It was this marvel of engineering, this infinitely sophisticated machine which had only recently developed and which would flourish for another seventy million years, that floated along the shore of the lagoon that night, and when the little mammal came out of its nest at dawn, it saw her twisting her neck out toward the lagoon, then inland toward the chalk cliff.
Finally she turned and swam back toward the swamp at the foot of the cliff. When she reached there she sniffed the air in all directions, and one smell seemed familiar, for she turned purposefully toward fern trees at the far end of the swamp and from them appeared the male diplodocus for which she had been searching. They approached each other slowly poling themselves along the bottom of the swamp, and when they met they rubbed necks together.
She came close to him, and the little mammal watched as the two giant creatures coupled in the water, their massive bodies intertwined in unbelievable complexity. When he rutted he simply climbed on the back of his mate, locking his forepaws about her, and concluded his mating in seven seconds. The two reptiles remained locked together most of the forenoon.
When they were finished they separated and each by his own route swam away to join the herd. It consisted of fifteen members of the diplodocus family, three large males, seven females and five young animals. They moved together, keeping to the deep water most of the time but never loath to come into the river for food. In the water they poled themselves along with their feet barely touching bottom, their long tails trailing behind, and all kept in balance by that subtle arrangement of bone whereby the heaviest hung close to the bottom, allowing the lighter to float on top.
The family did not engage in play such as later animals of a different breed would; they were reptiles and as such were sluggish. Since they had cold blood with an extremely slow metabolism, they needed neither exercise nor an abundance of food; a little motion sufficed them for a day, a little food for a week. They often lay immobile for hours at a time, and their tiny brains spurred them to action only when they faced specific problems.
After a long time she felt another urge, positively irresistible, and she moved along the shore to a sandy stretch of beach not far from the chalk cliff. There she swept her tail back and forth, clearing a space, in the middle of which she burrowed both her snout and her awkward forelegs. When a declivity was formed, she settled herself into it and over a period of nine days deposited thirty-seven large eggs, each with a protective leathery shell.
When her mission ashore was accomplished, she spent considerable time brushing sand over the nest with her tail and placing with her mouth bits of wood and fallen leaves over the spot so as to hide it from animals that might disturb the eggs. Then she lumbered back to the lagoon, soon forgetting even where she had laid the eggs. Her work was done. If the eggs produced young reptiles, fine. If not, she would not even be aware of their absence.
It was this moment that the furry animal had been watching for. As soon as diplodocus submerged herself in the lagoon, he darted forth, inspected the nest, and found one egg that had not been properly buried. It was larger than he, but he knew that it contained food enough for a long time. Experience had taught him that his feast would be tastier if he waited some days for the contents to harden, so this time he merely inspected his future banquet, and kicked a little dirt over it so that no one else might spot it.
After the thirty-seven eggs had baked four days in the hot sand, he returned with three mates, and they began attacking the egg, gnawing with incisors at its hard shell. They had no success, but in their work they did uncover the egg even more.
At this point a dinosaur much smaller than any which had appeared previously, but at the same time much larger than the mammals, spotted the egg, knocked off one end and ate the contents. The pantotheres were not sorry to see this, for they knew that much meat would still be left in the remnants, so when the small dinosaur left the area, they scurried in to find that the broken eggshells did yield a feast.
In time the other eggs, incubated solely by action of the sun, hatched, and thirty-six baby reptiles sniffed the air, knew by instinct where the lagoon lay, and in single file, they started for the safety of the water.
Their column had progressed only a few yards when the flying reptile that had tried to snatch the mammal spotted them and with expert glide swooped down, catching one in its beak, taking it to its hungry young. Three more trips the reptile made, catching an infant diplodocus each time.
Now the small dinosaur that had eaten the egg also saw the column, and he hurried in to feed on six of the young. As he did so, the others scattered, but with an instinct that kept them moving always closer to the lagoon. The original thirty-seven were now down to twenty-six, and these were attacked continuously by the rapacious flier and the carnivorous dinosaur. Twelve of the reptiles finally reached the water, but as they escaped into it a large fish with bony head and jagged rows of teeth ate seven of them. On the way, another fish saw them swimming overhead and ate one, so that from the original thirty-seven eggs, there were now only four possible survivors. These, with sure instinct, swam on to join the family of fifteen grown diplodocuses, which had no way of knowing the young reptiles were coming.
As the little ones grew, diplodocus herself had no way of knowing that they were her children. They were merely reptile members that had joined the family, and she shared with other members of the herd the burden of teaching them the tricks of life.
When the young were partly grown, their thin snakelike bodies increasing immensely, diplodocus decided that it was time to show them the river. Accompanied by one of the adult males, she set out with the four youngsters.
They had been in the river only a short time when the male snorted sharply, made a crackling sound in his throat, and started moving as fast as he could back to the lagoon. Diplodocus looked up in time to see the most terrifying sight the tropical jungle provided. Bearing down upon the group was a monstrous two-legged creature towering eighteen feet high, with huge head, short neck and rows of gleaming teeth.
