The commonest mammalian remains from Arrisdrift belong to a species of hyracoid, Prohyrax hendeyi Pickford, 1994. The same species has been found at Auchas, but it is extremely rare there. It has also been found in the Baken Diamond Mine on the South African bank of the Orange River. P. hendeyi is similar in morphology to Prohyrax tertiarius Stromer, 1922, but is appreciably larger (Pickford et al., 1997).