Fifty-three million years ago, while the New Rockies were still developing and long after diplodocus had vanished, in the plains area, where the twin pillars formed, an animal began to develop which in later times would give man his greatest assistance, pleasure and mobility. The progenitor of this invaluable beast was a curious little creature, a four-legged mammal, for the age of reptiles was past, and he stood only seven or eight inches high at the shoulder. He weighed little, had a body covering of part-fur, part-hair and seemed destined to develop into nothing more than a small inconsequential beast.
He had, however, three characteristics which would determine his future potential. The bones in his four short legs were complete and separate and capable of elongation On each foot he had five small toes, that mysteriously perfect number which had characterized most of the ancient animals, including the great dinosaurs. And he had forty-four teeth, arranged in an unprecedented manner: in front, some peg-like teeth as weak as those of diplodocus; then a conspicuous open space; then at the back of the jaw, numerous grinding molars.
This little animal made no impression on his age, for he was surrounded by other much larger mammals destined for careers as rhinoceroses, camels and sloths. He lived carefully in the shady parts of such woods as had developed and fed himself by browsing on leaves and soft marsh plants, for his teeth were not strong and would quickly have worn down had they been required to eat rough food like the grass which was even then beginning to develop.
If one had observed all the mammals of this period and tried to evaluate the chances of each to amount to something, one would not have placed this quiet little creature high on the list of significant progenitors; indeed, it seemed then like an indecisive beast which might develop in a number of different ways, none of them memorable, and it would have occasioned no surprise if the little fellow had survived a few million years and then quietly vanished. Its chances were not good.
The curious thing about this little forerunner of greatness is that although we are sure that he existed and are intellectually convinced that he had to have certain characteristics, no man has ever seen a shred of physical evidence that he really did exist. No fossil bone of this little creature has so far been found; we have tons of bones of diplodocus and her fellow reptiles, all of whom vanished, but of this small prototype of one of the great animal families, we have no memorials whatever. Indeed, he has not yet even been named, although we are quite familiar with his attributes; perhaps when his bones are ultimately found—and they will be—a proper name would be ‘paleohippus,’ the hippus of the Paleocene epoch. When word of his discovery is flashed around the world, scholars and laymen in all countries will be delighted, for they will have come into contact with the father of a most distinguished race, one which all men have loved and from which most have profited.
Perhaps thirteen million years after ‘paleohippus’ flourished, and when the land that would contain the twin pillars had begun to form, the second in line and first-known in this animal family appeared and became so numerous that in the land about the future pillars hundreds of skeletons would ultimately be laid down in rock, so that scientists would know this small creature as familiarly as they know their own puppies.
He was eohippus, an attractive small animal about twelve inches high at the. shoulder. He looked more like a friendly dog than anything else, with small alert ears, a swishing tail to keep insects away, a furry kind of coat and a longish face, which was needed to accommodate the forty-four teeth, which persisted. The teeth were still weak, so that the little creature had to content himself with leaves and other soft foods.
But the thing that marked eohippus and made one suspect that this family of animals might be headed in some important direction was the feet. On the short front feet, not yet adapted for swift movement, the five original toes had been reduced to four; one had only recently disappeared, the bones which had once sustained it vanishing into the leg. And on the rear foot there were now three toes, the two others having withered away during the course of evolution. But the surviving toes had tiny hoofs instead of claws.
One could still not predict what this inconspicuous animal was going to become, and the fact that he would stand second in the sixty-million-year process of creating a noble animal seemed unlikely. Eohippus seemed more suited for a family pet than for an animal of distinction and utility.
And then, about thirty million years ago, when the land that was to form the twin pillars was being laid down, mesohippus developed, twenty-four inches high at the shoulders and with all the basic characteristics of his ancestors, except that he had only three toes on each of his feet. He was a sleek animal, about the size of our collie or red fox. The forty-four teeth kept his face long and lean and his legs were beginning to lengthen, but his feet still contained pads and small hoofs.
Then, about eighteen million years ago, a dramatic development took place which solved the mystery. Merychippus appeared, a most handsome three-toed animal forty inches high, with bristly mane, extended face and protective bars behind the eye sockets.
He had one additional development which would enable the horse family to survive in a changing world: his teeth acquired the remarkable capacity to grow out from the socket as they wore down at the crown. This permitted the proto-horse to quit browsing on such leaves as he found and to move instead to grazing on the new grasses that were developing on the prairies. For grass is a dangerous and difficult food; it contains silica and other roughnesses that wear down teeth, which must do much grinding in order to prepare the grass for digestion. Had not merychippus developed these self-renewing grinders, the horse as we know it could have neither developed nor survived. But with this almost magical equipment, he was prepared.
These profound evolutions occurred on the plains that surrounded the site of the twin pillars. There on flat lands that knew varied climates, from tropical to sub-arctic, depending upon where the equator was located at the time, this singular breed of animal went through the manifold changes that were necessary before it stood forth as an accomplished horse.
