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WALKER AND BRETT—POST-PALEOZOIC PATTERNS IN MARINE PREDATIONcuttlefish Sepia, the squids (Loligo), and Nautilus,are common in the Cenozoic (Nixon, 1988). TheSepiida, in particular, diversified greatly in theCenozoic. Benthic sepiids and cuttlefish mainly feedon small crustacea, such as prawns (Nixon, 1988).Drillholes in molluscan prey from Recentoctopods are well known (Fugita, 1916; Pilson andTaylor, 1961; Wodinsky, 1969; Nixon, 1980;Bromley, 1981; Kowalewski, 1993). Octopuses usesecretions and abrasion from an accessory salivarypapilla in the drilling process (Nixon, 1979, 1980).Their drillholes are distinctly irregular or oval, witha very small inner borehole diameter (Kabat 1990).Despite their ubiquity in modern habitats, theirability to select particular prey, and their shellcollectinghabits, few of their borings (trace fossilsof Oichnus spp.) have been reported in the fossilrecord (Bromley, 1993; Harper, 2002). Robba andOstinelli (1975) first reported octopod drillingsfrom the Pliocene of Italy. Bromley (1993) reportsoctopus drillings from the Pliocene of Greece.Walker (1991, 2001) reports octopod drillings fromthe late Pleistocene of the Galápagos Islands, andfor the late Pliocene of Ecuador. Harper (2002)records octopus drillings from the Plio-Pleistoceneof Florida. Octopods may also drill nautiloids,many shells of which have multiple drillholes(Saunders et al., 1991). Octopods also make“kitchen middens” of their favored prey type whichcan be found outside their den; the shells arecommonly drilled (Walker, 1990).Echinoderms.—Evidence for the rise of asteroidpredation in the Cenozoic is reviewed by Vermeij(1987). Gastropods were found within the oral discof the sea star, Ctenophoraster in Eocene–Oligocene deposits from Antarctica (Blake andZinsmeister, 1979). This type of in situ predationhas a long fossil history dating back to thePaleozoic, but is rarely reported from Cenozoiclocalities. It is important to note that manyCenozoic predators that ingest their prey whole,such as sea stars, don’t leave an imprint on theirprey (see Vermeij, 1987). These predators are stillabundant in the Cenozoic, and some have evolvedto prey on reef corals (such as Acanthaster plancii).Regular echinoids have emerged as a majorpredatory group. Using the jaws of their Aristotle’slanterns, echinoids are able to graze corals and evennibble on the tests of distantly related clypeasteroid“sand dollars” (Kier, 1977). An unusual modernpredatory interaction between deep-water cidaroidsand crinoids was documented by Baumiller et al.(1999): the cidaroid, Calcocidaris micans, devoursthe stalked isocrinoid, Endoxocrinus parrae.Another cidaroid, Histocidaris nuttingi, alsocontained crinoids in its gut (Baumiller et al., 1999).Chondrichthyes.—Most sharks areopportunistic predators, with limited exceptionssuch as the planktivorous whale sharks (Cortés,1999). Intriguingly, both sharks and bony fisheshave evolved similar suites of prey capturestrategies, including suction, grasping, biting,gouging, and filter feeding (Motta et al., 2002).Inertial suction feeding is thought to be ancestralin bony fishes, while the ancestral condition ofsharks most likely involved grasping the prey anddismembering it with little upper jaw protrusion(Lauder, 1985; Motta et al., 2002). Some sharks,especially durophagous forms, use an inertialsuction prey capture method similar to the bonyfish. Suction feeding has arisen many times withinthe shark group, chiefly in relation feeding onbenthic prey (Motta et al., 2002). Specializationsfor suction feeding include rapid jaw opening, around terminal mouth, reduced dentition, and theability to produce large suction pressures (Mottaet al., 2002). Whale sharks (Rhincodon) possessthese features, but are planktivorous. Thus,durophagy may be an exaptation from a primarilyadaptive form of suction feeding in sharks.Few shark groups are known to have evolveddurophagous members, and thus durophagy isconsidered a rare form of feeding. Seven speciesof chimaerids (Holocephali), one species of hornshark (Heterodontidae), one species of nurse shark(Orectolobiformes), two species of the classicallypredatory Carcharhiniformes, and seven species ofrays (Rhinobatoidea, Rajoidea, Myliobatioidea) areknown to be durophagous. Stout, flattened teethand robust jaws are the hallmarks of durophagy.Durophagy in sharks, however, does notnecessarily mean that they eat molluscs; many157