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This is a CBC Podcast. Hi, I'm Bob McDonald. Welcome to Quarks and Quarks. On this week's show, the curious case of smaller tyrannosaurs.

This changes everything we thought we knew about T-Rex. And the environmental price of opening up our northern peatlands for business. When we make any type of alteration to the amount of water in those soils, we have the chance to release that carbon back out into the atmosphere.

Plus, germwary ant architects redesign their living space, the evolutionary advantage of lead, and the unexpected outcome of eradicating invasive fish. All this today on Quarks and Quarks. Nobody move a muscle.

That's the sound of a Tyrannosaurus rex from Jurassic Park 3, spotting a group of people and then stomping after them. They'd be an easy meal for the T-rex if they're caught. It's just so massive, and the humans so pitifully small.

The King of the dinosaurs has long been a favorite favorite since the first Tyrannosaurus rex was discovered in Hell Creek, Montana over a hundred years ago. But not all Tyrannosaurus dug up in what is now western North America were as huge as

the ones brought to life in Jurassic Park. Some were curiously smaller. And that became a real headscratcher for paleontologists who long wondered, are these smaller specimens simply young, teenage T-rexes?

a new Tyrannosaur species altogether. Well, now, after decades of debate, paleontologists think they've solved it, thanks to a spectacular game-changing fossil called the Dooling Dinosaurs. Dr. James Napoli is a paleontologist at Stony Brook University in New York and the co-lead

author on the new study. Hello, and welcome to Quirks and Quarks. Thank you for having me. It's a pleasure to be here.

Dooling Dinosaurs? That hints at some kind of drama here. Tell me about this fossil, what does it look like? These fossils are absolutely incredible.

They are two of the most beautifully preserved dinosaurs I have ever seen, preserved right next to each other, and almost fully articulated. So both skeletons are nearly complete and they look like they would have looked basically as these animals died.

The Tyrannosaurus preserved on its back with its legs curled up, it's a very dramatic fossil. And what's the other one? The other one is the triceratops.

And the triceratops is preserved more or less on its side. So were they actually dueling at the time, do you think? That's a question we're still trying to answer. We know that these fossils were buried at the same time as one another, but we don't know

if they died at the same time. It's possible that they were both killed in some cataclysmic event. It's possible that they were actually fighting each other to the death and happened to die in a place where they could be fossilized.

It's possible that the triceratops was already dead and it was being eaten by the Tyrannosaur when both of them were buried. We just don't know for sure yet. So why then was this Tyrannosaur such a game changer?

Well, this Tyrannosaur turned out to be the answer to a decades-long scientific debate, which is whether these fossils are juveniles of Tyrannosaurus rex, everybody's favorite dinosaur, or whether they were members of a completely different species of Tyrannosaur that's been called Nanotyrannus. nanotaranos. Yes. Small tyrannosaur. Exactly. Exactly. And that tells you why we thought

these might be juveniles of T-Rex. They're about half the size of T-Rex at maximum. Okay. So I'm trying to picture that. How big would it be if I was to stand beside it? If you were to stand beside this animal, it would be about seven or eight feet tall when its head was held up very high, and it may have been about 20 feet long. So

I'm sorry, I'm American, I speak in feet here. Meters-wise, I think there's two to three meters tall and about four to five meters long. So how did you solve the debate about whether or not it was a teenage T-rex or a new species?

We used a lot of different kinds of evidence to make that decision. The first thing that we looked at were just the features of its anatomy. We saw that its arms were abnormally long for a tyrannosaur, much longer than the arms of even the biggest T-rex specimens we've seen.

hands in particular were very, very large and it had a huge hooked claws on each of its fingers. We also saw that it had a vestigial third finger unlike T-Rex which just has two fingers on each hand. In its tail there were about 10 fewer vertebrae than T-Rex had and in its skull we saw many more teeth in its jaws and a bunch of features showing that the cranial nerves and

blood vessels and sinuses were in different positions than they are in T-Rex adults. And so all of those things told us that we were probably dealing with a different species, but what clinched it for us is that when we took a section of one of the leg bones and looked at it under a microscope, we were able to look at its growth record. So we could see a complete

record of the animal's growth from its early childhood to its eventual demise. And what we saw is that at the moment it died, it was in the process of forming a feature of the bone microstructure that we call an external fundamental system, which just means that the lines of growth, just like the rings in a tree, were spaced very close together, telling us that

it was achieving maturity as it died. So this is an animal that died right on the cusp of full maturity at the cessation of growth. It was not able to keep growing up into a T-rex not only because of all the differences we saw, but because it was done growing at all.