Docent Demo - How to Become a Fossil

All right, so here at the University of Michigan Museum of Natural History we have so many fascinating objects and animals and especially dinosaurs. But dinosaurs haven’t been alive for about 65 million years. So how do we know that they lived at all? Well, paleontologists have found remains of dinosaurs and these are called fossils. So today we’re going to be talking about fossils, and what they are, how they’re made and where they’re found. So first we need to define what a fossil is. So here we have two objects. I have a little plastic Dimetrodon. I found this in the store. And here we have a mastodon tooth. And this was probably found in the ground.

So which one do we think is a fossil? 00:47 - Yeah? The tooth? Yeah exactly but why? What makes something a fossil? So why can’t this one be a fossil? Yeah? Because it’s plastic. Yeah, so what do fossils have to be made out of? Rock or something hard, right? Anything else? Fossils also have to be really old, right? This could have been made yesterday. I don’t know. So the first thing is you have to have some hard parts in your body. So for example this tooth, it was really hard so was able to become a fossil and that animal has to die. So when the animal dies, its remains are in the ground and minerals will seep into the bone and start replacing the bone.

01:44 - And this happens over a long period of time. And… eventually… what will happen is you’ll get an exact copy of this bone, except all of the minerals will be replaced by rock. So now here we have this fossil. It’s the… exact shape of it is just like the bone that was buried in the ground except now it’s replaced by the minerals from the ground. So they have to get buried preferably without oxygen and they’re to be covered quickly to become a fossil and then eventually, this bone will be dug up by a paleontologist and that’s how we find fossils. So the process of fossilization can also be affected by the environment of where the animal lived.

02:38 - So what are some animals you can think of that live in the open ocean? If you have any answers just shout them out. What’s that? Sharks? Yeah, what else was in the ocean? Whales? Yeah. We’ve got our cool whales in the atrium over there. So some more examples of things that might live in the open ocean are sea turtles and jellyfish. So sea turtles, you know that they have really hard shells on their back, right? So those can be fossilized We just said that things need to be hard to be able to to be able to be fossilized.

03:13 - But jellyfish, they don’t really have any hard parts, right? So when scientists find fossils, they usually find more sea turtles than jellyfish. But that doesn’t necessarily mean that there were more sea turtles living during that time than jellyfish. It just means that jellyfish are not able to be as fossilized as easy as sea turtles. So what about a swamp or a marsh? What kinds of things can you find in this environment? Yeah? Alligators and crocodiles? Sure. A tree? Yeah, there’s lots of trees in swamps. So trees are a little bit different.

So trees produce a lot of oxygen, right? Well, that’s bad for fossilization. So trees have to be covered up even faster. So usually they need to be covered up by mud or volcanic ash, and they need to be buried very quickly to be able to… …become fossils. And what about a coral reef? What are some things you can find in a coral reef? Yeah? Fish? Absolutely. Yeah. So another thing that you can find in a coral reef is something called a brachiopod, so we have one right here.

04:21 - It’s kind of like a shell, and it has a lot of hard parts, so this is something that can be fossilized. So, paleontologists study something called the fossil record and this basically dates… …fossils throughout time. So, one of the earliest fossils that we have is something called a trilobite. So this is kind of like a bug-like creature that lived a really long time ago. And we have a lot of these that you can see in the Museum. So afterwards, you can come up and touch any of the items that I have up here. So, let’s talk about this Mastodon tooth again. So is there anything you notice about the color of this tooth? Exactly So these black parts are the parts that have been fossilized. And then the white part is actually the real tooth and it hasn’t been fossilized yet. So the fossilization process hasn’t been completed, and this is an example of something called a body fossil.

05:23 - So, we did mention before that fossils have to have hard parts in an animal or a plant body, right? So how does that explain this fossil of a leaf? Is a leaf hard? Right, so… …things that aren’t hard those are considered trace fossils. So those usually leave an imprint in something else like mud, so that would be this leaf right here. And also we have… …this dinosaur skin. So this dinosaur left an imprint on something and then it created… …created this imprint of the dinosaur skin. So these are both examples of trace fossils. The skin and the leaf both don’t have hard parts.

06:12 - But we were still able to create fossils out of them. So, what do we have here? Has anybody seen this before? Yeah? Have you seen this? Did you see it upstairs? Do you know what it is? Yeah. Yeah, so this is coprolite , also known as dinosaur poop. So this is also a kind of rare fossil because dinosaur poop is not hard. But here we have one that’s cut open and polished so that you can see what’s inside. And this kind of tells us what the dinosaur ate and… …it reveals a lot about the dinosaurs diet. So here’s another way that we can preserve remains of plants and animals. We have here… …some amber, you may have heard of amber before because it’s found commonly in jewelry. So amber is kind of the sticky liquid and when it hardens it can trap feathers or insects and things inside. So I think this is an insect in this one. But unfortunately amber does not preserve DNA so we can’t have a Jurassic World situation here.

07:31 - So, today we can create lots of casts and molds of fossils so that we can send fossils back to their original location. And so that scientists all over the world can study fossils. A lot of the things we have here at the museum are casts and molds, including our male Mastodon in the atrium right here. And with 3D printing we can create exact copies of things that we don’t have. So for example… …the male Mastodon’s right hind leg… …we didn’t actually find that, so we took the other leg and made a 3D printed copy of it and… …

reversed it so that we could create another leg for the male mastodon. So the one that we have in the atrium was made a long time a long time ago. So it’s… …not the best, you can see it kind of has these facets. It looks a little pixelated. So we do have another Mastodon femur here. And this one is a beautiful copy. And you can see I can pick it up pretty easily because it is a cast. If this was a real fossil… …I would not be able to pick it up. It would be solid rock.

08:42 - So, this is what 3D printing kind of allows us to do today. That concludes my fossil demo. If you would like to come up to the table and look at any of the materials, please feel free to. We also have some… …feedback forms. If you would like to fill them out. We’re constantly looking to improve our demos at the Museum. Thank you! .