical process……………………………………………………….......23 1.4 Relevance of the Study………………………………………………...………........24 1.5 References…………………………………………………………....…………......25 Chapter 2 – A quantitative and statistical discrimination of morphotaxa within the Ediacaran genus Palaeopascichnus………………………………………………….......34 2.1 Introduction…………………………………………………………………...….....36 2.2 Geological Setting…………………………………………………………...……...37 2.3 Palaeopascichnus Palaeobiology…………………………………………..…….....40 2.3.1 Autecology……………………………………………………………..……41 2.3.2 Taphonomy…………………………………………………………...…..….42 2.4 Materials and Methods……………………………………………………..…….....44 2.4.1 Morphometric and Statistical Analysis…………………………………..….49 2.5 Results.……………………………………………………………….…………......53 2.5.1 Hierarchical clustering…………………………………………………........54 2.5.2 Palaeopascichnus specimens only…………………………………….….....54 2.5.3 Palaeopascichnus specimens compared to other chambered fossil taxa…....57 2.5.4 Palaeopascichnus specimens compared to other chambered fossil taxa and extant (agglutinated) protistan taxa…………………………………………..........60 2.5.5 Summary of Results………………………………………………..………..64 2.6 Discussion…………………………………………………………………..……....69 2.7 Conclusion………………………………………………………………...…….......73 2.8 Acknowledgements………………………………………………………..……......73 ! "#! 2.9 References………………………………………………………………………......74 Chapter 3 – New insights into Ediacaran taxa Beothukis and Culmofrons: a morphometric and statistical analysis approach……………………………………….79 3.1 Introduction………………………………………………………………………....81 3.2 Geologic Setting………………………………………………………………….....82 3.3 Rangeomorph Palaeobiology…………………………………………………….....86 3.4 The Beothukis/Culmofrons problem…………………………………………….......90 3.5 Materials and Methods………………………………………………………..….....92 3.5.1 Casting.…………………………………………………………………..…..92 3.5.2 Retrodeformation………………………………………………………….…93 3.5.3 Morphometric and Statistical Analysis……………………………………...94 3.5.4 Data pre-treatment…………………………………………………………...96 3.5.5 Analyses…………………………………………………………………......97 3.6 Results…………………………………………………………………………….....98 3.6.1 Iterations……………………………………………………………………..99 3.6.2 Hierarchical Clustering on Full Dataset…………………………………....100 3.6.3 Hierarchical Clustering on Reduced Dataset (excluding Culmofrons specimens)………………………………………………………………..…........106 3.6.4 Profile Plots……………………………………………………………...…111 3.6.5 Population Distributions………………………………………………........113 3.7 Discussion……………………………………………………………………....…117 3.7.1 Usefulness of characters………………………………………………........118 3.7.2 Taxonomic subdivision of Beothukis and Culmofrons……………………..119 3.7.3 Systematic Palaeontology………………………………………………......122 3.7.4 Future Work…………………………………………………………..……126 3.7 Conclusion………………………………………………………………………....127 3.8 Acknowledgements………………………………………………………………..127 3.9 References………………………………………………………………………....129 Chapter 4 – Summary…………………………………………………………….….....136 4.1 Introduction………………………………………………………………………..137 4.2 Outcomes of Chapter two……………………………………………………….....137 4.3 Outcomes of Chapter three……………………………………………………...…138 4.4 Concluding Statement…………………………………………………………..…141 4.5 References……………………………………………………………………....…142 ! #! List of Tables Table 2.1. Characters used in the study that categorize the clusters as determined by hierarchical clustering analysis (mm)…………………………………...............................68 Table 2.2. Comparing percentage of Palaeopascichnus from Ferryland placed in the same group (percentage group match) across iterations……………………………....................69 Table 3.1. Variables categorizing the clusters as determined by hierarchical clustering analysis…………………………………….......................................................................102 Table 3.2. Variables categorizing the clusters as determined by hierarchical clustering analysis, on the reduced dataset excluding specimens defined as “Culmofrons”......................................................................................................................108 Table 3.3. Comparing percentage of specimens placed in the same group (percentage group match) across all iterations………………………………………….......................111 ! #"! List of Figures Figure 1.1. Geological context for Ediacaran fossil localities of Avalonia…………….......8 Figure 1.2. Examples of Ediacaran fossils from Avalonia…………………………..........11 Figure 1.3. Rangeomorph branching architecture…………………………………….......16 Figure 1.4. Photographs of casting method used in study…………………………….......23 Figure 2.1. Geographic location of collected Palaeopascichnus specimens……………...38 Figure
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