What Is on Your Nose?

Menodus (junior synonym to Megacerops),
Field Museum, Chicago.

Megacerops has a pair of horn-like protuberances on the rostral end of the skull. In the mounted specimen from the Field Museum, shown here, those protuberances appear smaller than they are often illustrated. The nostrils do not appear, in this specimen, to be completely formed as external foramina, as one would expect. The nares are actually present in the concavity ventral to the the twin horns of the face. The nasal bones appear to extend over the premaxillae between the horns but do not recurve to meet the premaxillae at the chin. As expected in the list of rhinoceros-like traits, the optic foramina are small, relative to the entire skull, and offset laterally so that the animal most likely did not have a great deal of binocular vision. Not having depth perception, we can probably safely surmise that Megacerops was not adept at detecting predators visually. To make up for that deficit we can assume that the powers of smell and hearing may have been more sensitive in Megacerops (there may be more definitive answers that I have not found quite yet). Conversely, mixed herds and even the addition of non-mammalian (i.e. bird) members of the community may have aided in predator awareness, meaning that none of the senses would have had to have been highly adapted toward sensing predators. Either way, the horns on the face of Megacerops are not used for the purpose of combat primarily. As skeletal elements, a broken horn would be tremendously detrimental to the health of the animal. Such a danger would cause the animals to use their horns, both males and females possessed them, as a last resort in protecting themselves. The horns would have served to intimidate as much as the sheer size of the animal itself.