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LABANDEIRA—PREDATORS, PARASITOIDS, AND PARASITESlevels (Dudley, 1998), a predator-prey arms racecould have developed in which not only insectpredators approached the physiological upper limitsof arthropod size, but so did their prey (Vermeij,1987; Graham et al., 1995). A third mechanism ofphysical defense is the construction of larval cases,which may be used to shield against carnivores. Thismode of larval living is standard in fossil and extantcaddisflies (Sukacheva, 1982), bagworms(Weitschat and Wichard, 1998), coleophorid moths(Labandeira, 2002b), and certain chrysomelidbeetles (Poinar, 1999a). Nevertheless, one of themost intriguing recent investigations focuses on thegeochronology of nocturnal bat predation on largemoths, based on these insects’ ultrasound-detectingtympanal structures, or “ears,” that are located ontheir metathoraces, legs, and mouthparts (Göpfertand Wasserthal, 1999; Fullard and Napoleone,2001). These ultrasound-perceiving tympanalorgans, which alert the moth to the presence ofecholocating insectivorous bats, are prime evidencefor predator avoidance strategies. Although otherevidence suggests that this system existed by themiddle Eocene (Richter and Storch, 1980), pre-Eocene bats are unknown, as is the structure offossil moth tympanal ears.PATTERNS OF CARNIVORYAMONG CONTINENTAL PHYLAOf the approximately 40 extant and extinctphyla, only 12 have invaded the continental realmof freshwater and land habitats, and of these only afew have any significant species-level diversity—principally nematodes, molluscs, annelids, and,spectacularly, arthropods. These invertebrates haveexcelled at life on land (Fig. 3), although all have amarine origin, based on physiological, paleontological,or phylogenetic data (Conway Morris, 1981;Little, 1990; Gordon and Olson, 1995; Fortey andThomas, 1998). These twelve phyla are assigned totwo superphyla (Aguinaldo et al., 1997; Ruiz-Trilloet al., 1999): the Lophotrochozoa, characterized bythe presence or a derivative of the trochophore larva;and the Ecdysozoa, characterized by the keydevelopmental innovation of molting. The origin ofterrestrial carnivory is represented in all twelvephyla, but there are in fact multiple independentorigins within subclades of these phyla. For example,within the Crustacea alone—conventionally rankedas a subphylum of the Arthropoda—the Ostracoda,Branchiopoda, Amphipoda, Isopoda, and severallineages within the Decapoda have each developedcarnivory and either a facultative or obligatecontinental existence (Little, 1983).With the exception of the arthropods andprobably nematodes, all invertebrate continentalphyla have poor fossil records. Intriguingly, theAcanthocephala and Pentostoma, extant membersof which are endoparasitic on mammals, do notoccur in the fossil record, but are thought to haveoriginated in marine habitats during the earlierCambrian, based on sister-group relationships(Conway Morris and Crompton, 1982) and aremarkable early Paleozoic record (Andres, 1989;Walossek and Müller, 1994; Walossek et al., 1994).Similarly, the Tardigrada and Onychophora, thoughtoday free-living and carnivorous, have theirearliest occurrences in the Cambrian marine realm(Müller et al., 1995; Conway Morris, 1998), butappear, respectively, in Late Paleozoic compressiondeposits (Thompson and Jones, 1980; Rolfe et al.,1982) and Late Mesozoic amber (Cooper, 1964;Bertolani and Grimaldi, 2000). For othernonarthropodan phyla, early fossil documentationis limited to either systematically unassignable orquestionably attributed Late Paleozoic finds(Nemertinea, Nematoda, Mollusca) or to mid-Mesozoic earliest occurrences of modern classes(Annelida). The phyla with the poorest and mostrecent (Cenozoic) fossil records are thePlatyhelminthes, Rotifera, and Nematomorpha, andtheir fossil representatives are referable to extantfamilies and even genera (Fig. 3) (Wills, 1993).Structural specializations related to feeding onother animals are varied and have evolved multipletimes in both the Lophotrochozoa and Ecdysozoa.Predation and parasitism were common during theearly terrestrialization of these twelve phyla, as thereis no evidence for the direct transfer of aquatic filterfeeding and epibenthic or infaunal detritivory intoterrestrial habitats (Little, 1990). In this realm, the219