A Brief Overview of the Paleogene 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 Paleogene 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 Paleogene Period!

Paleogene Period Reading Passage for Middle School Science

Cretaceous - Paleogene Extinction Event

At the end of the Cretaceous period, 75 percent of life on Earth went extinct during the Cretaceous-Paleogene extinction event. Dinosaurs, both on land and in the ocean, disappeared completely.

Mammals

The animals that survived the extinction evolved rapidly to fill the environmental niches left by the dinosaurs. Mammals, who had been small and simple during the Mesozoic Era, grew bigger and diversified throughout the Paleogene period. By the end of the period, early primates, horses, bats, pigs, cats, and dogs had all evolved.

Birds

At the beginning of the period, birds were the dominant land animal on Earth. Large, flightless birds called Gastornis were carnivores that resembled dinosaurs. However, by the end of the period, most birds were confined to the skies as mammals took over the land.

Continental Drift

Throughout the period, the continents continued to drift apart. India began its slow collision with Asia, forming the Himalayan Mountains. Australia and Antarctica separated. Antarctica moved toward the South Pole, forming the Antarctic Circumpolar Current that still exists today. Ocean water naturally travels clockwise from west to east around Antarctica. This circulation of water keeps warm water away from the freezing continent.

Climate

With ice at the North and South Poles, Earth’s climate cooled during the Paleogene period. Sea levels dropped, and continents that had been covered with shallow seas during the Cretaceous period dried.

Grasses

By the end of the period, the first grasses were evolving. Horses evolved to eat the grass, and saber-toothed cats evolved to eat the horses.

Oceans

In the oceans, sharks moved to the top of the food chain when plesiosaurs disappeared. Fish, soft-bodied cephalopods, bivalves, and sea urchins thrived in the oceans. Whales also evolved from land animals during the Paleogene period.

Whales

Modern whales’ earliest ancestors were small mammals living along streams during the Paleogene period. When these animals were scared, they would jump into the streams to hide. Over time, these creatures spent more and more time in the water. Scientists know that whales evolved from land mammals because of their skeletons. Whale skeletons are closer to land mammals than fish. This can be seen in the way whales move. Fish swim by moving their tails side to side. Whales move by pushing their tails up and down. When four-legged mammals run, their spines also move up and down.

End of the Period

By the end of the Paleogene period, life on Earth looked similar to life on Earth today. Mammals, including early primates, were the dominant land animals. Fish and sharks were swimming in the oceans, and birds filled the skies. While the animals didn’t look exactly the same as they do today, the basic body structures were the same. During the Neogene period, animals would continue to evolve into the forms we recognize today.

Paleogene Period Picture Book

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