Dickinson paleontologist addresses new T-Rex study

A new research paper arguing that the Tyrannosaurus Rex should be split up into three different is making waves in the world of paleontology. We spoke with Badlands Museum Curator Denver Fowler to find out more.

The jaw of an ancient beast at the Badlands Dinosaur Museum is pictured.
Jackie Jahfetson / The Dickinson Press
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DICKINSON — Paleontologist Gregory Paul, critically acclaimed for his outside the box thinking and lack of formal credentials, recently authored a paper arguing that the classification Tyrannosaurus should be split into three separate species: rex, imperator and regina. Denver Fowler, curator at the Badlands Dinosaur Museum in Dickinson, shared his thoughts on the matter.

“The idea that T-Rex might actually be split up into different species that occurred at slightly different times is reasonable," Fowler said. "But the new paper doesn't actually show this strongly enough, it doesn't really show it very strongly at all. That is not to say that the new paper does come up with some really interesting observations."

One such observation includes a difference in the number of very small teeth in the front portion of the lower jaw, Fowler said, adding that he believes more work is needed to support Paul’s hypothesis. It’s possible that the distinctions Paul is pointing out are attributable to different stages of dinosaur life rather than genetics.

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“I don’t think they meet the standard of evidence required to name these new species,” Fowler said. “One of the things the new paper suggests is that there are two different forms of Tyrannosaurus just before they go extinct — that there's a robust, one larger, more bulky form. And then there's a sort of skinnier form. And that's the sort of thing that we expect to see, through growth, that the younger ones tend to be a bit sort of skinny, and gangly and like teenagers. Then when they get older, they get more bulky and their bones become heavier.”

Fowler pointed to the disparities among human beings, all of us belonging to the same species, in height and bone density. With carnivorous dinosaurs much of this variation was a result of the amount of meat they were able to consume, he said.


“Tyrannosaurus probably had similar if not a larger variation in full adult body size because the kind that’s very successful, he eats loads and loads of meat then gets bigger. We know this from farmed alligators. They get very well fed. They grow very fast and grow very large,” he said.

Although this new paper overlooks some factors in the size of ancient carnivores, it makes many intriguing points and is sure to spur worthwhile debates in paleontology, Fowler said.

“We're involved in a couple of these studies already to an extent — either specimens we already had here, or one of the things I actually do, I helped a little bit with the study that was just published because I figure out where in time particular dinosaur skeletons were collected from based on measuring the height in the cliffs they were collected from,” he said.

Fowler said he believes there may be a component other than growth stages that accounts for the size differences over a long period of time. A few years ago, Fowler and his wife Liz discovered a new species of dinosaur. He said the threshold for classifying a new species should be a high bar.

“The proposals in the study are not supported enough by data yet, they might well be true. My feeling is that we actually probably will be able to tell Tyrannosaurus from the bottom of the Hell Creek Formation, apart from Tyrannosaurus at the top of the Hell Creek Formation, eventually. Eventually, we'll figure out what features are changing through time. And I think it's very, very subtle. I think it's much more subtle than the Triceratops that I've worked on. I think that it's so subtle, that we haven't really got a grasp of it,” he said.

Hell Creek is a geological formation that Fowler has done excavation work in. It spans Montana, Wyoming and the Dakotas.

“So the ones at the bottom of the Hell Creek are 66.7 million years old. I think there's probably a reasonable chance that we can tell them apart from those at the very top, which are 66 million years old, they'll be about 700,000 years difference between them,” he said. “I reckon there might be a chance. But we probably need a lot more specimens. And we need to understand that growth better.”

Jason O’Day is a University of Iowa graduate, with Bachelor’s Degrees in Journalism and Political Science. Before moving to Dickinson in September of 2021, he was a general news reporter at the Creston News Advertiser in rural southwest Iowa. He was born and raised in Davenport, Iowa. With a passion for the outdoors and his Catholic faith, he’s loving life on the Western Edge.
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