Ancient horse ancestors and related animals. The evolution of the horse

Since ancient times, one of the most important animals among those that have been domesticated is a horse. Without it, it is impossible to imagine many episodes from the history of our civilization: the migration of peoples, the great battles and conquests of entire countries ... Of course, the domestication of this animal happened not in a couple of years, and the ancient ancestors of the horse gave us a modern "version" of their descendant relatively recently .

By the way, who were they, these same ancestors? If almost everyone knows about horses, then this topic is almost unknown. To correct this sad misunderstanding, we have prepared this article.

Hirakotery, 54-38 million years ago

This time is Eocene. At that time, the oldest member of the family of horses also walked along the Earth. Almost the whole surface of the planet is covered with dense tropical forests, the numerous inhabitants of which were perfectly adapted to life in such conditions. Mammals at that time already existed, but preferred to be smaller and behave as quietly as possible, and shelter left only with the onset of the night.

The most ancient ancestors of a horse, girakoterii, just were just such timid animals. In fairness, it should be said that modern scientists are the ancestor of horses this animal is considered only with great stretch. Firstly, it refers to the ancient family of Palaeotheria, which gave the ancestors not only of modern horses, but also long-extinct bronetothers. Secondly, this animal was as much as 20 centimeters at the withers, and there were no hoofs on its legs. In short, he was much more like a rare breed of cats than on horses.

And it was justified: the oldest ancestors of the horse were similar to their descendant only in that they were herbivorous. But! They fed on only the leaves of small shrubs, since grass in those distant ages on the surface of our planet was not. For all other reasons, they were typical inhabitants of the forest, which did not have a course in the steppe. It is the hiraktery - the oldest ancestor of a horse.

However, it is worth emphasizing once again that he did not have absolutely any features of a modern kind. To some extent, girakotheria can be considered the ancestors of a huge number of animals, many of which we probably already do not know. Just imagine: by the beginning of the Pleistocene, only a few cloven-hoofed animals numbered more than 200 varieties, and this (for those times) was far from the limit!

The same situation was observed with the equinohaires. Today there are a maximum of a dozen species on the planet, whereas in that historical period, their number could have numbered hundreds of species and a variety of subspecies!

Mesogippus, 40-32 million years ago

This animal can already be considered relatively similar to a horse. At the withers, the mesohippus already grew up to 60 cm, and on his legs it had only three fingers, the middle one being much longer and thicker than the other two.

But only if you look at the structure of his skull and teeth, it turns out that in front of us - a typical herbivorous animal, nourished almost exclusively by foliage and small twigs. He did not need the grass especially. Significant changes in its appearance are associated with sharply changed habitat conditions: if the hirakotery lived in dense and reliably protected forests, the mesohippus already had to move to a rare forest-steppe zone.

Spaces have become much larger, the number of enemies has also increased. Accordingly, these ancient ancestors of the horse were forced to run a lot, so as not to serve as a decoration for someone else's table. Thanks to this, they gradually began to atrophy lateral fingers, which only prevented rapid movement on the surface of the earth, the digestive system became coarser and increased its length, and the teeth became stiffer and shorter.

We do not forget about the above mentioned bronotothers, which were the largest odd-toothed animals that ever lived on Earth. Unlike the "horses" of that period, these animals resembled the modern rhinos most of the time and, with the passage of centuries, only became larger and more massive. By the way, they also had a horn on their head, but, unlike a rhinoceros (in a rhinoceros horn comes from the skin), it really was bone.

At the end of the Oligocene with climate, changes were not very pleasant for the inhabitants of the planet: it became drier, forests with juicy foliage became smaller. Giant and gluttonous bronotia simply died out from hunger, but the history of horses at that time was just beginning. They became more and more diverse, new evolutionary branches appeared. Of course, many of them became dead-end, but still some gave rise to animals that survived millions of years.

Myoippus, 36-24 million years ago

Mesogippuses gradually died out, and myogippus replaced them. At that time, for the first time, really big open spaces appeared (like modern prairies), but at the same time huge forests were preserved, which this beast could use to the full. It is one of the rarest mammals, which had at once two very different subspecies, forest and steppe. Gradually, the forest subspecies migrated to the territory of North America, from which an anteromist emerged. But the real ancient horses of that period are its steppe varieties.

The main difference from mesohippus was that not only fingers but also teeth were strengthened in myogippus. They became much stronger and tougher. Ideal tool for grinding large amounts of hard steppe grass. By the way, it was the adaptability to digesting hard and inadequate food that served the ancestors of horses a good service at the beginning of the global cold snap. The species that preferred a gentle leaf and young branches of trees died out in large numbers.

Ankhitheria, the "offspring". 24-5 million years ago

So who was the same anchitis from the forest "version" of the myogippus? Most of all, it resembled a mesohippus, which by the time of its appearance was completely dying out: its naga had three fingers, it fed on branches and foliage. As you can guess, the evolution of the horse in his case ended: the ancestor of these animals in their modern form, he did not.

