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 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. Diet Ceratopsids were adapted to processing high-fiber plant material with their highly derived dental batteries and advanced dentition. They may have utilized fermentation to break down plant material with a gut microflora. Mallon et al. (2013) examined herbivore coexistence on the island continent of Laramidia, during the Late Cretaceous. It was concluded that ceratopsids were generally restricted to feeding on vegetation at, or below, the height of 1 meter. Physiology Ceratopsians probably had the "low mass-specific metabolic rat[e]" typical of large bodied animals. Sexual dimorphism According to Scott D. Sampson, if ceratopsids were to have sexual dimorphism modern ecological analogues suggest it would be in their mating signals like horns and frills. No convincing evidence for sexual dimorphism in body size or mating signals is known in ceratopsids, although was present in the more primitive ceratopsian Protoceratops andrewsi whose sexes were distinguishable based on frill and nasal prominence size. This is consistent with other known tetrapod groups where midsized animals tended to exhibit markedly more sexual dimorphism than larger ones. However, if there were sexually dimorphic traits, they may have been soft tissue variations like colorations or dewlaps that would not have been preserved as fossils. Evolution Scott D. Sampson has compared the evolution of ceratopsids to that of some mammal groups: both were rapid from a geological perspective and precipitated the simultaneous evolution of large body size, derived feeding structures, and "varied hornlike organs." The earliest ceratopsids, including members of both Centrosaurinae and Chasmosaurinae are known from the early Campanian stage, though the fossil record for early ceratopsids is poor. All but one of