One of the biggest changes in the antecedents of the horse appeared about six million years ago, when pliohippus, the latest in the breed, evolved with only one toe on each foot and with the pads on which his ancestors had run eliminated. It now had a single hoof. This animal was a medium-sized beautiful horse in almost every sense of the word, and would have been recognized as such, even from a considerable distance. There would be minor refinements, mostly in the teeth and in the shape of the skull, but the horse of historic times was now foreshadowed.
He arrived as equus about two million years ago, as splendid an animal as the ages were to produce. Starting from the mysterious and unseen ‘paleohippus,’ this breed had unconsciously and with great persistence adapted itself to all the changes that the earth presented, adhering always to those mutations which showed the” best chance of future development. ‘Paleohippus,’ of the many capacities, eohippus of the subtle form, merychippus with the horse-like appearance, pliohippus with the single hoof—these attributes persisted; there were dozens of other variations equally interesting which died out because they did not contribute to the final form. There were would-be horses of every description, some with the most ingenious novelties, but they did not survive, for they failed to adjust to the earth as it was developing; they vanished because they were not needed. But the horse, with its notable collection of virtues and adjustments, did survive.
About one million years ago, when the twin pillars were well formed, a male horse with chestnut coloring and flowing tail lived in the area as part of a herd of about ninety. He was three years old and gifted with especially strong legs that enabled him to run more swiftly than most of his fellows. He was a gamin creature and had left his mother sooner than any of the other males of his generation. He was the first to explore new arrivals on the prairie and had developed the bad habit of leading any horses that would follow on excursions into canyons or along extended draws
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One bright summer morning this chestnut was leading a group of six adventurous companions on a short foray from the main herd. He took them across the plains that reached out from the twin pillars and northward into a series of foothills that contained passageways down which they galloped in file, their tails flowing free behind them as they ran. It was an exhilarating chase, and at the end of the main defile they turned eastward toward a plain that opened out invitingly, but as they galloped they saw blocking their way two mammoths of extraordinary size. The great smooth-skinned creatures towered over the horses, for they were gigantic, fourteen feet tall at the shoulders, with monstrous white tusks that curved downward from the head. The tips of the tusks reached sixteen feet, and if they caught an adversary, they could toss him far into the air. The two mammoths were imposing creatures, and had they been ill-disposed toward the horses, could have created havoc, but they were placid by nature, intending no harm.
The chestnut halted his troop, led them at a sober pace around the mammoths, coming very close to the great tusks, then broke into a gallop which would take him onto the eastern plains, where a small herd of camels grazed, bending awkwardly forward. The horses ignored them, for ahead stood a group of antelope as if waiting for a challenge. The seven horses passed at full speed, whereupon the fleet antelope, each with a crown of four large antlers, sprang into action, darting after them.
For a few moments the two groups of animals were locked in an exciting race, the horses a little in the lead, but with a burst of speed the antelopes leaped ahead and before long the horses saw only dust. It had been a joyous race, to no purpose other than the challenge of testing speed.
Beside the grazing area on which the antelope had been feeding there rested a family of armadillos, large rat-like creatures encased in collapsible armor. The horses were vaguely aware of them but remained unconcerned, for the armadillo was a slow, peaceful creature that caused no harm. But now the round little animals stopped searching for slugs and suddenly rolled themselves into a defensive position. Some enemy, unseen to the horses, was approaching from the south and in a moment it appeared, a pack of nine dire wolves, the scourge of the plains, with long fangs and swift legs. They loped easily over the hill that marked the horizon, peering this way and that, sniffing at the air. The wolf serving as scout detected the armadillos and signaled his mates. The predators hurried up, inspected the armor-plated round balls, nudged them with their noses and turned away. No food there.
With some apprehension, the horses watched the nine enemies cross the grassland, hoping that they would pass well to the east, but this was not to be. The lead wolf, a splendid beast with sleek gray coat, spotted the horses and broke into a powerful run, followed instantly by his eight hunting companions. The chestnut snorted and in the flash of a moment realized that he must not lead his six horses back into the canyons from which they had just emerged, for the two mammoths might block the way, allowing the dire wolves to overtake any straggler and cut him down.
So with an adroit leap sideways he broke onto the plains in the direction the antelope had taken and led his troop well away from their home terrain. They galloped with purpose, for although the dire wolves were not yet close at hand, they had anticipated the direction the horses might take and had vectored to the east to cut them off. The chestnut, seeing this maneuver, led his horses to the north, which opened a considerable space between them and the wolves.
