The Fossil Record of Shell-Breaking Predation on Marine Bivalves and Gastropods
Chapter 6 The Fossil Record of Shell-Breaking Predation on Marine Bivalves and Gastropods RICHARD R. ALEXANDER and GREGORY P. DIETL I. Introduction 141 2. Durophages of Bivalves and Gastropods 142 3. Trends in Antipredatory Morphology in Space and Time .. 145 4. Predatory and Non-Predatory Sublethal Shell Breakage 155 5. Calculation ofRepair Frequencies and Prey Effectiveness 160 6. Prey Species-, Size-, and Site-Selectivity by Durophages 164 7. Repair Frequencies by Time, Latitude, and Habitat.. 166 8. Concluding Remarks 170 References 170 1. Introduction Any treatment of durophagous (shell-breaking) predation on bivalves and gastropods through geologic time must address the molluscivore's signature preserved in the victim's skeleton. Pre-ingestive breakage or crushing is only one of four methods of molluscivory (Vermeij, 1987; Harper and Skelton, 1993), the others being whole organism ingestion, insertion and extraction, and boring. Other authors in this volume treat the last behavior, whereas whole-organism ingestion, and insertion and extraction, however common, are unlikely to leave preservable evidence. Bivalve and gastropod ecologists and paleoecologists reconstruct predator-prey relationships based primarily on two, although not equally useful, categories of pre-ingestive breakage, namely lethal and sublethal (repaired) damage. Peeling crabs may leave incriminating serrated, helical RICHARD R. ALEXANDER • Department of Geological and Marine Sciences, Rider University, Lawrenceville, New Jersey, 08648-3099. GREGORY P. DIETL. Department of Zoology, North Carolina State University, Raleigh, North Carolina, 27695-7617. Predator-Prey Interactions in the Fossil Record, edited by Patricia H. Kelley, Michal Kowalewski, and Thor A. Hansen. Kluwer Academic/Plenum Publishers, New York, 2003. 141 142 Chapter 6 fractures in whorls of high-spired gastropods (Bishop, 1975), but unfortunately most lethal fractures are far less diagnostic of the causal agent and often indistinguishable from abiotically induced, taphonomic agents ofshell degradation.
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