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PALEONTOLOGICAL SOCIETY PAPERS, V. 8, 2002herbivores, and omnivores, as well as carnivores,point out that only about 20% of reef fishes areherbivores. Widely spaced high peaks of turnoverin the Osteichthyes (Fig. 15) again illustrate theimportance of lägerstetten for documenting morecompletely the diversity of less easily preserved taxa,but, as with other groups discussed earlier, thegeneral track of the high points follows the overallpath of boundary-crossing standing diversity.Tetrapods.—Figure 16 illustrates the diversityof marine reptiles and predatory marine mammals.Marine birds, while important today, have too poora fossil record to be used in the analysis (no morethan eight genera are recorded for any interval).The diversity of marine reptiles fluctuated, but fromthe Triassic through the Early Cretaceous standingdiversity never rose far above 10 genera. However,there was a burst of diversification in the LateCretaceous, with continuing standing diversity risingabove 35 genera and total diversity within an intervalreaching 58 genera in the Maastrichtian. The end-Cretaceous extinction eliminated all marine reptilesexcept the sea-turtles, and these have persisted withlittle diversity change through the Cenozoic (fourof the five living genera are carnivorous; only oneis herbivorous; Parker, 1982). Marine mammals firstappeared in the Paleogene and diversifiedsignificantly in the Neogene, reaching continuingstanding diversity levels equal to that of marinereptiles in the Late Cretaceous. High turnover peaksfor total diversity recorded within intervals in theNeogene (as high as 100 genera) suggest thatNeogene marine predatory mammal diversity mayactually have significantly exceeded that of themarine reptiles of the Cretaceous. The close spacingof the high turnover peaks indicates that tetrapodfossils were not limited to infrequently occurringlägerstetten, but were preserved regularly throughtime. The high proportional turnover compared toboundary-crossing standing diversity, then, meansthat many taxa were confined to single intervals andimplies either rapid evolutionary turnover or rarityof taxa (or both).PREDATORS AND PREYReview of Predator Diversity in General.—Asseen in both Figures 3 and 17 the genus diversityof predators was low in the Cambrian, built upduring the Ordovician Radiation, fluctuated withno particular trend up or down until the end of theTriassic, increased slowly through the Jurassic andEarly Cretaceous, and has increased rapidly sincethe start of the Early Cretaceous, interrupted onlyFIGURE 17—Sequence of diversity dominance between groupings of predatory taxa based on thetiming of when the members of each group first reach relatively high diversity. Members of each grouplisted on the figure.342