The dimetrodon (a mammal-like reptile often mistaken for a dinosaur) actually liked hundreds of millions of years before dinosaurs roamed the Earth.
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Key Facts In This Video
Dinosaurs is Greek for "terrible lizards." 00:32
The extra holes in the skulls of dinosaurs allow them to be larger without getting too heavy to function. 01:26
Mosasaurs had double-hinged jaws like snakes, which allowed them to eat prey larger than their own heads. 08:00