A Brief Overview of the Triassic Period for Middle School Science Classes

Dec 15, 2024

3 min read

Earth history is a fascinating topic! It is also a massive topic! The reading passage below will teach you all about the Triassic Period. If you want to learn more (and why wouldn't you?!), you can check out my Earth History page. I also have all of my passages available at Teachers Pay Teachers. They come with so many extras to get your students thinking about the content! I also recommend scrolling to the bottom of the page to check out my digital picture book on the Triassic Period!

Triassic Period reading passage for middle school science

The Triassic period began right after the Permian-Triassic extinction event wiped out most life on

Earth. The life that did survive was able to thrive throughout the Triassic period.

The Climate of Pangaea

During the Triassic period, all of the land on Earth was concentrated in one supercontinent

called Pangaea. The interior of Pangaea was mostly dry desert with cold winters and hot

summers. The coasts had a monsoon climate. One season was rainy while the rest of the year,

the coasts were warm. The entire Earth was warmer during the Triassic period than it is today.

There were no ice caps at the poles.

Marine Life

In the oceans, 95 percent of marine species had gone extinct during the Permian-Triassic

extinction, so most of the fish fossils from the Triassic period are from the same species.

Ammonites, mollusks, and sea urchins also survived the extinction.

Ichthyosaurs

Early in the Triassic period, a tetrapod called ichthyosaur left land for the ocean. At first, it used

its entire body to swim similar to the way an eel swims today. Over time, it evolved to form a

dolphin-like body and snout. It began swimming like a fish. The ichthyosaurs breathed air and

gave birth to live young. By the middle of the Triassic period, it dominated the ocean food

chain.

Life on Land

On land, spiders, scorpions, millipedes, and centipedes continued to live in the conifer forests.

Grasshoppers appeared for the first time. Frogs, salamanders, crocodiles, turtles, and snakes all

lived along the coasts or near rivers and lakes.

Mammals

Most of the therapsids that had survived the Permian-Triassic extinction went extinct by the

middle of the Triassic period. However, mammals survived. These early mammals were just a

few inches long. Many of them lived in trees and were nocturnal. They were both herbivores

and insectivores. They had the same three ear bones as mammals today.

Eozostrodon

The first true mammal, Eozostrodon, appeared about 230 million years ago. It was three feet

long and resembled a shrew. It laid eggs, but then mothers provided milk for their young.

Pterosaurs

Archosaurs, the diapsids that survived the Permian-Triassic extinction, developed into crocodiles, dinosaurs, and pterosaurs. One pterosaur, Sharovipteryx, was a glider about the size of a crow. It would jump from high branches and glide to the ground. Another pterosaur, Icarosaurus, was the size of a hummingbird.

Dinosaurs

One of the first dinosaurs, Coelophysis, appeared around 225 million years ago. It was a

carnivore that stood on two feet. It was nine feet tall and weighed about one hundred pounds. It

ate small reptiles and amphibians. A few million years later, Plateosaurus appeared.

Plateosaurus was an herbivore that was twenty-seven feet long.

Seafloor Spreading

By the end of the Triassic period, seafloor spreading in the Tethys Sea was forcing Pangaea

apart. The supercontinent was separating into Laurasia and Gondwana.

Volcanoes

The subducting plates caused volcanoes to erupt. The erupting volcanoes filled the atmosphere

and ocean with carbon dioxide. Species of ammonoids, mollusks, and conodonts went extinct,

but dinosaurs and mammals survived.

The Triassic period ended with this extinction event.

Triassic Period Picture Book

Looking for another way to learn about the Triassic Period? Check out this picture book version. The pages are a part of my Earth History bundle on Teachers Pay Teachers.