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Uploaded:2014-04-16
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Crocodilia: Keeping it real for the last 83.5 million years.


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Producer, Writer, Creator, Host:
Emily Graslie

Producer, Editor, Camera:
Tom McNamara

Theme music:
Michael Aranda

Created By:
Hank Green

Production Assistant:
Katie Kirby

Special thanks to Alan Resetar, Collections Manager for Amphibians and Reptiles, for letting us borrow the specimens seen in this video!

Filmed on Location and Supported by:
The Field Museum in Chicago, IL
(http://www.fieldmuseum.org)

Grrrrrrrreat job to Jose Taveras, Tony Chu, Martina Šafusová, Seth Bergenholtz, and Kelleen Browning for translating the captions on this one!
(Intro)

Picture it: you've been abducted by an unknown group of people and thrown into a pit of large, and I mean extremely large, and very hungry 4-legged semi-aquatic reptiles. As they lift their heads out of the water and start slowly moving in your direction, you're struck with the horrible realization that you don't know if these are crocodiles or alligators. But never fear: this video will surely clear up any questions you may have in those last improbable moments so you can meet your death with grace and understanding.

The order 'Crocodilia' is an ancient group of archosaurs: egg-laying animals that share a close evolutionary history with birds and happen to be the nearest relatives to dinosaurs and pterosaurs that we have on the planet today. Croc-like animals first show up in the fossil record around 230 million years ago, although the crocodiles and alligators as we know them today have existed largely unchanged for the last 83 million years. We can be sure our modern-day Crocodilians were partying along the likes of T. Rex and velociraptor before those guys were wiped out by the mass extinction event signaling the end of the Cretaceous period 66 million years ago.

It's thought that members of Crocodilia survived the aftermath of that massive meteoric impact for a number of reasons, including their incredible ability to go dormant during unfavorable conditions. They're also down with eating just about anything and in addition to that, they can survive months without food. So keeping all of this in mind, it's no wonder that Crocodilia was able to survive through even the worst conditions.

The order Crocodilia includes three separate families. We have Crocodylidae, the crocodiles; Alligatoridae, the alligators; and Gavialidae, the gavialids. The gavialids are a little easier to distinguish from the other two because of their freakishly long and slender snouts, and they have an obscene amount of teeth, so we're not going to worry about those guys today. Instead, let's focus on the key characteristics distinguishing crocodiles from alligators.

The shape of the snout can be somewhat of a misleading indicator, but in general, crocodiles have a narrow and elongated V-shaped snout whereas alligators are going to have a more rounded, U-shaped snout. If you're close enough to be able to check out their teeth, you'll be able to tell pretty quickly if the animal is a crocodile or an alligator. This is because crocodiles always have the fourth lower tooth exposed whereas alligators have more of an overbite and their lower teeth are hidden when their mouths are closed.

Alligators tend to be a little bit smaller than crocodiles with the average length ranging between 6 and 10 feet, rarely exceeding 12 feet, and males are typically larger than females. The saltwater crocodile dwarfs any alligator species. Some adults can weigh up to 4,400 pounds and can be 22 feet in length. That's like four of me, stacked. Four. Stacked. Four.

Crocodiles are far more widely dispersed around the globe with 14 species compared to only 2 species of alligator: you have the American alligator, found in the southeastern parts of the United States, and the Chinese alligator found in the Yangtze river, although there is a little bit of overlap between the American crocodile and the American alligator. (Alligator growl)

Due to an adaptation that allows crocodiles to expel salt water, or sodium chloride, from a special gland in their tongues, they're better suited for saltwater environments. Since alligators don't have this adaptation, they go hang out in the fresh water.

Keeping all of this information in mind, your geographic location is going to be a big indicator as to what kind of animal you're looking at. Unless you believe in the possibility of monstrosities living in New York City sewers, if you're outside of the American Southeast or eastern China, you're probably looking at a crocodile.

So, remember kids: snouts don't count, teeth are key, and geography is... I can't think of anything that rhymes with geography. And you know what they say: "See ya later, alligator! After a while, crocodile!"

(Credits)

It still has brains on it.