Which toes are best developed in horses? How many toes does a horse have? More than you think! What scientists are talking about

In the ancestors of horses, extra toes played an important role, helping the legs to withstand heavy loads while running, but then all the toes, except the middle one, simply became redundant.

The very first ancestors modern horses lived about 50 million years ago. These were small animals, the size of a dog, they ran through the forests and had four and three toes on their legs (four on the back, three on the front).

Then climate changes happened, and new varieties of equines came out into the open. Here they began to increase in size, began to run faster, serious changes occurred in their anatomy - so, among other things, all their fingers gradually disappeared except the middle one, and hooves appeared - horny formations, the equivalent of our nail, completely covering the finger.

The evolution of horses is well understood thanks to the many bones remaining from a wide variety of ancient species. In the open spaces of steppes, savannas and meadows, horses needed to move quickly, and those individuals that were larger gained an advantage, and the disappearance of the lateral toes coincides well with an increase in body weight and lengthening of the legs. And yet - why only one finger?

In an article in Proceedings of the Royal Society B Harvard researchers are analyzing the history of horses from a biomechanical perspective. Stephanie Pierce ( Stephanie Pierce) and her colleagues used CT scans to assess how the leg bones of thirteen extinct species coped with stress.

As a result, the authors of the work came to the conclusion that in early horses the lateral toes played a fairly significant role. For example, Parahippus, who lived just at the time when forests were shrinking and vast plains were appearing, had three toes on each foot, although they were fused together and protected by one hoof (albeit not as developed as in subsequent horses) . The parahippus was already quite large, about a meter at the withers, and two lateral fingers helped distribute the load so as to prevent injuries - cracks, broken bones, etc.

But the horses continued to grow, their mass increased, their legs lengthened, they ran faster, and the load on their toes became more and more intense. The growing load was primarily felt by the middle finger, which gradually became larger. In the end, horses appeared that had a very overgrown, massive middle finger, and the side ones, in the best case, remained either in the form of rudiments or completely disappeared. When researchers tried to attach normal, well-developed additional toes to the feet of such “one-toed” horses, it turned out that from a biomechanical point of view they provide almost no advantage - the middle toe itself learned to cope with the entire load.

That is, it cannot be said that the fate of the lateral fingers of horses was predetermined from the very beginning - for the time being, they worked in the same way as the middle finger, taking on part of the weight and protecting the bones of the limbs from injury. But the horses were made bigger and faster, and at some point it became clear that the middle finger had become the main one, and the very small benefit that the side fingers could bring no longer justified the resources that needed to be spent on them.

Based on materials

When the question arises about how many toes a horse has, what comes to mind? The horse's toes?! Well, maybe one... However, in reality this is not entirely true. Although, even if you have your own horse, you still won’t be able to count more than one finger on it. Here the situation is much more complicated. Although scientists themselves still argue about this. However, this is definitely not one toe with a hoof.

What scientists are talking about

According to research published in the journal Royal Society Open Science, the idea that a horse's hoof consists of a single toe is false. Scientists have proven that these animals still have missing toes, but they have merged into the hoof. This happened due to the need to adapt, which all living things are subject to over time on our planet. The reason for this, first of all, is the change in climatic conditions.

The ancestors of horses had five toes on one limb. They have survived to this day, as evidenced by the skeleton of the animal. The five toes that merge into one hoof can also be felt through the soft tissues of the animal. However, over time, they have become somewhat deformed and are no longer complete.

Researching

Horses' toes were not lost during evolution. They just changed their shape. This has been proven by research. The middle, largest, finger forms the hoof; two more are located slightly above the hoof in a rudimentary, that is, underdeveloped state, as well as on the upper edges of the metacarpal bone. However, it is impossible to see these four fingers with the naked eye.

When the scientists cut open the hoof, they saw two separate sections and three more sections with phalanges, implying five toes that are hidden. It was also discovered that there are significantly more nerves and arteries than previously thought. And the vascular network is characteristic precisely for the presence of five fingers.

Study of ancestors

Bone structures that corresponded to such a number of fingers were also found in the studied remains. One specimen lived 35 million years ago, the second - 5 million years.

Mesohippus from the equine family, like Dinohippus, did not have hooves. They rested on three fingers, the middle of which had large size. At the same time, they were quite capable of trotting, like modern horses. Their ancestors were only the size of a fox.

