Evolution Read Free Page A

long dinosaur summer: relegated to the fringe of the reptiles’ great society, emerging from their burrows only at night, foraging for a living from dung, insects, and the small pickings of the forest.
    But tonight the rewards were meager, the droppings watery and foul-smelling. The volcano-damaged vegetation had provided poor fodder for the ankylosaurs, and what came out the other end was of little value to Purga.
    She moved across the clearing and into the forest. Here conifers towered grandly, rising to spreading mats of leaves far overhead. Among them were smaller trees a little like palms, and a few low bushes bearing pale yellow flowers.
    Purga scrambled briskly into the angular branches of a ginkgo tree. As she climbed she used the scent glands in her crotch to mark the tree. In her world of night, scent and sound were more important than sight, and if others of her kind found this mark, any time within the next week, it would be a sign like a neon light, telling them she had been here, even how long ago she had passed.
    It was pleasing to climb, to feel her muscles work smoothly as they hauled her high above the dangerous ground, to use the delicate balance afforded by her long tail— and, most of all, to jump, to fly briefly from one branch to another, using all her body’s equipment, her balance, her agility, her grasping hands, her fine eyes. She was forced to shelter in burrows on the ground. But everything about her had been shaped by an existence in the complex three-dimensional environment of the trees, where almost all primate species, throughout the family’s long history, would find refuge.
    But the acid rain of recent months had withered the trees and undergrowth; the bark was sour, and there were few insects to be found.
    Purga was perpetually hungry. She needed to consume her body weight every day: It was the price of her warm blood, and the milk she must produce for her two pups, safe in their burrow deeper in the forest. She clambered reluctantly back down the trunk of the ginkgo. Fear and hunger warring in her mind, she tried one or two more trees, but with no better luck.
    But now she lifted her head, whiskers twitching, bright eyes wide, to peer into the green dark of the forest. She could smell meat : the alluring stench of broken flesh. And she heard a forlorn, helpless piping, like that of baby birds.
    She scuttled away, following the scent.

    • • •
    In a small clearing at the base of a huge, gnarly araucaria there was a heap of roughly piled moss. At its edge, a small patch of debris-littered silt began to move. Soon the patch rose like a lid, and a small, scrawny neck poked out of the ground and through the layer of mud and debris. A beaklike mouth opened wide.
    Its little head quivering, tiny scales and feathers still moist with yolk, the infant dinosaur took its first breath. It looked like an oversized baby bird.
    It was the moment the didelphodon had been waiting for. This mammal, the size of a domestic cat, was one of the largest of its day. It was low slung, with a black-and-silver coat. Now it lunged forward and grabbed the chick by its thin neck, hauling it from its shell and flinging it into the air.
    The chick’s life was a handful of brief, vivid impressions: the cold air beyond its cracked shell, the blurred glow of the comet, a sense of flying. But now a hot cavern opened beneath it. Its skin still smeared with yolk, the chick died instantly.
    Meanwhile more chicks were pushing out of the ground, hatching all at the same time. It was as if the ground were suddenly swarming with baby dinosaurs. The didelphodon, and more predatory mammals, closed in to feed.
    An ancient survival strategy had been operating. Dinosaurs were reptiles who laid their eggs on the ground. Though some parents stayed with their brood, there was no way all the vulnerable eggs and chicks could be protected. So dinosaurs laid many eggs, and their hatchings were synchronized. There should have been