EVOLUTION OF THE HORSE

“Look back at our struggle for freedom,

Trace our present day’s strength to its source;

And you’ll find man’s pathway to glory

Is strewn with the bones of a horse.”

-Anonymous

The horse belongs to Kingdom Animalia, Phylum Chordata, Class Mammalia,

Order Perissodactyla, Family Equidae, and Genus Equus. The origin of this animal can

be traced back 60 million years ago to the Eocene period. Throughout its’ evolution the

horse came in many forms some resembling nothing like the horse of today. There were

five evolutionary step types of horse from 60 million years ago. They are as follows:

Eohippus, Mesohippus, Miohippus, Mercyhippus, and Pliohippus. These species evolved

over time becoming the modern Equus we know today.

In 1870 O.C. Marsh found the largest collection of the first horse fossils. With

this find the chain of the evolution of the horse had begun.The Eohippus was the earliest

form of the horse. It was recognized to have existed about 60 million years ago. This

creature was about the size of a cocker spaniel dog (about 14in at the shoulder) and

weighed only 12 lbs. This animal had no lateral vision on a deer-like head. It also had

teeth resembling those of a pig; short and crowned for eating plants. Its’ body looked

like that of a deer with a fawn coat and white spots for camouflage. The tail did not have

long hair like today’s horse and it had no mane at all. Also, the Eohippus had five toes

on each of its’ front feet and three toes on the back feet. These toes ended in a strong,

thick, horn-like nail and the middle of the bottom of the foot was covered with a callous

like pad.

It would be many many years before the horse would evolve further. This was normal though because the evolution of the horse is dotted with periods of non-development. The next change came 40 million years ago in the Oligocene period. This creature was known as Mesohippus. It was much larger than its’ ancestor standing 18 to 24 in at the shoulder. This animal had a longer head, neck, and legs and his back was less arched. It also lost two of its back toes and became one of the first three toed species. The fifth toe was completely eliminated, but the fourth toe turned into a nubin that can be seen on horses still today. The callous nub on the back of the legs at the fetlock is what is left of that toe. This animal because of its’ longer legs would be faster therefore the spots on its’ coat would start to disappear because less camouflage was needed. The color also darkened during this time. A plain brown Mesohippus with spots on his rump would be the common thing to see during this time.

Next in the horse evolution chain we have Miohippus. This creature showed up about 30 million years ago. Fossil evidence shows that Miohippus and Mesohippus coexisted for about four million years. They even split into different areas and developed two different species of themselves. Finally the Mesohippus died out and the Miohippus continued. This creature had begun to develope changes in the ankle joint and a slight concave appearance came to its’ face. This animal was much taller standing at a minimum of 24 in at the shoulder and weighing a considerable amount more than the Mesohippus. Also, this creature was the first to develop incisor teeth.

Five million years would pass before another change would occur in the evolution of the horse. This change gave us Mercyhippus. This horse stood over 36 inches at the shoulder (10 hands) and was very heavy. He still had three toes, but instead of the toes carrying all of the weight on the outside toes it now carried its’ weight on the inside toes. This made the outside toes have little of no purpose whatsoever. The head changed once again setting the eyes more to the side for better lateral vision and the neck got longer for easier grazing. The Mercyhippus began to develop defenses and a keen sense of smell and the teeth changed yet again to those more like today’s horse. They were fast and surefooted so they had few predators. Several different species among the Mercyhippus developed each one resembling more and more the horse of today. The useless outside toes began to shrink and the foot pad and single toe began to form what is now the hoof.

The Miocene, Pliocene, and Pleistocene eras would produce the single hoofed animals of today. The last link in the horse evolution chain before the modern Equus was the Pliohippus. This was the first single hoofed horse. It was a direct prototype of today’s horse standing 12 hands at the shoulder. This creature had strong leg ligaments to make it faster and more powerful. It is considered to be the direct descendent of today’s Equus which came five million years later. There were two other versions of this one creature the Astrohippus and the Dinohippus. The Dinohippus is believed more to be the direct descendent of the modern Equus because unlike the other two species it did not have a dished face.

