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Reuter, Katherine J., Ms May 2020 Geology Experimental Taphonomy of Penaeid Shrimp

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Reuter, Katherine J., Ms May 2020 Geology Experimental Taphonomy of Penaeid Shrimp REUTER, KATHERINE J., M.S. MAY 2020 GEOLOGY EXPERIMENTAL TAPHONOMY OF PENAEID SHRIMP: ANALYSES OF MORPHOLOGICAL DECAY IN DIFFERENT SEDIMENTARY CONDITIONS AND OF METHODOLOGICAL PROTOCOLS ABSTRACT (79 pp.) Thesis Advisor: Carrie Schweitzer, Ph.D. Experiments using artificial sea water, sediment, and varying combinations thereof to represent different environmental settings yielded different decay rates of penaeid shrimp. Experiments were monitored by scoring decay-induced morphologies, including those commonly observed in compressed shrimp fossils. Changes in microstructural layering of cuticle and pH were also monitored throughout decay. Burial of the shrimp in kaolinite mud (powder saturated with artificial sea water) inhibited decay while the fastest decay occurred with shrimp lying unburied on the sediment-water interface. A small percentage of lime (10%) with kaolinite also resulted in slightly decreased decay rates in shrimp that experienced minor sedimentation within artificial sea water. Procedural and methodological concerns were identified from this series of sediment-based experiments. Experimental protocols and considerations for future decay experiments are suggested along with potential experimental conditions, the results of which could further taphonomic interpretations of taxonomically characteristic morphologies preserved in shrimp or other commonly compressed fossils. EXPERIMENTAL TAPHONOMY OF PENAEID SHRIMP: ANALYSES OF MORPHOLOGICAL DECAY IN DIFFERENT SEDIMENTARY CONDITIONS AND OF METHODOLOGICAL PROTOCOLS A thesis submitted To Kent State University in partial Fulfillment of the requirements for the Degree of Master of Science by Katherine J. Reuter May 2020 © Copyright All rights reserved Except for previously published materials Thesis written by Katherine J. Reuter B.S., Wittenberg University, 2016 M.S., Kent State University, 2020 Approved by Carrie Schweitzer, Ph.D. , Advisor Daniel Holm, Ph.D. , Chair, Department of Geology James Blank, Ph.D. , Dean, College of Arts and Sciences TABLE OF CONTENTS TABLE OF CONTENTS ................................................................................................... iv LIST OF FIGURES .......................................................................................................... vii LIST OF TABLES .......................................................................................................... viii ACKNOWLEDGMENTS ................................................................................................. ix INTRODUCTION ...............................................................................................................1 METHODS AND EXPERIMENTAL PROTOCOLS.........................................................3 Experiment Set 1: Artificial Sea Water without Sediment ......................................4 Experiment Set 2: Immediate Burial in Kaolinite with Compaction .......................4 Experiment Set 3: Sediment – Water Interface........................................................5 Experiment Set 4: Gradual Sedimentation of Kaolinite-Lime and Pre-Punctured Carapace .......................................................................................6 Morphological Decay...............................................................................................7 MORPHOLOGICAL RESULTS ......................................................................................10 The Effects of Pre-Punctured Carapace and Variable Gradual Sedimentation (Set 4) ........................................................................................10 The Effects of Sediment ........................................................................................10 Simulation of Rapid Burial ...................................................................................12 Cuticle Decay ........................................................................................................13 Effects of Physical Agitation and Sieving Remains .............................................15 iv CHEMICAL RESULTS ...................................................................................................17 The Effects of Sediment and Other Factors of pH Variation.................................17 The Effects of Pre-Punctured Carapace and Variable Gradual Sedimentation (Set 4) ................................................................................................................18 COMPARING RESULTS TO PREVIOUS EXPERIMENTS AND THE FOSSIL RECORD ......................................................................................................................20 The Effects of Sediment.........................................................................................20 Morphological Decay Trends ...............................................................................23 Other Results .........................................................................................................25 TAPHONOMIC INTERPRETATIONS AND THE USE OF SEDIMENT IN EXPERIMENTAL TAPHONOMY ..............................................................................29 More Accurate Interpretations of Fossil Morphology and Taphonomy ................29 Complications with the Use of Sediment and the Importance of Burial Scenarios ................................................................................................31 Excavation Methods for Buried Specimens ...........................................................33 Monitoring Individual Specimens Versus Sequential Excavation of Different Specimens ..........................................................................................35 Compression Simulation ........................................................................................38 MEASUREMENTS OF DECAY AND THEIR IMPLICATIONS ..................................43 Methods for Tracking Morphological Decay and Total Amount of Decay ..........43 Other Measurements of Decay ...............................................................................50 v MATERIALS AND OTHER CONSIDERATIONS FOR EXPERIMENTAL PROTOCOL ..................................................................................................................53 Raw Materials, Basic Observations, and Record of Information ..........................53 Experimental Containers ........................................................................................55 CONCLUSIONS................................................................................................................57 The Use of Sediment and its Effects ......................................................................57 Measurements of Morphological and General Decay ..........................................59 Other Protocol for Future Experiments and Universal Treatment of Specimens .....................................................................................................61 FIGURES ...........................................................................................................................63 TABLES ............................................................................................................................73 REFERENCES ..................................................................................................................76 vi LIST OF FIGURES Figure Page 1 Design for Experiment Set 2 ................................................................................63 2 Design for Experiment Set 3 ................................................................................64 3 Morphological scores for unaltered versus pre-punctured shrimp .......................65 4 Morphological scores for 5g- versus 20g-sedimentation-shrimp ..........................66 5 Averaged morphological scores for all Experiment Sets ......................................67 6 Fresh and decayed cuticle samples (SEM) ........................................................... 68 7 pH for Experiment Sets 1, 3, and 4 .......................................................................69 8 Stratigraphic changes in pH for Experiment Set 3 ................................................ 69 9 The effects of pre-punctured shrimp on pH ..........................................................70 10 Excavation of buried shrimp from trial experiments .............................................70 11 Experiment Set 2 shrimp excavated via mesh .......................................................71 12 Sieved remains from Experiment Set 1 .................................................................71 vii LIST OF TABLES Table Page 1 Character states and corresponding decay scores used to monitor decay rates for all Experimental Sets. Modified from Klompmaker et al. (2017) ..................72 2 Explanations for each character state, modifications during the experimental Process, and some corresponding decay scores .....................................................73 viii ACKNOWLEDGMENTS Thank you to the Amoco Alumni Scholarship for providing research support and to Dr. D.E.G. Briggs and Dr. D.A. Waugh for providing experimental and instrumentation advice. I am so grateful to my advisor, Dr. Carrie Schweitzer, for guiding me through my master’s program and for supporting the exploration of this taphonomic research. I am grateful to my committee members, Dr. Rodney Feldmann and Dr. Neil Wells, for teaching me and providing guidance throughout my time at Kent State University. I am also thankful for the comradery and mutual
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