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.