THE ROLE OF PREDATION AND PARASITISM IN THE EXTINCTION OF THE INOCERAMID BIVALVES: AN EVALUATION by COLIN R. OZANNE A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Geology University of South Florida August 1999 Major Professor: Peter J. Harries, Ph.D. Graduate School University of South Florida Tampa, Florida CERTIFICATE OF APPROVAL Master's Thesis This is to certify that the Masters' Thesis of COLIN R. OZANNE with a major in Geology has been approved by the Examining Committee on July 20, 1999 as satisfactory for the thesis requirement for the Master of Science degree Examining Committee: Major Prd*ssor: Peter J. Harries, Ph.D. ,. j '', v " ~ .....,,.- Member: Terrence M. Quinn, Ph.D. ~emberdisa L. Robbins, Ph.D. ACKNOWLEDGEMENTS I would like to thank my advisor, Dr. Peter J. Harries, for his enthusiastic support, knowledge and guidance during my two years at USF. I also wish to thank Dr. Terry Quinn and Dr. Lisa Robbins, for their contributions as members of my committee and their invaluable instruction throughout my graduate career. I give special thanks to Dr. Donald Crowe, my stepfather and field assistant, for putting up with my ignorance and irritability in the field and his steadfast support, both financial and psychological throughout my studies. In addition, I would like to acknowledge Neal Larson ofthe Black Hills Institute for Geologic Research for his help and guidance in the field, without which this project would not have been completed. I would also like to thank Donnely Darnell and his family for generously allowing me to collect thousands of "useless" clams on their land in Wyoming. I am also indebted to Dr. Irek Walaszczyk for his photography and helpful insights and Dr. Neil Landman for his intellectual contributions. I owe a great deal of thanks to my parents, grandparents and siblings for their support and encouragement during the past two years and thanks to my friends and fellow graduate students who challenged me, prodded me, and suffered with me at times, through this endeavor. Funding for this project was provided by the Geological Society of America, The American Museum ofNatural History in New York and the Tampa Bay Fossil Club. It was essential for the completion of this project and I am very grateful for the support. TABLE OF CONTENTS LIST OF TABLES lll LIST OF FIGURES lV ABSTRACT Vll INTRODUCTION GEOLOGIC SETTING 3 Paleogeography/Paleoceanograpy of CWIS 3 Stratigraphy 6 STUDY AREA 10 METHODS 12 RESULTS 14 Taphonomy and Preservation 14 Types of Deformities 17 "Awl Mark' 17 "Wedge" 18 "Vampire Bite" 18 "Squiggle" 20 "Bubbly" Nacre 20 Hohlkehle 20 Other 23 Distribution of Deformities 23 Statistical Results 26 Incidence of Deformities, Wyoming Sample 26 Incidence ofDeformities, Montana Sample 26 Species Composition and Percent Deformed for Wyoming Sample 28 B. eliasi zone 30 Lower B. baculus zone 31 Mid- B. baculus zone 31 Upper B. baculus zone 31 Transition zone 36 Lower B. grandis zone 36 B. grandis zone 39 DISCUSSION 41 Potential Predators 44 Marine Reptiles 45 Fishes 46 Mollusks 48 Decapod Crustaceans 49 Parasites 50 Evolutionary Implications of Predation/Parasitism 51 Why Only in the Western Interior? 60 Did This Increase in Predation, Parasitism and/or Disease Bring About the Demise of the Inoceramids? 61 CONCLUSIONS 68 REFERENCES CITED 70 APPENDICES 78 Appendix 1. Descriptions of Individual Deformed Specimens 79 Appendix 2. Statistical Results 86 Appendix 3. Species Descriptions and Plates 88 11 LIST OF TABLES Table 1 Species present within each ammonite biozone from the Wyoming 42 sample. Table 2 The occurrence of specific deformities among species of inoceramids 43 from the Wyoming sample. Ill LIST OF FIGURES Figure 1. Generalized map of the Western Interior showing likely extent of the Pierre Seaway during the Late Campanian and Early Maastrichtian (after Gill and Cobban, 1966). 5 Figure 2. Generalized stratigraphy of the Pierre Shale, its various members, contiguous formations and corresponding Stages and Sub-stages in the vicinity of the Black Hills Uplift (after Gill and Cobban, 1966). 7 Figure 3. Lithostratigraphic zonation and time-stratigraphic ammonite zonation of the Pierre Shale in the vicinity of the Black Hills Uplift (Wyoming, Montana, South Dakota). The study interval spans the ammonite zones of B. eliasi, B. baculus, B. grandis (after Gill and Cobban, 1966; Larson et al., 1997. 9 Figure 4. Location Map of Study Area. (A) An approximation of the extent ofthe Western Interior Seaway during Late Campanian/Early Maastrichtian (after Gill and Cobban, 1966). (B) Study localities identified by an asterisk(*). 11 Figure 5. Photograph of inoceramid specimen MBT: P-23 (Species F) with two "awl mark" deformities near the ventral margin of the right valve. Each depression is approximately 0.3 em deep. Specimen is actual size. 19 Figure 6. Photographs of inoceramid specimens exhibiting the common "wedge" deformity. A) The "wedge" in the right valve of specimen MBMB: P-1 (Species A) is approximately 1. 