Cretaceous 145 to 65 Million Years Ago

About 140 million years ago, the Earth’s surface was on the move, as the continents were breaking apart and creeping into the positions we know today. When organisms  could no longer move between continents, certain plants and animals were stuck in one area, creating different ecosystems in each part of the planet.

During this period of our planet’s history, dinosaurs continued to reign but other animals were appearing too: new species of insects, plants, and mammals evolved around the world.

But big changes were about to take place: a giant extinction was on the horizon that would end the Cretaceous period in a bang!


Tyrannosaurus rex

Tyrannosaurus rex and other dinosaurs lived during the Cretaceous period. Source: Flickr

One of the fiercest and most famous dinosaurs to ever walk the planet was Tyrannosaurus rex . T. rex was huge – it was as long as a school bus (43 feet) and weighed as much as two elephants (9 tons)! But this giant’s size didn’t slow it down too much, since long strong legs helped it run surprisingly fast. If T. rex lived today, it could outrun many of us humans.

This powerful predator probably used its sharp claws to grab prey , but its short arms couldn’t reach its mouth. Instead, T. rex ripped its food apart with its super-sharp teeth, each the size of a banana. And its giant jaws meant that it could eat more than 500 pounds of food at once. That’s a big bite!


Many colorful flowers evolved lived during this time in the Earth’s history. Source: wikipedia

T. rex and the other dinosaurs that lived during the Cretaceous period were exciting, but plants really stole the show. During this time the first flowers appeared, sprinkling the prehistoric Earth with color.

But in order to have flowers, plants needed to be pollinated . Insects like bees, butterflies, ants, and beetles became essential to help these plants reproduce. This interaction was helpful for both the plant and the bug: pollinators got a snack from the flower’s nectar, and insect helped the plant reproduce.

As flowering plants became successful, the number of insects on Earth exploded too, and their close relationship helped both types of life spread around the world.

Living fossils

Today, this tiny ant looks a lot like it did more than 50 million years ago! Source: wikipedia

In 2008, a “new” species  of ant was discovered in the Amazon rainforest. But it turns out that this ant wasn’t really so new after all. In fact, the species—named Martialis heureka —has changed very little in many millions of years!

Scientists tested the ant’s DNA to figure out how long ago it evolved, and they found that the species is more than 50 million years old.

Not only is this ant species ancient, it’s also weird in other ways. It has no eyes, since it lives underground where it’s pitch black. The ant also has giant jaws, called mandibles, which it uses to catch its prey. These adaptations have helped these ants survive and thrive since the Cretaceous period, when it crawled along right under the thundering feet of T. rex and other dinosaurs.

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