The following is my translation of an article called: Bilder aus der Ahnenreihe des Pferdes von Dr Günther Schlesinger. It appeared in a German popular science magazine, Kosmos Handweiser für Naturfreunde 1914, Heft 5, Seiten 210-215. As usual, the helpful illustrations accompanying the original article aren't included here. It would be unwise to assume that all the systematic terminology of a 1914 article for a general audience is necessary valid a century later. For example, the author mentions Hipparion antilopium, a specific name which today qualifies as obscure.
I'm not aware of any previous translation.
Trevor Dykes.

Pictures from the ancestral line of the horse by Dr Günther Schlesinger

The Sun glows dark red behind the domes of the Viennese court museums; I guide my steps along the street on the opposite side. The traffic grows, as always towards the early evening, stronger from minute to minute. A thick confusion of restless figures stroll, hurry and walk along the pavement and roads accompanied by the mis-toned music of various instruments of noise: the melody is maintained by the horn blasts from the cars and the signal bells and whistles. Chords are added now and again by the squeaking horns of motor cycles, and bass tones by the purring trumpets of cargo lorries.

And in the midst of it all, like a warning from the days of Altwien (translator's note, 'old Vienna'), a simple "Hoi!" of the horse cab driver. It literally shocks all of my senses and draws my gaze to its place of origin. A poor nag is pulling an old coach. Feet, head, body, nothing fits with each other, just as for the person who is driving. Both have a mess of characters united in the same body.

A similar sight offers itself for a second and a third time. It is as if all the good horses, that were once the pride of the Viennese coachmen, had gone extinct from the petrol fumes. Finally, but finally, comes a private carriage with two fine animals in front! It is a delight to see how proudly and self-confidently such a thoroughbred stallion carries its head and sets its feet.

My thoughts are immediately excited into a particular direction. It saddens me, these proud but harnessed wild animals that, for all their passion, are nevertheless so well behaved.

Pictures from distant days arise in my imagination. It is as if Vienna has sunk for me and, in its stead, mighty post Ice Age steppeland spreads far and wide and, galloping across them, run herds of wild horses with high-held heads, open nostrils and flying manes.

A number of questions press forward. Where did they come from? How did they look through the course of time? I begin to reach back for my memories and rummage amongst the treasures of knowledge.

Today, whoever sees a horse in front of them generally fails to notice what remarkable characters the skeleton of this animal species displays. We are all so used to the build of the horse that it never enters our minds to consider where the upper thigh or upper arm of the horse lies, where the elbows or knees bend, and how the bones of the lower lying parts of the extremities correspond to which bones of other animals. Indeed, it does not even occur to us that this animal has only got a single toe and, what is more, it is the tip of it that contacts the ground. Still less do we find the dentition remarkable.

Should a layperson give thought to the bone structure, then they will attempt to look for the elbows and knees in the middle of the clearly visible extremities (marked a and a1 in Illustration1), whereas these bends lie much higher in reality (b and b1). The above mentioned, frequently false notion will also become easily apparent should one recall that the bend of elbows usually has an angle forwards, whereas that of the knees is backwards. For the lower joints of the extremities, however, the conditions are precisely reversed. In accordance with this, the lines running between a-b and a1-b1 show the lower arm and the lower leg; the long bone still lower down is a strongly elongated middle hand or foot bone.

One has been able to follow the ancestors of horses, due to careful study and fortunate finds, back to forms that had four toes on their front feet and three on the rear feet. A closely related genus, which does not actually fall into the direct ancestral lineage of the horse (Phenacodus), still carried five toes on each foot, and thus shows a fully original construction as has been maintained by a few mammals up until the present day, the hedgehog for example, many predators, all the apes and the hand and foot of the human.

Without doubt, the earliest ancestor of the horse was similarly built. The oldest secure ancestor is a small, hardly 30cm high animal that was found in America, and received the name of Eohippus. Extremely similar remains were also later found in England.

It was no significant runner. Nevertheless, it does show the construction of the foot was already changing from the beginning. At the front, it still bore four fingers but the small one is already very weak, the thumb missing and, in contrast, the middle finger is already stronger than the others. The back foot has only three toes, and the middle toe is best developed. In addition, the middle foot is elongated.

Let us research into the reason for these changes! We see that, as for all animals very prone to fleeing (eg. deer and mountain goats), the side toes are lost due to lack of use and the lower bones increase significantly in length. Similar causes allowed the reconstruction of the foot for Eohippus except, that here, only a single toe served as a real organ for movement while, for the examples cited, this work was shared by two.

The development of the steppeland in America during the early Tertiary obviously demanded an appropriate redevelopment in form. That such a basic reason was decisive for the lifestyle of this animal is also shown by the start of adaptation of the dentition.

