Sivatherium giraffid mammal, illustration. Sivatherium appeared during the Pliocene, around 5 million years ago, and may have become extinct as recently as 8000 years ago. It ranged throughout Africa to the Indian subcontinent. Sivatherium resembled the modern okapi, but was larger, being some 2.2 metres tall at the shoulder. It had a distinctive arrangement of antler-like ossicones on its head and above its eyes. It was a ruminant, feeding on plants.