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Dinosaur behavior is difficult for paleontologists to study since much of paleontology is dependent solely on the physical remains of ancient life. However, trace fossils and paleopathology can give insight into dinosaur behavior. Interpretations of dinosaur behavior are generally based on the pose of body fossils and their habitat, computer simulations of their biomechanics, and comparisons with modern animals in similar ecological niches. As such, the current understanding of dinosaur behavior relies on speculation, and will likely remain controversial for the foreseeable future. However, there is general agreement that some behaviors which are common in crocodiles and birds, dinosaurs' closest living relatives, were also common among dinosaurs. Gregarious behavior was common in many dinosaur species. Dinosaurs may have congregated in herds for defense, for migratory purposes, or to provide protection for their young. There is evidence that many types of dinosaurs, including various theropods, sauropods, ankylosaurians, ornithopods, and ceratopsians, formed aggregations of immature individuals. Nests and eggs have been found for most major groups of dinosaurs, and it appears likely that dinosaurs communicated with their young, in a manner similar to modern birds and crocodiles. The crests and frills of some dinosaurs, like the marginocephalians, theropods and lambeosaurines, may have been too fragile to be used for active defense, and so they were likely used for sexual or aggressive displays, though little is known about dinosaur mating and territorialism. Most dinosaurs seem to have relied on land-based locomotion. A good understanding of how dinosaurs moved on the ground is key to models of dinosaur behavior; the science of biomechanics, in particular, has provided significant insight in this area. For example, studies of the forces exerted by muscles and gravity on dinosaurs' skeletal structure have investigated how fast dinosaurs could run, whether diplodocids could create sonic booms via whip-like tail snapping, and whether sauropods could float. ==Ceratopsian behavior== Parental care is implied by the fossilized remains of a grouping of ''Psittacosaurus'' consisting of one adult and 34 juveniles. In this case, the large number of juveniles may be due to communal nesting. Fossil deposits dominated large numbers of ceratopsids from individual species suggest that these animals were at least somewhat social.〔 However, the exact nature of ceratopsid social behavior has historically been controversial.〔 In 1997, Lehman argued that the aggregations of many individuals preserved in bonebeds originated as local "infestations" and compared them to similar modern occurrences in crocodiles and tortoises.〔 Other authors, such as Scott D. Sampson, interpret these deposits as the remains of large "socially complex" herds.〔 Modern animals with mating signals as prominent as the horns and frills of ceratopsians tend to form these kinds of large, intricate associations.〔 Sampson found in previous work that the centrosaurine ceratopsids did not achieve fully developed mating signals until nearly fully grown.〔 He finds commonality between the slow growth of mating signals in centrosaurines and the extended adolescence of animals whose social structures are ranked hierarchies founded on age-related differences.〔 In these sorts of groups young males are typically sexually mature for several years before actually beginning to breed, when their mating signals are most fully developed.〔 Females, by contrast do not have such an extended adolescence.〔 Other researchers who support the idea of ceratopsid herding have speculated that these associations were seasonal.〔 This hypothesis portrays ceratopsids as living in small groups near the coasts during the rainy season and inland with the onset of the dry season.〔 Support for the idea that ceratopsids formed herds inland comes from the greater abundance of bonebeds in inland deposits than coastal ones. The migration of ceratopsids away from the coasts may have represented a move to their nesting grounds.〔 Many African herding animals engage in this kind of seasonal herding today.〔 Herds would also have afforded some level of protection from the chief predators of ceratopsids, tyrannosaurids.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dinosaur behavior」の詳細全文を読む スポンサード リンク
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