Rothschild's giraffe creamier hue compared to that seen on the reticulated giraffe. In addition, Rothschild's giraffe displays no markings on the lower leg, giving it the impression of wearing white stockings. Another distinguishing feature of Rothschild's giraffe, although harder to spot, is the number of ossicones on the head. This is the only "Giraffa" phenotype to be born with five ossicones. Two of these are the larger and more obvious ones at the top of the head, which are common to all giraffes. The third ossicone can often be seen in the center of the giraffe's forehead, and the other two are
Giraffe of faster evolution. The divergence of giraffe and okapi lineages dates to around 11.5 mya. A small group of regulatory genes in the giraffe appear to be responsible for the animal's stature and associated circulatory adaptations. The IUCN currently recognises only one species of giraffe with nine subspecies. In 2001, a two-species taxonomy was proposed. A 2007 study on the genetics of "Giraffa", suggested they were six species: the West African, Rothschild's, reticulated, Masai, Angolan, and South African giraffe. The study deduced from genetic differences in nuclear and mitochondrial DNA (mtDNA) that giraffes from these populations are reproductively isolated and