Mesohippus is a prehistoric dinosaur which lived approximately 40 to 30 million years ago – from the Late Eocene Period through the Middle Oligocene Period. It was first discovered during the 19th century and was given its name by Othniel Charles Marsh in 1875. Its name means “middle horse” in Greek.
When you first look at Mesohippus pictures, then you might mistake them for miniature horses, which is kind of what they look like. However, while they were smaller than the modern horse, they weren’t quite small enough to be called miniature horses. They were just a little too big to be placed in the same category.
Mesohippus was about 4 feet long, about 2 feet high and weighed around 75 pounds. Which would be really, really small for a horse. However, it wasn’t a true horse like the modern horse. It was an intermediary phase between animals such as the Phenacodus (which lived during the Eocene Period) and animals like Hipparion and Hippidion (which lived during the Pleistocene Period).
If you look at fossils of its feet and compare them with its ancestors, then you can almost see evolution unfolding right before your eyes. Instead of having four toes like Eohippus, it had 3 toes. That’s because evolution fused its middle toes together. And evolution would continue this shaping until the hoof emerged in Hipparion and which was eventually perfected in modern horses.
One of the most interesting facts about Mesohippus, however, was that it had a relatively large brain for its body size. In fact, even though it was quite small, it still had a brain that was about equivalent to the brain of modern horses. That would have given it the smarts to outwit just about any predator of its time. Which is a good thing because this horse probably wasn’t built for speed.
Another significant difference between Mesohippus and the modern horse is that these animals fed on twigs and fruits and horses feed on grass. Scientists have discovered this by the arrangement of its teeth – which clearly shows it was more suited for that type of diet.