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47 / Mesozoic
Therizinosaurus
Therizinosaurus cheloniformis
Meter-long hand claws belonged to a tall, feathered, pot-bellied herbivore.
- Time range
- About 70–66 million years ago
- Final stage
- End of the Cretaceous
- Geographic range
- Mongolian Plateau
01 / ANSWER FIRST
What was Therizinosaurus?
Therizinosaurus was a very large, long-necked theropod from Late Cretaceous Mongolia with enormous narrow hand claws and a plant-processing body plan.
It belongs inside Theropoda despite looking unlike a predator. The genus is known mainly from arms, claws and hindlimb fragments, so its pot belly, small head and feathers are reconstructed from more complete therizinosaur relatives.
02 / QUICK FACTS
Therizinosaurus at a glance
- Scientific name
- Therizinosaurus cheloniformis
- Age
- ~70 million years ago
- Length
- About 9–10 m; inferred
- Mass
- Several tonnes; uncertain
- Claws
- Bony cores up to ~1 m
- Diet
- Primarily herbivorous
- Covering
- Feathers inferred from relatives
- Range
- Mongolia
03 / CORE QUESTION
What were the giant claws for?
The claws were extremely long but thin, with curvature and stress performance better suited to hooking vegetation, display and deterrence than to absorbing repeated high-force slashes into struggling prey.
Defence remains plausible at close range, especially because reach made the animal dangerous. One exclusive use is unlikely: feeding, signalling and protection could all act on the same structure.
Read the complete claw-function guideHow to read the numbers
This page separates direct evidence, comparative inference and unresolved debate.
04 / LIFE & DISCOVERY TIMELINE
From mysterious turtle-like claws to giant herbivorous theropod
Nemegt browser
Therizinosaurus feeds in humid Mongolian habitats.
Giant claws found
Mongolian expeditions recover unusual forelimb bones.
Species named
The remains are initially interpreted as a turtle-like reptile.
Theropod identity solved
More complete relatives unite claws, pelvis, skull and feathers.
05 / ANATOMY
A giant theropod re-engineered for plants
Long hand claws
Three narrow unguals carried larger keratin sheaths.
Long neck
Relatives show a small head reaching broad feeding space.
Wide pelvis
A deep abdomen housed a large fermenting gut.
Feathered body
Basal relatives preserve filamentous feathers directly.
06 / DIET & BEHAVIOUR
What did Therizinosaurus eat?
Broad jaws and leaf-shaped teeth in relatives, a long neck and a large gut support mainly plant food, though opportunistic omnivory cannot be excluded.
Read the complete guide07 / DIET & BEHAVIOUR
How did it defend itself?
Great size, reach and claws could deter Tarbosaurus, yet no fossil records a fight or confirms a particular defensive stroke.
08 / RANGE & HABITAT
Where did Therizinosaurus live?
Definite remains come from the Nemegt Formation of Mongolia, a relatively humid Late Cretaceous landscape with rivers, woodland and seasonal floodplains.
Nemegt Basin
Type arms and hindlimbs anchor the genus.
River channels
Water supported productive vegetation.
Woodland
Tall and low plants offered browse.
Shared fauna
Tarbosaurus, hadrosaurs and ornithomimids shared the ecosystem.
09 / FOSSIL EVIDENCE
How do scientists know about Therizinosaurus?
Forelimbs
Arm and claw bones directly establish extraordinary reach.
Hindlimbs
Robust feet constrain size and support.
Close relatives
Complete skeletons supply skull, torso and feathers.
Biomechanics
Stress tests compare digging, cutting, hooking and display.
10 / DISAPPEARANCE & DEBATE
How much of Therizinosaurus is reconstructed?
The giant arms, claws and parts of the hindlimbs are direct; much of the skull, trunk, neck, feathers and total size comes from close relatives and scaling.
A responsible image keeps those evidence levels visible instead of treating a composite as one complete specimen.
12 / FREQUENTLY ASKED QUESTIONS
Therizinosaurus FAQ
How big was Therizinosaurus?
It is commonly reconstructed around 9–10 metres, but remains are incomplete.
How long were the claws?
The bony cores approached one metre, with keratin sheaths extending farther.
Was it a meat-eater?
It was primarily herbivorous despite theropod ancestry.
Did it have feathers?
Feathers are strongly inferred from close relatives.
Could it kill with its claws?
They could defend, but repeated slashing was probably not their main design.
Where was it found?
In Mongolia's Nemegt Formation.
04 / SOURCES & FURTHER READING
Check the source record
Use the scientific name to compare taxonomy, occurrence records and the fossil record. Database coverage and classifications may differ.
05 / REVISION HISTORY
How has this record changed?
- Expanded into a bilingual S-tier hub with two evidence-led guides.
- Verified authoritative entity sources and added three responsive reconstruction sizes.
- Initial bilingual species record published.
06 / CORRECTIONS & ADDITIONS