As they ran to their own safety, they passed a herd of camels that were slower-moving. The big awkward beasts saw the apprehension of the horses and took fright, although what the cause of the danger was they did not yet know. There was a clutter on the prairie and much dust, and when it had somewhat settled, the horses were well on their way to safety but the camels were left in the direct path of the wolves. The lumbering camels ran as fast as they could, scattering to divert attack, but this merely served to identify the slowest-moving and upon this unfortunate the wolves concentrated.
Cutting at him from all sides with fearful teeth, the wolves began to wear him down. He slowed. His head drooped. He had no defense against the dire wolves and within a few moments one had leaped at his exposed throat. Another fastened onto his right flank and a third slashed at his belly. Uttering a futile cry of anguish, the camel collapsed, his ungainly feet buckling under the weight of the wolves. In a flash, all nine were upon him, so that before the horses left the area, the camel had been slain.
At a slow walk they headed south for the hills that separated them from the land of the twin pillars. On the way they passed a giant sloth who stood sniffing at the summer air, dimly aware that wolves were on the prowl. The huge beast, twice the size of the largest horse, knew from the appearance of the horses that they had encountered wolves, and retreated awkwardly to a protected area. An individual sloth, with his powerful foreclaws and hulking weight, was a match for one wolf, but if caught by a pack, he could be torn down, so battle was avoided.
Now the chestnut led his horses into the low hills, down a gully and out onto the home plains. In the distance the twin pillars—white at the bottom where they stood on the prairie, reddish toward the top, and white again where the protecting caps rested—were reassuring, a signal of home, and when all seven of the troop were through the pass, they cantered easily back to the main herd. Their absence had been noted and various older horses came up to nuzzle them. The herd had a nice sense of community, as if all were members of the same family, and each was gratified when others who had been absent returned safely.
Among the six followers accompanying the chestnut on his foray was a young dun-colored mare, and in recent weeks she had been keeping close to him and he to her. They obviously felt an association, a responsibility each to the other, and normally they would by now have bred, but they were inhibited by a peculiar awareness that soon they would be on the move. None of the older animals had signified in any way that the herd was about to depart this congenial land by the twin pillars, but in some strange way the horses knew that they were destined to move ... and to the north.
What was about to happen would constitute one of the major mysteries of the animal world. The horse, that splendid creature which had developed here at twin pillars, would desert his ancestral home and emigrate to Asia, where he would prosper, and the congenial plains at the pillars would be occupied by other animals. Then, about four hundred thousand years later, the horse would return from Asia to reclaim the pastures along the river, but by the year 6000 B.C. he would become extinct in the Western Hemisphere.
The horses were about to move north and they knew they could not accommodate a lot of colts, so the chestnut and the mare held back, but one cold morning, when they had been chasing idly over the plains as if daring the dire wolves to attack them, they found themselves alone at the mouth of a canyon where the sun shone brightly, and he mounted her and in due course she produced a handsome colt.
It was then that the herd started its slow movement to the northwest. Three times the chestnut tried unsuccessfully to halt them so that the colt could rest and have a fighting chance of keeping up. But some deep instinctive drive within the herd kept luring them away from their homeland, and soon it lay far behind them. The dun-colored mare did her best to keep the colt beside her, and he ran with ungainly legs to stay close. She was pleased to see that he grew stronger each day and that his legs functioned better as they moved onto higher ground.
But in the fifth week, as they approached a cold part of their journey, food became scarce and the wisdom of this trek, doubtful. Then the herd had to scatter to find forage, and one evening as the chestnut and the mare and their colt nosed among the scrub for signs of grass, a group of dire wolves struck at them. The mare intuitively presented herself to the wolves in an effort to protect her colt, but the fierce gray beasts were not deluded by this trick, and cut behind her and made savage lunges at it. This enraged the chestnut, who sprang at the wolves with flashing hoofs, but to no avail. Mercilessly, the wolves cut down
the colt. His piteous cries sounded for a moment, then died in harrowing gurgle as his own blood drowned him.
The mare was distraught and tried to attack the wolves, but six of them detached themselves and formed a pack to destroy her. She defended herself valiantly for some moments while her mate battled with the other wolves at the body of the colt. Then one bold wolf caught her by a hamstring and brought her down. In a moment the others were upon her, tearing her to pieces.
The whole group of wolves now turned their attention to the chestnut, but he broke loose from them and started at a mad gallop back toward where the main herd of horses had been. The wolves followed him for a few miles, then gave up the chase and returned to their feast.
Mammals, unlike reptiles, had some capacity for memory, and as the trek to the northwest continued, the chestnut felt sorrow at the loss of his mate and the colt, but the recollection did not last long, and he was soon preoccupied with the problems of the journey.
It was a strange hegira on which the horses of Centennial were engaged. It would take them across thousands of miles and onto land that had been under water only a few centuries earlier. For this was the age of ice. From the north pole to Pennsylvania and Wisconsin and Wyoming vast glaciers crept, erasing whatever vegetation had developed there and carving the landscape into new designs.