In lieu of an abstract, here is a brief excerpt of the content:

589 What Did Dinosaurs Eat: Coprolites and Other Direct Evidence of Dinosaur Diets Karen Chin What did the Mesozoic dinosaurs really eat? This question has spawned numerous hypotheses from scientists, dinosaur enthusiasts, and fantasy writers . Speculations about dinosaur diets are frequently based on indirect evidence such as surveys of available food (i.e., contemporaneous organisms) and theories about foraging abilities inferred from functional morphology. Such analyses are important tools that suggest generalized dinosaur feeding strategies. Even so, indirect evidence cannot tell us more specifically which available foods were actually eaten. Did dinosaurs really feast on ferns, munch on mammals, and eat each other? We will never completely understand dinosaur food habits, but scrutiny of the fossil record has revealed a number of fortuitous traces of dinosaur feeding activities. These clues are usually rare and often controversial, but they provide paleobiological information that can help us better understand dinosaurs and their interactions with other organisms. In order to look for direct evidence of dinosaur diets, we can consider all stages of feeding behavior, including search, capture, ingestion, digestion , and defecation (Bishop 1975). Although these activities often leave little preservable evidence, animals spend a substantial proportion of their time seeking food, so it is not surprising that some traces of feeding activity have been preserved. Clues have been gleaned from a variety of trace fossils (fossils that indicate the activity of organisms) and from distinctive assemblages of skeletal material. These disparate sources of fossil evidence provide multiple perspectives on dinosaur feeding habits. The act of looking for food might seem to be untraceable, but dinosaurs occasionally left tracks that suggest that they were actively seeking dinner. At a famous Early Cretaceous site along the Paluxy River in Texas, tracks from one or more theropods appear to follow several sauropod trackways. It is apparent that the sauropods preceded the theropods because the theropod footprints are superimposed on top of several of the sauropod tracks. Furthermore, sedimentological evidence suggests that this track layer was deposited in a single event; thus, it is possible that the tracks on this surface were laid down within a relatively short time frame (J. O. Farlow personal communication). Early dinosaur tracker Roland T. Bird suggested that the dovetailing trackways indicate that the theropods were hot on the heels of the sauropod herd (Farlow 1987), and more recent analysis supports that at least one theropod closely followed one of the sauropods (J. O. Farlow personal communication). This fortuitous sequence of tracks thus appears Trackways as Evidence of the Search for Food 28 28.1. Map of the Yale Deinonychus quarry in Montana (YPM 64–75) showing partial skeletal remains of both Deinonychus and Tenontosaurus and more than 35 Deinonychus teeth scattered about the site. The abundance of shed teeth is consistent with an increased incidence of tooth loss during feeding. Figure published in the Journal of Vertebrate Paleontology (Maxwell and Ostrom 1995). Karen Chin 590 to provide rare evidence of theropod hunting behavior. Hunting activity is also suggested by another set of Upper Cretaceous theropod/sauropod trackways in Bolivia, where several theropod trackways parallel and overlap prints made by a group of sauropods (Leonardi 1984; Lockley 1991). Another possible theropod hunting scenario is presented by a Cretaceous trackway assemblage in Australia. This site contains thousands of tracks and has been interpreted as a dinosaur “stampede” triggered by a single large theropod stalking a mixed group of small coelurosaurs and ornithopods (Thulborn and Wade 1979). Although the large theropod footprints do not actually follow the smaller dinosaur tracks, the long stride lengths and parallel trackways of the more than 100 small dinosaurs suggest that they were fleeing a significant threat. Surprisingly, fossil tracks may also provide information about the foraging behavior of herbivorous dinosaurs. A set of intriguing Cretaceous footprints in the roof of a Utah coal mine were found clustered around fossil tree trunks that were preserved in growth position. The tracks are oriented toward the tree trunks and suggest the shuffling steps of browsing hadrosaurs (Parker and Rowley 1989; L. Parker personal communication). Predator/prey interactions can occasionally be inferred from taphonomic associations of different organisms in exceptional fossil assemblages. Concentrations of theropod teeth among the bones of other animals are particularly telling. Dinosaur teeth were continually shed as new ones grew in, so we should expect to find them in feeding areas where vigorous biting accelerated tooth loss. Probable theropod feeding sites are indicated by the discovery of numerous theropod teeth with sauropod skeletons in the Upper Jurassic...

Share