Paragipus, 24-17 million years ago

In general, the paraghippus was most reminiscent of those modern horses, whose ancestor he was. In his "arsenal" there were completely new legs and teeth. More precisely, they were not so much new, as much improved. This animal first began to run not on the whole area of the foot, namely on its short, thickened fingers.

The fact is that in the Miocene forests it became even smaller, but the number of steppes covered with herbaceous plants increased sharply. Accordingly, there were practically no shelters at all, and therefore the ancestors of horses had to accelerate even more.

Here it is worth making a digression. The history of horses knows several cases of how the ungulates in this time went the other way. It's about the tapirs. They are also distant from their (horses) ancestors, who preferred to go along with the retreating jungle, and not to adapt to the difficult conditions of the steppes.

Merikhippus, 17-11 million years ago

Merikhippus in many respects was similar to paraghippus. In the shoulders this "mini-horse" already reached a meter, and on his feet were real hoofs. The teeth of this animal were ideally suited for eating grass, but not foliage, as in its numerous relatives.

It is worth noting that in those days the forests began to gradually revive. Theoretically, Merikhippus could once again become a forest inhabitant, moving on easy to harvest foliage. But only in the forests there were still myohippus and anchyteres, and therefore the food niche was completely occupied. Thus, the ancestors of horses and related animals were often in a state of intense biological confrontation, since they used the same food base.

It is possible that in the case of a full-scale return of forests on our planet, today it would be the descendants of the Anchitis and other forest inhabitants, but the climate continued to become increasingly severe. Whatever it was, but in the woods, where the most ancient ancestor of the horse originated, practically no one returned (on some exceptions from this rule we spoke above).

Hipparion, 15-2 million years ago

These animals numbered about 20 species, and it was for the first time that they could be considered true horses, without special reservations. Most of all they looked like modern horses, they were about the same size. On their feet still remained the third and fourth fingers, but only in the form of rudimentary processes. These were the true ancestors of horses. These horses can rightfully be considered extremely successful from a biological point of view.

These species lived almost on the entire surface of the planet. The main mystery for paleontologists is the reasons for their extinction. It was an extremely successful species, perfectly adapted to the conditions of its habitat. Some scientists believed (and still believe) that these animals should be considered the main branch of the evolution of the odd-toed-hoofed animals, while the evolution of the horse was a secondary branch. In principle, there is no clearly accepted opinion about the reasons for their extinction to this day. Perhaps this is due to all the same climatic changes.

Pliogippus, 12-5 million years ago

And now we will consider a really dead-end branch in the development of the family - pliogippus. For a long time it was believed that he was the true, direct ancestor of all modern horses. But later paleontologists and biologists considered that the structure of his skull was too different from the horse's.

However, there was no particular error: after all, this animal was a direct descendant of Merikhippus, as were the hypparions. Most likely, pliogippuses were a kind of transitional form between forest and steppe representatives of the family. At a time when the climate was relatively balanced and soft, they easily got along with everyone, but then the cooling continued, and this kind simply could not stand the competition with its more specialized relatives.

Perhaps, it was in those times (about 2 million years ago) that our "wild" ancestors and wild horses first met each other. It is very likely that this meeting was exclusively gastronomic. In those centuries, Australopithecus lived on the planet, and they were unlikely to be interested in taming horses.

5 million - 8,000 years ago

Do you think that by the beginning of the Pleistocene modern horses completely survived the "old men" in the face of the hypparions and astrogippus? By no means. At that time, there were more and more cloven-hoofed herbivores with which the ancestors of horses had not been very good relations, since they used a common food base.

In addition, at that time in South America, extremely ancient and primitive forms of the ungulates were still preserved, which in other places had long since died out. But then it was time for the Pleistocene, and another glacial period came to the planet. There were many species (like elasmotheria) that could exist only in the harsh conditions of that climate. Scientists today agree that the extinction of such animals was not due to human activities, but with quite natural causes.

But after all, we describe the history of the appearance of horses. How is all this connected? The fact is that because of the sharp cooling, many old species (ierikhippus) finally died out definitively, and therefore the ancestors of these horses received "complete freedom of action", beginning to actively develop and capture new spaces.

Four million years ago - our days

Of course, all archaic species did not become extinct in one season. So, pliogippus disappeared only five million years ago, so in the historical sense they lived almost yesterday.

Since even Australopithecus appeared not earlier than 3 million years ago, people in their extinction are not to blame. First, the planet became colder. Secondly, artiodactyl animals appeared on the scene , the digestive system of which was many times more perfect. By the way, the reason for the extinction of many mammoths is the same food, and not a man with his primitive spears. The lack of food made the ancient horses "drier" and faster, and many of their species simply disappeared.

Horses in those days have already acquired a modern look and characteristic features of the internal structure. The climate became more and more moderate, so they began to settle over large areas. Further evolution of the horses followed the path of atrophy of the remains of the third and fourth fingers, as well as the development of the gastrointestinal tract. Today the evolution of this species did not stop, but it was seriously complicated by the influence on the given process of man.

How to know how different the appearance of horses would be if they were still living in savannahs and prairies of the world, where man did not appear!