Evolution Page 7

  And they deployed their most terrible weapon. Diplo tails lashed, all around the herd, and the air was filled with the crackle of shock waves, stunningly loud. A hundred and forty-five million years before humans, the diplos had been the first animals on Earth to break the sound barrier.

  The allosaurs retreated quickly. Nevertheless one of them was caught by the tip of a supersonic whip-tail that crashed into her ribs. Allosaurs were built for speed and their bones were light; the tail cracked three ribs, which would trouble the allosaur for months to come.

  But the attack, in those few blistering moments, had been successful.

  Already one great leg had collapsed under the male diplo, its ripped tendons leaving it unable to sustain its share of the animal’s weight. Soon his loss of blood would weaken him further. He raised his head and honked mournfully. It would take hours yet for him to die — the allosaurs, like many carnivores, liked to play — but his life was already over.

  Gradually the crackle of whiplash tails ceased, and the herd grew calmer.

  But it was the big matriarch who delivered the last whiplash of all.

  When the allosaurs had attacked, the orniths, suddenly united in terror, had fled the clearing. Now Listener and Stego skulked side by side in the forest-edge scrub, their unused weapons in their hands, their hunt thwarted. But it wasn’t all bad news. When the allos were done feeding there might be meat to be scavenged from the fallen diplo.

  Then came that last whiplash. The huge diplo’s tail landed clean across Stego’s back, laying his skin open to the bone. He screamed and fell, tumbling out into the open, his mouth agape. The slit pupils in his eyes pulsed as he gazed up at Listener.

  And one of the allosaurs, not far away, turned with glassy interest. Listener stood stock still, shocked.

  With a single bound the allo reached Stego. Stego screamed and scrabbled at the mud. The allo poked him curiously, almost gently, with her muzzle.

  Then, with astonishing speed, the allo’s head shot forward and delivered a single clean bite, all but severing Stego’s neck. She grabbed him by the shoulder, lifting him high. His head dangled by a few threads of skin, but his body twitched still. She carried him to the edge of the forest, away from the herd, where she began to feed. The process was efficient. The allo had joints within her jaw and skull, so that like a python she could open her mouth wide and position her teeth, the better to consume her prey.

  Listener found herself staring stupidly at an allosaur track, a three-toed crater firmly planted in the trampled mud. A hunter without her mate is like a herd without its matriarch: The ornith proverb sounded in her head, over and over.

  The big matriarch diplo swung her head around to stare directly at Listener. Listener understood. The orniths’ antics had given the allos their chance to attack. So, with her whiplash, the matriarch had exposed Stego. She had given him to the allos. It had been revenge.

  The matriarch turned away, lowing, as if contented.

  Something hardened, a dark core, in Listener’s mind.

  She knew she would spend the rest of her life with this herd. And she knew that the matriarch was its most important individual; providing protection to the rest with her sheer bulk, leading them with her wisdom acquired over long years. Without her the herd would be much less well coordinated, much more under threat. In a way, this matriarch was the most important individual creature in Listener’s life. In that moment, she swore vengeance of her own.

  Each night the orniths retreated to their ancestral forest, where once they had hunted mammals, insects, and the nests of diplodocus. They scattered in little pockets, and surrounded the area with heavily armed sentries. That evening, the mourning was extensive. This ornith nation was only a few hundred strong, and could ill afford to lose a strong, intelligent young male like Stego.

  Even as the cold of night drew in, Listener found it hard to rest.

  She gazed up at a sky across which auroras flapped, steep three-dimensional sculptures of light, green and purple. In this age Earth’s magnetic field was three times the strength it would be in the human era, and, as it trapped the wind streaming from the sun, the shining auroras would sometimes blanket the planet from pole to pole. But the lights in the sky meant nothing to Listener, and brought no comfort or distraction.

