Free Evolution by Stephen Baxter Page A

creatures with mammalian features, a lumpen, ugly, unfinished lot. But that handful of species would ultimately give rise to all the mammals— including humans— and to the great lineages of birds, crocodiles, and dinosaurs.
    As if in response to the vast landscape in which they found themselves, the diplos had grown huge. Certainly their immensity was suitable for these times of unpredictable, mixed vegetation. With her long neck a diplo could work methodically across a wide area without even needing to move, taking whatever ground cover was available, even the lower branches of trees.
    In the clever orniths, though, the diplos faced a new peril, a danger for which evolution had not prepared them. Nevertheless, after more than a century of life, the matriarch had absorbed a certain deep wisdom, and her eyes, deep red with age, betrayed an understanding of the nimble horrors that pursued her kind.

    • • •
    Now the patient orniths had their best opportunity.
    The diplos still crowded around the wrecked ginkgo grove, their great bodies in a starburst formation. Their heads on their long necks dipped over the scattered foliage like cherry picker mechanical claws. Youngsters clustered close, but for now they were excluded by the giant adults.
    Excluded, forgotten, exposed.
    Stego ducked his head toward one of the diplo young. She was a little smaller than the rest— no larger than the largest African elephant, a genuine runt. She was having trouble forcing her way into the feeding pack, and she snapped and prowled at the edge of the formation with a massive birdlike twitchiness.
    There was no real loyalty among the diplos. The herd was a thing of convenience, not a family grouping. Diplos laid their eggs at the edge of the forest, and then abandoned them. The surviving hatchlings would use the cover of the forest until they had grown sufficiently massive to take to the open land and seek a herd.
    The herds made strategic sense: Diplos helped protect each other by their presence together. And any herd needed new blood for its own replenishment. But if a predator took one of the young, so be it. In the endless Pangaean forests, there was always another who would take her place. It was as if the herd accepted such losses as a toll to be paid for its continuing passage through the ancient groves.
    Today it looked as if this runty female would pay that toll.
    Listener and Stego took their whips of diplo leather from around their waists. Whips raised, spears ready, they crept through the rough scrub of saplings and ferns that crowded the edge of the forest. Even if the diplos spotted them they would probably not react; the diplos’ evolutionary programming contained no alarm signals for the approach of two such diminutive predators.
    A silent conversation passed in subtle movements, nods, eye contacts.
    That one, said Stego.
    Yes. Weak. Young.
    I will run at the herd. I will use the whip. Try to spook them. Separate the runt.
    Agreed. I will make the first run . . .
    It should have been routine. But as the orniths approached, coelurosaurs scuttled away and pterosaurs flapped awkwardly into the air.
    Stego hissed. Listener turned.
    And looked into the eyes of another ornith.
    There were three of them, Listener saw. They were a little larger than Listener and Stego. They were handsome animals, each with a distinctive crest of spiny decorative scales running down the back of its head and neck; Listener felt her own spines rise up in response, her body obeying an unbidden, ancient instinct.
    But these orniths were naked. They had no belts of woven bark around their waists like Listener’s; they carried no whips, no spears; their long hands were empty. They did not belong to Listener’s hunting nation, but were her remote cousins— wild orniths— the small-brained stock from which her kind had arisen.
    She hissed, her mouth gaping wide, and strode into the open. Get away! Get out of here!
    The wild orniths stood their