Dreadnoughtus, possibly the largest dinosaur discovered...

SciWorks Radio is a production of 88.5 WFDD and SciWorks, the Science Center and Environmental Park of Forsyth County, located in Winston-Salem.

You probably know that kid, the one who just loves dinosaurs. Maybe she has a stack of dinosaur books, or even her own fossil hunting kit. Some of those kids go on to become paleontologists. Others get their start in a different way.

Most paleontologists you meet will tell you that they've loved dinosaurs ever since they were two or three years old. The first time I got interested was when I was in college.

That's Alison Moyer, Micropaleontology PHD Candidate at North Carolina State University. As an undergrad at Drexel University, she was involved in the discovery of Dreadnoughtus, possible the largest known dinosaur yet discovered.

Dreadnoughtus, and many other dinosaurs, have been discovered in the Patagonia region of South America. This doesn't mean these dinosaurs were exclusive to the region, it just means that the conditions there are ideal for locating fossils.

That is what Patagonia has to offer. Geologically we have a lot of rock that is of the proper age, in the Cretaceous. And then a lot of it is exposed with very little plant covering it.

Dreadnoughtus is a Sauropod, walking on 4 legs. Like Apatosaurus, Brachiosaurus, and other similar dinosaurs, it had large body with a long neck and tail.

Nothing walking on Earth today can come even close to its size. You're looking at an animal that was moving around that was nearly the size of a house. It was two and a half stories tall, 85 feet long and probably weighed 55 tons. So, a pretty magical and massive creature.

What kind of setting is needed for an animal to get that big?

Enough space and enough food are going to be the two main criteria you need to get that big. We don't have eggs for Dreadnoughtus. The eggs of other Titanosaurs, for example, are smaller than a modern day ostrich egg. And they grew to these truly massive animals. And it probably happened relatively quickly. Like 15 years or so. So they had to spend all their time eating.

  Dreadnoughtus is the largest known dinosaur to have been discovered. But what does that really mean?

There's a caveat there. It is the largest dinosaur ever for which we can confidently estimate. There are other dinosaurs that have been suggested to be larger than Dreadnoughtus, but they have been discovered from very fragmentary remains. For example, Argentinosaurs is currently probably one that's estimated to be the largest, but it's described from a handful of bones.

How do scientists assess the overall size of a dinosaur?

If you want to to accurately estimate the size of a dinosaur you need its limb bones. So you need its arm bones, the humerus, and you need leg bone, thigh bone, the femur. We don't have both those bones from most of the most massive dinosaurs we've discovered. So, with Dreadnoughtus, we have both of those bones. And scientists looking at modern day elephants and other large terrestrial animals today, have come up with a formula. You take certain measurements around the bone, you measure its length, you measure its circumference. You plug it into this formula and then you get an estimate.

So if we don't know if Dreadnoughtus is actually the largest dinosaur to have lived, what's so important about this discovery?

The fact that we have so much of the skeleton is a bigger point than its actual size. It is likely that something was bigger. We know that when this dinosaur died it wasn't done growing, which is amazing to think about. How big it could have got, we don't know. We know it was still growing because of two things. The shoulder blade, the scapula, and the coracoid in dinosaurs are fused when the dinosaur is an adult. That those bones weren't fused in the dinosaur yet tells us it wasn't fully mature. The other thing is that when bone is fully mature there's an outer layer on the bone that tells you that the dinosaur was done growing. And that outer layer is missing in Dreadnoughtus. So that's a second piece of evidence that this dinosaur wasn't done growing.

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