Rock Doc

What are the odds?

That was my thought when I read recent pieces about a very special fossil from the Hell Creek Formation of South Dakota.

Here’s some background: if you saw the movie Jurassic Park, you may think that Tyrannosaurus rex was the biggest predator of all time. That’s certainly the way the movie portrays the 40-foot-long dinosaur that could weigh seven tons. But there’s actually been a long debate in scientific circles about whether T. rex was a predator chasing down live prey or a scavenger feasting on dead carcasses.

A number of scientists have thought that T. rex was too huge to be fast on his feet. The big dino, in this view, couldn’t chase down other dinosaurs, some of whom were much smaller and seem more built for speed. These scientists have argued that T. rex likely “made a living” like vultures do today, eating the flesh of animals that were already dead.

The debate about the nature of T. rex has gone on for decades. There just wasn’t solid evidence that could clinch the case one way or another. Some people saw T. rex as a giant killing machine, some as a much more passive scavenger. But the debate has now changed due to an incredibly lucky break several scientists got from a fossil recovered in South Dakota.

The fossil is from the tail of a duckbill dinosaur. Embedded in one of the bones in the tail is a tooth. And that tooth, scientists say, is from a T. rex.

“The features of the tooth are like fingerprints, and we were able to identify it as T. rex,” said David Burnham to CNN. Burnham is a paleontologist at the University of Kansas.

Burnham and his colleagues on the project took the fossil for a CT scan at a hospital. A doctor joked, “It’s too late for your patient.”

The important part of the story is that the tooth is embedded in a piece of tailbone that has healed over. In other words, a T. rex bit the tail of a duckbill dinosaur hard enough its tooth broke off. The duckbill, however, escaped and lived long enough that its bones healed, likely over a period of a few years.

That’s quite a story to come from one fossil.

“We were giddy like school kids,” Burnham said to CNN. “This now returns T. rex (to the ranks of) a predator. So the monsters we see in dinosaurs are real. They did go chasing after things, kill them and eat them. They actively pursued their prey.”

The analysis of the special fossil was worthy of publication in the prestigious Proceedings of the National Academy of Sciences.

I’m left with two thoughts. One is that I’m glad T. rex no longer roams the land. Even as a scavenger he seemed worthy of our nightmares, and as a predator he is over the top. The other is that eight-year-olds everywhere can rejoice with the news they were right about the giant beast all along.

Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.