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View - Kowalewski, M. - Virginia Tech

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WALKER AND BRETT—POST-PALEOZOIC PATTERNS IN MARINE PREDATIONTABLE 4—Cenozoic marine vertebrates and their functional feeding groups.TaxonomicGroupFunctionalFeedingGroupPreyForensic Evidence(potentially traceable in thefossil record)Mustelidae(Sea otters)GeneralistcarnivoresAbalone (Haliotis ); seaurchins (Strongylocentrotusfranciscanus, S. purpuratus );kelp crabs (Pugettia ); rockcrabs (Cancer ); turban snails(Tegula ); octopus (Octopus );bivalves (Tivela, Saxidomus,Tressus ); sea stars (Pisaster )Cetaceans Generalists Krill, whales, dolphin, squid,callianassids, small bivalves;no specialistsPinnipeds Generalist Two genera are specialists onmolluscs and crustaceaSea Turtles Generalist One genus (Caretta ) specialiston molluscsShell damage consisted of:fractured middle sections ofshells as a result of being hit withstones by sea otter; larger shellsmay have fractured middlesections; edge damage may bedue to otter gnawing on theedges of the shell or chippingwith a stoneGray whales suck pits in thebenthos to gather food; pits maybe ephemeral, but may bepreserved; no other informationavailableWalruses may leave marks onshells, but no record of this as yetCaretta may leave marks onmolluscan prey, but no record ofthis as yetSea Snakes Generalists Crush prey, but no record of theirpredatory prowess as yetDiving Marine Birds Generalists Eat crustacea, molluscs, fish;one genus appears tospecialize on molluscsMarine Crocodiles Generalist Birds, fish, turtles, humans,golf balls, etc.Extensive literature on birds andhow they forensically alter preyNo forensic information availablebenthic invertebrate prey. Vermeij (1987) reviewedthe molluscivorous habits of some of these groups,and here we discuss their more generalist feedingbehavior, add or update several other groups, andsuggest possible alternative scenarios to hisescalatory hypothesis.Stomatopods.—Stomatopod crustaceans areobligate carnivores and vicious predators.Stomatopods that crush the shells of their prey bypounding them with blunt expanded segments oftheir maxillipeds (e.g., Burrows, 1969) did notevolve until the Cenozoic (Hof and Briggs, 1997;Hof, 1998). Two major groups of stomatopods existtoday: the squilloids and the gonodactyloids, whichhave very different means of feeding. The squilloidseither attack prey with their dactylar spines, or graspprey between the toothed margins of their propodusand dactylus (Kunze, 1983). Squilloids typicallyprey on fish, polychaetes, and very small crustaceans(Schram, 1986). In gonodactyloids, the propodus isswung from an anterioventral position, and prey is“smashed” on the lower part of the dactylus (Kunze,1983). Gonodactyloids feed typically on hardshelledprey like molluscs and large crustaceans(Schram, 1986). Both types, however, can also scoopup prey from the benthos with their maxillipeds.153

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