The white rhinoceros or flat-nosed rhinoceros (Ceratotherium simus), so named because its upper lip is short and does not advance when falling back above the lower one, almost completely disappeared in the late nineteenth century. Also named Burchell or Oswell rhinoceros, after the travelers who observed it, english-speakers call it square-mouthed rhinoceros. It is the largest of all current rhinos. The conformation of its skull and lower jaw, which results in the shortness and square shape of the muzzle, distinguishes it from all other species.