End of an Era

Klicks set off leaping around the crater wall. I gave chase. The donut of dark, crumbling earth had been providing some shade, but we came out into the fierce sun as we moved around back. It took us several minutes of mad hopping to circumnavigate the thirty-meter-wide crater, returning to the part of the wall upon which the Sternberger was perched.

"That’s amazing," I said, catching my breath, my head swimming. "But what could possibly account for it?"

"Who knows?" Klicks sat down on the dried mud. Even in less than half a g, leaping up and down like an idiot is enough to tire you out. I crouched about ten meters away from him, wiping sweat from my soaked forehead. The heat was stifling. "I’ll tell you one thing it accounts for, though," said Klicks. "Giantism in dinosaurs. Matthew of the AMNH asked the question a century ago: if the elephant is the largest size our terrestrial animals can now manage, how could the dinosaur have grown so much larger? Well, we’ve got the answer now: they evolved in a lesser gravity. Of course they’re bigger!"

I saw in an instant that he was right. "It also explains the extensive vascularization in dinosaur bones," I said. Dinosaur bone is remarkably porous, which is part of the reason it fossilizes so well through permineralization. "They wouldn’t need as much bone mass to support their weight in a lower gravity."

"I thought that vascularization was because they might be warm-blooded," said Klicks, sounding genuinely curious. He was, after all, a geologist, not a biologist. "Haversian canals for calcium interchange, and all that."

"Oh, there’s probably a correlation there, too. But I’ve never bought the idea of warm-blooded brontosaurs, and even they have bones that look like Swiss cheese in cross section. I’m sure you’ve seen the studies that say they’d break their own legs if they tried to walk faster than three kilometers an hour. That figure assumed normal gravity, of course. And, say, speaking of odd bone structure — it never quite seemed possible to me that Archaeopteryx and the pterosaurs could really fly. Their skeletons are weak for normal gravity, but they should be more than adequate in this."

"Hmmm," said Klicks. "It does explain a lot, doesn’t it? We’ll have to have a good look at dinosaurian heat production while we’re here. I seem to remember that another argument in favor of warm-blooded dinosaurs was that their fossils have been found inside the Cretaceous Arctic Circle, where the nights would be months long."

"That’s right," I said. "The idea was that dinosaurs must be warm-blooded because they couldn’t have possibly migrated far enough to avoid the long nights."

"Hell," said Klicks, taking off his boot and shaking it upside down to get rid of a pebble that had found its way inside, "I could walk to here from the Arctic Circle in this gravity."

"Yeah," I said. "But I’d still like to know why the gravity is less. I guess the gravitational constant could have increased in value over time."

"That would mean it’s not much of a constant, then, wouldn’t it?"

"Well, I don’t know a lot of physics," I said, ignoring his smart-ass comment, "but didn’t Einstein more or less pull the value for G out of the air to get his equations to balance? We’ve only been measuring its value for a century, and measuring it precisely for only a few decades. A general tendency for it to increase over time might not have shown up yet."

"I suppose, although I’d expect to find—" Suddenly he fell silent, his head swinging around. "What was that?" he said.

"What?"

"Shhsh!"

He pointed to the deciduous forest, the sun now well above the trees. There was a rustling as something man-sized pushed aside fronds. I caught a flash of emerald in my peripheral vision. My heart began pounding and my mouth went dry. Could it be a dinosaur?

We didn’t have much of an armament. Hell, we didn’t have much of a budget. Someone had suggested we bring modern automatic assault weapons to protect ourselves, but no corporate donor came through with any of those — bad PR to be associated with killing animals, after all. All we had were a couple of old elephant guns, each holding two bullets at a time.

Klicks had brought his elephant gun with him when he’d come out this morning. It was propped up against the crater wall, about a dozen meters away. He sauntered over to it, casually picked it up, and motioned for me to follow. It took about forty seconds for us to reach the dense wall of trees. Pushing foliage aside with his hands, Klicks made his way into the forest. I was right behind him.

We heard the rustling again. Breath held tight, I strained to listen, scanning the dense growth for any sign of an animal. Nothing. Branches and leaves stood still, as if they, too, were frozen in anticipation. Seconds ticked by, heartbeats added up. Whatever it was must be nearby, either to my left or in front of me.