Since ancient times, one of the most important animals among those that have been domesticated by humans is the horse. Without it, it is impossible to imagine many episodes from the history of our civilization: migrations of peoples, great battles and conquests of entire countries ... Of course, the domestication of this animal did not happen 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, and who were they, these same ancestors? If almost everyone knows something about horses, then this topic is almost unknown. To correct this sad misunderstanding, we have prepared this article.
Giracoterium, 54-38 million years ago
This is the time of the Eocene. At that time, the oldest representative of the horse family also walked the Earth. Almost the entire surface of the planet is covered with dense tropical forests, the numerous inhabitants of which were perfectly adapted to life in such conditions. Mammals already existed at that time, but preferred to be smaller and behave as quietly as possible, and shelters left only at nightfall.
The most ancient ancestors of the horse, gyracoterias, were just such timid animals. In fairness, it should be said that modern scientists consider this animal to be the progenitor of horses only with a big stretch. Firstly, it belongs to the ancient Paleoterium family, which gave the ancestors not only modern horses, but also the long-extinct brontotheriums. Secondly, this animal was already 20 centimeters at the withers, and there were no hooves on its legs. In a word, he looked much more like some rare breed of cats than horses.
And it was justified: the most ancient horse ancestors were similar to their descendant only in that they were herbivorous. But! They ate exclusively the foliage of small shrubs, since grass in those distant centuries on the surface of our planet was not found. By all other indications, they were typical inhabitants of the forest, who had no access to the steppe. It is hyracoterium - the most ancient ancestor of a horse.
However, it is worth emphasizing once again that he had absolutely no features of a modern look. To some extent, hyracoteria can be considered the ancestors of a huge number of animals, many of which we probably will not know anything. Just imagine: by the beginning of the Pleistocene alone artiodactyls, there were more than 200 species, and this (for those times) was far from the limit!
With equidae, approximately the same situation was observed. Today on the planet there are a maximum of one and a half dozen species, while in that historical period their number may have totaled hundreds of species and the most diverse subspecies!
Mesogippus, 40-32 million years ago
This animal can already be considered relatively similar to a horse. At the withers, the mesogippus already grew up to 60 cm, and on his feet he already had only three fingers, the middle one was much longer and thicker than the other two.
But just looking at the structure of his skull and teeth, it turns out that we are faced with a typical herbivorous animal that ate almost exclusively foliage and small twigs. He especially did not need grass. Significant changes in its appearance are associated with sharply changed living conditions: if the hyracoteria lived in dense and reliably protecting their forests, then the mesogippus were already forced to move to a rare forest-steppe zone.
The spaces have become much larger, the number of enemies has also increased. Accordingly, these ancient horse ancestors were forced to run a lot, so as not to serve as a decoration for someone else's table. Due to this, their lateral fingers gradually began to atrophy, which only prevented them from quickly moving on the surface of the earth, the digestive system became rougher and increased its length, and the teeth became harder and shorter.
Do not forget about the brontoterias mentioned above, which were the largest equine animals that have ever lived on Earth. Unlike the “horses” of that period, these animals were most reminiscent of modern rhinos and over the centuries became only larger and more massive. By the way, they also had a horn on their head, but, unlike a rhinoceros (in a
rhino, the horn comes from the skin), it really was bony.
At the end of the Oligocene, climate changes that were not very pleasant for the inhabitants of the planet began to occur: it became drier, forests with lush foliage became less. Giant and gluttonous brototeries simply died out from starvation, 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 ends, but still some gave rise to animals that have survived millions of years.
Myogippus, 36-24 million years ago
Mesogippus gradually died out, replaced by myogippus. At that time, really large open spaces appeared for the first time (like modern prairies), but at the same time huge forests remained, which this beast was able to take full advantage of. It is one of the rarest mammals that immediately had two very different subspecies, forest and steppe. Gradually, the forest subspecies migrated to the territory of North America, and ancestry evolved from it. But the real ancient horses of that period are its steppe varieties.
The main difference from the mesogippus was that not only the fingers, but also the teeth became stronger in the myogippus. They have become much stronger and tougher. An ideal tool for grinding a large amount of hard steppe grass. By the way, it was precisely the ability to digest hard and nutritious food that served the ancestors of horses in good stead at the beginning of the global cooling. Species that preferred the tender leaf and the young branches of the trees died out in droves.