The premolars were mostly similar to the molar teeth. While both do display in ground the cusped characteristics of the omnivore, as has also been retained by the apes and in humans; yet the cusps are already starting to melt into ridges. (Ill. 2 shows this ancestor of our majestic odd-toed ungulate in its natural environment; the sketch of the foot construction (Ill. 3) will make the comprehension of the points mentioned much easier.) (Additional note: but not for you, dear reader.)

The extremities of Eohippus already display particular remains of reduction of the toes as can be observed in the skeleton of any horse. The difference is that it is the first finger and fifth toe of this ancestor that have reached this level of degradation (see Ill. 3a and b).

Now the adaptations progressively continue along the same selected path. During the second stage of the deep Tertiary, larger forms appear (Protorohippus and Epihippus) which, apart from the loss of the outer splint bones and the stronger build of the tooth ridges, do not otherwise have significant differences.

However, already by the Oligocene, the uppermost stage of the old Tertiary, an important advance had been made; the first three-toed horses hurried across the grasslands. The species of the genus Mesohippus carried the strengthened middle toe and two weaker side toes on the front and rear foot of the body (see Ill. 4a and 4b); the dentition developed to an ever clearer area for filing and crushing grooves, in that individual teeth were similarly shaped with richly folded crowns closing up with each other. Simultaneously, the roots became shorter, the crown, in contrast, gained in height, and the greatest possible provision of tooth substance was made available for chewing.

At the transition from the Lower to Upper Tertiary, a land connection must have existed between the New and Old Worlds. For the first time, herds of three-toed horses namely appeared in Europe, and populated the forests and savannahs in numbers. One species of this genus (Anchitherium aurelianense) is found particularly frequently in the deposits that have been left to us by the extensive oceanic coverage of the Upper Tertiary.

It was a small animal with three toes on each foot and, due to its low height and the form of the legs, and also its dentition, was better adapted for life in forests than for hurried flights across dry steppe. It populated the shore areas of the inner European Mediterranean throughout virtually the whole Miocene, and lived alongside of the elephant-like tetrabelodonts or mastodons, primitive rhinoceros, tapirs, stages, apes and many other species in the midst of a tropical animal community.

Meanwhile, in America, the further development of the horse lineage continued its progress.

Step by step, the feet took on the requirements for a rapid form of movement. The only method of survival on the endlessly open plains lay in flight! The side toes played an ever more minor role in movement. At first, they only contact the ground by chance or during rest and, finally, retreated to such a height that they had the character of functionless vestiges.

In compensation, the middle toe grew increasingly stronger, the middle foot bone grew in length: it was the only significant support for the whole body.

The teeth also made rapid advances in development. Previously, the root had still provided a substantial part of each tooth. By the stage reached by the genus named Merychippus, the roots are uncommonly diminished, the grinding area took up most of the crown, and this gave the greatest possible room for chewing. About a year ago, we had the opportunity to see a similar phenomenon of growth in the height of the crown at the expense of the root in the course of development of the elephant lineage, and this resulted from similar causes (see Kosmos, 1913, Heft 3.) (Additional note: or look at A brief history of elephants.)

Up until this point, the main developments of the entire horse lineage were limited to America; one side branch, that of Anchitherium, had used a landbridge to migrate at the start of the Upper Tertiary, but it disappeared in Europe with little change at the end of the Miocene, and did not leave any descendants.

The conditions changed completely at the start of the Pliocene. At the same time as a blockage cut off the Mediterranean, causing a lowering of sea levels and an increasingly strong retreat of the water, and also at the same time that the landbridge between North and South America arose and mastodons migrated southwards and, finally, at the same time as mighty steppes allowed the origin of real elephants in India, large herds of three-toed horses moved into Europe and lived on the vast, arid steppes of the Lower Pliocene.

The genus Hipparion, several species of which lived all over our homeland, represents the immediate ancestral form of our wild horses. This type bears all the characteristics of its ancestor, Merychippus, but they are much more strongly pronounced. The side toes are still clearly present, but they are completely away from the ground. The middle foot is little different in powerful build and height to that of the true horse (see Ill. 5a and b). The grinding teeth are almost rootless and present, by being tightly up against one another, a very effective grinding surface with many folds for breaking up the hard grasses which the steppe offered. Hipparion reached the size of a middle strong horse but, in some species, it remained less in this regard. In general, it had a plump and low build, short-necked and wide-headed, and it could in no way be termed a "beautiful animal" (see Ill. 6). The mane may well have been, as for the zebra, somewhat donkey-like.

During the Pliocene, one sees a competitive race in all continents of the world to achieve the ideal horse type. In Europe, a heavy, single-hoofed form (Equus stenonis) developed from Hipparion, and it populated the steppes of the Upper Pliocene that once covered the greater part of the now sea floor. It appears to have been the ancestor of the occidental race of wild horses.

Along with this, a migrationary branch of Hipparion (Hipp. antilopium) may have moved into the Orient, and have originated the oriental races of wild horses.

