My breath came slowly back and the pain subsided and I was able to take a look at where I was.

The hole was some three feet in diameter and perhaps as much as seven deep. It slanted slightly toward the forefront of the slope and its sides were worn smooth. A thin trickle of dirt ran down from the edge of it, soil that I had loosened and dislodged when I had hit the hole. And about halfway up was a cluster of small rocks, the largest of them about the size of a human head, projecting more than half their width out of the wall. I thought, idly, as I looked at them, that some day they'd come loose and drop into the hole. And at the thought I squirmed around a little to one side, so that if they took a notion to fall I'd not be in the line of fire.

Looking down, I saw that I'd not fallen to the bottom of the hole, for the hole went on, deeper in the ground. I had come to rest at a point where the hole curved sharply, to angle back beneath the swale top.

I hadn't noticed it at first, I suppose because I had been too shook up, but now I became aware of a musky smell. Not an overpowering odor, but a sort of scent — faintly animal, although not quite animal.

A smooth-sided hole and a musky smell — there could be no other answer: I had fallen not into just an ordinary hole, but into a burrow of some sort. And it must be the burrow of quite an animal, I thought, to be the size it was. It would have taken something with hefty claws, indeed, to have dug this sort of burrow.

And even as I thought it, I heard the rattling and the scrabbling of something coming up the burrow, no doubt coming up to find out what was going on.

I did some scrabbling myself. I didn't waste no time. But about three feet up I slipped. I grabbed for the top of the hole, but my fingers slid through the sandy soil and I couldn't get a grip. I shot out my feet and stopped my slide short of the bottom of the hole. And there I was, with my back against one side of the hole and my feet braced against the other, hanging there, halfway up the burrow.

While all the time below me the scrabbling and the clicking sounds continued. The thing, whatever it might be, was getting closer, and it was coming fast.

Right in front of me was the nest of rocks sticking from the wall. I reached out and grabbed the biggest one and jerked and it came loose. It was heavier than I had figured it would be and I almost dropped it, but managed to hang on.

A snout came out of the curve in the burrow and thrust itself quickly upward in a grabbing motion. The jaws opened up and they almost filled the burrow and they were filled with sharp and wicked teeth.

I didn't think. I didn't plan. What I did was instinct. I dropped the rock between my spread-out legs straight down into that gaping maw. It was a heavy rock and it dropped four feet or so and went straight between the teeth, down into the blackness of the throat. When it hit it splashed and the jaws snapped shut and the creature backed away.

How I did it, I don't know, but I got out of the hole. I clawed and kicked against the wall and heaved my body up and rolled out of the hole onto the naked hillside.

Naked, that is, except for the bush with the inch-long thorns, the one that I'd jumped over before I fell into the burrow. It was the only cover there was and I made for the upper side of it, for by now, I figured, the big cattle drive had gone past me and if I could get the bush between myself and the valley side of the swale, I might have a chance. Otherwise, sure as hell, one of those dogs would see me and would come out to bring me in.

For while there was no questions that they were dinosaur herders, they probably couldn't tell the difference between me and a dinosaur. I was alive and could run and that would qualify me.

There was always the chance, of course, that the owner of the burrow would come swarming out, and if he did I couldn't stay behind the bush. But I rather doubted he'd be coming out, not right away, at least. It would take him a while to get that stone out of his throat.

I crouched behind the bush and the sun was hot upon my back and, peering through the branches, I could see, far out on the valley floor, the great herd of milling beasts. All of them had been driven together and there they were, running in a knotted circle, while outside the circle prowled the pinkish dogs and something else as well — what appeared to be men driving tiny cars. The cars and men were all of the same color, a sort of greenish gray, and the two of them, the cars and men, seemed to be a single organism. The men didn't seem to be sitting in the cars; they looked as if they grew out of the cars, as if they and the cars were one. And while the cars went zipping along, they appeared to have no wheels, It was hard to tell, but they seemed to travel with the bottom of them flat upon the ground, like a snail would travel, and as they traveled, they rippled, as if the body of the car were some sort of flowing muscle.

I crouched there watching and now, for the first time, I had a chance to think about it, to try to figure out what was going on. I had come here, across more than sixty million years, to see some dinosaurs, and I sure was seeing them, but under what you might say were peculiar circumstances. The dinosaurs fit, all right. They looked mostly like the way they looked in books, but the dogs and car-men were something else again. They were distinctly out of place.

The dogs were pacing back and forth, sliding along in their sinuous fashion, and the car-men were zipping back and forth, and every once in a while one of the beasts would break out of the circle and the minute that it did, a half dozen dogs and a couple of car-men would race to intercept it and drive it back again.

The circle of beasts must have had, roughly, a diameter of a mile or more — a mile of milling, frightened creatures. A lot of paleontologists have wondered whether dinosaurs had any voice and I can tell you that they did. They were squealing and roaring and quacking and there were some of them that hooted — I think it was the duckbills hooting, but I can't be sure.

Then, all at once, there was another sound, a sort of fluttering roar that seemed to be coming from the sky. I looked up quickly and I saw them coming down — a dozen or so spaceships, they couldn't have been anything but spaceships. They came down rather fast and they didn't seem too big and there were tails of thin, blue flame flickering at their bases. Not the billowing clouds of flame and smoke that our rockets have, but just a thin blue flicker.

For a minute it looked like one of them would land on top of me, but then I saw that it was too far out. It missed me, matter of fact, a good two miles or so. It and the others sat down in a ring around the milling herd out in the valley.

I should have known what would happen out there. It was the simplest explanation one could think of and it was logical. I think, maybe, way deep down, I did know, but my surface mind had pushed it away because it was too matter-of-fact and too ordinary.

Thin snouts spouted from the ships and purple fire curled mistily at the muzzle of those snouts and the dinosaurs went down in a fighting, frightened, squealing mass. Thin trickles of vapor drifted upward from the snouts and out in the center of the circle lay that heap of dead and dying dinosaurs, all those thousands of dinosaurs piled in death.

It is a simple thing to tell, of course, but it was a terrible thing to see. I crouched there behind the bush, sickened at the sight, startled by the silence when all the screaming and the squealing and the hooting ceased. And shaken, too — not by what shakes me now as I write this letter, but shaken by the knowledge that something from outside could do this to the Earth.

For they were from outside. It wasn't just the spaceships, but those pinkish dogs and gray-green car men, which were not cars and men, but a single organism, were not things of earth, could not be things of earth.