Free Evolution by Stephen Baxter Page B

ground. They glared back at Listener, their own mouths gaping, heads bobbing.
    A tinge of apprehension touched Listener. Not so long ago three like these would have fled at her approach; the wild ones had long learned to fear the sting of weapons wielded by their smarter cousins. But hunger outweighed their fear. It had probably been a long time since these brutes had come across a diplo nest, their primary food source. Now these clever opportunists probably hoped to steal whatever Listener and Stego managed to win for themselves.
    The world forest was getting crowded.
    Listener, confronted by this unwelcome reminder of her own brutish past, knew better than to show fear. She continued to stalk steadily toward the three wild orniths, head dipping, gesturing. If you think you are going to steal my kill you have another think coming. Get out of here, you animals. But the mindless ones replied with hisses and spits.
    The commotion was beginning to distract the diplodocus. That runty female had already ducked back into the mass of the herd, out of reach of the hunters. Now the big matriarch herself looked around, her head carried on her neck like a camera platform on a boom crane.
    It was the chance the allosaurs had been waiting for.
    The allos stood like statues in the forest’s green shade, standing upright on their immense hind legs, their slender forearms with their three-clawed hands held beneath. This was a pack of five females, not quite fully grown but nevertheless each of them was ten meters long and weighed more than two tons. Allosaurs were not interested in runtish juveniles. They had targeted a fat male diplo, like themselves just a little short of full maturity. As the herd milled, distracted by the commotion of the squabbling orniths, that fat male got himself separated from the protective bulk of the herd.
    The five allos attacked immediately, on the ground, in the air. With hind claws like grappling hooks they immediately inflicted deep, ugly wounds. They used their strongly constructed heads like clubs, battering the diplo, and teeth like serrated daggers gouged at the diplo’s flesh. Unlike tyrannosaurs they had big hands and long, strong arms they used to grab on to the diplo while dismembering him.
    Allosaurs were the heaviest land carnivores of all time. They were like upright, meat-eating, fast-running elephants. It was a scene of immense and ferocious carnage.
    Meanwhile the diplo herd was fighting back. The adults, bellowing in protest, swung their huge necks back and forth over the ground, hoping to sweep aside any predator foolish enough to come close. One of them even reared up on her hind legs, a vast, overpowering sight.
    And they deployed their most terrible weapon. Diplo tails lashed, all around the herd, and the air was filled with the crackle of shock waves, stunningly loud. A hundred and forty-five million years before humans, the diplos had been the first animals on Earth to break the sound barrier.
    The allosaurs retreated quickly. Nevertheless one of them was caught by the tip of a supersonic whip-tail that crashed into her ribs. Allosaurs were built for speed and their bones were light; the tail cracked three ribs, which would trouble the allosaur for months to come.
    But the attack, in those few blistering moments, had been successful.
    Already one great leg had collapsed under the male diplo, its ripped tendons leaving it unable to sustain its share of the animal’s weight. Soon his loss of blood would weaken him further. He raised his head and honked mournfully. It would take hours yet for him to die— the allosaurs, like many carnivores, liked to play— but his life was already over.
    Gradually the crackle of whiplash tails ceased, and the herd grew calmer.
    But it was the big matriarch who delivered the last whiplash of all.
    When the allosaurs had attacked, the orniths, suddenly united in terror, had fled the clearing. Now Listener and Stego skulked side by side in the forest-edge