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Paleontologists dig for Jurassic dinosaur fossils

We visit the Morrison Formation in the western North America, where a team from AMNH digs for fossils and explains how and why they study them. Created by American Museum of Natural History.

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Video transcript

[MUSIC PLAYING] >>MARK NORELL (Curator emeritus, Division of Paleontology): The basic way that we extract fossils from the ground is just like Barnum Brown did when he was tearing around here and stuff in the 1890s. He'd dig around, and he'd cover them with plaster. He'd roll them over, cover with plaster, and then bring the whole thing home. Some other things have changed though. One is that we don't have to use horse plows anymore because we have jackhammers. We can't use dynamite anymore, which I wish we could. [CHUCKLING] The Morrison formation is one of the most iconic formations within paleontology because it represents an interval of time in the late Jurassic period about 140 million years ago. But also what's so important about the Morrison formation in general is that it's the place where the first great dinosaur discoveries were made in North America during the big dinosaur rush of the late 19th century. The dinosaurs from the Morrison formation became probably the best known dinosaurs in the world. So all these familiar names like stegosaurus and brontosaurus and allosaurus were all found first in the Morrison formation. When the early dinosaur hunters came out, they dismissed a lot of the smaller animals because they were looking for big animals to fill their dinosaur halls, and that's one of the reasons that we started this excavation is to try to fill in the picture by looking at the stuff that was ignored by all the early collections. [MUSIC PLAYING] Because it is so large, thousands and thousands of square miles. The Morrison formation is probably more than one thing, but what really needs to be looked at now is a site by site basis to see how all of these fit in together to see if there's any north, south, or even east, west differences among these different fonts to have a better understanding of the evolution of these animals during the Jurassic period in this part of the world. Well, this is actually a pretty typical site I would say for the Morrison in the sense that it's a combination of sand, and then like heavily like what we call integrated which basically it just means glued together sandstones. And we think that these animals that they died, and they were either deposited in one of two ways-- that they either died and floated into rivers and then they got hung up or that they're in what we call over bank deposits and that's in areas where the river would flood and then go out onto a floodplain and then cover animals. So these sediments right here just really silty. So they have a lot of clay in them. So this was a over bank deposit very near to the bank upstream. It speaks to the kind of preservation that we have here. Rarely do we find a wholly articulated animal. The bones are kind of like here and there, mismatched. Occasionally, you'll find some vertebrae together and things like that. One of the animals that we were excavating today, that it's a vertebral sequence of what we think of right now as a camarasaurid, not a full size one but a juvenile. And we found theropod teeth around it, and that's usually a sign that things were scavenging this dead carcass after the animal perished. There's a lot of bones. And we just have to figure out which ones are the most scientifically important. When I come out here and stuff, it's not just to find new dinosaur species and describe them. I'm really a biologist who works on fossils, and I'm more interested in a lot of the biological questions. >>CARL MEHLING (Senior Museum Specialist): One of the most important things that we found is a diplodocid skull. So it's a long-necked dinosaur skull, and they're very rare. They're very fragile. Although the bones have shifted a bit, it seems to be complete and it has a beautiful braincase, which is of the entire skull, the most important part of that body part. >>NORELL: We're going to have a much better understanding of what the brains looked like in these animals. We're going to have a lot better understanding of whether or not they had beaks. >>MEHLING: It's an extremely important and exciting specimen that we're probably going to wind up CT scanning and imaging soon because it's so fragile it can't even be removed from the rock safely. >>NORELL: Recently, we found some beautiful-- what are called Sphenodontians, but they're relatives of the tuatara which only lives in New Zealand today. Also very early mammals are found in some of these beds as well. It gives us one of the best pictures of the origin of a lot of the major animal groups, be they frogs, be they lungfish, be they lizards. We're not really intent on putting a lot of these things on display. Our goal is to be able to do some really great science on them, so the way in which that we prepare them in the laboratory is very different than how you would prepare them just to put the mount on display. Soft tissue is present in a lot of dinosaur fossils. Sadly that wasn't recognized until maybe 10 years ago. So a lot of these things were just prepared away back in the museums and things because people just thought that they were plants or just discolorations. But certainly we've learned a lot now, and there are things like skin imprints. There's other sorts of things that we're only beginning to be able to understand. >>MEHLING: It may seem like we've been doing paleontology for a long time, but we really have just begun. And there's so much that we don't know about the history of life, any time we go out, it's new discoveries. Without a doubt. It's just an automatic part of what we do. [MUSIC PLAYING] >>NORELL: It's really hard to consider a successful expedition all the time you're doing it, even for a few years afterwards. Nevertheless, we hope that we're able to generate a lot of interest from other scientists as well as our own students and colleagues to be able to weave it into the bigger story, the Morrison formation as a whole. I think this might be a bone, like a surface, this rounded thing here. So if it is, this could be a therapod metatarsal. [MUSIC PLAYING]