A baby Rapatosaurus humerus.

So the exact same bone as the big one I was showing you on the table before, but obviously this is much, much smaller.

And it's finds like this that make paleontologists start to question how did dinosaurs grow?

How do we go from something this teeny tiny to something this huge?

And it has now become a whole field of study about ontogeny and osteology.

So that's bones and growth, or growth and bones, rather, um, looking at the inside of bones to try to understand how they're growing over time, whether it's fast or slow, if they grow more like us or more like lizards or more like birds, and they do things like make these slides.

So this, I'll also hold this in front of the vest, because that one might be even harder to see.

But this is one tiny thin slice of a dinosaur bone, a rapetosaurus bone, actually.

And you can see it's got lots of different parts on the inside, and scientists can look at all the different parts of the bone in there and make determinations about how fast something was growing.

Um, and we know now that dinosaurs, at least sauropod dinosaurs, grew pretty quickly.

So they'd go from this little tiny baby to this huge adult pretty fast, um, faster than people used to think they did, and that's pretty amazing.

All right, Dave, want to hit mammals?

All righty.

So let me talk about mammals.

And in the context of the project that we have, we have found over 30 years about 25,000 specimens of backboned animals, and that's a pretty phenomenal number.

I'm really a specialized uh paleontologist.

I study fossil mammals.

And so I went to Madagascar trying to find fossil mammals.

And so of those 25,000 specimens, there's only 14 mammals.

12 of those are just little bits of teeth or little bits of jaw.

But then in 2010, we discovered this.

This is a complete skull of a fossil mammal.

And there's many things that are interesting about it.

First of all, is its size.

This is the largest sorry, the second largest mammal that lived during the age of dinosaurs.

But like all the things that Sierra and I have been showing you, it's funky.

It's different in a number of different ways.

So one of the things is that it has this big flange on the side of its skull, and that's used for big muscles to attach for chewing.

Using some techniques that we use in medicine today, we've looked inside of the skull, and we see that the brain is very different than in most mammals as well.

Again, because all of these animals that we find are new to science, we get to name them.

We named this one vintna because we found it in a big plaster jacket that we thought was filled with fish.

And then when we did a scan of it to look at the inside, we saw a skull of this.

And that was what I had been looking for for about 15 years up to that point.

And I was so excited to see this inside the scan.

I didn't sleep for two days.

So for that reason, we named it vintna, which literally means luck in the Malagasy language in the Madagascar language.

And this is the reconstruction of what ventinum might have looked like.

So it was big, probably um uh about the size of a beaver today.

And uh it from the outside, it doesn't look that strange, right?

But if you look at the skull itself, it is quite different.

And then to top things off, remember we had 12 just fragments of teeth and isolated uh bits of jaw.

Then we found this skull, and then we found that, which is almost a complete skeleton of another fossil mammal.

Belongs to the same group of mammals as Vincena, but it's really, really weird.

For one thing, it's got more parts of the backbone than any other mammal living today or extinct that we know of.

It's also pretty big for a mesozoic mammal.

Most mesozoic mammals were the size of shrews or mice or rats, but this thing was much bigger, and it's got things on the skull that we have no idea what they were used for.

So there's holes on the top of the skull.

We don't know what those holes, what pass through those holes.

And because it's so unique and because it was new to science, we got to name that one too.

And we used a Malagasy word, and we used a Greek word, and its name is a Dolitherium, but in Malagasy and Greek, that means crazy beast, because it's a really crazy beast.

So those are kind of the bones and the reconstructions that we have, but I know that Sierra wants to show you something that is not bone that we think is very interesting too.

Yes, I do.

So this is something that not that many people think about when they think about paleontology, but it can give us important information, and that is coprolites.

So a coprolite is a piece of fossilized feces or poop.

I mean, it kind of looks like poop, doesn't it?

Um, coprolites are really cool because they can give us a lot of important information about the environment that was around, what animals were eating.

Um, even if you can't link the coprolite to the specific animal that pooped it out, um, like with these ones, we don't know whose poops these are.

We can still look inside these coprolites and look for plant material, animal material, maybe even bugs, things that sometimes don't fossilize unless they're eaten.

And that can tell us a lot about the environment.

So they're pretty cool little trace fossils.