Skip to content

Check Out These Fingernails!

These dinosaurs had very long claws. But they didn’t use them to fight.

A dinosaur with a red head, a short tail, and very long claws on its front feet

© Corey A Ford, Henry Saint John/; Photo illustration Encyclopædia Britannica, Inc.

Therizinosaurs were dinosaurs that lived between 100 million and 66 million years ago. They weighed up to six tons, making them as heavy as Tyrannosaurus rex. But the giant Therizinosaurus had something even T. rex didn’t have. Its claws were 3 feet (1 meter) long! That makes Therizinosaurus claws the longest of any animal that ever existed. 

You might think that Therizinosaurus used these claws to fight. That’s what scientists thought for a long time. But a new study shows that’s not true. Instead of being used as weapons or as digging tools, the claws were probably used to show off!

Scientists in England and China worked together to study Therizinosaurus claws. They used computers to scan the fossils of claws. Then they made computer models of the claws. These models were just like the real thing. But the scientists could study them without worrying about causing damage to them. The scientists worked to find out if the claws would have been good tools for fighting or digging. They did tests on the models. And they compared them to the claws that other animals have. What they learned is that Therizinosaurus claws were too long and narrow to fight or dig. The claws would not have been strong enough.

So, why did Therizinosaurus have such long claws? Scientists believe the claws were meant to attract mates. Today, many types of birds have bright feathers that send the message, “Hey, look at me!” The claws of Therizinosaurus probably had the same purpose.


Happy April Fools’ Day!

Shoes with fake spiders, bugs and Happy Fools' Day note on white wooden table

© Liudmila Chernetska—iStock/Getty Images Plus

April 1 is April Fools’ Day! You can read all about fun April Fools’ Day tricks right here!

Fun Fact Icon

Fun Fact

© Moloko88, Ernest Akayeu/, Wellcome Collection, London (39916i, 40983i, 40985i); Photo illustration Encyclopædia Britannica, Inc.

Dinosaurs died out long before the first humans appeared on Earth. When people first discovered dinosaur fossils, they were looking at bones of animals they had never seen. Scientists think these strange fossils may have led people to believe in creatures that aren’t real, like dragons and unicorns!

Bird Beauties

A peacock standing in front of a mirror and saying I look beautiful today.

© Markus Gann, Aidarseineshev/, © glamstock—Imazins/Getty Images; Photo illustration Encyclopædia Britannica, Inc.

You might know that peacocks are famous for their beautiful blue and green tail feathers. But did you know that only the males are blue and green? Females, which are called peahens, have brown feathers.

The males use their bright feathers to attract females. When they really want to show off, they fan out their tails. Scientists think peacocks also fan out their tails when they want to scare off predators—animals that try to eat them—like snakes or large wild cats.

Dinosaur Deep Dive

© Orlando Florin Rosu/

Did you know that the word dinosaur means “terrible lizard”? 

Do you have a favorite type of dinosaur? You can read about it at Britannica School!

Word of the Day Icon

Word of the Day


Part of speech:



: one of the sharp claws on the feet of some birds

Definitions provided by
Merriam-Webster Logo
Game Icon


How many answers do you know?


In Case You Missed It

Ryan Redington is the winner of the Iditarod, the world’s most famous sled dog race!


Kids in Iceland work hard to help baby puffins get where they need to go.


Mia Brookes did an amazing trick on snowy slopes. Now she’s a snowboarding champion!


Scientists plan to figure out what time it is on the Moon!