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Dino History

5 animals with prehistoric ancestors

Published on August 13, 2017 | Last Updated April 08, 2022
A little red and yellow crab in the sand, holding out its pincers

Even though dinosaurs died out millions of years ago, there are still some modern-day animals that have a connection to them. From birds to alligators, here are five species that count dinosaurs as relatives or neighbours!


A rooster surrounded by smaller chickens

Believe or not, chickens are related to dinosaurs. (Pixabay)

The Tyrannosaurus rex was one of the largest, most fearsome animals ever to exist. Surely, anything related to a T. rex must be absolutely terrifying, right?

Well, not quite! It turns out the king of the dinosaurs actually shares a surprising amount of DNA with modern day chickens! In fact, birds are commonly thought to be the only animals around today that are direct descendants of dinosaurs.

So next time you visit a farm, take a moment to think about it. All those squawking chickens are actually the closest living relatives of the most incredible predator the world has ever known!


A close-up look at a crocodile, showing it's sharp teeth

Dinosaurs were reptiles, just like alligators and crocodiles. (Pixabay)

Although birds may be the only “modern" dinosaurs, there are plenty of animals around today that share some impressive connections with ancient animals.

For example, dinosaurs are reptiles, a group that also includes turtles, crocodiles and snakes! Although they split off pretty early on, dinosaurs and these animals share common ancestors.

Modern crocodiles and alligators are almost unchanged from their ancient ancestors of the Cretaceous period (about 145–66 million years ago). That means that animals that were almost identical to the ones you can see today existed alongside dinosaurs!

Sea Turtles

a sea turtle swims underwater above a coral reef

A large sea turtle out for a swim. (Pixabay)

Like crocs and 'gators, sea turtles are  reptiles too. Just like dinosaurs.

In fact, they’re often called “cousins” of dinosaurs! They developed alongside dinosaurs, emerging as a distinct type of turtle about 110 million years ago.

The seven species of sea turtle still around today all have ancient origins, but the most impressive turtle of all time is probably the Archelon. Living about 80 million years ago, the Archelon was over four metres long and was almost five metres wide from flipper to flipper. A grown man could easily fit inside its shell.

Today, the leatherback sea turtle is its closest living relative.


A large shark swimming in blue water

Careful little fish, this shark looks hungry. (Photo Elias Levy via Visualhunt / CC BY)

Sharks have been around a long, long time. The earliest sharks first emerged around 450 million years ago, with modern sharks first appearing around 100 million years ago.

Today’s sharks are descended from relatives that swam alongside dinosaurs in prehistoric times. In fact, the largest predator of all time was a shark called a Megalodon. It lived just after the dinosaurs, 23 million years ago, and only went extinct 2.6 million years ago. It could reach lengths of up to 20 metres and could weigh up to 103 metric tonnes!


A small red crab on wet rocks

Careful! This crab seems a little... crabby. (Pixabay)

Crabs first emerged in the Jurassic period (about 200–146 million years ago), but they flourished in the Cretaceous period, just before dinosaurs went extinct.

One of the most interesting species of crab alive during this time was the Megaxantho Zogue, which was found in Mexico. Larger than the crabs of today, it was the first crab to evolve a claw that was specially developed to break the shells of prey.

This was an important evolutionary step, and one that many crabs still have today!

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