Nightmares & Geezenstacks by Fredric Brown

went on four legs; or had gone on four legs until he had met them, Then they had stopped going.
    There had been others more nearly like himself. Some had been many times bigger than he, but he had killed them with ease. The biggest ones of all had little heads and small mouths and ate leaves off the trees and plants on the ground.
    Yes, there had been giants on the earth, those days. A few of them. Satisfying meals. Things you could kill and eat your fill of, and lie gorged and somnolent for days. Then eat again if the pesky leather-wings with the long bills of teeth hadn’t finished off the Gargantuan feast while you had slept.
    But if they had, it did not matter. Stride forth again, and kill again to eat if hungry, for the pure joy of fighting and killing if you were not hungry. Anything that came along. He’d killed them all—the horned ones, the armored ones, the monster ones. Anything that walked or crawled. His sides and flanks were rough and seamed with the scars of ancient battles.
    There’d been giants in those days. Now there were the little things. The things that ran, and flew, and climbed. And wouldn’t fight.
    Ran so fast they could run in circles around him, some of them. Always, almost always, out of reach of his curved, pointed, double-edged teeth that were six inches long, and that could—but rarely had the chance to—shear through one of the little hairy things at a single bite, while warm blood coursed down the scaly hide of his neck.
    Yes, he could get one of them, once in a while. But not often enough, not enough of them to satisfy that monstrous hunger that was Tyrannosaurus Rex, king of the tyrant reptiles. Now a king without a kingdom.
    It was a burning within him, that dreadful hunger. It drove him, always.
    It drove him today as he went heavy-footed through the forest, scorning paths, crashing his way through heavy underbrush and sapling trees as though they were grass of the plains.
    Always before him the scurry and rush of the footsteps of the little ones, the quick click of hoofs, the pad-pad of the softer feet as they ran, ran.
    It teemed with life, that forest of the Eocene. But with fleet life which, in smallness and speed, had found safety from the tyrant.
    Life, it was, that wouldn’t stand up and fight, with bellowing roars that shook the earth, with blood streaming from slavering jowls as monster fought monstrosity. This was life that gave you the runaround, that wouldn’t fight and be killed.
    Even in the steaming swamps. There were slippery things that slithered into the muddy water there, but they, too, were fast. They swam like wriggling lightning, slid into hollow rotten logs and weren’t there when you ripped the logs apart.
    It was getting dark, and there was a weakness upon him that made it excruciating pain for him to take another step. He’d been hungry a hundred years, but this was worst of all. But it was not a weakness that made him stop; it was something that drove him on, made him keep going when every step was effort.
    High in a big tree, something that clung to a branch was going “ Yahh! Yahh! Yahh! ” mocking and monotonously, and a broken piece of branch arced down and bounded harmlessly off his heavy hide. Lese majesty. For a moment he was stronger in the hope that something was going to fight.
    He whirled and snapped at the branch that had struck him, and it splintered. And then he stood at fullest height and bellowed challenge at the little thing in the big tree, high overhead. But it would not come down; it went “ Yahh! Yahh!Yahh! ” and stayed there in cowardly safety.
    He threw himself mightily against the trunk of the tree, but it was five feet thick, and he could not even shake it. He circled twice, roaring his bafflement, and then blundered on into gathering darkness.
    Ahead of him, in one of the saplings, was a little gray thing, a ball of fur. He snapped at it, but it wasn’t there when he closed his jaws upon the wood. He saw only a dim gray