Ceratogaulus - the horned gopher
When: Miocene to early Pliocene (~17 to 5 million years ago)
Where: The great plains region of North America, the best fossils coming from Nebraska
What: Ceratogaulus is an extinct rodent. They are most notable as they are not only the sole horned rodent known, but the smallest horned mammal of all time; reaching an average length of 1 foot (~30cm) as adults. While Ceratogaulus was a digging animal, and lived in burrows, the horns were not useful for digging. For this use it’s horns would need to be both placed more forward on the snout and angled anteriorly. This is also why the horns were not well suited for fighting between individuals. The best interpretation of their use in life is for defense from predation. With their upward angle and rearward position the horns of Ceratogaulus would be excellent for defending the back and neck of the rodent.
Ceratogaulus is a very basal rodent. It’s closest living relative is the mountain beaver, which is in turn somewhat of a living fossil. More broadly it is fairly closly related to the squirrel family.