The document summarizes the evolution of the horse over 50 million years from Eohippus to modern Equus. Key stages included Mesohippus which lived 38 million years ago in North America and had 3 toes, with the middle toe larger. Merychippus originated 12-6 million years ago and was the first single-toed horse with strong legs to increase speed and power. Pliohippus resembled a pony and lived in the late Miocene period in North America, being considered a direct link to modern Equus horses.

1. EVOLUTION OF THE HORSE
BY:
THOMAS CHINNAPPAN .A ,
M.SC.APPLIED GEOLOGY,
PERIYAR UNIVERSITY,
SALEM.

3. 1) Introduction
2) Eohippus [Hyracotherium]
3) Mesohippus [Intermediate horse]
4) Merychippus [Ruminant horse]
5) Pliohippus [Pliocene horse]
6) Equus [Modern horse]
7) Conclusion.

4. INTRODUCTION :
The evolution of the horse, a mammal of the family
Equidae, occurred over a geologic time scale of 50 million
years, transforming the small, dog-sized, forest-dwelling
Eohippus into the Modern horse. Horses are placed in the
suborder Hippomorpha, superfamily equoidea and family
Equidae under order perissodactyla (suborder
Hippomorpha) (odd toed ungulates).
Paleozoologists have been able to piece together a
more complete outline of the evolutionary lineage of the
modern horse than of any other animal. Much of this
evolution took place in North America, where horses
originated but become extinct about 10,000 years ago.
Horses are one of the oldest forms of mammals.

6. SCIENTIFIC CLASSIFICATION OF HORSE
Kingdom : Animalia
Phylum : Chordata
Class : Mammalia
Order : Perissodactyla
Family : Equidae
Genus : Equus
Species : E.ferus
Sub- species : E. f. caballus

9. MESOHIPPUS
Name : Mesohippus
Time period : Oligocene
* Mesohippus means 'middle" horse. Mesohippus
was living in 38 million years ago.
* It was live in North American region.

10. * The mesohippus was lost some of its toes.
* The evolved mesohippus was 3 toed.
* The middle toed
was larger in size and the
all three toed was
supporting the animals
weight.
*It stand the size 18 to
24 inches at the shoulder.

11. * It has longer legs, neck, compared with the
Eohippus.
* Larger limbs and legs is useful for the species run
faster.
* The evolution of horse has
low crowned molors. Its
premolar teeth became more
like molar.
* The fossil of the species
was found in Oligocene
layers.

15. Considered to direct link to the Equus, which is in short compared to
Equus.
Originated 12-6 million years ago.
First single toed, or hooved horse. Strong leg ligaments, to increase
speed and power.
Fore feet – 1 finger,2 splint ;hind feet – 1 toe, 2 splint.
Had a dished face. Resembled a pony in many factors.
Fossils of pliohippus are found at many late miocene localities in
colorado,the great plain of US and Canada.