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BAMBACH—SUPPORTING PREDATORSby the devastation of the end-Cretaceous massextinction event and a brief pause in the lateEocene. Within this overall pattern is a progressiveshift in diversity dominance, as also shown inFigure 17. Although the predatory taxa thatdominated in the Cambrian actually increased indiversity during the Ordovician, they ended up onlyequal in diversity to the predator taxa that wereadded during the Ordovician Radiation. Theybecame a minority of predator taxa after the end-Ordovician extinction and were all extinct (exceptfor a few genera of conodonts) by the end of thePaleozoic. Those taxa that diversified during theOrdovician Radiation dominated predator diversitythrough the rest of the Paleozoic. In the post-Paleozoic, the taxa that had diversified first in theOrdovician Radiation recovered the diversity theylost in the end-Permian extinction (and then some),but their total diversity in the Late Cretaceous andCenozoic remained only about equal to that of allpredators from the Ordovician through Devonian.The explosive Cenozoic increase in predatordiversity was predominantly confined to groupsthat diversified strongly only after the Paleozoic,although a few early representatives of those taxawere present in the Paleozoic. This burst ofdiversification in the last hundred million years hasbrought predator diversity to a level some eighttimes greater than at any time in the Paleozoic.Evolutionary Dynamics of PredatorsCompared to Prey.—We have seen several groupsof predators with noticeably high turnover peaks(e. g., cephalopods, trilobites, all fish combined inthe Devonian and Carboniferous, and Cretaceousand Cenozoic Osteichthyes). Although it appearsthat the turnover peaks of predators as a whole, asshown in Figure 3a, frequently may beproportionately larger than the turnover peaks ofnon-predator taxa (Fig. 3b), it is not easy to judgeby eye whether this is the general case. However, ifthe differences in proportion of origination andextinction between the two groups are calculatedon an interval-by-interval basis (Fig. 18), it is clearthat the proportion of origination and extinction ofpredators is consistently greater than that for nonpredators(potential prey). The median proportionof origination for predators (Fig. 18a) is 1.4 timesthat for non-predators, and only 10 of 107 intervalsthrough the whole Phanerozoic (all in the Paleozoic,with six in the Middle and Late Ordovician whenthe overall pattern of diversity is leveling off fromthe Ordovician Radiation) have a lower proportionof origination for predators than for non-predators.From the start of the Jurassic through the Paleogene,27 intervals have the proportion of predatororigination compared to non-predators above themedian and only eight below. The same is true forthe proportion of extinction (Fig. 18b). The medianvalue for proportion of extinction of predators is1.49 times that for non-predator taxa and onlyseven of 107 intervals have a lower proportion ofextinction for predators than non-predators. Fromthe start of the Triassic through the Paleogene, 33intervals have the proportion of extinction forpredators above the median for the comparison tonon-predators and only eight are below.The increased evolutionary volatility ofpredators compared to non-predators thatcharacterizes the Mesozoic and Cenozoic actuallybegan in the Devonian. From the start of the LateDevonian through the Permian, 14 intervals show aproportion of origination for predators higher thanthe median for predators compared to non-predators,and only nine below (Fig. 18a). For the comparisonof proportion of extinction in these intervals, 17 areabove the median and only six below (Fig. 18b).Before the Late Devonian, although the proportionof origination and extinction of predators wasgenerally greater than that of non-predators, onlysix of 38 intervals had a proportion of originationhigher than the median for predators compared tonon-predators and only four of 38 intervals had aproportion of extinction of predators higher than themedian value for the comparison to non-predators.Figure 18 illustrates that predators have alwayshad more volatile evolutionary dynamics than nonpredators.Several factors other than the possibilityof intrinsically higher rates of evolution could havecontributed to the higher apparent evolutionaryvolatility of predators compared to non-predators.Because predators must always be less commonthan prey, their higher frequency of rare taxa, which343