Hi. My name is Dustin and I love dinosaurs.
Hi. I'm Dustin 
and I'm Zack
and we love
dinosaurs!
That was pretty good. That worked out pretty well. High five!
Zak:  What is a dinosaur? 
Dustin: That's a really good questions. Zak, that's a great question. 
Especially for the first episode of the show that's all about dinosaurs
we should probably establish exactly what is a dinosaur.
Dinosaurs were the first group of animals that completely abandoned life in the seas. 
They are the first animals to be like
"You know what? Peace out ocean! I'ma live exclusively on land."
The first habitually terrestrial animals on planet earth.
So, in order to determine what is a dinosaur and what isn't a dinosaur
is kind of similar to determining what is a cat and what is not a cat.
Taxonomists are scientists that classify groups of organisms based on shared characteristics. 
And that's how we know when we see like a puma or an ocelot,
even if we have never seen it before, we can pretty much figure out that's a member of the cat family.
Zak: The fur
the four legs, the tail
the teeth
the ears
and their habitat?
Taxonomists and paleontologists classify dinosaurs as dinosaurs based on certain shared characteristics
and there are a whole suite of these
the most important of which are probably certain positioning of holes in the skull.
'Vertebral morphology' - morphology being basically just a fancy science word for shape.
Dinosaurs were the first group of animals that put their legs directly under their body.
They have a ball and socket joint in their pelvis that allows their legs to come straight down under their body.
If you are a crocodile or an alligator, or most reptiles
you got your arms splayed out to the side 
you are kind of inefficiently locomoting with a side to side movement 
that's kind of reminiscent of when they used to live in water 
and they had fins that needed to be pushing water from side to side.
So, dinosaurs are like "Peace out, I am going on land!"
"It's not going to be very efficient for me to move if I have legs splayed out to the side."
"Kinda doing this weird side to side motion."
Zak: Sounds exhausting.
Dustin: It is. I once tried it out for an entire day.
So, you put your legs right under your body
It's much more easy not only just to stand here.
Does it take a lot of energy right now?
No.
No, you just got to balance.
Then when it comes time to move, when it comes time to locomote
you can do it much more efficiently and move a lot faster.
But that's not the only thing that makes a dinosaur a dinosaur.
Do you know what else makes a dinosaur a dinosaur, and you not a dinosaur?
Zak: Yes!
Dustin: Of course you do
and that brings us to
THE THING OF THE WEEK
According to our flowchart
Are you a dinosaur?
Step 1
Are your legs directly under your body?
Yes, legs are directly under your body
Check!
Big check!
Step 2
Scales or feathers?
No.
I don't think so either.
No scales, no feathers.
Not a dinosaur.
I'm sorry, man.
Zak: So anything that has its legs directly underneath its body,
and scales or feathers,
is a dinosaur.
Dustin: Yes. Everything that I have found.
If you can find something that disproves this flow chart, please let me know.
Can you think of an animal that just happens to have their legs directly under their body
but does have scales or feathers?
Birds!
[Dustin makes a chicken sound]
Birds.
Absolutely right.
But that's a whole nother topic for a whole nother episode.
As always, leave your questions or comments in the sedimentary layers below
and don't forget to subscribe by hitting the fancy red button right here.
And remember, whether you're searching for dinosaurs
asking questions or simply flossing:
Never stop digging!
