Is This Fossil a Baby T. Rex or a Controversial ‘Nano’ Dinosaur?

A full set of teeth in the fossil's upper jaw were found, along with fragments of hip and skull bones.

Hell Creek is heaven for paleontologists. The Montanan wildlife refuge is rife with clay and stones that hold clues to our prehistoric past.

It was in Hell Creek that researchers from the University of Kansas recently stumbled on the remains of a young Tyrannosaurus rex—they think.

"We just set off prospecting and a student came across some bone fragments," says David Burnham, a paleontologist from the University of Kansas. In Hell Creek, you're bound to find them. "If you put a black dot on the map for every fossil found in that area, it would be all black."

Fossils from various periods have been found there, and this isn't the first T. rex fossil to be found, but University of Kansas scientists think it could be one of the most intact. The entire fossil remains of the upper part of the dinosaur's jaw, with all its teeth, was found.

Paleontologists dug up parts of a skull, foot, hips, and backbones.

If the remains do in fact belong to a T. rex, that would make them around 66 million years old.

Adding to the rarity of the find is the fact that the fossils may belong to a juvenile.

"They're hard to find," says Burnham. "Ours is so important because we have so many bones. Every tooth position is filled."

Burnham says the teeth they've since cleaned suggest it's a juvenile T. rex, but more work will need to be done to say for sure.

"Our young selves look nothing like we do as adults," he says, noting, for instance, the degrees to which a skull can change shape in a person's lifetime. He says the same is true for T. rex, though it can be difficult to know how exactly those skeletons change because so few juveniles have been found.

Further work will determine whether the team actually has a T. rex on their hands, or possibly a Nanotyrannus, a tiny genus of tyrannosaur that's a matter of scientific debate. Many paleontologists think that so-called Nanotyrannus fossils are actually juvenile T. rex specimens.

"We're trying to keep our minds open," Burnham says of studying the remains. He believes the fossil could be an illuminating touchstone for the paleontological debate.

"We know it will be pivotal. It's one thing that's been lacking all of those years, and it will provide a lot of information," he adds.

While the skeleton fragments they do have are helping craft a clearer picture of what the dinosaur was, Burnham says they're not done digging it up. This summer, he and his research team plan to return to the site where it was found.

"We'd like to find a femur or tibia," he says, but adds they'll be looking for all of its remains.