Court, N. 1992 04 15: Cochlea anatomy ofNumidotherium koholense: auditory acuity in the oldest known proboscidean. Lethaia, Vol. 25, pp. 211–215. Oslo. ISSN 0024–1164.
A natural cast of the spiral cochlea space from the inner ear of the oldest known proboscidean, Numidotherium koholense, is described. The cast was sectioned to reveal internal structures. Cochlea structure in numiodtheres, and by inference auditory acuity, is shown to have been very different from that of living proboscideans. The cochlea of Numidotherium is deemed to reflect tuning to relatively high frequencies and contrasts with the low-frequency specializations seen in the inner ear of living proboscideans. It is suggested that evolution of the elephant otic region might be explained by a shift in developmental timing such that features occurring earlier in ontogeny are characteristic of the adult stage. *Proboscidea, Numidotherium, cochlea, natural cast, auditory acuity.