A Brief Overview of the Jurassic 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 Jurassic 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 Jurassic Period!

Triassic-Jurassic Extinction Event

The Triassic-Jurassic extinction event was one of the five biggest extinction events in Earth’s history. Around half of the life on Earth went extinct, but plants, mammals, and dinosaurs survived.

Seafloor Spreading

Tectonic activity continued to break apart Pangaea during the Jurassic period. In the north, Laurasia split into North America and Eurasia while eastern and western Gondwana separated in the south.

The seafloor spreading in the Tethys Sea created subduction zones along the outer edges of Pangaea. The new seafloor was pushing the old crust back into the mantle. These subduction zones created many volcanoes and mountain ranges. The Rocky Mountains and the Andes were both formed during this period.

Climate

Erupting volcanoes and lava from seafloor spreading added large amounts of carbon dioxide into the atmosphere. As a greenhouse gas, the carbon dioxide made the planet warmer. Pangaea had dry, hot summers and dry, cold winters because it was so big. The new smaller continents were humid and warm all year.

Plants

Plants thrived in this warm environment. Gymnosperms, such as conifers and ginkgoes, dominated the landscape. However, flowering plants would not appear until the Cretaceous period.

Ocean Life

Life diversified in the oceans. Sponges, snails, mollusks, and fish lived in the coral reefs in the shallow coastal waters. Ichthyosaurs, cephalopods, and ammonites also lived in the ocean. Ocean predators included giant marine crocodiles, sharks, and rays. The largest predator of the Jurassic period were plesiosaurs. They were fifteen feet long and had long necks. They swam through the water using flippers similar to the way sea lions swim today.

Sauropods

On land, dinosaurs roamed the Earth. The fossils of sauropods have been found on every continent except Antarctica. Sauropods were giant herbivores that could be fifty feet tall and eighty-five feet long. Brachiosaurus and Diplodocus were both sauropods. Carnivores, such as the Allosaurus, would not have tried to attack these giant prey. Instead, they would target the young, sick, or old members of a herd.

Allosaurus

While the Tyrannosaurus rex was a star of the movie Jurassic Park, the Tyrannosaurus rex did not live during the Jurassic period. The Allosaurus looked similar to the Tyrannosaurus rex, but the two were only distantly related. The Allosaurus was smaller than the T-rex with a longer jaw and heavier forelimbs. Like the Tyrannosaurus rex, the Allosaurus was a carnivore.

Birds

Archaeopteryx, the first bird, evolved from dinosaurs during the Jurassic period. The pterosaurs of the Triassic period were still flying in the skies of the Jurassic period, but these were flying reptiles, not birds.

Mammals

Mammals no bigger than rats scurried around the trees during the Jurassic period. They were all herbivores or insectivores. One mammal, Adelobasileus, looked like a shrew and had the ear and jaw bones of a mammal. These bones provide the link between the cynodonts of the Triassic period and the mammals of today.

Jurassic Extinction Event

The Jurassic period ended with a minor mass extinction event. Many of the giant sauropods died along with shallow water creatures such as bivalves and ammonites. As always, new life would evolve to take the place of the species lost to the extinction.

Jurassic Period Picture Book

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