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FARLOW AND HOLTZ— PREDATION IN DINOSAURSTHE FOSSIL RECORD OF PREDATION IN DINOSAURSJAMES O. FARLOW 1 AND THOMAS R. HOLTZ, JR. 21Department of Geosciences, Indiana-Purdue University Fort Wayne,2101 Coliseum Boulevard, East, Fort Wayne, Indiana 46805 USA2Department of Geology, University of Maryland, College Park, Maryland 20742 USAABSTRACT—Predatory theropod dinosaurs can usually be identified as such by features of their jaws, teeth, andpostcrania, but different clades of these reptiles differed in their adaptations for prey handling. Inferences abouttheropod diets and hunting behavior based on functional morphology are sometimes supported by evidence fromtaphonomic associations with likely prey species, bite marks, gut contents, coprolites, and trackways. Very largetheropods like Tyrannosaurus are unlikely to have been pure hunters or scavengers, and probably ate whatevermeat they could easily obtain, dead or alive. Theropods were not the only dinosaur hunters, though; other kindsof large reptiles undoubtedly fed on dinosaurs as well. The taxonomic composition of dinosaurian predator-preycomplexes varies as a function of time and geography, but an ecologically remarkable feature of dinosaurianfaunas, as compared with terrestrial mammalian faunas, is the very large size commonly attained by bothherbivorous and carnivorous dinosaurs. The K/T extinction event(s) did not end dinosaurian predation, becausecarnivorous birds remained prominent predators throughout the Cenozoic EraINTRODUCTIONCARNIVOROUS DINOSAURS (Fig. 1)included some of the biggest, most spectacularpredators of all time, but also numbered in their ranksa diversity of smaller predators. In this paper wesurvey what is known about the diets of theropoddinosaurs, and briefly consider morphologicaldifferences among taxa that presumably affected theway they dealt with prey. We will also consider nondinosauriancarnivores that likely fed upondinosaurs. Finally, we will compare the taxonomiccomposition of herbivores and carnivores indifferent dinosaurian faunas, and examine someecological questions posed by the huge body sizesattained by many predatory dinosaurs.IDENTIFYING DINOSAURIANPREDATORS AND PREYMorphological features.—It is possible toidentify most extinct tetrapods as herbivores orcarnivores from skeletal morphology by judiciouscomparison with extant animals of known foodhabits. Plant-eaters usually have dentitions suitablefor shredding, crushing, slicing, or grinding theirfodder (and patterns of tooth wear consistent withsuch oral processing), capacious guts for housingmicrobes that assist in breaking down plant fibers,and toes that terminate in blunt nails or hooves ratherthan claws (cf. Reisz and Sues, 2000). Carnivores,in contrast, have sharp teeth for ripping, cutting, ortearing flesh, narrower gut regions, and sharp clawsfor restraining and dispatching prey.On the basis of such criteria, most ornithischiansand sauropodomorphs are presumed to have beenprimarily herbivorous (Farlow, 1997; Ryan andVickaryous, 1997; Sander, 1997; Upchurch andBarrett, 2000), although some taxa may have beenmore omnivorous (Barrett, 2000). Most adulttheropods were probably vertebrate-eaters, but thereare exceptions: therizinosaurs were probably planteaters(Russell, 2000), troodontids may have beenomnivores (Holtz et al., 1998), and ornithomimidswere likely filter-feeders that consumed aquatic plantsand/or small invertebrates (Norell et al., 2001).Even among those theropods that clearly weremeat-eaters, there are major morphological251