The new miniature society worked efficiently. Though Crest managed to grab one piece of fruit for himself, he was quickly pushed away by Whiteblood. But Whiteblood was in turn usurped by Patch. Though she was not much more than two-thirds of Whiteblood’s size, the infant clinging to her chest was like a badge of authority. Whiteblood took one fruit and, grumbling, moved back, giving way to Patch.

While this was going on Roamer, like the brothers, knew that she would get no nearer to the fruit until the dominant ones had taken what they wanted.

Alone, she walked carefully, all four limbs grasping, toward the edge of the raft, where the tangle of branches was a little looser. The two terrified crowders, huddled together, skittered away as she approached. Through the foliage she could see murky brown water, littered with bits of wood and leaf, rippling languidly. The sun glimmered in a hundred places, shining through gaps in the cover of the fallen tree, and the dancing light was entrancing, distracting.

Roamer was hungry, but she was also thirsty. She dipped her hand cautiously into the water — it was cool — and scooped up a mouthful. The water was mildly salty — not bitterly so, for even so far from land the river’s powerful outflow diluted the ocean’s brine. But as she drank the taste of salt began to build up in her mouth, and she spat out her last mouthful.

Hungry, bored, the brothers came to inspect her as she drank, head bent down into the foliage, arm outstretched, buttocks raised. They sniffed her curiously, but they could smell how young she was, too young to mate.

When the older ones were done, Roamer and the others fell on the fruit.

With their bellies full for now, the anthros were calming down. But already the haphazard raft had drifted out of sight of the land, already the anthros had eaten much of the fruit from the drowned mango tree. And already the potbelly, complacently munching, had stripped half the branches of their leaves.

And none of them had seen the pale gray triangle that slid silently through the water, not meters away.

The shark circled the crude, disintegrating raft. Alerted by the feeding frenzy as the drowned inhabitants of the riverbank forest were washed out to the waiting mouths of the ocean, the shark had been attracted by the scent of stale blood that leaked from the indricothere carcass. But now it sensed motion on the tangled foliage that floated overhead. It circled, calculating, patient.

The shark was not as intelligent as its parallels on land. But then it was not much like an animal at all. The bones of its back were not bone, but tough cartilage that gave the shark better flexibility than more advanced fish. Its jaw was cartilage too, in which were loosely attached teeth, serrated like steak knives, perfect for shearing flesh. Its projecting snout looked crude, but it cut through the water with the precision of a submarine’s engineering, and it was equipped with nostrils that could detect minute traces of blood. Beneath the snout was a special organ with extraordinary sensitivity to vibration, enabling it to sense the struggles of a frightened animal across immense distances. Behind its small head, the shark’s entire body was made of muscle, designed for power, for forward drive. It was like a battering ram.

Sharks had already been the ocean’s top predators for three hundred million years. They had endured through the great extinctions, while families of land predators had come and gone. They had seen off competition from new classes of animals, some much younger, like the true fish. Over that vast period of time, the sharks’ body design had barely modified, for there was no need.

The shark was relentless, unable to be deflected by guile, prepared to keep on attacking as long as its senses were appropriately stimulated. It was a machine designed for killing.

The shark could sense the great mass of dead meat drifting at the heart of this raft, but it could also hear the scurrying of live animals on its surface. The dead thing could wait.

Time to attack. It went in headfirst, its jaws open. The shark had no eyelids. But to protect its eyes, it rolled them back, so that they turned white, in the last instant before it struck.

Patch was the first to see the approaching fin, to glimpse the white torpedo body gliding through the water toward the raft, to look into the white eyes. She had never seen such a thing before, but her instincts yelled that this sleek form spelled trouble. She ran over the loose foliage to the raft’s far side.

The other anthros were panicking. The two crowders were squalling like tiny birds, running and leaping this way and that. Only the potbelly sat placidly on its branch, munching another handful of leaves.

Scrap, separated from her mother, didn’t react.

Patch was terrified. She had expected her infant to follow her to the far side of the raft. But the infant hadn’t seen the approaching peril. A human mother would have been able to visualize her child’s point of view, understand that the child might not be able to see everything she saw. That transference of understanding was beyond Patch; in that respect, just like Noth, she was like a very young human child herself, imagining that every creature in the world saw what she saw, had the same beliefs she did.

The shark rammed its blunt nose up through the loose foliage. To Roamer this eruption of a gaping mouth from under the world was a nightmarish vision. She hooted and ran helplessly, unable to escape the raft’s confines.

The infant was lucky. As the raft shuddered under the shark’s assault she lodged in an angle of branch and trunk. Her mother lurched across the spinning raft, leaping over the gaping hole the shark had ripped, and snatched up the child.

But the shark came again. This time it drove its wedge-shaped nose between two of the great trunks that formed the raft’s crude structure. The trunks separated, a great lane of leaf-strewn water opening up between them. One of the crowders fell, squeaking, into the widening gap.

The shark’s mouth was like a cavern opening up before it. The crowder’s pinprick mind was snuffed out in a second. The shark was barely aware of taking the tiny warm morsel. Its work was barely begun.

The anthros screamed and ran to the edge of the raft, getting as far from the rift as they could — but they cowered back from the desolate ocean beyond.

Whiteblood saw that the fat, complacent potbelly sat where she had always sat, on her leafy branch, that ridiculous red swelling blazoned across her chest — even though the shark’s vandalism had opened up the ocean right before her. In this instant of ultimate stress, new circuits closed in Whiteblood’s inventive mind. It was a chain of logic beyond all but the brightest of his kind. But then, on average, every generation of anthros was just a little brighter than the last.

Whiteblood took a flying leap. Both his feet rammed into the potbelly’s back. She was pitched precipitately into the sea.

This fat struggling creature was what the shark had been waiting for. It bit into its prey, in the middle of its torso. The shark’s whole body flexed as it shook the potbelly, and its jagged-edged teeth tore a lump out of the hapless creature. Then, closing through a cloud of diffusing blood, it waited for its victim to bleed to death.

The potbelly was utterly bewildered, suddenly immersed in water, overwhelmed by stunning pain. But her brain flooded with chemicals, and the centers of her functional mind closed down, granting her a sort of peace in this bloody darkness.

Whiteblood sat panting over the scene of his assault, where nothing remained of the potbelly but a pile of thin, ill-smelling shit, and handfuls of crushed leaves. Gradually the gap in the raft closed, as if it were healing itself. The anthros cowered, too stressed even to groom.