subspecies – namely O. gazella, O. b. beisa, O. b. callotis, O. dammah, and O. leucoryx – were compared with the standard karyotype of Bos taurus. The number of autosomes in all karyotypes was 58. The X and Y chromosomes were conserved in all five species. Physical description The scimitar oryx is a straight-horned antelope that stands just over at the shoulder. The males weigh and the females . The body measures from the head to the base of the tail. The tail is long and ends with a tuft. They are sexually dimorphic with males being larger than females. Its coat is white with a red-brown chest and black markings on the forehead and down the length of the nose. The coat reflects the sun's rays, while the black portions and the tip of the tongue provide protection against sunburn. The white coat helps to reflect the heat of the desert. Calves are born with yellow coats and lack distinguishing marks, which appear later in life. Their pelage changes to adult coloration at 3–12 months old. Both male and female oryxes have horns, with the females' being more slender. The horns are long, thin, and symmetrical, and curve backward (a distinctive feature of this species); they can reach in both sexes. The hollow walls of the horns are so thin that they can easily break. The female's udder has four teats. The large, spreading hooves are well adapted to allow these antelopes to walk on the sand of their dry habitats. A scimitar oryx can live as long as 20 years. At Smithsonian National Zoo, a female oryx died at 21, an exceptional age since females generally have a lifespan of about 15 years. Diseases and parasites The scimitar oryx can be infected with cryptosporidiosis, a parasitic disease caused by protozoan parasites of the genus Cryptosporidium in the phylum Apicomplexa. A study in 2004 revealed that C. parvum or similar organisms infected 155 mammal species, including the scimitar oryx. An analysis in 2005 found Cryptosporidium parasites in stool samples from 100 mammals, including the scimitar oryx. Oocysts of a new parasite, Eimeria oryxae, have been discovered in the feces of a scimitar oryx from Zoo Garden in Riyadh. In France, Streptococcus uberis was isolated for the first time in an oryx. It had caused vegetative endocarditis in the animal, leading to fatal congestive heart failure. Ecology and behavior The