Having watched plenty of science-fiction movies, I thought I had the answer. “Another T. rex,” I said.
Pick, who I thought had fallen asleep on his perch, suddenly opened his eyes and said, “Mike, you are exactly right.”
The next day, we found more teeth mixed in with the top T’s neck vertebrae and ribs. This meant, Laura said, another T, probably the one below, had locked on its throat. The next thing we found was a short, heavy bone that Laura said was the humerus of a Tyrannosaur arm. It was so small I had trouble believing it really belonged to the massive skeleton but Laura shrugged, saying, “Growing bones and muscles takes energy, you know, and life is inherently lazy.”
“What do you mean by that?” I asked.
“Just what I said. To evolve away from some physical characteristic takes work at the cellular level, maybe even below it. Unless there’s some compelling reason to do it, the animal will stay the same. In this case, the T. rex got bigger because it needed to be bigger to eat the animals it ate. Its arms, on the other hand, just stayed the same size because they weren’t useful. Anyway,” she waved her hand in a dismissive gesture, “we don’t know why their arms were so small. They just were.”
Then we found our first skull or at least part of it. It was, based on its size, the bottom T’s lower jawbone which was missing some teeth. Then we found the upper jaw and other bones of the skull. Laura explained T. rex skulls didn’t come in a unit but were a complex maze of bones and hollow spaces. “We’ll jacket them in their matrix,” Laura said. “Otherwise, they could get damaged.”
Laura found an exposed socket in the jaw and tried some of the teeth we’d found in the top T’s neck. One of them fit perfectly. Pick came down and knelt over our find and we all waited for him to make his appraisal. “They were fighting,” he said, “and the inferior T got a good bite onto the superior’s throat. But I don’t think it killed him. Keep digging and we’ll find out what did.”
“We must map everything first,” Laura insisted.
Pick sighed. “Of course, you’re right. Map, map, map.”
“And jacket.”
He waved his hands tiredly, not that he had done any real work. “All right. Jacket.”
We mapped and jacketed, then dug like crazy people. Yes, we were careful, but we dug as fast as we could. I forgot all about Toby and the cows and all the rest of that mystery, which seemed unreal compared to the mystery we were solving right before our eyes. Then we found the other skull. It was oddly posed, the neck contorted, the head thrown back. Laura said this was the classic death posture of dinosaurs. As rigor mortis set in, tendons tightened and pulled the head backwards. “Why isn’t the other skull like that?” Ray asked.
“Because its teeth were embedded in the neck of the superior T,” Pick answered from above.
We gathered around our latest find. This skull was gigantic, thick, and yet, as we exposed it from the gritty dirt of Blackie Butte, we observed that parts of it were shattered, others parts punctured. And in one of those punctures on a bone that Laura said was the nasal bone, we found a hole too big to be made by the teeth of the smaller T. We also found the animal’s sinus cavities and palate had been crushed into splinters. It looked like a sledgehammer had been used.
Pick came down and inspected the damage done to the skull. “I think while the inferior T held this T’s neck, another T clamped its jaws on the superior’s head until the bones in the skull were crushed and death ensued.” That was a clinical way of saying the big T had been bitten on the head by something even bigger. And meaner, I presumed.
“How do we know this skull wasn’t crushed postmortem by the pressure from the burial?” Laura challenged.
“Mud doesn’t puncture bone like this,” Pick replied. He stood up and fastidiously wiped the dirt from his pants. “When we dig deeper, I think we’re going to find broken ribs. By the posture of the inferior, it had to be beneath the superior’s feet which were equipped with extremely sharp claws. Those claws would have done enormous damage. While the inferior T held onto the superior’s neck, the superior would have been tearing the stomach and intestines out of the inferior. The flow of blood must have been like a river. Yet, this smaller T hung on, giving another T, a big one and probably female, time to provide the death bite.”
“You’re saying the inferior Tyrannosaur sacrificed his life?” Laura asked.
“I’m certain of it,” Pick replied.
Laura was dubious. “Assuming it had the mental capacity for sacrifice, what would be its motive?”