A herd of different goat descendants stood knee-deep in the water. They had webbed feet that kept them from sinking in soft mud and sand. Each had a broad bill-like mask before its face. Sculpted from horns, these bills were used for browsing on the soft weeds found at the edge of the lakes. Sucking peacefully at the lakeside vegetation, these goats were like nothing so much as the hadrosaurs, the long-vanished duck-billed dinosaurs.

And, just as the hadrosaurs had been the most diverse group of dinosaurs before the comet fell, so this rediscovery of an ancient strategy was enabling a new radiation. Already many species of the duck-billed goats, subtly distinguished by differences in horn design, size, and diet preferences, were to be found at many of the water courses of the world’s tropical regions and elsewhere.

Meanwhile, all around this scene of relatively peaceful herbivorous thirst-quenching — just as there had always been — intent predatory eyes watched the herbivores at work.

Watching this scene with half-closed eyes it would not have been impossible to imagine that the animals obliterated by human action had been restored. But on this new African savannah the familiar roles had been taken up by new actors, descended from creatures that had best survived the human extinction event. These were those that had resisted all of mankind’s attempts at extirpation: the vermin, especially the generalists — starlings, finches, rabbits, squirrels — and rodents like rats and mice. Thus there were rabbits morphed into gazelles, rats become cheetahs. Only subtleties were changed — a nervous twitchiness about the rabbits, a hard-running intensity about the rats that had replaced the cats’ languid grace.

There was a sudden flurry of activity, a great clash like a bone breaking. Two of the great goat-elephants, males, had begun a dispute. Their heads bobbed and swayed atop long giraffelike necks, and their horns, elaborately curling before their faces, clashed like baroque swords.

Remembrance cowered deep into the shade of her acacia. As the great herbivores began to mill around her, disturbed by the battle, she wasn’t so safe. This tree, trunk and all, could be smashed up and devoured in a few heartbeats.

And now the watchful predators took advantage of the confusion.

A pack of them erupted from cover. Lean and vulpine, with long, powerful shanks and thickly padded feet, they were more rats. Working closely together, they moved wedgelike to separate one older goat-elephant from the rest of the herd. His huge horn-tusks chipped and scarred by a lifetime of battles, this big male bellowed his rage and fear and began to run. The rats settled into the pursuit, running closely together.

These rat derivatives were like dogs, yet they were not dogs. Their characteristic rodents’ incisors had been subtly modified from teeth designed for processing seeds and insects into blades with stabbing points. Their rear molars were like shears, well equipped for shredding meat. And they moved more closely than any dog pack had ever run, with a liquid, slithering power. But, like a dog pack, their basic strategy was to chase the goat-elephant until he was exhausted.

Soon the prey and his pursuers had passed out of sight.

The goat-elephants settled down once more to their drinking and fighting — though some of them turned their great heads to the place where the old one had stood, remembering his absence.

Remembrance took the opportunity to creep forward.

The water was scum laden. But she scooped it up in her hands and let it trickle into her mouth, leaving her palms and fingers coated with fine green slime.

From the water, two yellow eyes watched her with abstract instinct. It was a crocodile, of course. These ancient survivors had ridden out the human apocalypse as they had survived so many before: by living off the gruesome brown food chain of the dying lands, by burrowing into the welcoming mud in drought. And even now no animal, no pig or rabbit or primate, no fish or bird, reptile or amphibian — not even the rodents — had managed to dislodge the crocodiles from their watery kingdom.

Remembrance shuddered, and backed off from the water’s edge.

A new predator stalked over the bluff toward the lake. Again Remembrance scurried for cover, screened by the huge, impassive bodies of a herd of duck-billed goats.

This predator was more rodent stock; in fact it came from a kind of mouse. But its behavior was not like any dog or cat’s. It came to the edge of the water, and lifted itself up on its massive hind legs. The herbivores at the water’s edge cowered away. But the mouse-raptor had no interest in the creatures milling before it. With lordly dismissal it dipped its ferocious muzzle to taste the water. Then it stalked back to dry land where it used its small, feeble-looking hands to pluck at the grass, as if testing it.

It looked like one of the great carnivorous dinosaurs of the Cretaceous days. Its forearms were small, its tail was thickened for balance, and its hind legs were awesomely powerful machines of muscle and bone. Its incisors had developed into ferocious slashing weapons, to be deployed by thrusts of the heavy head. The mouse-raptor was a land shark, like a tyrannosaur, a body design rediscovered and made devastatingly effective. And yet this arrogant creature retained the small ears and brown fur of the diminutive rodents from which it had derived.

The mouse-raptor seemed satisfied with the water and the grass. It squealed, spat, and drummed its tail on the ground. From the distance there was a series of answering calls, drums, and cries.

More mouse-raptors approached the lake. They fanned out over a swath of grassland, sniffing the air. A few kits ran around the legs of the adults, wrestling and nipping at each other with the ancient playful curiosity of predators.

When they had gathered, the adult mouse-raptors turned, opened their throats, and set up a kind of synchronized wailing. In response, a herd of another kind of animal came lumbering toward the water.

These were big creatures, as big as the goat-elephants. Nervously they huddled together, querulously jostling. But even as they stumbled toward the water, under the apparent guidance of the mouse-raptors, they cropped hastily at the grass under their feet.

Their bodies were coated with sparse fur. Their heads were crested, their skulls shaped to allow anchorage for the tremendous cheek muscles that worked their immense lower jaws: Their heads looked rather like those of robust pithecines, in fact. Their ears, plastered back over their massive skulls, were huge and veined, great radiator fins designed to extract waste heat from their huge bodies. Though their hind legs were massive, enabling them to support their weight, they had the peculiar wrong-way-bending look of the rabbit-gazelles: legs meant for fleeing.

These animals were ugly, elephantine. But they had not descended from goat or pig. They had forward-looking eyes under heavy browridges, huge dark eyes that peered at the world, baffled and fearful. They walked on all fours, but they supported themselves on the folded knuckles of their hands, a posture that had once been called knuckle-walking.

Like Remembrance, their ancestors had once been human.

Remembrance waited until the big dull animals had settled to their drinking, jostling querulously, their ears spreading in the cooling air of the afternoon. Then she crept away.

It had taken millions of years for the great rebound of life to be completed.

Today, to the north of Remembrance’s tropical forest, a great band of temperate woodland and grassland marched around the Earth, stretching from Europe-Africa across Asia to North America. Here more rabbit types browsed the cool foliage, while things like hedgehogs and pigs worked the undergrowth. In the trees there were birds and squirrels — and many, many bats. This diverse group of mammals had continued to proliferate and diverge, and now there were some nocturnal flyers who had lost their eyes altogether, others who had learned to compete with the birds for the richer pickings of the day.