• Not all big prehistoric reptiles are dinosaurs.
• What defines a true dinosaur from the rest of reptiles, is the shape of its hips and legs.
• While most walking reptiles move as lizards do, with their legs holding up the body from its sides, dinosaurs walk with straight upright legs, that support the body as pillars.
• So, in simple words, if it swims, flies, or walks as a lizard, it is not a dinosaur.
• If it walks with two or four straight upright legs, it is a true dinosaur.
• Many dinosaurs developed internal heat, similar to mammals and birds.
• Many dinosaurs also developed feathers, to keep their heat inside the body.
• Some of these feathered dinosaurs eventually evolved into birds.
• While most dinosaurs got extinct after the KT event, birds survived until today.

Triceratops skull; photo by Tiseb cc-by	Velociraptor skeleton ; photo by Kabacchi cc-by

Sources:

-The Variety of Life, Colin Tudge, 2000

Citation: García, A.I. 2015. The Tree Of Nature (Online) at http://thetreeofnature.com

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