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What Is a Dinosaur?

Five important characteristics that all dinosaurs share. Plus, common misperceptions.

  • Grades: 3–5, 6–8

Adapted from Dinosaurs: The Very Latest Information and Hands-On Activities From the Museum of the Rockies by Liza Charlesworth and Bonnie Sachatello-Sawyer. A Scholastic Professional Book.

 

Dinosaurs were a special group of animals that roamed the Earth long ago. Their fossil remains suggest that they were very closely related to ancient and modern-day birds. In fact, a number of paleontologists now believe that birds actually evolved from dinosaurs. Dinosaurs can be described by the following five important characteristics.

1. All Dinosaurs Lived During The Mesozoic Era, 245 To 65 Million Years Ago. However, not all animals that lived during this time were dinosaurs. Dinosaurs lived in varied ecological communities along with an abundance of other creates, including mammals, amphibians, and insects.

2. All Dinosaurs Lived On Land. While some dinosaurs might have been able to wade or paddle through water, they did not live in oceans, lakes, or rivers. Mosasaurs and Plesiosaurs, the giant swimming reptiles that also lived during the Mesozoic Era, were not dinosaurs. Nor were the ancient flying reptiles, known as pterosaurs.

3. All Dinosaurs Were Vertebrates. Large or small, dinosaurs were all backboned animals that shared similar skeletal features.

4. All Dinosaurs Walked With Their Legs Positioned Directly Underneath Their Bodies, Like Birds. This adaptation made dinosaurs efficient walkers and runners, and was very likely one of the keys to their long-term survival.

5. All Dinosaurs Were Diapsids, Meaning They Had Two Holes In Their Skull Located Behind Their Eyes. These holes helped to lighten their skulls and provided important attachment places for facial muscles.

Devouring Misperceptions

  • Dinosaurs did not live with humans.
  • Pterosaurs, the flying reptiles, were not dinosaurs.
  • Dinosaurs did not live in the water.
  • Dinosaurs were not cold-blooded.
  • Dinosaurs did not have pea-sized brains.
  • Dinosaurs did not drag their tails on the ground.
  • Most species did not spend the majority of their time killing one another.

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  • Subjects:
    Archaeology, Dinosaurs, Paleontology and Fossils
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