The diagrams illustrates the evolution of 4 different kind of horses over a span of 40 million years.
First, diagram shown the Eohippus. This type of horses exist in the world over 40 million years ago. It had four toes in its legs, and every toes are nearly the same size.
Second was Mesohippus, which was from 30 million years ago. This was a little bigger than Eohippus and has 3 toes like Eohippus but there was slight different in toes. Middle toes of the Mesohippus was little bigger than the Eohippus.
Third was Merychippus from 15 million years ago. The size of this horse was bigger than the rest horses I described earlier, and its foot was also bigger, but the shape of the foot was the same.
Lastly, the modern one from this era. That is biggest horse from last 40 million years, and the shape of its foot has totally changed. They doesn’t even have any toes in their legs, but they have two hooves.