7 em long and 1.1 em wide at the margin. B) The "wedge" in right valve of specimen MBG: P-28 (Species I) is approximately 3.9 em long and 1.1 em wide at the margin. Specimens are actual size. 19 Figure 7. Photographs of inoceramid specimens exhibiting the "vampire bite" deformity. A) The "vampire bite" in the right valve of specimen MBT: P-25 (J aff. barabini) is approximately 1. 7 em long and 1.1 em at the margin. B) The "vampire bite" in the right valve of specimen MBT: P-4 (Species F) is approximately 1.3 em long and 1.0 em wide at the margin. Specimens are actual size. 21 Figure 8. Photographs of inoceramid specimens exhibiting the "squiggle" deformity. A) Specimen MBT: P-13 (Species F). B) Specimen MBT: P-6 (Species F). Specimens are actual size. 21 lV Figure 9. Photograph of inoceramid specimen exhibiting the "bubbles" or "bubbly" nacre. Specimen is actual size. 22 Figure 10. Photograph of inoceramid specimen SMB:Be Ps-2 (1. aff. barbini) exhibiting Hohlkehle. The characteristic U-shaped groove extends 6.0 em from the umbo, in a postero-ventral orientation, to the margin. Specimen is actual size. 22 Figure 11 . Photographs of irregular, "other" deformity in inoceramid specimens, A) MBG: P-18 ("I" subcircularis) and B) MBT: P-5 (Species F). Specimens are actual size. 24 Figure 12. The distribution of shell deformities showing the relative abundance of deformities for the entire sampled interval (B. eliasi - B. grandis) from populations of inoceramids from Wyoming. Note the relative abundance ofthe "wedge" and "vampire bite" deformities, comprising approximately 40% of the total deformities. 25 Figure 13. Incidence of shell deformities in populations of inoceramids from Wyoming. A general trend of increasing incidence is apparent between the ammonite zones of B. eliasi and B. grandis. 27 Figure 14. Incidence of shell deformities in populations of inoceramids from Montana. Like the Wyoming sample, a general trend of increasing incidence is apparent between the ammonite zones of B. eliasi and Transition. Units represent horizons sampled within each zone. 29 Figure 15. Species composition and the percent of each species deformed for the B. eliasi ammonite zone. The entire sample is composed of I. aff. barabini (assuming the unidentifiable specimens were also I. aff. barabini) and only 20% of the identifiable specimens showed evidence of deformity. 32 Figure 16. Species composition and the percent of each species deformed for the Lower B. baculus ammonite zone. Two species were identified, I. incurvus and I. subcircularis. Only I. incurvus showed evidence of deformity, approximately 4% of the population were deformed. 33 Figure 17. Species composition and percent of each species deformed from the Mid-B. baculus ammonite zone. Two species were identified, Species A and Species B. Species A made up the majority of the population sampled, yet had a lower percentage of deformed individuals than Species B. 34 v Figure 18. Species composition and the percent of each species deformed for the Upper B. baculus ammonite zone. Three new species were identified, Species C, D, and E, and a I aff. barabini morphotype reappeared. 20% or more of each species showed evidence of deformities. 35 Figure 19. Species composition and percent of each species deformed for the Transition ammonite zone. Five new species were identified within this zone, Species F, G, H, I, and Trochoceramus sp., as well as I aff. barabini morphotype from the previous zone. Note the high percentage of deformed individuals within each species and, although Trochoceramus sp. makes up over 20% of the total sample there is no evidence of deformity among T sp. individuals. 3 7 Figure 20. Species composition and percent of each species deformed for the Lower B. grandis ammonite zone. All species from the Transition zone persist into the Lower B. grandis except for Species G and a new species, Species J, appears. The percentage of deformed individuals for each species is consistently above 10% except forT sp., which again comprises a significant proportion of the total sample, but less than 10% ofT sp. individuals exhibit deformity. 38 Figure 21. Species composition and percent of each species deformed for the B. grandis ammonite zone. All species present within the Lower B. grandis zone persist into this zone except for Species J. An I aff. subcircularis morphotype reappears and a new species, I aff. vanuxemi, is present. This is the most speciose zone sampled and the zone with the highest percentage of deformed individuals per species. 40 Figure 22. Composite figure showing diachronous extinction of the inoceramids from global sections. Black lines represent evidence from body fossils. Gray lines represent evidence from inoceramid shell prisms (see MacLeod, 1993 for discussion of sampling).