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PALEONTOLOGICAL SOCIETY PAPERS, V. 8, 2002Conodonts.—Feeding in conodonts is still notfully understood, but recent studies of both growthpatterns and evidence of wear of conodont elements(summarized in Purnell, 2001) indicate thatconodontophorids were not suspension (filter)feeders, but were macrophagous. The combinationof their life habits as swimming animals (shownby fin-like features in well-preserved specimensplus their general facies-crossing distribution), thepresence of large eyes (also shown in wellpreservedspecimens), and the evidence ofmacrophagy suggests they were predators. Thegenus diversity of conodontophorids (Fig. 13a)reached a peak in the Ordovician, droppedmarkedly in the Ordovician extinction, recoveredbut to a plateau at about half the Ordovicianmaximum extending from the Silurian through theEarly Carboniferous (with another sharp hit andrecovery in the Late Devonian), and then declinedgradually to extinction by the end of the Triassic.Agnathans.—Although some living jawlessfish are parasites and can effectively be consideredpredators, there is little direct evidence of the dietof most fossil agnathans. Recent opinions,summarized by Purnell (2001), range frompredation (two claims in the last decade) to filterfeeding(two claims), but strongly favor depositfeeding(nine claims) as a major mode of life foragnathans. On this basis I omit the jawless fish fromthe count of predators even though some livingagnathans are harmful parasites that can beresponsible for the death of their food suppliers.Classes of Jawed Fish.—Three classes ofjawed fish with predominantly cartilaginousinternal skeletons became important in thePaleozoic: the placoderms, acanthodians, andchondrichthyans. As a group (Fig. 13b) these threeclasses had relatively high diversity in theDevonian and Carboniferous, declining diversityin the Permian, slowly rising diversity from thestart of the Triassic through the Early Cretaceous(when they again reached diversity levels close tothose achieved in the Devonian and Carboniferous),and then a major increase in diversity in the LateCretaceous with a slower, but steady, increasethrough the Cenozoic. The Late Cretaceous andCenozoic increase in diversity was restricted to theChondrichthyes, the only one of the three classeswith cartilaginous internal skeletons to survive thePaleozoic. The large increase was predominantly thediversification of the Neoselachians, in which “therelationship between the braincase and the jaws ismodified to form a more maneuverable feedingapparatus” (Carroll, 1988, p. 74). Carroll goes on topoint out that this permits modern sharks to dig intolarger prey and gouge out large pieces of flesh, andalso permits the jaws of bottom-feeding forms toform an effective suction device. When the diversityof conodontophorids is added (Fig. 13c), the patternof high Ordovician through Carboniferous diversity,low Permian through Early Cretaceous diversity, andhigh Late Cretaceous and Cenozoic diversity is evenmore striking and is similar to the arthropods andechinoderms. Note that the bony fishes, theOsteichthyes, are not included in this grouping,which is limited only to those classes of vertebratesthat achieved major peaks of diversity in thePaleozoic. If we consider only the Paleozoic(Fig. 14a), but look at all predatory vertebrateclasses, including the Osteichthyes, we see asequential replacement in diversity dominance fromacanthodians in the Silurian and Early Devonian toplacoderms in the Middle and Late Devonian (withsignificant, but subordinate, contributions from theacanthodians, Osteichthyes, and Chondrichthyes) todiversity dominance by the Chondrichthyes in theCarboniferous and Permian. In the post-Paleozoic(Fig. 14b) the Chondrichthyes have increased indiversity more or less monotonically, with an offsetin the early part of the Late Cretaceous. On theother hand, the Osteichthyes diversified at aboutthe same rate as the Chondrichthyes during theentire Mesozoic, as can be seen by the near 50-50division between the two groups of their combineddiversity, including the “burst” in the LateCretaceous; but the bony fish skyrocket in diversityduring the Cenozoic (Figs. 14b and 15).The Late Cretaceous jump and the rapidCenozoic rise of diversity in predatory bony fishlargely reflects the radiation of the teleosts. Most,but not all, teleosts are predators. Moyle and Cech(1996), who note that teleosts include detritivores,338