View - Kowalewski, M. - Virginia Tech

PALEONTOLOGICAL SOCIETY PAPERS, V. 8, 2002THE POET TENNYSON described natureas “red in tooth and claw,” a metaphoric andseemingly apt description of predation. His imageof vertebrates dispatching other vertebrates by theuse of carnassials and talons, however, is clearlyexceptional, considering where the preponderanceof terrestrial carnivory resides; this picture shouldbe replaced by the equally grisly image ofhemolymph-encrusted mouthparts and tarsi—for itis among the invertebrates, and particularly thearthropods, where the overwhelming bulk ofcarnivory occurs in terrestrial settings. The abovequotation from Downes (1971a) about predationin the biting midge Probezzia is emblematic of theinvertebrate world, which forms an important partof the trophic capstone in terrestrial food webs. Inthis contribution, the fossil history of terrestrialinvertebrate carnivory is explored, with a focus onarthropods and especially insects. The discussionincludes examples from both freshwater andterrestrial environments, both of which belong tothe continental realm. This paper begins with adefinition of carnivory and its subcategories, thenaddresses the nature of the fossil evidence, entersinto a discussion of the historical pattern ofcarnivory, delves into four salient issues regardingits evolution, and ends in a summary. The brevityof this review does not allow for adequate coverageof all relevant issues, and it is hoped that theinterested will consult the cited references foradditional information and insight.THE NATURE OF CARNIVORYThere are three basic types of carnivory:predation, parasitoidism, and parasitism (Vinsonand Barbosa, 1987). All three comprise the thirdtrophic level characterized by the consumption oforganisms, especially of herbivores and othercarnivores. The ultimate basis of carnivory is inprimary producers whose energy originates eitherfrom the sun (photoautotrophs) or the chemicalbonds of oxidized compounds (chemoautotrophs).Primary producers provide food, via herbivores andeventually carnivores, for the sustenance of foodwebs. This trophic pyramid, together with a crucialside-loop for organisms that degrade all types ofFIGURE 1—A, Two biting midges of Probezziaconcinna (Diptera: Ceratopogonidae), in copulowith the female simultaneously feeding on the malethrough a single puncture of his head capsule. B,Posterior female abdomen of a closely relatedgenus, Palpomyia, after mating, with attached,torn-off male genitalia in light-grey shading. Bothredrawn from Downes (1971a).dead tissues (saprobes), is characterized by a typical90 percent loss in biomass and energy assimilatedat each interface between levels (DeAngelis, 1992).Interestingly, this decrease in mass and energytransferred between adjacent levels is also evidentfor each trophic type in the fossil record. Recordsof carnivory are much scarcer than records of plantherbivoreassociations (Labandeira, 2002a).212