the Chasmosaurinae. The following cladogram shows the phylogeny of Chasmosaurus according to a study by Scott Sampson e.a. in 2010. Paleobiology Chasmosaurus shared its habitat, the east coast of Laramidia, with successive species of Centrosaurus. A certain niche partitioning is suggested by the fact that Chasmosaurus had a longer snout and jaws and might have been more selective about the plants it ate. The function of the frill and horns is problematic. The horns are rather short and the frill had such large fenestrae that it could not have offered much functional defense. Paul suggested that the beak was the main defensive weapon. It is possible that the frill was simply used to appear imposing or conceivably for thermoregulation. The frill may also have been brightly colored, to draw attention to its size or as part of a mating display. However, it is difficult to prove any sexual dimorphism. In 1933, Lull suggested that C. kaiseni, which bore long brow horns, was in fact the male of C. belli of which the females would have short ones. In 1927 C.M. Sternberg concluded that of the two skeletons he had mounted in the Canadian Museum of Nature, the smaller one, NMC 2245, was the male and the larger, NMC 2280, the female. However, today the two are referred to different species. A juvenile Chasmosaurus belli found in Alberta, Canada by Phil Currie et al., reveals that Chasmosaurus may have cared for its young, like its relative, Triceratops, is hypothesized to have done. The juvenile measured five feet long and was estimated to be three years of age and had similar limb proportions to the adult Chasmosaurus. This indicates that Chasmosaurus was not fast moving, and that juveniles did not need to be fast moving either to keep pace with adults. The fossil was complete save for its missing front limbs, which had fallen into a sinkhole before the specimen was uncovered. Skin impressions were also uncovered beneath the skeleton and evidence from the matrix that it was buried in indicated that the juvenile ceratopsian drowned during a possible river crossing. Further study of the specimen revealed that juvenile chasmosaurs had a frill that was narrower in the back than that of adults, as well as being proportionately shorter in relation to the skull. See also Timeline of ceratopsian research References Chasmosaurines Late Cretaceous dinosaurs of North America Fossil taxa described in