The diagram shows data on the evolution of horses.
Horse evolution.
Recent pleistocene; equus; 3 million years ago.
Pliocene; pliohippus; 7 million years ago.
Miocene; merychippus; 25 million years ago.
Oligocene; miohippus; 40 million years ago.
Eocene; hyracotherium; 60 million years ago.
the first horse was the size of a German shepherd dog of today. it also had a foot which looked like 3 toes. the have evolved to the modern horse to best adapt.