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VERMEIJ—EVOLUTION IN THE CONSUMER AGEtime among molluscs in warm, shallow marinewaters (Vermeij, 1977).The history of predation following the earlyphase can be characterized as an enemy-drivenprocess of escalation involving predators, theircompetitors, and their prey (Vermeij, 1987, 1994).Slow methods of predation, reflecting low risks tothe predator during prey capture, have persistedalongside newer, more sophisticated, and notablyfaster modes such as breakage and envenomationthat also increased the size range of available prey.These higher-energy forms of predation, whichemphasize greater sensory acuity and locomotorperformance as well as greater subjugationalpower, particularly characterize productive,energy-rich environments, where prey haveadapted accordingly with highly sophisticateddefenses. As these methods evolved, predators andprey with less well developed weapons anddefenses became restricted or expanded into partsof the biosphere—the deep sea, caves, areas of lowtemperature, the safe bodies of well-defendedorganisms, and such physically constrained habitatsas deep layers in sediments or spaces beneathboulders—where access to energy and nutrients islimited (Vermeij, 1987). Very few habitatreversals—that is, from energy-poor to energy-richenvironments—are known. For example, a fewdeep-sea lineages may have penetrated shallowwaters, but they did so only at polar latitudes andin caves. Many tropical clades have invadedtemperate latitudes, but few if any have gone theother way, possibly with the exception of cladesimmediately following mass extinction.Details of the timing of significantbreakthroughs and of episodes of escalation remainstubbornly elusive, and deserve attention in futurestudies; but the summary below broadly capturesour present understanding. This account nicelycomplements Bambach’s synthesis of the globaldiversity of predators through time (Chapter 12, thisvolume), as well as inferences about the temporalincrease in productivity over the course of thePhanerozoic (Vermeij, 1987; Bambach, 1993, 1999).Predation by drilling is the most thoroughlydocumented form of consumption in the fossilrecord. During the Paleozoic, when most drillingis recorded in echinoderms and brachiopods, a peakin the intensity of (successful) drilling was reachedin the Devonian (Smith et al., 1985). Incidenceswere low from the Carboniferous to the LateCretaceous (Kowalewski et al., 1998, 2000)—generally less than 0.06 for most prey species.Modern high incidences, generally exceeding thoseof the Paleozoic, were established during earlyPaleocene to early Eocene time, and were generallymaintained through the rest of the Cenozoic. Thereare temporary declines in the late Eocene, asinferred from whole assemblages in the GulfCoastal Plain of the United States, and among earlyOligocene turritellid gastropods from the sameregion (Allmon et al., 1990; Kelley and Hansen,1993, 1996; Kelley et al., 2001).My unpublished compilation with PeterRoopnarine indicates that edge drilling, a modifiedand evolutionarily derived form of drilling in whichthe predator excavates a hole where valve marginsmeet in bivalved prey, appeared in the Jurassic(Harper et al., 1998) but did not become commonuntil the Recent.Prey effectiveness against drilling, measuredas the number of incomplete holes divided by thetotal number of holes in a sample of a given species(Vermeij, 1987), has generally increased over timesince the Late Cretaceous within lineages ofmolluscs in which the adaptive syndromehighlights passive resistance to drilling predators.Kelley (1989, 1992) has provided the mostthorough documentation of this trend in her studyof five genera of bivalves in the Chesapeake Groupof Maryland. Although there are a few exceptions,successive populations of species (whichpresumably form lineages, although this remainsto be verified) show increases in effectivenessagainst drilling from the early Miocene (Langhian)Calvert Formation to the middle Miocene(Serravalian) Choptank Formation and the earlylate Miocene St. Mary’s Formation (Tortonian).Higher effectiveness is accompanied by relativelythicker valves. Similar trends appear in some LateCretaceous to Paleogene lineages of slowburrowingbivalves (Kelley and Hansen, 1993).383