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WALKER AND BRETT—POST-PALEOZOIC PATTERNS IN MARINE PREDATIONevolved drilling apparatuses (Woelke, 1957; Sliter,1971; Carriker, 1981; Hallock and Talge, 1994).Eight families or superfamilies of molluscshave evolved drilling behavior. Naticids are the beststudied, but the other groups of shell drillers werereviewed by Kabat (1990). Gastropods, inparticular, have evolved a variety of means to preyupon hard-shelled prey, and one major family(Cassidae) and two little known groups(Marginellidae and Nassariidae) of shell drillersoriginated in the Cenozoic; the naticids andmuricids persisted from the Mesozoic into theCenozoic (Fig. 7). In drilling gastropods (e.g.,muricids, naticids), the small rasping organ (theradula) and the accessory boring organ are used todrill holes in prey shells (Carriker, 1969). Predatorycephalopods, such as the octopus, also use theradula to bore into mollusc shells.Capulids (Capulidae, Mesogastropoda) arespecialized ectoparasites on molluscs andechinoderms (Kabat, 1990). Capulids drill their preyto extract nutrients from the host’s feeding currents.They drill sharp-sided cylindrical holes and leavean attachment scar on their host’s shell (Matsukama,1978; Kabat, 1990). Capulid-host associations dateback to the Late Cretaceous, where capulids areknown to associate with inoceramid bivalves(Hayami and Kanie, 1980). Drilled inoceramids,however, are not reported for this assemblage.Capulid attachment scars and shell morphology thatconforms to their host are reported in modern andmiddle Pleistocene assemblages (Orr, 1962; Grant-Mackie and Chapman-Smith, 1971). Suchassociations should be highly reliable, and couldpotentially be found in the fossil record (Boucot,1990). Actual evidence of capulid drilling, however,is known only from one report from the latePleistocene of Japan (Matsukama, 1978). Thus, verylittle is known about this intriguing parasitic drillingbehavior in the fossil record.Cassid (Tonnoidea, Mesogastropoda) predatoryholes (not true drillholes, but rather rasped areas) inechinoderms date back to the Early Cretaceous, buthave been little studied despite their ubiquity inCenozoic and modern echinoids (Hughes andHughes, 1981; Nebelsick and Kowalewski, 1999).Cassids use sulfuric acid from their proboscis glandand the radula to cut out (rather than drill) anirregular hole in echinoderm tests (Kabat, 1990);however, most workers use the term “drillhole” fortheir predatory traces. Although the earliest drilledechinoderm dates back to the Early Cambrian, mostdrilling predation on echinoids is known only fromthe Cretaceous and Cenozoic (Sohl, 1969; Beu etal., 1972; Nebelsick and Kowalewski, 1999). Theearliest drillholes attributed to cassids weredescribed from the Early Cretaceous (Albian) ofTexas, but the cassid drilling record is much moreextensive in the Cenozoic, especially from theEocene to present (Hughes and Hughes, 1981;McClintock and Marion, 1993; Nebelsick andKowalewski, 1999).Muricids (Neogastropoda) diversified greatlyin the Paleogene, occurring primarily in tropicalto subtropical waters, although they are found intemperate and cooler regions as well (Vokes, 1971,1990; Vermeij, 1996; Vermeij and Carlson, 2000).During times of reduced food, muricids may drillconspecifics (Spanier, 1986, 1987). An increase insuch cannibalistic boring in muricids has beenassociated with sea level changes in the Red Sea(Spanier, 1987). Rarely, some muricids drill theirown opercula or bore into dead empty shells(Prezant, 1983). While increasing drillhole size canbe correlated with increasing size of muricidpredator for some species, this does not hold forothers (Urrutia and Navarro, 2001). Muricids mayalso change their drilling behavior and preferreddrilling location on the prey with ontogeny (Urrutiaand Navarro, 2001). Drillholes in inarticulatebrachiopods are rare but reported in Recentcommunities, and may be due to muricid predation(Paine, 1963; Kowalewski and Flessa, 1997).Similar drillholes in fossil inarticulate brachiopodsreported from the Tertiary of Seymour Island,Antarctica, and the eastern United States (Cooper,1988; Wiedman et al., 1988; Bitner, 1996) may beattributed to a muricid predator.The record of naticid predatory drillholes hasbeen used extensively to examine the evolution ofpredatory behavior, escalation hypotheses, andcost-benefit analyses in modern and fossil155