) on display at the
Museum of Osteology Although most goat-antelopes are gregarious and have fairly stocky builds, they diverge in many other ways – the
muskox (
Ovibos moschatus) is adapted to the extreme cold of the
tundra; the
mountain goat (
Oreamnos americanus) of
North America is specialised for very rugged terrain; the
urial (
Ovis orientalis) occupies a largely infertile area from
Kashmir to
Iran, including much desert country. The
Armenian mouflon (
Ovis gmelini gmelini) is thought to be the ancestor of the modern
domestic sheep (
Ovis aries). Many species have become extinct since the last
ice age, probably largely because of human interaction. Of the survivors: • Five are classified as endangered, • Eight as vulnerable, • Seven as of concern and needing conservation measures, but at lower risk, and • Seven species are secure. Members of the group vary considerably in size, from just over long for a full-grown
grey goral (
Naemorhedus goral), to almost long for a musk ox, and from under to more than . Musk oxen in captivity have reached over . The lifestyles of caprids fall into two broad classes: 'resource-defenders', which are territorial and defend a small, food-rich area against other members of the same species; and 'grazers', which gather together into herds and roam freely over a larger, usually relatively infertile area. The resource-defenders are the more primitive group: they tend to be smaller, dark in colour, males and females fairly alike, have long, tessellated ears, long manes, and dagger-shaped horns. The grazers (sometimes collectively known as
tsoan caprids, from the Hebrew ''
tso'n'' meaning sheep and goats) evolved more recently. They tend to be larger, highly social, and rather than mark territory with scent glands, they have highly evolved dominance behaviours. No sharp line divides the groups, but a continuum varies from the serows at one end of the spectrum to sheep, true goats, and musk oxen at the other. ==Evolution==