  She sought refuge in memories of happier, simpler times when she and Stego, emulating their distant ancestors, had hunted for diplo eggs. The trick was to seek out a patch of forest floor, not too far from the edge, that looked apparently lifeless, strewn with leaves and dirt. If you put your sensitive ear to the ground you could hear, if you were lucky, the telltale scratching of diplo chicks in their eggs. Listener had always preferred to wait, to guard “her” nest from others, until the diplo chicks began to break out of their eggs and stick their tiny heads out of the scattered dirt.

  For an inventive mind like Listener’s, there was no end to the games you could play.

  You could try to guess which chick would come up next. You could see how quickly you could kill a new emergent, snuffing it out within a heartbeat of its first glimpse of daylight. You could even let the chicks come out of their shells altogether. Already a meter long, with their flimsy tails and necks dangling, the chicks’ only priority was to escape to the deeper forest. You could let a chick get all the way to a patch of scrub — almost — and then haul it back. You could nip off its legs one by one, or bits of its tail, and, crunching the little morsels, see how it still struggled, as long as its brief life lasted, to get away.

  All smart carnivores played. It was a way of learning about the world, of how prey animals behaved, of honing reflexes. For their time, orniths had been very smart carnivores indeed.

  Once, not more than twenty thousand years ago, a new game had occurred to one of them. She had picked up a handy stick in her grasping hand, and she used that to probe for unbroken eggs.

  By the next generation the sticks had become hooks to drag out the embryos, and sharpened spears to stab them.

  And by the next, the new weapons were being trialed on bigger game: juvenile diplos, younger than five or six years, not yet part of a herd but already a meat haul worth hundreds of embryonic chicks. Meanwhile a rudimentary language was born, of the subtle communications of pack hunters.

  A kind of arms race followed. In this age of immense prey, the orniths’ better tools, more sophisticated communication, and complex structures were quickly rewarded by bigger and better hauls of meat. Ornith brains rapidly expanded, the better to make the tools, and sustain societies, and process language — but there was a need for more meat to feed the big expensive brains, requiring better tools yet. It was a virtuous spiral that would operate again, much later in Earth’s long history.

  The orniths had spread all over Pangaea, following their prey herds as they crisscrossed the supercontinent along their vast ancestral corridors of parkway.

  But now conditions were changing. Pangaea was breaking up, its backbone weakening. Rift valleys, immense troughs littered with ash and lava, were starting to open. New oceans would be born in a great cross shape: Eventually the Atlantic would separate the Americas from Africa and Eurasia, while the mighty equatorial Tethys would separate Europe and Asia from Africa, India, Australasia. Thus Pangaea would be quartered.

  It was a time of rapid and dramatic climate change. The drift of continental fragments created new mountains which, in turn, cast rain shadows across the lands; the forests died back, and immense dune fields spread. Generation by generation — as their range disintegrated, and the vegetation no longer had time to recover from their devastating passage — the great sauropod herds were diminishing.

  Still, if not for the orniths, the sauropods might have lingered much longer, even surviving into the great high summer of dinosaur evolution, the Cretaceous.

  If not for the orniths.

  Though Listener went on to take more mates and to raise proud clutches of healthy and savage young, she never forgot what had become of her
first mate, Stego. Listener did not dare challenge the matriarch. Everyone knew that the best chance of the herd’s survival was for the powerful old female to continue her long life; after all, no new matriarch had emerged to replace her.

  But, slowly and surely, she drew up her plans.

  It took her a decade. Over that time the numbers of diplos in the herd halved. The allosaurs too went into steep decline across the supercontinent as their prey animals became scarce.

  At last, after a particularly harsh and dry season, the old one was observed to limp. Perhaps there was arthritis in her hips, as there evidently was in her long neck and tail.

  The time was close.

  Then Listener smelled something in the wind from the east, a taste she had not known for a long time. It was salt. And she realized that the fate of the matriarch was no longer important.

  At last she achieved a consensus among the hunters.

