What Is A Dinosaur？

A depiction of the massive, long-necked, plant-eating dinosaur, Argentinosaurus, reaching for leaves in a forest.

Are you looking for an easy way to teach your child about dinosaurs? We’ve put together a set of free materials that parents and teachers can use right away. In this lesson, your child will dive into the fascinating world of dinosaurs. 

We’ll explore the characteristics, types, and extinction of these ancient reptiles. Explore science in a more engaging way with captivating 3D videos and interactive quizzes. Download our app to get started!

What You Will Learn From This Lesson

  • Dinosaurs had unique legs directly under their bodies, unlike crocodiles.
  • Dinosaurs varied significantly in size and appearance, from tiny to massive.
  • An asteroid impact 66 million years ago caused the extinction of most dinosaurs.

What Made Dinosaurs Unique?

A cartoon T-Rex and a crocodile illustrate that dinosaurs had legs positioned directly under their bodies, unlike crocodiles, whose legs are on their sides.

Dinosaurs were ancient reptiles that lived about 230 million years ago and once ruled the Earth. Like crocodiles, which are also reptiles, most dinosaurs had scales. However, dinosaurs and modern crocodiles differ in a key structural way.

A major difference is the placement of their legs. Dinosaurs had legs positioned directly under their bodies, unlike crocodiles, whose legs are on their sides. This leg structure allowed dinosaurs to support their great weight and run very fast. Dinosaurs were known for their speed, running faster than modern crocodiles.

How Different Were Dinosaurs?

Scientists have discovered and named over 1,200 species of dinosaurs that varied significantly in size and appearance. Some dinosaurs were covered in armor, while others had feathers. Some species had long necks and huge bodies, and others were ferocious predators.

Dinosaur sizes ranged from the massive Argentinosaurus to the tiny Epidexipteryx. The Argentinosaurus was the longest dinosaur, growing over 130 feet long, which is about the length of four school buses. In contrast, the smallest dinosaur, the Epidexipteryx, was only about 10 inches long, or the size of a pencil case.

Why Did Dinosaurs Vanish?

A dramatic image showing an asteroid impact and widespread destruction, which caused dinosaurs to become extinct.

Most dinosaurs became extinct 66 million years ago. Scientists have a theory about what caused this mass extinction event. They believe that an asteroid collided with the Earth.

The impact of the asteroid is thought to have caused widespread disasters. These included huge earthquakes and violent volcanic eruptions. Toxic gases and dust then filled the air, making the environment too harsh for the dinosaurs to survive.

Fun Fact

  • The smallest dinosaur, the Epidexipteryx, was about the length of a pencil case (around 10 inches).
  • The Argentinosaurus was enormous, growing as long as four school buses put together (over 130 feet).
  • Dinosaurs were faster than modern crocodiles because of where their legs were positioned.
  • Over 1,200 types of dinosaurs have been found and named by scientists.
  • The Ankylosaur had thick armor plates and a club on its tail.

Vocabulary

  • Argentinosaurus: The longest known dinosaur, reaching over 130 feet long.
  • Epidexipteryx: The smallest known dinosaur, which was only about 10 inches long.
  • Reptiles: A group of animals that includes crocodiles and most dinosaurs; they often have scales.
  • Extinct: The state of a species that no longer has any living members. Most dinosaurs became extinct 66 million years ago.