Gross anatomy of the skull of hippopotamus (Hippopotamus amphibius)

Morphological studies were conducted on the skull of a hippopotamus brought to the Veterinary college for postmortem examination.  Skull of the hippopotamus was huge and notable for its little brain case and high supra-orbital ridges. The skull had a larger splanchnocranium than the neurocranium.  From the dorsal view, the skull had a watch glass appearance because of its narrow middle portion (at the region of maxillae) and wide caudal and rostral portions.  Maxilla showed a large Eminenta canina and two infraorbital foramina leading to two separate infraorbital canals. The premaxilla lodged two huge incisors and just above the central incisor, there was a large rough eminence for the elevated nostrils. Three to four large rounded lacrimal bullae were seen on the floor of the bony orbit.  Frontal bone presented a strongly convex smooth supra-orbital ridge that formed upper margin of the orbit which projected from the surface of the skull.  The median sagittal crest was very high that diverged to accommodate the concave forehead in front. Temporal fossa was very extensive.  Caudal surface of the skull showed a concave nuchal surface and the external occipital protuberance was in the form of a crest. The paramastoid process and external auditory process were very short. Bulla tympanica was conical with a pyramidal muscular process.  Anatomical peculiarities of the skull and their functional significance are discussed.