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PALEONTOLOGICAL SOCIETY PAPERS, V. 8, 2002impact on potential prey, focusing on benthicinvertebrates. Predator guilds (e.g., marine reptiles)during the Mesozoic are surprisingly similar tothose in the Cenozoic (e.g., marine mammals),except that the players have changed. Despite thesetbacks of mass extinctions, the diversity ofpredators remained at a nearly constant proportionfrom the Late Triassic to mid-Cretaceous(Bambach and Kowalewski, 1999). However,during the last 110 million years (Late Cretaceous–Neogene), predators diversified faster than the restof the fauna (Bambach and Kowalewski, 1999).We also examine the patterns of predation inpost-Paleozoic shell structure (e.g., conchiolin andspines), shell repair, and shell drilling. However, datafrom drilling and shell repair thus far do not showunambiguous escalatory trends. For the sake ofargument, escalation is not a continual trend fromthe Mesozoic to the Cenozoic; rather, within eachera it is dependent on the suite of predators and prey.In the final section of the paper we reconsiderthe Mesozoic Marine Revolution hypothesisproposed by Vermeij (1977, 1978, 1987), and askquestions that may guide future research: Is thepattern of putative armor in invertebrates strictlyrelated to predation, or might there be otherhypotheses that could explain armor in organisms?Is there evidence that most predators are specialistson particular prey and thus might cause extremeselection in invertebrates who then respond withvarious escalating strategies (e.g., spines,chonchiolin) to mitigate the increased predationpressure? Does diffuse selection from generalistpredators cause antipredatory armor to arise in anumber of groups of invertebrates? If mostpredators are generalists, as appears to be the casebased on the evidence amassed herein, then perhapsthere was not a sufficiently intense selective forceto produce a major “sea change” in antipredatoryarmor in any one group of marine invertebrates,especially in post-Paleozoic organisms. Thus, forexample, durophagy may not necessarily mean thata predator ate molluscs; durophagous dentitioncould also indicate the eating of crustaceans, otherhard-shelled prey, or even soft prey (e.g., Plotkinet al., 1993; Wilga and Motta, 2000). Perhaps also,as Gould and Vrba (1982) have recognized, thereare a number of historical and non-adaptive routesby which specific aptations may ultimately arisein organisms, and such may also be the case withcertain antipredatory strategies.Despite its length, this paper is not an exhaustivereview. However, we did strive both to provide abroad overview of Mesozoic and Cenozoic predatorsand their potential prey, and, perhaps moreimportantly, to demonstrate that there are alternativeways to think about these predatory patterns.TRIASSIC PREDATORSAND PREDATIONAll marine benthic ecosystems were profoundlyaltered by the Permo-Triassic extinction (Fig. 1).Many Paleozoic predators were eliminated, includingmost phyllocarids, platyceratid gastropods, goniatiteammonoids, and many primitive lineages of sharks.Other active predatory groups preferentially madeit through this bottleneck, including the hybodontidsharks and the root-stocks of Mesozoic crustaceansand ammonoids (Knoll et al., 1996).Gastropods and Bivalves.—Varied archaeo- andmesogastropod taxa rediversified in the Triassic.Nonetheless, records of gastropod drilling predationare surprisingly rare in this period (Kowalewski etal., 1998). However, in a few instances, drillers seemto have had a significant impact (Fürsich andJablonski, 1984; Kowalewski et al., 1998). The firstnaticid-like mesogastropods (Ampullina) areknown from this time (see Fig. 7) (Fürsich andJablonski, 1984; Newton, 1983; Kowalewski et al.,1998). Given the rarity of naticid-like boreholesfrom the Late Triassic to the mid-Cretaceous(Albian), it has been suggested that predatorydrilling was relatively ineffective and largely lostduring the Triassic, only to be evolved again,successfully, during the Cretaceous (Kowalewski etal., 1998). Predatory septibranch bivalves alsooriginated at this time (Skelton et al., 1990).Ammonoids.—Ammonoids were nearlyextinguished by the Permo-Triassic crises.However, the ceratitic ammonoids staged a rapidrediversificiation in the Triassic. Like other120