  The great diplo cow was now 120 years old. Her hide bore the scars of failed predator attacks, and many of the bony spines on her back had snapped off. Still she was growing, now massing a remarkable twenty-three tons. But the degeneration of her bones, after their heroic lifetime of load-bearing, had slowed her cruelly.

  On the day her strength finally ran out, it took only a few minutes of the herd’s steady, ground-covering trot for her to become separated from the pack.

  The orniths were waiting. They had been waiting for days. They reacted immediately.

  Three males moved in first, all of them sons of Listener. They stalked around the matriarch, cracking their whips, flimsy bits of treated leather that emulated the supersonic crackle of the diplos’ tails.

  Some of the diplo herd looked back dimly. They made out the matriarch, and her tiny predators. Even now the million-year programming of the diplos’ small brains could not accept that these skinny carnivores presented any threat. The diplos turned away, and continued their relentless feeding.

  The matriarch could see the capering, diminutive figures before her. She rumbled her irritation, the great boulders grinding in her stomach. She tried to lift her head, to bring her own tail to bear, but too many joints had fused to painful immobility.

  Now the second wave of hunters moved in. Armed with poison-tipped spears, and using the claws of their hands and feet, they attacked the matriarch as allosaurs once had, striking and retreating.

  But the matriarch had not survived more than a century by chance. Summoning up the last of her energy, ignoring the hot aches that spread from the pinpricks in her side, she reared up on her hind feet. Like a falling building, she towered over the band of carnivores, and they fled before her. She crashed back to the earth with an impact like a sharp earthquake, her slamming forefeet sending waves of pain through every major joint in her body.

  If she had fled then, if she had hurried after her herd, she might have survived, even thrown off the effects of the spears. But that last monumental effort had briefly exhausted her. And she was not given time to recover. Again the hunters closed in, striking at her with their spears and claws and teeth.

  And here came Listener.

  Listener had stripped naked, discarding even the whip around her waist. Now she flew at the diplo’s flank, which quivered mountainously. The hide itself was like thick leather, resistant even to her powerful claws, and it was crisscrossed by gullies, the scars of ancient wounds, within which parasitic growths blossomed, lurid red and green. The stink of rotten flesh was almost overwhelming. But she clung there, digging in her claws. She climbed until she had reached the spines that lined the matriarch’s back. Here, Listener bit into the diplo’s flesh and began to rip away at the horny plates embedded beneath.

  Perhaps in some dark corner of her antique mind the diplo remembered the day she had ruined this little ornith’s life. Now, aware of new pains on her back, she tried to turn her neck, if not to swipe away the irritation, at least to see the perpetrator. But she could not turn.

  Listener did not stop her frantic, gruesome excavation until she had dug down to the spinal cord itself, which she severed with a harsh bite.

  For long days the mountain of meat served to sustain the nation of hunters, even as the young played in the cavernous hall of the matriarch’s great ribs.

  But Listener was criticized, in angry head bobs, dances, and gestures. This is a mistake. She was the matriarch. We should have spared her until another emerged. See how the herd is becoming scattered, ill-disciplined, its numbers falling further. For now we eat. Soon we may starve. You were blinded by your rage. We were foolish to follow you. And so on.

  Listener kept her own counsel. For she knew the damage the loss of the matriarch had done to the herd, how badly it had been weakened, how much less were its chances of survival. And she knew it did not matter, not anymore. For she had smelled the salt.

  When the matriarch was consumed, the hunting nation moved on, following the savannah corridor to the east as it had always done, walking in the herd’s unmistakable wake of trampled ground and crashed trees.

  Until they ran out of continent. Beyond a final belt of forest — beyond a shallow sandstone cliff — an ocean lay shining. The giant diplos milled, confused, in this unfamiliar place, with its peculiar electric stink of ozone and salt.

  The herd had reached the eastern coast of what would become Spain. They were facing the mighty Tethys Sea, which had forced its way westward between the separating continental blocks. Soon the Tethyan waters would break through all the way to the west coast, sundering a supercontinent.

