They moved on to the meteorology charts, and Amos was off again, discoursing avidly about the patterns of weather across the world. He smiled briefly as he remarked on the ignorance of students who supposed that meteorology was the study of meteors. Then on to seasonal patterns, and the significance of El Nino, which was a global effect.
Suppose she got involved in moving a heavy prop, and it snagged on her blouse, and tore it open, and Amos saw her bra? No, scratch that; she simply didn’t yet have enough bra-filler. So suppose she had to sit on the floor, spread-legged, to wrestle something into place, and he was helping her, and he got a really close look up under her skirt, and—no, scratch that too; he was immune to bare thighs. He had demonstrated that for years.
So how could she get his attention? There was only one way: by engaging his intellect. That was after all his most appealing feature. So she would have to start really paying attention, and maybe arrange to say something that made him realize that she wasn’t just another anonymous classroom face, she was a person with a mind. His first love was obviously science, and so hers would have to be too. Meanwhile she hummed “Why Was I Born Too Late?” to herself as she worked.
Now they were working on assorted fossils of sea creatures. They were inherently dull, even loathsome, being like squished bugs. “Ah, the trilobites,” Amos said with satisfaction. “Perhaps the success story of the Paleozoic era. Isn’t this a beauty!” He held up a fossil of what looked like the granddaddy of multi-legged under-the-rock creepers. “This phylum of arthropods didn’t disappear until the extinction that ended the era. That means they endured for close to two hundred and fifty million years. The dinosaurs were pikers. Of course then the dinosaurs faced their own extinction at the end of the Mesozoic, ushering in the Age of Mammals, misnomer which that is.”
Colene was getting interested again. Extinctions were wholesale dyings, and she had been pondering death increasingly, since the rape. Was it a way out?
But she wasn’t quite ready to bring up the subject of death yet. She preferred to come at it obliquely, so that he never caught on to her real interest in it. So she addressed a secondary curiosity. “The Age of Mammals is a misnomer?” Misnomer was one of those four-bit words teachers liked to use; it meant that the name was wrong. One of the ways to nail down a good grade was to spot such words early, and get them right.
“Of course,” he said happily. “The arthropods remain the most diverse and prolific phylum today, with about eighty percent of all species.”
“Ick!” Colene said, dismayed. “You mean spiders and flies and beetles?”
“And the crustaceans,” he agreed. “But even if you limit it to the chordates, even to the vertebrates, the fishes are the most diverse in the sea, and the birds on land. We might as well call it the Age of Aves.”
Now to slide in slantwise to the subject of death. “And it was the reptiles, until that last big extinction. What killed them?”
He smiled. He really seemed to appreciate her interest. Probably it was rare for any student ever to evince interest if there wasn’t a grade on the line. “That remains a matter of conjecture. Actually that wasn’t the greatest of the extinctions. The one at the end of the Paleozoic was, with about ninety-six per cent of all species disappearing. Possibly the one at the end of the Precambrian era, five hundred and seventy million years ago, was worse, but we can’t know because the fossil record is insufficient. There did seem to be multi-celled life forms then, none of which survived; life had to rediscover that after the extinction. That ushered in the Cambrian explosion.”
“Explosion? Somebody set off a bomb?” She smiled to show that she wasn’t really that dumb, just in case he should forget. Also, it was an excellent excuse to smile at him.
He returned the smile, and she felt like melting. “Figurative, Colene. New species appeared so suddenly that it seems like an explosive radiation. Most didn’t survive, but for a while there was an unparalleled diversity of types. We learn that from the Burgess Shale. There were more fundamentally different types of creature then than now, perhaps. We think it was because the seas of the world were empty of multi-cellular life, so there was for a time completely free diversification. Then the process of selection took hold, and many promising species were winnowed out. It’s too bad; there were some really intriguing varieties, like none known ever since.”
“You mean like BEMs—bug-eyed monsters?”
“Yes, though most of these were small compared to the monsters of today. Many were a fraction of an inch long. But strange. Here, look at Marrella.” He brought out a picture.
Colene looked. It was a weird bug with long horns extending across its back and sides, and too many legs to count, and two different sets of feeler-antenna reaching out in front. “Yuck! That’s the ugliest centipede I ever saw!”
“But a lovely unique arthropod,” he said. “Some eighty percent of the fossils found in the Burgess Shale were of this creature, so it was highly successful in its time. As you can see, it is also quite sophisticated in physical detail, not clumsy or primitive as we might have expected. Note that it is biramous.”
“It’s what?” This time he had lost her, but she forgave him that.
“Let me explain,” he said, almost radiating pleasure at the prospect. “The term means that each leg is divided. One part may be used for walking, in the way we consider normal. The other may be a gill.” He grabbed a pencil and made a sketch. “Each segment thus has two appendages, and each appendage has two parts.”
“That looks almost like a little man with wings,” she remarked.
“A cute analogy. Early arthropods tended to be this way. But those upper ones are gills. So you might say that Marrella breathed with its legs.”
She laughed, not even having to force it. “What a weird way to do it!”
“But many species lost their biramous features, and became uniramous,” he said. “Just one part to each leg, as is the case with us. I sometimes wonder what a modern biramous creature would be like, if it had evolved and come onto land with the rest of us. Of course we’ll never know, but it’s an amusing fantasy.”
“Yeah. Maybe even triramous, or quadriramous.”
He shook his head. “Three or four divisions to each appendage? I really don’t know what a creature would do with such a structure. I suspect it would be unwieldy.”
“Yeah. Fancy two of them trying to make love. He gets his trirames tangled up with her birames.”
This time he laughed. “What an image! But I doubt that they copulated in any such manner. The arthropods are more apt to do it tail-to-tail.”
Almost before she knew it, she had spoken words she shouldn’t have. “No rapes among them?”
He glanced sharply at her. “What is your interest in such a subject?”
“Oh, nothing,” she lied quickly, flustered. “Just foolish curiosity.” She hoped she wasn’t blushing.
He shrugged. “Rape is known among animals, and in some species it’s the rule. One has only to watch the way of a rooster with hens in a barnyard to appreciate that. But normally copulation is voluntary on both sides, except that pheromones can make it involuntary. So perhaps it’s a matter of opinion.”
Colene looked at another picture, not really interested in it, but hoping to guide the subject safely away from the danger zone. “What’s this—a cutaway view of the interior of a BEM airliner?”
He had to smile again. “That is Sarotrocercus, a tiny Burgess Shale arthropod. It swam on its back, and those ‘airplane seats’ are its gill branches, which we suspect it used for swimming. So if you are amused by legs used for breathing, now you can be further amused by gills used for swimming. These creatures had their own ways. But if you want to see real novelty, let me show you some of the others.” He sorted through the pictures. “Here is Wiwaxia. What does it look like to you?”