It was allosaurus, king of the carnivores, with jaws that could bite the neck of diplodocus in half. When the great beast entered the water to attack her, she lashed at him with her tail and knocked him slightly off course. Even so, the monstrous six-inch claws on his prehensile front feet raked her right flank, laying it open.
He stumbled, righted himself and prepared a second attack, but again she swung her heavy tail at him, knocking him to one side. For a moment it looked as if he might fall, but then he recovered, left the river and rushed off in a new direction. This put him directly behind the male diplodocus, and even though the latter was retreating as fast as possible toward the lagoon, the momentum of allosaurus was such that he was able to reach forward and grab him where the neck joined the torso. With one terrifying snap of the jaws, allosaurus bit through the neck, vertebrae and all, and brought his victim staggering to his knees. The long tail flashed, but to no avail. The body twisted in a violent effort to free itself of the dagger-like teeth, but without success.
With great pressure, allosaurus pushed the giant reptile to the ground, then, without relinquishing its bloody hold, began twisting and tearing at the flesh until the mighty teeth joined and a large chunk of meat was torn loose. Only then did allosaurus back away from the body. Thrusting its chin in the air, it adjusted the chunk of meat in its mouth and dislocated its jaw in such a way that the huge morsel could slide down into the gullet, from whence it would move to the stomach, to be digested later. Twice more it tore at the body, dislodging great hunks of meat which it eased down its throat. It then stood beside the fallen body for a long time as if pondering what to do. Crocodiles approached for their share, but allosaurus drove them off. Carrion reptiles flew in, attracted by the pungent smell of blood, but they too were repulsed.
As allosaurus stood there defying lagoon and jungle alike, he represented an amazing development, as intricately devised as diplodocus. His jaws were enormous, their rear ends lashed down b
y muscles six inches thick and so powerful that when they contracted in opposing directions they exerted a force that could bite through trees. The edges of the teeth were beautifully serrated, so they could cut or saw or tear; sophisticated machines a hundred and forty million years later would mimic their principle.
The teeth were unique in another respect. In the jaw of allosaurus, imbedded in bone beneath the tooth sockets, lay seven sets of replacements for each tooth. If, in biting through the neck bones of an adversary, allosaurus lost a tooth, this was of little concern. Soon a replacement would emerge, and behind it six others would remain in line waiting to be called upon, and if they were used up, others would take place in line, deep within the jawbone.
Now allosaurus lashed his short tail and emitted growls of protest. He had killed this vast amount of food but could not consume it. Other predators appeared, including the two smaller dinosaurs that had visited the beach before. All remained at a safe distance from allosaurus.
He took one more massive bite from the dead body but could not swallow it. He spit it out, glared at his audience, then tried again. Covered with sand, the flesh rested in his gaping mouth for several minutes, then slid down the extended neck. With a combative awk-awk from deep within his throat, allosaurus lunged ineffectively at the watchers, then ambled insolently off to higher ground.
As soon as he was gone, the scavengers moved in—reptiles from the sky, crocodiles from the lagoon, two kinds of dinosaurs from land and the unnoticed mammals from the roots of the ginkgo tree. By nightfall the dead diplodocus, all thirty-three tons of him, had disappeared and only his massive skeleton lay on the beach.
Wounded diplodocus and the four young dinosaurs that had witnessed this massacre now swam back to the lagoon. In the days that followed, she began to experience the last inchoate urge she would ever know. Sharp pains radiated slowly from the place where allosaurus had ripped her. She found no pleasure in association with the other members of the herd. She was drawn by some inexplicable force back to the swamp at the chalk cliff, not for purposes of recreating the family of which she was a part but for some pressing reason she had never felt before.
For nine days she delayed heading for the swamp, satisfying herself with half-sleep in the lagoon, poling herself idly half-submerged from one warm spot to another, but the pain did not diminish. Vaguely she wanted to float motionless in the sun, but she knew that if she did this, the sun would destroy her. She was a reptile and had no means of controlling body heat; to lie exposed in the sun long enough would boil her to death in her own internal liquids.
Finally on the tenth day she entered the river for the last time. stepping quietly like some gracious queen. She stopped occasionally to browse on some tree, lifting her head in a glorious are on which the late sun shone. Her tail extended behind, and when she switched it for some idle purpose it gleamed like a scimitar set with jewels.
How beautiful she was as she took that painful journey, how gracefully coordinated her movements as she swam toward the chalk cliff. She moved as if she owned the earth and conferred grace upon it. She was the great final sum of millions of years of development. Slowly, swaying from side to side with majestic delicacy, she made her way to the swamp that lay at the foot of the cliff.
There she hesitated, twisting her great neck for the last time as if to survey her kingdom. Thirty feet above the earth her small head towered in one last thrust. Then slowly it lowered; slowly the graceful arc capsized. The tail dragged in the mud and the massive knees began to buckle. With a final surge of determination, she moved herself ponderously and without grace into a deep eddy.
