After finishing with such plants as were at hand, she moved into the channel. The mammal, still crouching among the roots of the gingko tree, watched with satisfaction as she moved past. It had been afraid that she might plant one of her massive feet on its nest as another dinosaur had done, obliterating both the nest and its young. Indeed, diplodocus had left underwater footprints so wide and so deep that fish used them as nests. One massive footprint might be many times as wide as the fish was long.
And so diplodocus moved away from the lagoon and the apprehensive watcher. As she went she was a veritable poem in motion. Placing each foot carefully and without haste, and assuring herself that at least two were planted solidly on the bottom at all times, she moved like some animated mountain, keeping the main bulk of her body always at the same level, while her graceful neck swayed gently and her extremely long tail remained floating on the surface.
The various motions of her great body were always harmonious; even the plodding of the four gigantic feet had a pleasant rhythm. With the graceful neck and the tapering tail, this large reptile epitomized the beauty of the animal kingdom as it then existed.
She was looking for a stone. For some time she had instinctively known that she lacked a major stone, and this distressed her. Keeping her head low, she scanned the bottom of the stream but found no suitable stones.
This forced her to move upstream, the delicate motion of her body conforming to the shifting bottom as it rose slightly before her. Now she came upon a wide selection of stones, but prudence warned her that they were too jagged for her purpose, and she ignored them. Once she stopped and turned a stone over with her blunt nose. She scorned it—too many cutting edges.
Preoccupied with her futile search, she failed to notice the approach of a rather large land-based dinosaur that walked on two legs. He did not come close to approaching her in size, but he was quicker of motion, and had a large head, a gaping mouth and a ferocious complement of jagged teeth. He was a meat-eater, always on the watch for the giant water-based dinosaurs who ventured too close to land. He was not large enough to tackle a huge animal like diplodocus if she was in her own element, but he had found that usually when the large reptiles came into the stream, there was something physically wrong with them, and twice he had been able to hack one down.
He approached diplodocus from the side, stepping gingerly on his two powerful hind feet, keeping his two small front feet ready like hands to grasp her should she prove to be in a weakened condition. He was careful to keep clear of her tail, for this was her only weapon.
She remained unaware of her would-be attacker, and continued to probe the river bottom for an acceptable stone. The carnivorous dinosaur interpreted her lowered head as a sign of weakness. He lunged at the spot where her vulnerable neck joined the torso, only to find that she was in no way incapacitated, for at the moment of attack she twisted adroitly and presented him with the broad and heavy side of her body. This made him stumble back. As he did so, diplodocus stepped forward, and slowly swung her tail in a mighty arc, hitting him with such force that he was thrown off his feet and sent crashing into the brush.
One of his small front feet was broken by the blow and he uttered a series of awk-awks, deep in his throat, as he shuffled off. Diplodocus gave him no more attention and resumed her search for the stone.
Finally she found what she wanted. It weighed about three pounds, was flattish on the ends and both smooth and rounded. She nudged it twice with her snout, satisfied herself that it suited her purposes, then lifted it in her mouth, raised her head to its full majestic height and swallowed the stone. It slid easily down her long throat into her gullet and from there into her grinding gizzard, where it joined six smaller stones that rubbed together gently and incessantly as she moved. This was how she chewed her food, the seven stones serving as substitutes for the molars she lacked.
With awkward yet oddly graceful motions she adjusted herself to the new stone, and could feel it find its place among the others. She felt better all over and hunched her shoulders, then twisted her hips and flexed her long tail.
Night was closing in. The attack by the smaller dinosaur reminded her that she ought to be heading back toward the safety of the lagoon, back where fourteen other reptiles formed a protective herd, but she was kept in the river by a vague longing she had experienced several times before but could not remember clearly. Like all members of the diplodocus family, she had an extremely small brain, barely large enough to send signals to the various remote parts of her body. For example, to activate her tail became a major tactical problem, for any signal originating in her head required some time to reach the effective muscles of the tail. It was the same with the ponderous legs; they could not be called into instant action.
Her brain was too small and too undifferentiated to permit reasoning or memory; ingrained habit warned her of danger, and only the instinctive use of her tail protected her from the kind of assault she had just experienced. As for explaining in specific terms the gnawing agitation she now felt, and which had been the major reason for her leaving the safety of the herd, her small brain could give her no help.
She therefore walked with splashing grace toward a spot some distance upstream. How beautiful she was as she moved through the growing darkness! All parts of her great body—the gently swaying neck, the stalwart trunk, the slow-moving mighty legs and the delicate tail extending almost endlessly behind and balancing the whole—responded splendidly to one central impulse. It would require far more than a hundred million years of experiment before her equal would be seen again.
She was moving toward a white chalk cliff that she had known before. It stood some distance from the lagoon, sixty feet higher than the river at its feet. Here, back eddies had formed a swamp, and as she approached this protected area, diplodocus became aware of a sense of security. She hunched her shoulders again and adjusted her hips. Swishing her long tail, she tested the edge of the swamp with one massive forefoot. Liking what she felt, she moved slowly forward, sinking deeper and deeper into the dark waters until she was totally submerged except for the knobby tip of her head, which she left exposed so that she could breathe.
