The Long War

keep these crests in view. Why so complex a display? I’ll have our scholars try passing them through pattern analyser suites . . .’
    Yue-Sai touched Roberta’s shoulder and pointed again, further along the river bank.
    More beasts drinking. These were like big flightless featherless birds, Roberta thought, walking almost daintily, balanced on two big back limbs but with two small grasping arms in front. Their heads were long, almost snake-like, but with wide duck-like beaks. When they dipped to the water, sucking noisily, long muscular tails waved behind them.
    Roberta asked, ‘Birds, or dinosaurs?’
    Yue-Sai shrugged. ‘They’re all the same big family. Don’t expect anything, Roberta. Don’t be surprised by anything . . .’
    Roberta understood the principle. The histories of the parallel worlds of the Long Earth had been shaped by similar processes, but differed in the detail. You had to imagine you were travelling across a kind of probability tree, where you found worlds on which some long-past event had turned out differently, thus reshaping life’s subsequent history and providing novel raw material for natural selection to mold . . .
    ‘For example,’ Yue-Sai said, ‘those duckbills look bird-like, or dinosaurid. But those big crested beasts are mammals. Some kind of marsupial, it seems. And there ’ s something you’d never have seen back in the Cretaceous.’ She pointed.
    Elves.
    Stepping humanoids. There was a pack of them, maybe twenty, including children and nursing infants. They had found a spot away from the big herbivores, and far enough back from the deep water to be safe from the crocodiles and any other threats. They were scooping up water with their hands, and digging into the mud for roots and worms and molluscs. A few of the younger males were bickering; with irritable pant-hoots they flickered between the worlds, so that to watch them was like trying to follow a badly edited movie.
    ‘There are other sorts here too,’ Yue-Sai said softly. ‘I spotted them in the deeper forest—’
    The conversation was cut short by a sound of thunder.
    Yue-Sai and Roberta shrank back into deeper cover. Some of the duckbills kept drinking, but the big adults looked up suspiciously. The crest-roos dipped their great heads and backed into a rough circle.
    There was a crash, the splintering of wood, a groan as a young tree was felled, and the forest parted like a flimsy stage set as a tremendous animal burst into the open. Its body must have been fifteen yards long, balanced exquisitely on two striding legs. Its arms were small, comparatively, but longer and more muscular than Roberta’s own legs, and the right arm had some kind of creeper wrapped around it. Its skin was covered with feathers, brilliantly coloured, like the costume of an Aztec priest. The head was a gaping nightmare of teeth and blood, and when it opened its mouth to roar Roberta imagined she could smell raw meat.
    It strode forward, huge, purposeful. It seemed more mechanical than animal, a killer robot, an automaton, and yet it breathed and pawed the earth. The herbivores were already fleeing, following the water’s edge, galloping and bellowing.
    But the elves did not run, not immediately. They scattered into a loose arc, facing the creature, the adults to the fore with stone blades in their hands, the young behind them, but even the young were snarling defiance. It was like another movie scene, Roberta thought. Stone-tool-wielding man-apes against the dinosaur.
    Yue-Sai was staring, as if unwilling to miss a second of the spectacle. ‘A dinosaur, all right. Or its sixty-five-million-years-later descendant. Tyrannosaur-like, or something else evolved to fit the same niche.’
    ‘Of course China had its own magnificent dinosaur lineages,’ Captain Chen reminded them sternly. ‘There are other comparisons to be used, Lieutenant.’
    ‘Yes, sir,’ Yue-Sai said absently. ‘It could even be a flightless bird. If it is like a tyrannosaur, the odds are this is a female. They had ranges a few miles across; the males were sparser, one every few tens of miles. But what’s that on its arm? . . .’
    The predator’s roars and the humanoids’ responding snarls and gestures were reaching a climax. Abruptly the predator charged, right into the middle of the elf group.
    The young with their parents scattered. The adult elves started flickering in and out of existence, faster than the predator could catch them, though she