Key Concepts

• Geological Time Period: The Mesozoic Era is the era of geological time that lasted from about 252 to 66 million years ago.
• Periods: The Mesozoic Era is divided into three periods: the Triassic, Jurassic, and Cretaceous periods.
• Dominance of Reptiles: The Mesozoic Era is often called the "Age of Reptiles" due to the dominance of dinosaurs and other reptiles during this time.
• Mass Extinction: The Mesozoic Era ended with a mass extinction event, often associated with the extinction of dinosaurs and many other species.

Triassic Period

• Time Frame: Approximately 252 to 201 million years ago.
• Key Events: The early dinosaurs and mammals appeared during this period. Pangea began to break apart, leading to the formation of separate continents.

Jurassic Period

• Time Frame: Approximately 201 to 145 million years ago.
• Key Events: The period is known for the dominance of dinosaurs, including iconic species like Brachiosaurus, Stegosaurus, and Allosaurus. The first birds and the earliest flowering plants also appeared during this time.

Cretaceous Period

• Time Frame: Approximately 145 to 66 million years ago.
• Key Events: The period saw the rise of even larger dinosaurs, such as Tyrannosaurus rex and Triceratops. It also witnessed the diversification of flowering plants and the emergence of new types of mammals and reptiles.

Mass Extinction

The Mesozoic Era ended with a mass extinction event known as the Cretaceous-Paleogene extinction event. This event led to the extinction of the non-avian dinosaurs, as well as many other species. It is widely believed that this extinction was triggered by a combination of factors, including a massive asteroid impact and volcanic activity.

[Mesozoic] Related Worksheets and Study Guides:

• Geologic timeScience • Eighth Grade