Aktautitan hippopotamopus. Illustration and photo-reconstruction of two ancient hornless Aktautitan hippopotamopus walking in the water along a grassy riverbank. Aktautitan is an extinct animal from the Brontotheriidae family, that lived in the middle Eocene. This animal got its generic name from the Aktau mountains in Kazakhstan, where its fossils were found. It reached a height of up to 2.5 metres at the shoulders. Based on its short legs and its fossils being found in lake sediments, it is thought it was semi-aquati.