In terms of cladistics, which reflects evolutionary history, mammals are the only living members of the Synapsida; this clade, together with Sauropsida (reptiles and birds), constitutes the larger Amniota clade. The early synapsid mammalian ancestors were sphenacodontpelycosaurs, a group that included the non-mammalian Dimetrodon. At the end of the Carboniferous period around 300 million years ago, this group diverged from the sauropsid line that led to today's reptiles and birds. The line following the stem group Sphenacodontia split into several diverse groups of non-mammalian synapsids—sometimes incorrectly referred to as mammal-like reptiles—before giving rise to Therapsida in the Early Permian period. Mammals originated from cynodonts, an advanced group of therapsids, during the Late Triassic. The modern mammalian orders arose in the Paleogene and Neogene periods of the Cenozoic era, after the extinction of non-avian dinosaurs, and have been the dominant terrestrial animal group from 66 million years ago to the present.
The Island Fox (Urocyon littoralis) is a small fox that is native to six of the eight Channel Islands of California. It is the smallest fox species in the United States. There are six subspecies of the fox, each unique to the island it inhabits, reflecting its evolutionary history. Other names for the Island Fox include Coast Fox, Short-Tailed Fox, Island Gray Fox, Channel Islands Fox, Channel Islands Gray Fox, California Channel Island Fox and Insular Gray Fox. The Island Fox shares the Urocyongenus with the mainland Gray Fox, the fox from which it is descended. Its small size is a result of island dwarfing, a kind of allopatric speciation. Because Island Foxes are geographically isolated they have no immunity to parasites and diseases brought in from the mainland and are especially vulnerable to those domestic dogs may carry. In addition, Golden Eagle predation and human activities devastated fox numbers on several of the Channel Islands in the 1990s. Four Island Fox subspecies were federally protected as an endangered species in 2004, and efforts to rebuild fox populations and restore the ecosystems of the Channel Islands are being undertaken.
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Did you know?
...that one burrow of the eastern chipmunk(pictured) was found to contain 390 acorns?
A 2-month old domesticgoat (Capra aegagrus hircus) kid in a field of capeweed. Goats are one of the oldest domesticated species. For thousands of years, goats have been used for their milk, meat, hair, and skins over much of the world. Female goats are referred to as does or nannies, intact males as bucks or billies; their offspring are kids.
A portrait of a cheetah at Whipsnade Zoo in Bedfordshire. Cheetahs have small and streamlined heads. Their ears are small, short, and rounded, marked by black patches on the back and tawny edges. Their high-set eyes have round pupils, while their whiskers are fine and inconspicuous. Their faces have unique "tear streak" markings that may serve to reduce glare or define facial expressions.
The leopard (Panthera pardus) is one of five extant species in the genus Panthera, a member of the cat family, Felidae. This photograph shows a leopard devouring an impala in Kruger National Park, South Africa. Compared to other wild cats, the leopard has a relatively large skull with powerful jaws, a long body and short legs. It can climb trees very skilfully, often rests on tree branches and can descend to the ground head first. An adult leopard is strong enough to drag a carcass heavier than itself up into a tree, where the prey may be eaten straight away or cached to be consumed later.
A domesticated yak at Yamdrok Lake in Tibet. The animals are important to Tibetan culture, and have been kept for thousands of years. The yaks are a method of transportation and serve as beasts of burden. Their feces are a source of fuel, and their milk can be used for butter, which is then made into sculptures or consumed.
The impala (Aepyceros melampus) is a medium-sized African antelope. The name comes from the Zulu language. They are normally reddish-brown, with lighter flanks, white underbellies, and a characteristic "M" marking on the rear. Males have lyre-shaped horns, which can reach up to 90 cm (35 in) in length. They are strong jumpers, able to reach distances more than 10 m (33 ft) in a single bound. They are also fast runners, capable of reaching speeds up to 90 km/h (56 mph).
Zootomical terms of location overlap considerably with terms used in human anatomy. In animals, the head end is called the "cranial end" and the tail end is the "caudal end". The side of the body normally oriented upwards is the "dorsal" side; the opposite side, typically the one closest to the ground when walking on all legs, swimming or flying, is the "ventral" side.
A portrait of an African elephant, highlighting its trunk. The trunk, which contains some 150,000 muscle fascicles, is a fusion of the nose and upper lip with a unique nerve running along both sides. An elephant can use its trunk for power functions, such as lifting up to 350 kg (770 lb), or more delicate functions, such as wiping its eye.
A Braunviehcow wearing a cow bell below Fuorcla Sesvenna in the Engadin, Switzerland. Of Swiss origin, these cows were imported to the United States in the 19th century where they became the origin of the modern Brown Swiss cattle breed. Since the 1960s, Brown Swiss cattle have been crossed back into the Braunvieh stock of Europe. They are commonly various shades of brown in colour with lighter points.
Drymoreomys is a genus of South American rodent represented by a single species, D. albimaculatus. First formally described in 2011, the species prefers dense, moist, montane and premontane forest. Morphological evidence suggests they are tree dwellers.
The greater kudu (Tragelaphus strepsiceros) is a species of woodland antelope in the genus Tragelaphus found throughout eastern and southern Africa. Despite occupying widespread territory, they are sparsely populated in most areas due to declining habitat, deforestation and poaching. The greater kudu is one of two species commonly known as kudu, the other being the lesser kudu, T. imberbis. Greater kudus have a narrow body with long legs, and their coats can range from brown or bluish grey to reddish brown. They possess between four and twelve vertical white stripes along their torso. The head tends to be darker in colour than the rest of the body, and exhibits a small white chevron running between the eyes. The helical horns of adult males grow as the animal ages, reaching '"`UNIQ--templatestyles-00000007-QINU`"' 2+1⁄2 rotations at about 6 years old.
This picture shows a greater kudu bull photographed near Groot Okevi in Etosha National Park, Namibia. Bulls weigh 190–270 kg (420–600 lb), up to a maximum of 315 kg (690 lb), and stand up to 160 cm (63 in) tall at the shoulder.