The family Cervidae, commonly referred to as "the deer family", consists of 23 genera containing 47 species, and includes three subfamilies: Capriolinae (brocket deer, caribou, deer, moose, and relatives), Cervinae elk, muntjacs, and tufted deer), and Hydropotinae, which contains only one extant species, Chinese water deer. However, classification of cervids has been controversial and a single well-supported phylogenetic and taxonomic history has yet to be established. Cervids range in mass from 20 lbs to 1800 lbs, and all but one species, Chinese water deer, have antlers. With the exception of caribou, only males have antlers and some species with smaller antlers have enlarged upper canines. In addition to sexually dimorphic ornamentation, most deer species are size-dimorphic as well with males commonly being 25% larger than their female counterparts. Cervids have a large number of morphological synapomorphies (e.g., characteristics that are shared within a taxonomic group), and range in color from dark to very light brown; however, young are commonly born with cryptic coloration, such as white spots, that helps camouflage them from potential predators. Cervids can be found in a wide range of habitats, from extremely cold to the tropics. They have been introduced nearly world wide, but are native throughout most of the New World, Europe, Asia and northwestern Africa, with Eurasia exhibiting the greatest species diversity. Although most cervids live in herds, some species, such as South American marsh deer, are solitary. The majority of species have social hierarchies that have a positive correlation with body size (e.g., large males are dominant to small males).