Anchiteria, "secondary offspring." 24-5 million years ago
So who was the very ancestry descended from the forest “version” of the myogippus? Most of all, he resembled a mesogippus, which by the time of its appearance was already dying out: it had three fingers on its naga, it ate branches and foliage. As you might guess, the evolution of the horse in his case ended: he did not become the ancestor of these animals in their modern form.
Paragippus, 24-17 million years ago
In general, paragippus already most closely resembled those modern horses, the ancestor of which he was. In his "arsenal" appeared completely new legs and teeth. More precisely, they were not so much new as much improved. This animal for the first time began to run not on the entire area of the foot, but on its short, thickened fingers.
The fact is that in the Miocene of 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 the horses had to accelerate even more.
Here it is worth making a digression. The history of horses knows of several instances in which artiodactyls went the other way at this time. It's about tapirs. They are also their distant ancestors (horses), who preferred to leave with the retreating jungle, and not adapt to the difficult conditions of the steppes.
Merigippus, 17-11 million years ago
Merikgippus was in many ways similar to parahippus. In the shoulders, this "mini-horse" has already reached a meter, and the legs were real hooves. The teeth of this animal were ideally suited for eating grass, but not foliage, like its many relatives.
It is worth noting that in those days, forests began to gradually revive. Theoretically, Merigippus could again become a forest inhabitant, switching to easy-to-extract foliage. But myogippus and anchiteria still lived in the forests, but because 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 feed base.
It is possible that in the event of the full-scale return of forests on our planet today, it would be the descendants of the Anchiteria and other forest inhabitants, but the climate continued to become more severe. Be that as it may, but practically no one returned to the forests where the most ancient ancestor of the horse came from (we spoke about some exceptions to this rule above).
Hipparion, 15-2 million years ago
These animals numbered about 20 species, and it was they who for the first time could be considered true horses, without special reservations. Most of all, they looked like modern horses; they were approximately the same in size. The third and fourth toes still remained on their feet, 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 equids, while the evolution of the horse was a side branch. In principle, there is still no clearly accepted opinion about the causes of their extinction. Perhaps this is due to the same climate 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 is too different from the equine.
However, there was no particular mistake: after all, and this animal was a direct descendant of the Merikgippus, as were the hipparions. Most likely, pliogippus were a kind of transitional form between forest and steppe representatives of the family. At a time when the climate was relatively balanced and mild, they easily got along with everyone, but then the cooling continued, and this species simply could not stand the competition with its more specialized relatives.
Perhaps it was in those days (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 nature. Australopithecus lived on the planet in those centuries, and they were hardly interested in taming horses.
5 million - 8,000 years ago
Do you think that by the beginning of the Pleistocene, modern horses had completely survived the "old men" in the person of hipparions and astrogippus? Not at all. At that time, there were more and more artiodactyl herbivores with which the ancestors of horses had not very good relations, since they used a common feed base.
In addition, at that time, extremely ancient and primitive forms of artiodactyls that had died out long ago in other places were still preserved in South America. But then the time of the Pleistocene came, and the next ice age came to the planet. Many species appeared (like elasmotherium) that could exist only in the harsh conditions of that climate. Scientists today agree that the extinction of such animals was not at all connected with human activity, but with completely natural causes.
But after all, we describe the history of the appearance of horses. How is all this connected? The fact is that due to a sharp cooling, many old species (hierikigippus) finally died out completely, and therefore the ancestors of these horses received "complete freedom of action", starting to actively develop and capture new spaces.
Four million years ago - today
Of course, all archaic species in one season did not die out. So, pliogippus disappeared only five million years ago, so in a historical sense, they lived almost yesterday.
Since even Australopithecus appeared no earlier than 3 million years ago, people are not to blame for their extinction. First, the planet was getting colder. Secondly, cloven-hoofed animals entered the scene, whose digestive system 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 had already acquired a modern look and characteristic features of the internal structure. The climate was becoming more and more temperate, so that they began to spread over large areas. Further evolution of horses followed the path of atrophy of the remains of the third to fourth fingers, as well as the development of the gastrointestinal tract. Today, the evolution of this species did not stop, but was seriously complicated by the influence of man on this process.
Who knows how different the horses would have been if they still lived in the savannahs and prairies of the world, where man never appeared!