A Common Mistake: What's a Dinosaur?

So when I volunteer at museums, one of the most common mistakes I hear people make is calling everything in the building a dinosaur. Which in some cases would be a fair mistake, aside from the sign in front of them that calls the specimen something else. But I have to say, what really baffled me was my high school yearbook calling the floating mass of bones surrounded by modern ocean creatures in the middle of the museum lobby (and two floors down from the Mesozoic fossils) a dinosaur.

...it was too big, it swims, and its a mammal. Its a whale.

So, why not go through a little bit about what dinosaurs are (and are not?)

To keep it simple, lets just focus on the non-avian dinosaurs. While we don't know everything, there are a few things we do know.

But a general rule to live by at museums: if in doubt, there is probably a sign somewhere. Museums are for learning. I love reading the signs; I never know what new thing I'm going to learn.

The reason that this is so sad to me is because paleontology is full of really cool things, not just dinosaurs. And its really sad to see little kids get so disappointed when they learn that the shark tooth they are holding isn't from a T. rex. What really made me sad was back home when a mom blatantly told her kid that he had just found a dinosaur tooth while digging through sharks teeth, knowing perfectly well herself that she was telling him wrong (she told me this when I started to point it out.) There is a lot of really cool stuff to learn out there, if people open their minds to learning it.

If you have your heart set on dinosaurs, Cleveland Lloyd or Dinosaur National Monument are well worth a visit. They are truly incredible.

But please, read the signs. We're here to learn. Even the museum workers are trying to learn more. That's the purpose of a museum.

Dinosaurs Don't Fly or Swim
Now, some paleontologists will tell you that birds are dinosaurs. Aside from that though, dinosaurs did not fly. Flying is basically limited to birds, bats, pterosaurs, insects, etc. There are also several species that can glide. It is thought that some dinosaurs had developed the ability to glide (which, is argued, would have led to them eventually being able to fly, but the two acts required different structures and motions) but that is about the closest they would have gotten to being airborne.

As for swimming, there was a theory at the very beginning of paleontology that dinosaurs had to have lived in swamps because their weight would have been too great for gravity to support. It also would have been hard for them to run away from predators. However, we now know from some very clever modelling by paleontologists who are capable of using computers (that is, not me...) have figured out that even the sauropods, mathematically, would have been able to resist gravity on land, and their sheer size would have been a pretty good defense. There were a lot of swimming reptiles around during their time. And where I come from, there are shark teeth EVERY WHERE. But aside from needing water to survive, there isn't currently a reason to think that a dinosaur would have loved water any more than most land animals.

Dinosaurs are from the Mesozoic

That means that dinosaurs are from a time period spanning from 250 to 65 million years ago. At this point, I turn to small children and tell them that yes, that is older than their parents. That said, there are things a lot older than dinosaurs, and younger. And some of them do look really weird. This is not a perfect system though; small mammals were running around at the time of the dinosaurs, as were many other weird creatures that aren't dinosaurian.

Dinosaurs Don't Sprawl

Ever watch a modern reptile scurry away from you?

Not snakes. This only applies to animals with legs.

But you know how their knees face outward and they sprawl, and they run kind of funny?

Well, ever since paleontologists started finding the bones that allowed them to figure this out, we've been pretty sure that the legs and hips and knees of dinosaurs (and feet) allowed them to walk upright. See how the sauropod on the left (yes, he is a dinosaur, and he has a jersey on) has his legs directly beneath him? They have a different kind of hip socket then other reptiles

One of the first people (Owen, I believe) to propose this actually may have been suggesting it as part of his argument that dinosaurs were advanced creatures rather than slow minded, cold blooded lizards. In this way, he may have been trying to show that creatures hadn't been on a steady march of advancement throughout the Earth's history, because they were more advanced than some modern animals. Potentially, he was trying to fight the theory of evolution. Fun fact.

Dinosaurs are Diapsids

Basically, this means they have two holes behind their eyes in their skulls. In contrast, mammals are synapsids (with one hole) and other reptiles are anapsids (they have no holes behind the eye.)

See the difference? 

Not all Extinct Animals are Dinosaurs

Ever see this guy lumbering around your back yard? If you had been in North America oh, less than a million years sooner, you would have. He is one the giant ground sloths that walked around the same time as the mammoths. Big guy, big claws... herbivore. Still, I wouldn't want to make him mad.

The point is, however, he, like modern sloths, was a mammal. Just one of many prehistoric beasts outside of the dinosaur family.

Not all Bones are Dinosaurian

You don't really need a picture for this one. Have you ever broken a bone, and had an x-ray done? Remember the really white areas in the picture? Those are bones, just like the ones of other animals that you may see in your museum. Or, if you live somewhere with a lot of wildlife, there may be modern ones in your yard. If you run your finger down the middle of your back, you'll feel bumps. Those are your vertebrae. They protect your spinal cord, which your brain uses to control your entire body. They also let you stand upright so you that you don't look like living jelly (an octopus does not have this luxury.) Dinosaurs also have this, but so do a lot of animals. Bones are just a very useful thing to have.

"Round rocks" Aren't Always Dinosaur Eggs

Everyone has done this. Really. I've done this. I recently caught up with a friend from elementary school, and honestly me finding an "egg" was one of the adventures with me she remembered. Turns out what I had was igneous rock.

Dinosaur eggs do fossilize sometimes. It's rare, but it happens, and its really exciting when it does. The first instance of this was in the Gobi desert. By this, I mean that was the first time that someone found one, recognized it, and published it. But a round rock isn't always a dinosaur egg. Especially if, like me in my younger days, you weren't in an area with dinosaurs in the first place. That makes it a little hard for the eggs to get there. 

That said, I encourage people to do some reading on dinosaur eggs. A lot can be learned from them, and if you do manage to come across one, any museum would be dying to know. And really, we see it so much that paleontologists have become very good humored about this. Pseudo fossils are just fun. Any time you bring in a fossil, be willing to laugh a bit. And if someone does tell you its a concretion, don't go to every paleontologist in town just looking for the answer you want. We'll likely say the same thing. 

"Fossil" Doesn't Mean "Dinosaur."

The one I see the most often here. Just like not every bone is a dinosaur (or a fossil), not every fossil is a dinosaur. An insect stuck in amber is a fossil. And, that said, still an insect. A plant fossil? Still a plant.

Some of them are still really cool though. How often in the modern day do you see a palm leaf as tall as my dad? Even better, it has a fish on it!!

There is a lot of really cool stuff out there. If you just focus on one family of animals, you are going to miss out on a lot. Our ecosystems require a lot of organisms of a lot of different shapes and sizes, and our fossil record reflects that, even down the micro fossils. There is definitely more to this field than dinosaurs.