The first ancestors of horses appeared in North America. Previously, the Bering Strait did not exist, but in its place there was a land bridge. It was along this route that ancient horses moved to Europe. Over time, individuals developed, new species became larger. The toes were replaced by hooves to adapt to the new conditions of the changing climate.

Even more ancient ancestors of horses were Eohippus. They lived about 50 million years ago. Ancient animals had spotted colors to blend in with their surroundings and hide from predators. They were no larger in size than the most ordinary domestic cat, but in appearance they still resembled a horse. The animal could run very fast thanks to its long legs. Of course, he didn’t have any hooves, but he had widely spaced toes. There were still five of them on each leg, although the fifth was located higher than the others and was much shorter.

Thus, it can be seen that with the development of each subsequent equine species, their limbs changed, there were fewer fingers, and some remained in an underdeveloped state. And the size of the individuals became larger and larger.

Most scientists are confident in the existence of one ancestor of mammals, which was five-toed, and from it many animals familiar to us, including horses, descended.

Animal Features

These animals have very large eyes and excellent vision. However, there are some problems with recognizing colors of browns and grays.

Their hearing is also excellent. To listen to sounds from all directions, horses can rotate their ears.

Their sense of smell is no better than that of other animals, but it is significantly higher than that of humans.

The first ancestors of horses appeared on our land ten million years after the extinction of the dinosaurs.

Underdeveloped four fingers, represented by residual bones, often cause injuries to the fibula.

The milk of these animals contains little fat and protein, but a lot of lactose and has a useful vitamin composition. Koumiss, a fermented milk drink, has particular benefits.

These representatives of the animal world can live up to 25 years or more.

In the ancestors of horses, extra toes played an important role, helping the legs to withstand heavy loads while running, but then all the toes, except the middle one, simply became redundant.

Modern horses have only one toe on each foot – but what a toe! (Photo: virgonira / Depositphotos.)

The very first ancestors of modern horses lived about 50 million years ago. These were small animals, the size of a dog, they ran through the forests and had four and three toes on their legs (four on the back, three on the front).

Horse toe structure, i.e. the areas of the fetlock, coronoid and hoof bones, is very difficult. Here there is an originality in the location and shape of the bones, a large number of ligaments running in different directions, powerful tendon endings of the muscles, a highly developed elastic crumb that softens shocks and shocks when resting the limbs on the ground, and a strong insensitive horny capsule that protects the tissues contained in it from damage.

Hoof trimming and shoeing affect, to varying degrees, the condition and function of the entire lower limb. With hoof diseases, pathological processes often spread upward to adjacent areas of the toe. Therefore, to justify the rules of shoeing and to navigate hoof diseases, knowledge is required anatomical structure of a horse's toe in general and especially the topographical relationship of its individual parts.

Ancestors horses were five-toed plantigrade animals. They rested on the ground with five outstretched rays of their paws, i.e., the hand and foot participated in the support.

In progress historical development there was a gradual transformation of the paw and raising it above the ground; At the same time, the rays of the paw, which are not involved in resting on the ground, were reduced. Thus, in a horse, the metacarpus (metatarsus) and the first two phalanges of the third toe were raised above the ground (the horse rests on the ground only with the last phalanx of the third toe) and became part of the main column of the free limb that supports the body. The resulting elongation of the limb contributed to the capture of more space when moving, hence the speed and ease of running.

At the same time as the skeleton of the paw, other organs in this area were also rebuilt. Lower section The limbs of a horse consists of a bony skeleton, ligaments and tendons, covered with skin with a heavily keratinized epidermis at the distal end. The short muscles of the fingers, found in other animals, are absent in the horse.

The skin of the finger also underwent changes. A special device at the distal end of the finger in the form of elastic crumbs for stepping and touching, quite prominently expressed in predatory animals (finger crumbs), in the horse has lost to a large extent its tactile functions and has taken the form of a wedge forked by a longitudinal groove, acting at different gaits as an elastic body .

For horses characterized by the presence of another formation that is absent in other animals - spinal cartilage; they cover the crumbs from the sides and soften the impact of the hoof on the ground.

In carnivorous animals, a hard, keratinized skin tip curved with a hook forms a case for the last phalanx of the finger and is adapted for climbing and tearing food. U horses it took the shape of a truncated cone, with the base facing down, with a clearly visible plantar surface in the form of an open circle, creating a fairly perfect support for the limb.

Changes in the histological structure of the skin are especially pronounced in the area of the third phalanx and led mainly to an increase in the strength and elasticity of the skin tip.