However, also in the ancestral land of the entire lineage, North America, the development ran along a similar parallel course. Forms developed from Merychippus which show great similarities with our Hipparion; these then led to a further single-hoofed species, Pliohippus, the immediate ancestor of the wild horses that went extinct before a European foot had entered the land. The early prehistoric residents of America, in contrast, made these the object of a keen persecution. The horse has been missing from the New World since the Ice Age. When it was introduced by the discoverers, it astonished the Indians as if a miracle. But they soon got used to the new arrival, and learned how to tame and used the mustang, wild descendants of European domestic horses.

A descendant of Pliohippus (Hippidium) used the appearance of a landbridge between North and South America to migrate, and also became the ancestor of South American horses that died out during prehistoric times.

However, as well as these types, Hipparion also returned to its land of origin, and achieved a somewhat altered form (Neohipparion). But it found no opportunity to develop further, and died out during the course of the Pliocene.

Before taking a brief look at the living species and races of the genus Equus, we would like, with the aid of the diagram (Ill. 7), to review a short summary of the evolutionary history of the horse.

The oldest form included in the diagram, Orohippus, had four toes at the front, three toes at the back, the tooth roots were large, the crowns very low, and their folding was not very complicated. Mesohippus is three-toed on all feet, and the tooth crown is much higher.

For the next type (Hipparion), the build of the extremities is progressive, the teeth are very similar with the recent form (Equus). Pliohippus, finally, is only differentiated from the modern horse by the gradation of its characteristics. This presentation shows that, step by step, the individual features of reconstruction and adaptation have always proceeded in the same direction.

Through a similarly gradual advance, the size of horse ancestors also increased. Originally, literally small animals, they had already reached impressive sizes with the three-toed species and, eventually shortly before the Ice Age, they achieved a size that our strongest plough horses are smaller than. Illustration 8 brings the difference clearly to the consciousness.

Of the many species that populated all continents during the Pliocene, very few have wild descendants still alive in the present day.

Europe has no wild forms at all. The tarpan, which populated the Russian steppelands in great herds during previous centuries, is completely extinct, and so quickly did it disappear that not even one certain stuffed specimen exists of it. Its appearance was recently "reconstructed" by O. Antonius (Vienna). Furthermore, its genuine wildness has been doubted on a number of occasions, and descent from domestic horses has been assumed, as appears to be the case for the Shetland pony.

Nevertheless, it must be assumed that wild horses lived in Europe deep into historical time, and possibly even the Grimme Schlech of the Nibulungenliedes has nothing to do with the giant stag (Cervus euryceros), as one usually hears, but rather refers to a large wild horse. Nevertheless, that is nothing more than assumption. Subsequent classification of wild horses is always extremely difficult as domestic horses turn feral very quickly, and they rapidly take on the character of the original form.

Asia is home to a small wild horse (Equus przewalski) that, although first discovered only a few decades ago, is already standing close to extinction.

A second species (Equus hemionus), the wild donkey or onager (Dschiggetai), is often encountered in Inner Asiatic steppe areas. It was a very common animal over the whole of Eurasia during the Diluvian, and migrated onto post Ice Age steppeland from the east.

Africa is the home of a number of reliably identified wild horse species. Its areas south of the Sahara are grazed by a number of forms known as Tigerpferde (Additional note: literally 'tiger horses', an unusual phrase for 'zebras', a word the author prefers to reserve for a single species.) Of these, two rather rare species (quagga and dauw- Additional note: both names seem to refer to the same species.) prefer the plains and valleys whereas, in higher areas, the zebra (Equus zebra) can still be encountered in impressive numbers. (All) these zebras are characterized by having ornamental stripes over the whole body. They are extremely unruly, almost completely untameable animals, and they combine a prodigious running speed with extraordinary sharp kicks. Additionally, Africa is also the land of origins of the immediate ancestors of the domestic donkey (Equus asinus) which, in its original wild state, is found as two races (Equus asinus africanus and somalicus) called the steppe and Somalia donkey living in free nature.

Many more interesting things could be mentioned about domestic races and the mixed pedigrees of lots of forms of horse. But- it is not good to prod more wasp nests with sticks. The simple words, 'the history of races of horse' could be quite enough to result in a hubble and bubble. (Additional note: The author's chosen term is Hexensabbath, literally a 'witches' Sabbath'. 'Uproar' would've done, but 'hubble and bubble' is more MacBethian despite the extra toil and trouble.) We want to spare this article from impassioned controversies leading to possibly unfortunate incidents with the sharp weapon on the rear ends of certain insects, which could bring back memories of bitter childhood tears.

An index of more of my translations of old Kosmos articles can be found at:

Kosmos Translations Archive
kosmostranslations.htm

A number of Mesozoic (and post-Mesozoic) location summaries can be found at Localities.