Evolution

There were creatures like raccoons but more closely related to the hoofed animals of the future, and scurrying insectivores whose descendants would include the shrews and the hedgehogs. Here was a taeniodont, like a small, fat wombat. It grubbed in the soil, expert at digging out roots and tubers. None of the grubbing creatures in this clearing would have been familiar to a watching human. They were furtive, odd, ungainly, almost reptilian in their behavior, forever looking over their shoulders, like petty thieves expecting the return of the householder.

These mammals were holdovers from the Cretaceous. Then, it had been as if the whole Earth had been a vast city, shaped for the needs of its owners, the dinosaurs. But now the dominant inhabitants were gone, the great buildings erased, and the only creatures left alive were the urban species who had lived in the drains and sewers, subsisting on garbage.

But the recovering Earth had become a very different place from the dreamy Cretaceous. The Earth’s new forests were much more dense now. There were no great herbivores: The sauropods had gone, and the elephants lay far in the future. There were no animals big enough to topple these trees, to smash clearings and corridors and make parklike savannah. In response the vegetation had gone crazy, filling the world with greenery of a density and profusion not seen since the first animals had walked onto the land.

But it was an oddly bare stage. In these thick jungles there were no more predatory dinosaurs — but neither were there yet jaguars, leopards, tigers. Practically all of the forest’s inhabitants were small, tree-dwelling mammals like Plesi. For an extraordinary span of time — for millions of years — the animals would cling to their Cretaceous habits, and no mammal species would grow to even moderately large sizes. They still contented themselves with the darkness and the corners of the empty world, nibbling on insects, eschewing any evolutionary innovations more spectacular than a new set of teeth.

Like long-term prisoners, the survivors of the impact were institutionalized. The dinosaurs were long gone — but for the mammals, habits ingrained over a much longer span, a full hundred and fifty million years of incarceration, were not so easy to give up.

But things were changing.

At last Plesi heard the quiet mewling of her young.

At the edge of the clearing Strong was huddled, pathetically, in a kind of nest of browned fronds. After she had fallen out of the tree and tumbled into the clearing, at least she had had the sense to seek cover. But she was far from safe: a large, scarlet-bellied predatory frog was watching her, an absent curiosity in its blank eyes. When she saw Plesi, Strong dashed forward and fell on her mother. She tried to find Plesi’s nipples, just as her sister had, but Plesi snapped at her, denying her comfort.

Plesi was deeply disturbed. A carpolestid who was strong in the nest but who had no instinct for the trees — who lacked even the sense to keep silent when exposed — had poor survival prospects. Suddenly Strong didn’t look so strong after all. Plesi felt an odd impulse to find a mate, to breed again. For now, though, she merely nipped at Strong’s flank with her sharp incisor teeth, and led the way back toward the tree from which she had descended.

But she had gone no more than a few body lengths when she froze.

The predator’s blank eyes fixed Plesi with lethal calculation.

The predator was an oxyclaenus.

He was a sleek, four-footed, dark-furred animal: long-bodied, stout-legged, he looked like an outsized weasel, though his face and muzzle were more reminiscent of a bear’s. But he was related to neither weasel nor bear. In fact he was an ungulate, an early member of that great family that would one day include the hoofed mammals like pigs, elephants, horses, camels, even the whales and dolphins.

This oxy might have seemed clumsy, slow, even unfinished to an eye used to cheetah or wolf. But his kind had learned to stalk prey through the sparse undergrowth of the endless forest. He could even climb, pursuing his quarry into the lower branches of the trees. In this archaic time, this oxy had little competition.

And, as he looked on Plesi’s timorous, flattened form, two cold questions dominated the oxy’s mind: How will I trap you? And, How good will you be to eat?

Plesi lay flat against the floor, quivering, her whiskers twitching, her small, sharp teeth bared. But she was equipped with instincts honed over a million centuries at the feet of the dinosaurs. And in the cold calculus of her mind, a reassessment of risk was beginning. In this open place she could not hide. She could not reach a tree to clamber out of the oxy’s grasp. Surely if she tried to outrun him he would trap her easily with one of those cruel claws.

Only one option was left.

She arched her back, opened her mouth and hissed, so violently that she spattered the oxy with her spittle.