Its murky waters crept up her legs, which would never again be pulled forth like reeds; this was the ultimate capture. The torn side went under; the tail submerged for the last time, and finally even the lovely arc of her neck disappeared. The knobby protuberance holding her nose stayed aloft for a few minutes, as if she desired one last lungful of the heavy tropical air, then it too disappeared. She had gone to rest, her mighty frame imprisoned in the muck that would embrace her tightly for a hundred and thirty-six million years.
It was ironic that the only witness to the death of diplodocus was the little pantothere that watched from the safety of a cycad tree, for of all creatures who had appeared on the beach, he was the only one that was not a reptile. The dinosaurs were destined to disappear from earth, while this little animal would survive, its descendants and collaterals populating the entire world, first with prehistoric mammals themselves destined to extinction—titanotheres, mastodons, eohippus—and subsequently with animals man would know, such as the mammoth, the lion, the elephant, the bison and the horse.
Of course, certain smaller reptiles such as the crocodile, the turtle and the snake would survive, but why did they and the little mammal live when the great reptiles vanished? This remains one of the world’s supreme mysteries. About sixty-five million years ago, as the New Rockies were emerging, the dinosaurs and all their immediate relations died out. The erasure was total, and scholars have not yet agreed upon a satisfactory explanation. All we know for sure is that these towering beasts disappeared. Triceratops with its ruffed collar, tyrannosaurus of the fearful teeth, ankylosaurus the plated ambulating tank, trachodon the gentle duck-billed monster—all had vanished.
Ingenious theories have been advanced, some of them captivating in their imaginativeness, but they remain only guesses. Yet because the mystery is so complete, and so relevant to man, all proposals merit examination. They fall into three major groups.
The first relates to the physical world, and each argument has some merit. Since the death of the dinosaurs coincided with the birth of the New Rockies, there may have been a causal relationship, with the vast lowland swamps disappearing. Or temperatures may have risen to a degree that killed off the great beasts. Or plant life may have altered so rapidly that the dinosaurs starved. Or the disappearance of the extensive inland sea changed water relationships and dried up lagoons. Or mountain building somehow involved loss of oxygen. Or a combination of changes in plant food doomed the reptiles. Or a single catastrophic sun flare burned the dinosaurs to death, while the mammals, with their built-in heat-adjusting apparatus, survived.
The second theory is more difficult to assess, because it deals with psychological factors, which, even though they may be close to the truth, are so esoteric that they cannot be quantitatively evaluated. Classes of animals, like men, empires and ideas, have a predestined length of life, after which they become senescent and die out. Or the dinosaurs had overspecialized and could not adapt to changes in environment. Or they became too large and fell of their own weight. Or they reproduced too slowly. Or their eggs became infertile. Or carnivores ate the vegetarian dinosaurs faster than they could reproduce and then starved for lack of food. Or for some unknown reason they lost their vital drive and became indifferent to all problems of survival.
The third combines all the reasons that relate to warfare between a declining reptilian world and a rising mammalian one. Mammals ate the eggs of the dinosaurs at such a rate that the reptiles could not keep producing enough to ensure survival. Or mammals of increasing size killed off the smaller reptiles and ate them. Or mammals preempted feeding grounds. Or mammals, because of their warm blood and smaller size, could adjust more easily to the changes introduced by the mountain building or other environmental shifts. Or a world-wide plague erupted to which the reptiles were subject while the mammals were not.
For each of these theories there are obvious refutations, and scholars have expounded them. But if we reject these proposals, where does that leave us in our attempt to find out why this notable breed of animal vanished? We must know, lest the day come when we repeat their mistakes and doom ourselves to extinction.
The best that can be said is that an intricate interrelationship of changes occurred, involving various aspects of life, and that the great reptiles failed to accommodate to them. All we know for sure is that in rocks from all parts of the worl
d there is a lower layer dating back seventy million years in which one finds copious selections of dinosaur bones. Above it there is an ominous layer many feet thick in which few bones of any kind are found. And above that comes a new layer often crowded with the bones of mammal predecessors of the elephant, the camel, the bison and the horse. The dead reach of relatively barren rock, representing the death of the dinosaurs, has not yet been explained.
Long after they disappeared, and after man had risen to the point where he could search out the fossilized skeletons of the dinosaurs, it would become fashionable to make fun of the great reptiles which had vanished through some folly of their own. The lumbering beasts would be held up to ridicule as failures, as inventions that hadn’t worked, as proof that a small brain in a big body makes survival impossible.
Facts prove just the opposite. The giant reptiles dominated the earth for one hundred and thirty-five million years; man has survived only two million and most of that time in mean condition. Dinosaurs were some sixty-seven times as persistent as man has so far been. They remain one of the most successful animal inventions nature has provided. They adjusted to their world in marvelous ways and developed all the mechanisms required for the kind of life they led. They are honored as one of the world’s longest-lived species, and they dominated their vast period of time just as man dominates his relatively brief one.