The final step in the evolution of the horse brings us to today’s horse of Equus. Early Equus’ had zebra like bodies and short donkey like heads. They had short stiff tails and and stiff straight up manes. This creature comes in many shapes sizes and groups. Its’ long powerful legs and muscular body make it one of the most powerful per pound animals on the earth.

In early times horses were divided into four groups:

Pony 1= lived in northwest Europe

Similar to what we know

As the Exmoors and Icelandic breeds

Brown or bay in color stood 12-12.5 hands

Pony 2= similar to Asian wild horses

Modern counterpart is Highland Pony

Stood 14-14.2 hands

Convex profile and much stockier

Yellow to dun in color

Pony 3= Central Asia deserts

Like todays Akhal-Teke

Stood 14.3 hands with narrow body

Pony 4= like today’s Arabian

Stood 12 hands

Long mane and tail straight profile and fine boned

These four groups included all of the horses that existed at this time. Later they were

divided into four different groups and then into three groups which is still used today.

The domestication of the horse started in between 4500 and 2500 B.C. By the time 1000 B.C. came domestication had spread all over Europe, Asia, and North Africa. At this time horses were grouped into four new categories: pony 1 and 2 and horse 1 and 2.

Pony 1= Northwest Europe

12 hands

bay in color

direct descendent of Shetland Pony

Pony 2= North Eurasia

Dun in color dorsal stripe and bars on legs

Descendent od Przswalski’s Horse

Horse 1= central Asia and into Europe

Long narrow neck, lonf narrow head, long ears

Slab sides and sparse mane and tail

Descendent of the Andalusian

Horse 2= west Asia

12 hands

fine boned

high set abundant tail and abundant mane

descendent of the Arabian

All breeds of horsed are crosses of the descendants of these four major groups of the time. Ponies are crosses between Pony 1 and 2. Draft horses are crosses between Pony 2 and Horse 1 and light horses are crosses between Horse 1 and 2. The physical features of each of these groups was originally determined by climat. In cold areas horses were considered “cold blooded” they had thick bodies , thick skin and were calmer in manner. In hot areas horses were considered “hot blooded” they have longer bodies, are larger, thinner skin and are more active.

Today horses are only grouped into three groups:

Heavy Horse = draft breeds like Clydesdales and Belgiums

Used for agricultural reason now and then

Cold blooded with deep chests, short thick legs and broad

Hooves

Very strong, but not fast

Pony = body length exceeds its’ height

Less than 15 hands tall

Light Horse = seperated into horse and pony

Horse 15 hands and taller

Sloped shoulder and narrow bodies

Thoroughbreds and Arabians are examples of

Over 5000 years ago a strong bond was made between man and horse. This bond has

helped the horse to survive and man to thrive.

In 1841 Richard Owen, a leading biologist, saw no connection with the early horses and today’s horse. Instead he thought that it was the descendent of the hyrax or rock badger. He was latter proved wrong by other scientist and fossil proof. The fossils of horses found do not give their exact age it is just estimated to be about 60 million years ago. Also, similarities between the limbs of frogs, reptiles, and mammals show that they all evolve from a common anscestor. The horse is one of the commonly used explanations for evolution.

It was once said:

“Better to give a Prince a good horse than jewels, power or riches

for a horse will not recognise the Prince for anything other than a man,

By the time the Prince has developed the qualities which make him a fine rider,

The horse will have made him, a King among men.”

HORSE FACTS:

FACT: Horses are measured in hands from ground to shoulder not feet or inches (one hand= 4 inches).

FACT: The largest breed of horse is the English Shire Horse which can be 20 hands.

FACT: The smallest breed is the Fallabella which is only 4 hands high.

FACT: Modern horses have 17, 18, or 19 pairs of ribs.

FACT: Ponies are horses under 14.2 hands high.

FACT: The genetic information for coding for extra toes is present, but switched off in most modern horses.

FACT: Boy foals are called colts and girls are called fillies.

FACT: They are called colts and fillies until they are 3 years old.

FACT: They are called yearlings when they reach 1 year old.

FACT: When a colt is born their legs are almost their full adult length.

FACT: A horse gets all its’ teeth by the time it is five years old.

FACT: Horses communicate their feelings by facial expressions.

FACT: A horse can move in four ways walk, trot, canter, and gallop.