"Brontosaurs are not real bright. When they get alarmed they raise their heads and rear up on their hind legs to take a look around. If the ceiling is too low they smash their teeny heads against it and stun themselves."

"You've spent time around dinosaurs?"

"I grew up on a dinosaur ranch." I took her elbow and steered her out of the way of a manure loader. We watched as it scooped up a pile of watermelon-sized pellets.

"What a stench."

I said nothing. The smell had both good and bad associations for me. It took me back to my childhood, where one of my jobs had been operating the manure loader.

Behind us, the massive doors to the swamp began rumbling open, letting in a blast of air even hotter and more humid than that inside the barn. In a moment a long neck poked inside the door, ending in an almost negligible, goofy-looking head. The neck kept coming in for a very long time before the massive body made its entrance. By then another head and neck had appeared.

"Let's get back here out of the way," I suggested to Brenda. "They won't step on you if they see you, but they tend to forget where you are not long after they look away from you."

"Where are they going?"

I pointed toward the open gate across from us. The sign on it said "Mating Pen Number One."

"Mating season's just about over. Wait till Callie gets them penned up, then we can take a look. It's pretty interesting."

One of the brontosaurs made a mournful honk and moved along a little faster. In one-sixth gee, even a thunder lizard could be sprightly. I doubt they set any speed records back on Old Earth. In fact, I wondered how they stood up at all, out of the water.

The reason for the burst of speed was soon apparent. Callie entered the barn, mounted on a tyrannosaur. The big predator responded instantly to every touch of the reins, hurrying to block an attempted retreat by the male, rearing up and baring its teeth when it looked as if the female might make a stand. The big herbivores waddled quickly into the mating pen. The doors closed automatically behind them.

The thing the ancient paleontologists had never got right about dinosaurs was their color. You'd think the examples of so many modern reptiles might have given them a hint. But if you look at old artists' conceptions of dinosaurs, the predominant colors were mud-brown and khaki-green. The real item was much different.

There are several strains of b-saur but the type Callie prefers are called Cal Tech Yellowbellies, after the lab that first produced them. In addition to the canary undersides, they range from that old reliable mud-brown on their backs to a dark green, emerald green, and kelly green on their sides and necks. They have streaks of iridescent violet trailing back from their eyes, and white patches under their throats.