A Brief Overview of the Eocene Epoch for Middle School Science Classes

Dec 17, 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 Eocene epoch. 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 Eocene epoch!

Eocene epoch reading passage for middle school science

Paleocene-Eocene Thermal Maximum

The Eocene epoch began during the Paleocene-Eocene Thermal Maximum. At this time, the Earth

got much warmer. This lead to extinctions across the globe. After the warming event, the climate

of the Eocene epoch remained warm and wet.

Rainforests

Rainforests covered the Earth. Fossils of tropical plants have been found as far north as

Greenland and Alaska. There was no snow at the poles. Antarctica was covered in deciduous

forests and tundra.

Mammals

Mammals from the Paleocene epoch continued to evolve. The first modern mammals appeared

during the Eocene epoch. These are the ancestors of the mammals that are alive today.

Ungulates

Ungulates, or hoofed animals, are a good example of the evolution of mammals during the

Eocene epoch. At the beginning of the epoch, Phenacodus was a small ordinary looking animal

with hooves. By the end of the period, ungulates had grown much larger. Brontotherium and

Embolotherium were so big, scientists call them “thunder beasts.”

Andrewsarchus

Some carnivores were also getting bigger. Andrewsarchus, the largest meat-eating mammal to

ever live on land, hunted ungulates during the Eocene epoch.

Whales

Another important mammal, whales, moved from the land to the sea during the Eocene epoch.

Basilosaurus, one of the first primitive whales, was sixty feet long and weighed up to seventy-five

tons.

Small Mammals

While some mammals grew larger during the Eocene epoch, most mammals remained small.

Scientists believe this is because the smaller animals handled the heat of the epoch better than

larger animals.

Continental Drift

During the Eocene epoch, the continents continued to move to their current locations. India was

crashing into Asia, forming the Himalayas, and North America, Greenland, and Europe

continued to pull away from each other.

Antarctic Circumpolar Current

Australia and Antarctica separated and created the Antarctic Circumpolar Current. Water

moving around Antarctica naturally moves in a circle from west to east. This keeps Antarctica

surrounded by cold water.

A Cooling Climate

Toward the end of the epoch, the Earth began to cool. Scientists believe lower carbon dioxide

levels may have caused this cooling. As a result, the tropical rainforests in North America and

Europe were replaced by deciduous forests. The interiors of all of the continents got drier with

fewer trees. For the first time in the epoch, the poles were covered in ice.

Grande Coupure

The Eocene epoch ended with a major extinction event called the Grande Coupure or “Great

Break.” These extinctions could have been caused by cooler temperatures, falling sea levels, or

the introduction of new predators into the food chain. There is also evidence that a meteorite hit

in Siberia around this time. Whatever the cause, the Grande Coupure caused significant changes

to life on Earth.

Eocene Epoch Picture Book

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