Therizinosaurus was one of the strangest known theropod dinosaurs, combining a small head, long neck, bulky body, feathered covering, and huge hand claws. It lived during the Late Cretaceous Period in what is now Mongolia, about 70 million years ago. Its unusual body shows that not all theropods were fast, meat-eating predators like Velociraptor or Tyrannosaurus.
Studying Therizinosaurus helps paleontologists understand how diverse dinosaur lifestyles became before the end-Cretaceous extinction.
Key Facts
- Therizinosaurus lived about 70 million years ago during the Late Cretaceous Period.
- Estimated body length was about 9 to 10 m, making it one of the largest known therizinosaurs.
- Its hand claws could reach about 1 m in length, among the longest claws of any known animal.
- Therizinosaurus was a theropod, the same major dinosaur group that includes Tyrannosaurus and modern birds.
- Evidence from related species suggests Therizinosaurus was feathered and likely ate mostly plants.
- Fossil interpretation uses comparison: unknown trait + related fossils + anatomy = scientific reconstruction.
Vocabulary
- Therizinosaurus
- Therizinosaurus was a large Late Cretaceous theropod dinosaur known for its extremely long, curved hand claws.
- Theropod
- A theropod is a bipedal dinosaur from the group that includes meat-eating dinosaurs, many omnivores, and modern birds.
- Paleontology
- Paleontology is the scientific study of ancient life using fossils, rocks, and comparisons with living organisms.
- Fossil
- A fossil is preserved evidence of past life, such as bone, tooth, footprint, shell, or trace mark.
- Herbivory
- Herbivory is a feeding strategy based mainly on eating plants or plant material.
Common Mistakes to Avoid
- Calling Therizinosaurus a typical predator is wrong because its small head, broad body, and related species suggest a mostly plant-eating lifestyle.
- Assuming the claws were only weapons is wrong because they may also have helped pull branches, strip vegetation, display, or defend the animal.
- Drawing Therizinosaurus as scaly and featherless is misleading because close relatives show evidence that feathers were likely present.
- Treating reconstructions as exact photographs is wrong because paleontologists infer missing features from partial fossils, related species, and anatomy.
Practice Questions
- 1 A Therizinosaurus is estimated to be 10 m long. If a human is 1.7 m tall, about how many human heights equal the dinosaur's body length?
- 2 One Therizinosaurus claw is estimated at 1.0 m long. If a student's pencil is 0.19 m long, how many pencil lengths is the claw? Round to the nearest whole number.
- 3 Therizinosaurus had huge claws, a small head, a long neck, and a bulky body. Explain why these traits support the idea that it was not a typical fast predator.