She wanted to fall asleep, but the gnawing feeling of hunger kept her awake, even though she could feel the new stone working on the foliage she had consumed that day. The buzzing of the day insects had ceased, indicating that night was at hand, and she knew she should sleep but could not, After some hours the tiny brain sent signals along the extended nerve systems and she pulled herself through the swamp with noisy sucking sounds. Soon she was back in the main channel, still hunting vaguely for something she could neither define nor locate. And so she spent the long tropical night.
Diplodocus was able to function as capably as she did for three reasons. When she was in the swamp at the foot of the cliff, an area that would have meant death for most animals, she was able to extricate herself because her massive feet had a curious property; although they made a footprint many inches across as they flattened out in mud, they could, when it came time to withdraw them from the clinging muck, compress to the width of a foreleg, so that for diplodocus to pull her huge leg and foot from the mud was as simple as pulling a reed from the muck at the edge of the swamp; there was nothing for the mud to cling to, and the leg pulled free with a swooshing sound.
Diplodocus, ‘double beams,’ was so named because sixteen of her tail vertebrae—twelve through twenty-seven behind the hips—were made with paired flanges to protect the great artery that ran along the underside of the tail. But the vertebrae had another channel topside, and it ran from the base of the head to the strongest segment of the tail. In this channel lay a powerful and very thick sinew that was anchored securely at shoulder and hip and could be activated from either position. Thus the long neck and the sweeping tail were the precursor of the mechanical crane, which in later time would lift extremely heavy objects by the clever device of running a cable over a pulley and counterbalancing the whole. The pulle
y used by diplodocus was the channel made by the paired flanges of the vertebrae; her cable was the powerful sinew of neck and tail; her counterbalance was the bulk of her torso. Had she had powerful teeth, her neck was so excellently balanced that she could have lifted into the air the dinosaur that attacked her in the same way that the claw of a well-designed crane can lift an object many times its own weight. Without the advanced system of cable and pulley endowed by nature, diplodocus could have activated neither her neck nor her tail, and she could not have survived. With it, she was a sophisticated machine, as well adapted to her mode of life as any animal that might succeed her in generations to come.
The third advantage she had was remarkable, and raises questions as to how it could have developed. The powerful bones of her legs, which were underwater most of the time, were of the most heavy construction, thus providing her with necessary ballast, but the bones that were higher in her body were of successively lighter bulk, not only in sheer weight but also in actual bone composition, and this delicate construction buoyed up her body, permitting it almost to float.
That was not all. Many fenestrations, open spaces like windows, perforated the vertebrae of her neck and tail, thus reducing their weight. These intricate bones, with their channels top and bottom, were so exquisitely engineered that they can be compared only to the arches and windows of a Gothic cathedral. Bone occurred only where it was required to handle stress. No shred was left behind to add its weight if it could be dispensed with, yet every arch required for stability was in place. The joints were articulated so perfectly that the long neck could twist in any direction, yet the flanges within which the sinews rode were so strong that they would not be damaged if a great burden was placed on her neck or head.
It was this marvel of engineering, which had only recently developed and 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. Once there she sniffed the air in all directions, and apparently one smell was familiar, for she turned purposefully toward fern trees at the far end of the swamp, from which appeared the male diplodocus she had been seeking. They approached each other slowly, 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 were locked together most of the forenoon.
When they finally separated, each by his or her own route swam away to join the herd, which 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 and coming 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 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, one that was 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 with 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 eggs, each with a protective leathery shell.
When her mission ashore was completed, 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, and he knew that it contained enough food 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 uncovered the egg even more.
At this point a dinosaur much smaller than any that 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 of the egg would still be left, 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 the action of the sun, hatched, and thirty-six baby reptiles sniffed the air, knew by instinct where the lagoon lay, and in single file 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, swooping down, caught one infant in its beak to take it to its hungry young. The reptile made three more trips, catching a little 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.
As the little ones grew, diplodocus 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 a huge head, short neck and rows of gleaming teeth.
It was allosaurus, king of the carnivores, with jaws that could bite the neck of the 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 on
e 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 speed 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, to no avail. The body twisted in a violent but futile effort to free itself of the daggerlike teeth.
Allosaurus pushed the giant reptile to the ground, and then, without relinquishing its bloody hold, began twisting and tearing at the flesh until 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 which it would descend to the stomach, to be digested later. Twice more the beast 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 the denizens of lagoon and jungle alike, he presented an amazing appearance; he was as intricately devised as diplodocus. His jaws were enormous, their muscles so powerful that when they contracted in opposing directions they exerted a force that could bite through tree trunks. The edges of the teeth were beautifully serrated, so they could not only cut but also saw; elaborate machines a hundred and forty million years later would mimic their principle. The teeth were unique in another respect. In the jaw of allosaurus, embedded 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.