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Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, D is for:
When I was a kid, dimetrodon was my favorite dinosaur. It has a sail on its back. How cool is that?
Then I found out that dimetrodon is not a dinosaur. It’s just a lizard. Then I found out from this video that it’s not even a lizard.
Also, pterodactyls aren’t dinosaurs. Neither are plesiosaurs or ichthyosaurs. None of my favorite dinosaurs were actually dinosaurs! Frustrating, isn’t it?
So today, I thought I’d give you a quick tip on how to tell when a “dinosaur” is actually not a dinosaur. Sciency Words is all about defining scientific terms, and paleontologists use several key features to define what is or isn’t a dinosaur. For example: the number of openings in the skull, the shape of the hip bone, the type of joint at the ankle….
If you’re a professional dinosaur scientist, you need to know this stuff. But for the rest of us, the easiest way to tell (in my opinion) is by looking at the orientation of the legs. Dinosaur legs are vertical to the ground, not horizontal. They go straight up and down, rather than being splayed out to the sides.
So if you think it’s a dinosaur, but the legs are splayed apart, it’s not a dinosaur.
If you’ve ever seen a crocodile or salamander try to run, you can understand why having your legs splayed apart like that is a disadvantage.
Standing upright on their vertical legs, dinosaurs had a much easier time walking and running on land. Also, vertical legs can support more weight, allowing dinosaurs to become much bigger and much heavier than their cousins, the amphibians, reptiles, and whatever the heck dimetrodons were.
Next time on Sciency Words: A to Z Challenge, we’ll find out what our planet’s name is.