Welcome to Cool Stuff Daily, where every day of the week we dig up the weird, the wild,

and the wonderfully nerdy corners of science, tech, and history.

I'm Reggie Rizzou, and on today's episode we're talking about dinosaurs,

specifically a dinosaur that's just flipped decades of research on its head.

Because it turns out a smaller teenage T-Rex,

scientists have been arguing about for nearly 80 years,

well, it's not a teenager at all.

It's a completely different species.

Okay, our story starts back in 2006,

in the Hell Creek Formation of Montana,

one of the most famous fossil sites in the world.

That's where paleontologists uncovered a pair of dinosaurs literally locked in combat,

a triceratops and a small-bodied Tyrannosaur.

They got the nickname Dueling Dinosaurs.

For a year, scientists assumed that the smaller predator was just a young

Tyrannosaurus rex, but now a new study published in nature says that

assumption was wrong. It wasn't a teenage T-Rex but a fully-grown adult of an

entirely different species called nanotorinus Lansinces. Or as the study's co-author

Lindsay Zano puts it,

quote, this fossil doesn't just settle the debate, it flips decades of T-Rex research on its head, end quote.

So the mystery actually goes all the way back to the 1940s, when a small Tyrannosaur skull was dug up in Montana.

For decades, paleontologists couldn't agree, was it a baby

...