Addax

The addax (Addax nasomaculatus), also known as the white antelope and the screwhorn antelope, is an antelope native to the Sahara Desert. The only member of the genus Addax, it was first described scientifically by Henri de Blainville in 1816. As suggested by its alternative name, the addax has spiral horns that are 55 to 80 cm (22 to 31 in) long in females and 70 to 85 cm (28 to 33 in) in males. In the winter, its coat is greyish-brown with white hindquarters and legs, and long, brown hair on the head, neck, and shoulders; in the summer, the coat turns almost completely white or sandy blonde. Males stand from 105 to 115 cm (41 to 45 in) at the shoulder, with females at 95 to 110 cm (37 to 43 in). They are sexually dimorphic, as the females are smaller than the males.

The addax lives in arid regions, semideserts and sandy and stony deserts in North Africa. It mainly eats grasses and leaves of shrubs, leguminous herbs and bushes. It can live without water for long periods of time. Addax form herds of five to 20 members, consisting of both males and females. The herd is usually led by one dominant male. Breeding season is at its peak during winter and early spring.

The addax is listed as critically endangered on the IUCN Red List. It was once abundant, but is currently restricted to Chad, Mauritania and Niger. It is threatened by unregulated hunting and is locally extinct in Western Sahara, Algeria, Libya, Egypt and Sudan.

The scientific name of the addax Addax nasomaculatus was proposed by Henri Marie Ducrotay de Blainville in 1816 who described a specimen in William Bullock's Pantherion and the Museum of the Royal College of Surgeons. Its type locality is probably in the Tunisian part of the Sahara.

The generic name Addax is thought to be obtained from an Arabic word meaning a wild animal with crooked horns. It is also thought to have originated from a Latin word. The name was first used in 1693. The specific name nasomaculatus comes from the Latin words nasus (or the prefix naso-) meaning nose, and maculatus meaning spotted, referring to the spots and facial markings of the species. Bedouins use another name for the addax, the Arabic bakr (or bagr) al wahsh, which literally means "the cow of the wild". That name can be used to refer to other ungulates as well. The other common names of addax are "white antelope" and "screwhorn antelope".

The addax has 29 pairs of chromosomes. All chromosomes are acrocentric except for the first pair of autosomes, which are submetacentric. The X chromosome is the largest of the acrocentric chromosomes, and the Y chromosome is medium-sized. The short and long arms of the pair of submetacentric autosomes correspond respectively to the 27th and 1st chromosomes in cattle and goats. In a study, the banding patterns of chromosomes in addax were found to be similar to those in four other species of the subfamily Hippotraginae.

In ancient times, the addax occurred from northern Africa through Arabia and the Levant. Pictures in a tomb, dating back to 2500 BCE, show at least the partial domestication of the addax by the ancient Egyptians. These pictures show addax and some other antelopes tied with ropes to stakes. The number of addax captured by a person were considered an indicator of his high social and economic position in the society. The pygarg ("white-buttocked") beast mentioned in Deuteronomy 14:5 is believed by Henry Baker Tristram to have been an addax. But today, excess poaching has resulted in the extinction of this species in Egypt since the 1960s.

Addax fossils have been found in four sites of Egypt – a 7000 BCE fossil from the Great Sand Sea, a 5000–6000 BCE fossil from Djara, a 4000–7000 BCE fossil from Abu Ballas Stufenmland and a 5000 BCE fossil from Gilf Kebir. Apart from these, fossils have also been excavated from Mittleres Wadi Howar (6300 BCE fossil), and Pleistocene fossils from Grotte Neandertaliens, Jebel Irhoud and Parc d'Hydra.