Dinosaurs

Dinosaurs were a group of reptiles that lived millions of years ago during the Mesozoic Era. They were the dominant terrestrial vertebrates for over 160 million years, and their fossils have been found on every continent on Earth.

Types of Dinosaurs

There were many different types of dinosaurs, each with its own unique characteristics. They can be broadly classified into two groups: Saurischia and Ornithischia.

Saurischian Dinosaurs

• Includes the theropods, such as Tyrannosaurus rex and Velociraptor
• Also includes the long-necked sauropods, like Brachiosaurus and Diplodocus

Ornithischian Dinosaurs

• Includes the horned dinosaurs, like Triceratops
• Also includes the armored dinosaurs, such as Ankylosaurus and Stegosaurus

Extinction

The mass extinction event at the end of the Cretaceous Period, about 65 million years ago, led to the extinction of non-avian dinosaurs. The cause of this extinction is still a topic of scientific debate, but one widely accepted theory is that a large asteroid impact contributed to their demise.

Study Guide

1. What are dinosaurs?
2. Describe the two main groups of dinosaurs.
3. When did dinosaurs go extinct, and what are some theories about their extinction?
4. List three famous dinosaur species and describe their characteristics.
5. What evidence do scientists use to study and understand dinosaurs?

Use this study guide to review the key concepts of dinosaurs and prepare for any quizzes or exams on the topic. Good luck!

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