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WALKER AND BRETT—POST-PALEOZOIC PATTERNS IN MARINE PREDATIONboreholes, holes drilled by muricids are considerablyless frequent in the Cretaceous than in most Eoceneand younger samples (Vermeij, 1987).Cephalopods.—As in the Jurassic, there werea host of belemnoids, ammonoids and nautiloidspresent in the Cretaceous (Fig. 6). All of these wereprobably nektonic predators, though their food mayhave ranged from zooplankton and larvae to othercephalopods (Packard, 1972). Cretaceous octopiare also known. While modern nautiloids appearto be extensively drilled by octopods (Saunders etal., 1991), no data exists for drilling predation onMesozoic nautiloids. As in the Jurassic, Cretaceousammonoids are thought to have been carnivorous.However, many species are thought to have eatenzooplankton (Ward, 1986).Stomatopods.—Stomatopods are known tohave extreme specialization in their limbs that isrelated to their predatory activities; no other majorextant malacostracan group has such specialization(Kunze, 1983). All stomatopods are obligatecarnivores (Table 1)—they eat only live prey—anduse their large raptorial second maxillipeds for preycapture (Kunze, 1983). These folding raptorialthoracopods can be used in two ways: as eithersmashing or spearing appendages. Folding raptorialthoracopods are known from the Carboniferouspalaeostomatopods (Schram, 1969), and within theMesozoic forms. The extant superfamilies ofstomatopods are thought to have originated in theCretaceous (approximately 100 Ma; Ahyong andHarling, 2000); however, the true fossil record ofthis group begins in the Cenozoic, and will bediscussed in that section.Based on fossil mouthparts, specialization forthe stomatopod’s zealous carnivorous life styleevolved very early, by the Late Devonian or EarlyCarboniferous, and the trend continued into theMesozoic (Schram, 1979). Mouthparts shred theprey, and food is stuffed into the mouth, not unlikethe way an energetic, hungry teenager feeds.Undigestible shell and cuticular material isregurgitated. The regurgitated remains have notbeen examined from a taphonomic perspective.Decapods.—In contrast, to stomatopods,decapods are not obligate carnivorous predators;most are scavengers (Schram, 1986). The majorityof the durophagous forms evolved in the Cenozoic,with just a few forms evolving in the Cretaceous(Table 1). The portunids and xanthids evolved inthe Cretaceous, and today are generalist andopportunistic feeders, occasionally eating hardshelledprey like molluscs. The slipper lobsters mayhave evolved in the Late Cretaceous, and they arethought to feed on scyphozoans (Table 1).Chondricthyes.—The neoselachian sharksradiated during the Cretaceous. Cartilaginous sharkskeletons do not fossilize well, and consequently,their teeth are used to infer their feeding behavior(Shimada, 1997). Despite popular accounts thatCretaceous sharks were some of most voraciousof all predators, it is still not clear whether theirattacks were on live or scavenged organisms.Healed injuries are usually taken to be attacks onlive prey, but these are rare in the fossil record.Necrosis around bite marks is also used to inferpredatory shark attacks (Schwimmer et al., 1997).Additionally, animals associated with sharkremains are usually interpreted as the shark’s lastmeal or as associative potential prey. For instance,in the Late Cretaceous Niobrara Chalk, a lamniformshark (Cretoxyrhina mantelli) is accompanied bywell-preserved cartilagenous skeletal elementspresumably from its last meal, the fish Xiphactinusaudax (Shimada, 1997).Late Cretaceous lamniform sharks(Cretoxyrhina) up to 6 m in length attacked orscavenged mosasaurs and perhaps plesiosaurs, and,in turn, were themselves possibly attacked orscavenged by other sharks (anacoracids; Shimada,1997). Dental arcades of Cretoxyrhina are similarto those of modern predatory mako sharks, and,not surprisingly, they belong to the FamilyLamnidae that includes the mako (Isurus), greatwhite (Carcharodon), and salmon shark (Lamna)(Shimada, 1997). Although shark taxa are differentthrough geologic history, Late Cretaceous sharks’functional feeding capabilities in ecosystems showparallels to modern sharks (Shimada, 1997).Direct evidence of shark predation on mosasaursis very rare. Shimada (1997) discusses severalreports of putative shark attacks on mosasaurs, either141