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PALEONTOLOGICAL SOCIETY PAPERS, V. 8, 2002actually getting buried in more settings (Sepkoski,Bambach, and Droser, 1991; Bambach, 1993). And,as a last point, (4) as determined from thecomposition of oceanic sediments, the diversity andabundance of phytoplankton has increased duringthe post-Paleozoic. Recent work on photosyntheticsystems in marine autotrophs (Kirk, 1994;Falkowski and Raven, 1997) indicates that differenttaxa (red algae, brown algae, dinoflagellates,diatoms, coccolithophorids), common both in thephytoplankton and algal benthos, utilize differentwavelengths of light, and some function underlower light intensities than green algae, implyingthat they can conduct photosynthesis successfullyat greater depths, or in more turbid water, than greenalgae alone, thus potentially increasing the volumeof water in which primary production can occur.As an example, some dinoflagellate, rhodophyte,and diatom photosymbionts in various foraminiferaare known to conduct photosynthesis at depths twoto four times greater than chlorophytephotosymbionts (Goldstein, 1999). Although redalgae (Rhodophyta) and several types of greenalgae (Chlorophyta, Prasinophyta, and Acritarcha)are known from the Proterozoic, and charophytes(which are overwhelmingly fresh-water) and oneproblematic species of dinoflagellate are reportedfrom Silurian rocks, the Mesozoic saw a burst ofnew phytoplankton diversity. Dinoflagellatesappeared consistently for the first time in theMiddle Triassic and radiated in the Jurassic(building from 4 to 31 families); coccolithophoridsfirst appeared in the Late Triassic and radiated inthe Jurassic and Early Cretaceous (building from 2to 14 families); and diatoms first appeared in theLate Jurassic and radiated in the Cretaceous andPaleogene (building from one to 23 families) (datafrom Benton, 1993; older species diversitydiagrams also in Tappan and Loeblich, 1973). Soit may be that primary productivity in the oceansdid, in fact, expand during the Mesozoic andCenozoic, enlarging the base of the food chain tosupport the observed increase in predator diversity.Vermeij and Lindberg (2000) wrote anintriguing paper documenting that herbivory isgenerally present only in fairly derived clades andbecame important late in the history of life. Theyargue that microphagy (including suspensionfeeding),detritus feeding, and carnivory are the basalfeeding strategies. This startling, but, in the contextof phylogeny, clearly well-grounded idea nicelymaps with the dominance of suspension-feeders(brachiopods, bryozoa, crinoids) in the Paleozoicoceans. Vermeij and Lindberg place the origin ofmany important herbivorous clades in the Mesozoicand Cenozoic. The spread of herbivory would haveopened opportunity for added diversification ofpotential prey taxa and also quantitatively enlargedthe base of the trophic pyramid for marine animals.Both factors could have contributed to the increasein specialization and diversity of predators in theMesozoic and Cenozoic noted previously by others(Vermeij, 1977, 1987; Kowalewski et al., 1998) andcensused here.All of the patterns noted here are based ontaxon richness alone. To document the precisemeaning of these changes in diversity will requirequantitative evaluation of the abundance of taxa—both predators and prey. Evaluation of size (or someother proxy for biomass) will also be important.Only then can we know whether the inferencesdrawn from the changes in diversity documentedhere are correct. But until then, this is the bestpicture we have of the general history of marinepredators through the Phanerozoic.ACKNOWLEDGMENTSI want to thank Michal Kowalewski for invitingme to compile the data on predator diversity andAndy Knoll for providing opportunity for me tobegin to appreciate the importance and history ofprimary producers, the foundation on which allanimals depend. Arnie Miller and Geerat Vermeijprovided very useful and constructive reviews ofthe manuscript.350