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Therizinosaurus

life science Maturity 5-7 Next article →

The Therizinosaurus was a massive dinosaur from the Late Cretaceous period.

Therizinosaurus Restoration
Therizinosaurus Restoration

It lived in what is now Asia. This animal belongs to a group called the Therizinosauria.

Therizinosaurus known material
Therizinosaurus known material

It was one of the largest members of this unique group. Some scientists think it was the largest maniraptoran ever found. Maniraptorans are a specific group of dinosaurs that includes birds. This giant lived in a world with other famous creatures like Tarbosaurus. Its huge size likely helped it avoid competition for food.

therizinosaurus size
therizinosaurus size

This dinosaur had a very interesting way of living. It was a slow-moving herbivore, which means it ate plants.

Therizinosaurus arm diagram
Therizinosaurus arm diagram

It had a long neck to reach high leaves. A rhamphotheca, or a horny beak, helped it eat. Its wide torso was useful for processing all that food. The most famous part was its three fingers. These fingers had huge claw bones called unguals.

Therizinosaurus ungual morphology
Therizinosaurus ungual morphology

These claws were very stiff and long. They were likely used to pull branches toward its mouth. These claws were too fragile to be used for attacking. They might have been used to look scary to others.

Finding the truth about this dinosaur took many years.

Therizinosaurus PIN 551-483 unguals
Therizinosaurus PIN 551-483 unguals

A Mongolian expedition first found some bones in 1948. These bones were found in the Gobi Desert. A scientist named Evgeny Maleev described them in 1954. At first, he thought the animal was a giant turtle. He even gave it a name that means "turtle-shaped."

Therizinosaurus known material
Therizinosaurus known material

Later, other scientists like Anatoly K. Rozhdestvensky suggested it was a theropod. This means it was actually a type of meat-eating dinosaur lineage. This discovery changed how everyone understood the animal.

Many different fossils have been found since those first bones.

Therizinosaurus MPC-D 100 15 arms
Therizinosaurus MPC-D 100 15 arms

In 1973, a much more complete specimen was found. This included arms and some ribs. Another important find was a right hindlimb in 1973. This limb showed that the dinosaur had four toes.

Erlikosaurus
Erlikosaurus

Most other theropods have a smaller first toe called a dewclaw. The Therizinosaurus had a foot that looked more like a sauropodomorph. Sauropodomorphs were another group of dinosaurs with different foot shapes. These findings helped scientists place the animal in the Theropoda group.

We can use things we know to picture this giant.

therizinosaurus size
therizinosaurus size

The Therizinosaurus was incredibly large. Some experts estimate it weighed about 5,000 kilograms. That is roughly the weight of a large elephant. Its claws were also truly enormous. They could grow longer than 72 centimeters. That is longer than many people's arms! Even though we do not have a full skeleton, we know a lot. Its body was built to be a powerful plant-eater. It was a truly remarkable part of the ancient world.

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🖼️ Images & Media (28)
File:Cretaceous-aged dinosaur fossil localities of Mongolia.PNG
Cretaceous-aged dinosaur fossil...
File:Therizinosaurus PIN 551-483 unguals.jpg
Therizinosaurus PIN 551-483 unguals.jpg
File:Therizinosaurus MPC-D 100 15 arms.jpg
Therizinosaurus MPC-D 100 15 arms.jpg
File:Therizinosaurus known material.jpg
Therizinosaurus known material.jpg
File:therizinosaurus size.png
therizinosaurus size.png
File:Therizinosaurus Restoration.png
Therizinosaurus Restoration.png
File:Therizinosaurus arm diagram.png
Therizinosaurus arm diagram.png
File:Therizinosaurus ungual specimens.png
Therizinosaurus ungual specimens.png
File:Therizinosaurus ungual morphology.png
Therizinosaurus ungual morphology.png
File:Therizinosaurus IGM 100 45 diagram.png
Therizinosaurus IGM 100 45 diagram.png
File:Erlikosaurus.jpg
Erlikosaurus.jpg
File:Alxasaurus Tyrrell.jpg
Alxasaurus Tyrrell.jpg

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