Evolution

But the sea ran away from her, exposing glistening mud. And as fast as she pursued it, the sea ran faster.

A fish flopped at her feet. She stopped and plucked it out of the dirty mud and popped it into her mouth. In the fish’s tiny awareness was a kind of relief; this death was quick compared to the grisly suffocation it had endured on the new beach.

The sea bottom, uncovered for the first time in millions of years, was a glistening floor of life. It was littered with clams, crustaceans, squid, fish, ammonites of all sizes, all of them drowning in the air.

Further south there were giant shapes. The suchomimus saw a giant plesiosaur, stranded like the rest. Eight meters long, it lay gasping on the mud with its four huge flippers splayed and broken around it. It struggled, tons of marine carnivore flipping this way and that, huge fins waving, savage teeth snapping in rage at the fate that had stranded it.

On any other day it would have been a remarkable sight. The suchomimus turned away, bewildered.

When she looked north to the land, she could see creatures creeping out of the devastated forests, the wind-scoured marshland. Many of them were ankylosaurs and other armored creatures, protected thus far by the heavy armor that had evolved to fend off the teeth and claws of tyra

But now the ankylosaurs opened their mouths and began to retreat once more. The suchomimus watched them, baffled. They were bellowing, but she couldn’t hear them.

She turned back to face the sea. And then she saw what had frightened them.

As air, so water.

From the impact site, powered by the immense pulse of heat, a circular shock wave now marched outward through the body of the ocean. Its destructive power was limited because the impact had not occurred in deep ocean water. Still, as it neared the coastline of North America, the wave was already some thirty meters high. And as it reached the shallower water of the Texas coast, the tsunami gathered itself, rearing ten to twenty times its initial height.

Nothing in the suchomimus’s evolutionary heritage had prepared her for this. The returning sea was like a moving mountain range, hurtling out of the retreated ocean. She could not hear it, but she could feel how it made the exposed seabed shudder, smell the sharp stink of salt and pulverized rock. She stood upright and bobbed her head, baring her teeth defiantly at the approaching tsunami.

The water towered above her. There was an instant of pressure, of blackness, a huge force that compressed her. She died within a second.

The tsunami rolled landward, dwarfing the lumbering ankylosaurs before crushing them, armor and all. On it went, ramming its way into the ancient, long-dried sea way. When it receded, the water left behind debris, great banks of it dredged from the sea bottom. It had been an immense slosh, from the stone thrown into this Cretaceous pond.

On the land, in Texas, nothing survived.

In the sea, only a handful of creatures lived through the oceanic catastrophe.

One of them was the sea turtle. She had burrowed deep enough into the mud for the tsunami waters to spare her. When she could sense that something like calm was restored, she struggled out of the mud, and ascended up through water cloudy with debris and bits of dead animals and plants.

The turtles, ancient, had already passed the zenith of their diversity. But where more spectacular creatures had perished en masse, the turtle had survived. In a dangerous world, humility made for longevity.

The impact had sent an energy pulse through the body of the Earth. In North and South America, across thousands of kilometers, faults gaped and landslides crashed, as the shocked ground shuddered. The rocky waves weakened as they propagated, but the Earth’s internal layers acted like a giant lens to refocus the seismic energy at the impact’s antipode, the southwestern Pacific. Even there, the width of the planet away, the ocean floor heaved in swells ten times higher than the 1906 San Francisco earthquake.

The shock waves would continue to pass through the planet’s body, crossing, interfering, reinforcing. For days, the Earth would ring like a bell.

Seen from space, a glowing wound was spreading out over the Earth around the still-burning impact point. It was a great cloud of molten rock, hurled into space.

In the vacuum the scattered droplets were begi

But most of the ejecta would fall back to Earth.

Already the great hailing had begun. The first to fall was the coarser debris from the perimeter of the crater, much of it fragments of smashed-up ocean-bottom limestone. These chunks had not been melted by the heat pulse of the initial impact. But as they fell back into the Earth’s warm pond of air, they began to glow brightly. Streaks of light hundreds of kilometers long were drawn across the sky, like an insane geometrical exercise. Some of the debris chunks were large enough to crack open as they heated, and secondary tracks fa

Of all the creatures within a few thousand kilometers of the impact, the great aerial whale had been least affected so far.

He had watched the great light descend over the Yucatan Peninsula — had seen that stabbing laser beam of vaporized seabed and comet, had even glimpsed the formation of the crater, as great ripples of rock pulsed through the exposed seabed before congealing into place in a great chthonic clench. Had he been able to describe what he saw, the whale could have provided posterity with a compelling eyewitness account of the catastrophe, the most violent impact since the end of the formative bombardment four billion years earlier.

But the whale cared nothing for that. The whale had not even been troubled by the wind; he flew too high, and had been able to continue feeding as the great sheets of discolored air fled across the ground far beneath him. Distant lights in the sky, trouble on the ground — like the creamy-swirl weather systems that often crossed the land and oceans — meant nothing to a creature who flew at the fringe of space. So long as the wispy aerial plankton that fed him continued to drift up from the lands below, he prowled his thin niche untroubled.

But this storm was different.

The air whale was used to meteors. They were just streaks of light in the purple-blue sky above. Almost all of the billions of bits of cosmic debris that fell to Earth burned up far above the stratosphere, the whale’s realm.

But some of these tracks were reaching down into Earth’s thicker air, passing far below him. The whale had no hearing — he had no need of it in this thin, silent air, where no predators worked — but if he had he might have made out the thin howl of the meteors as they plunged back to the planet from which they had so recently been flung. He could even see where the first sea-bottom chunks fell: On the ground, far below, sparks of light bloomed like tiny flowers, one after the other. It was like the view from a high-altitude bomber.

For the first time since he was a chick the whale began to know fear. Suddenly this was no aerial light show but a rain of light and fire. It was a rain that was falling all around him — and it was getting thicker. Belatedly he turned. With a slow flap of his immense wings, he headed north.