The pictures illustrate the evolution of the horse over a 40 million-year period.
Overall, the horse underwent 3 main stages to develop as the modern horse nowadays which made limbs become larger and longer, then the disappearance of its toes replaced by sole hooves.
Back forty million years ago, this animal was firstly called Eohippus and had some fundamental characteristics. Evidently, Eohippus was tiny and did not have hair along the back of its neck. Its tail was short and also for its legs, which had four thin toes.
After 10 million years, it transformed into Mesohippus, whose tail became longer and body changed to prominent. It is remarkable that the feet had lost one toe and enlarged to create a symmetrical structure, and it had also developed the form of horse mane.
15 million years ago, with continuous growth, it had a new name – Merychippus. The body of this animal became half the size of the modern horse with a longer mane and the middle toe protruded more to the front. Nowadays, after experiencing a long period, finally horse is chosen to be the core name. It is clear to see that it has a bulkier body and longer tail. Moreover, the modern horse has a full mane and four lengthier legs as well as full round hooves.