  Listener stood on the edge of the cliff, her forest-adapted eyes dazzled by its light, and smelled the ozone and salt she had detected so many days ago. The matriarch was dead, destroyed, but it did not matter. For, after walking across a supercontinent, the diplodocus herd had nowhere to go.

  The orniths might have fared better had they had a more flexible culture. Perhaps if they had learned to farm the great sauropods — or even simply not to pressure them so hard in this time of change — they might have survived longer. But everything about them was shaped by their origins as carnivorous hunters. Even their rudimentary mythos was dominated by the hunt, by legends of a kind of ornitholestes Valhalla. They were hunters who could make tools: that was all they would ever be, until there was nothing left to hunt.

  The whole of the orniths’ rise and fall was contained in a few thousand years, a thin slice of time compared to the eighty million years the dinosaur empire would yet persist. They made tools only of perishable materials — wood, vegetable fiber, leather. They never discovered metals, or learned how to shape stone. They didn’t even build fires, which might have left hearths. Their stay had been too brief; the thin strata would not preserve their inflated skulls. When they were gone the orniths would leave no trace for human archaeologists to ponder, none but the puzzle of the great sauropods’ abrupt extinction. Listener and her culture would vanish. Like the great air whale and innumerable other fabulous beasts, they would vanish forever.

  With a sudden stab of loss, Listener hurled her spear into the ocean. It disappeared into the water’s glimmering mass.

  CHAPTER 3

  The Devil’s Tail

  North America. Circa 65 million years before present.

  I

  Once interplanetary impacts had been constructive, a force for good.

  Earth had formed close to the brightening sun. Water and other volatiles had quickly boiled away, leaving the young world an empty theater of rock. But the comets, falling in from the outer system, delivered substances that had coalesced in that cooler region: especially the water that would fill Earth’s oceans, and compounds of carbon, whose chain-based chemistry would lie at the heart of all life. Earth settled down to a long chemical age in which complex organic molecules were manufactured in the mindless churning of the new oceans. It was a long prelude to life. It would not have come about without the comets.

  But now the time of the impacts was done, so it seemed. In the new solar system, the re
maining planets and moons followed nearly circular orbits, like a vast piece of clockwork. Any objects following more disorderly paths had mostly been removed.

  Mostly.

  The thing that now came out of the dark, its surface of dirty slush sputtering in the sun’s heat, was like a memory of Earth’s traumatic formation.

  Or a bad dream.

  In human times, the Yucatan Peninsula was a tongue of land that pushed north out of Mexico into the gulf. On the peninsula’s northern coast there was a small fishing harbor called Puerto Chicxulub (Chic-shoe-lube). It was an unprepossessing place, a limestone plain littered with sinkholes and freshwater springs, agave plantations, and brush.

  Sixty-five million years before that, in the moist age of the dinosaurs, this place was ocean floor. The plains of the Gulf of Mexico were flooded up to the foothills of the Sierra Madre Oriental. The shallow Yucatan Peninsula itself lay under nearly a hundred meters of water. The sediments that would later form Cuba and Haiti were part of the deep seafloor, yet to be lifted by fault movements to the surface.

  In an age dominated by warm shallow seas, drowned Chicxulub was an unremarkable place. But it was here that a world would end.

  Chicxulub is a Mayan word, an ancient word coined by a lost people. Later, when the Mayans were gone, nobody would know for sure how it translated. Local legend said it meant the Devil’s Tail.

  In its last moments the comet flew in from the southeast, passing over the Atlantic and South America.

  II

  In bright, shallow waters the huge ammonite cruised.

  This sea-bottom hunter, the size of a tractor tire, looked something like a giant snail, with an elaborately curved spiral shell from which arms and a head protruded cautiously. As it had grown, it had extended its shell’s spiral structure, gradually moving from one chamber outwards to the next; now the linked, abandoned chambers were used for buoyancy and control.