For maniraptoran standards, Therizinosaurus obtained enormous sizes, estimated to have reach 9 to 10 m (30 to 33 ft) in length with ponderous weights from 3.6 to 5 t (3,600 to 5,000 kg), or possibly over 5 tonnes.
These dimensions make Therizinosaurus the largest therizinosaurs known and the largest known maniraptorans.
Along with the contemporaneous Deinocheirus, these were the largest maniraptoriforms.
Though the body remains of Therizinosaurus are relatively incomplete, inferences can be made about their physical characteristics based on more complete and related therizinosaurids.
Like other members of their family, Therizinosaurus had proportionally small skulls bearing a keratinous beak atop long necks, with bipedal gaits and heavy, deep, broad bellies for foliage processing (as evidenced by the wide pelvis of other therizinosaurids) with the addition of sparse feathering.
Their hindlimbs ended in four functionally, weight-bearing toes unlike other theropod groups in which the first toe was reduced to a dewclaw.
In 2010, Senter and James used hindlimb length equations to predict the total length of the hindlimbs in Therizinosaurus and Deinocheirus.
They concluded that an average individual of Therizinosaurus may have had approximately 3 m (9.8 ft) long legs.
More recently, Mike Taylor and Matt Wedel suggested that the whole neck would be 2.9 times the size of the humerus, which was 76 cm (760 mm), resulting in a 2.2 m (7.2 ft) long neck based on comparisons with the cervical vertebrae series of Nanshiungosaurus.

Therizinosaurus can be distinguished from other therizinosaurids in having very straight manual unguals that are side to side compressed (flattened) and hypertrophied (elongated) with poor curves, an extended deltopectoral crest on the humerus, the length of metacarpal I is larger than 2/3 the length of metacarpal III, and the metacarpal I has an enlarged inner crest that connects the inner lower condyle and upper inner lobe.
The most distinctive feature of Therizinosaurus was the presence of gigantic claws on each of the three digits of their front limbs.
These were common among therizinosaurs but particularly large in Therizinosaurus, and they are considered as the longest known from any terrestrial animal.
For maniraptoran standards, Therizinosaurus obtained enormous sizes, estimated to have reach 9 to 10 m (30 to 33 ft) in length with ponderous weights from 3.6 to 5 t (3,600 to 5,000 kg), or possibly over 5 tonnes. These dimensions make Therizinosaurus the largest therizinosaurs known and the largest known maniraptorans. Along with the contemporaneous Deinocheirus, these were the largest maniraptoriforms. Though the body remains of Therizinosaurus are relatively incomplete, inferences can be made about their physical characteristics based on more complete and related therizinosaurids. Like other members of their family, Therizinosaurus had proportionally small skulls bearing a keratinous beak atop long necks, with bipedal gaits and heavy, deep, broad bellies for foliage processing (as evidenced by the wide pelvis of other therizinosaurids) with the addition of sparse feathering. Their hindlimbs ended in four functionally, weight-bearing toes unlike other theropod groups in which the first toe was reduced to a dewclaw. In 2010, Senter and James used hindlimb length equations to predict the total length of the hindlimbs in Therizinosaurus and Deinocheirus. They concluded that an average individual of Therizinosaurus may have had approximately 3 m (9.8 ft) long legs. More recently, Mike Taylor and Matt Wedel suggested that the whole neck would be 2.9 times the size of the humerus, which was 76 cm (760 mm), resulting in a 2.2 m (7.2 ft) long neck based on comparisons with the cervical vertebrae series of Nanshiungosaurus.
Therizinosaurus can be distinguished from other therizinosaurids in having very straight manual unguals that are side to side compressed (flattened) and hypertrophied (elongated) with poor curves, an extended deltopectoral crest on the humerus, the length of metacarpal I is larger than 2/3 the length of metacarpal III, and the metacarpal I has an enlarged inner crest that connects the inner lower condyle and upper inner lobe. The most distinctive feature of Therizinosaurus was the presence of gigantic claws on each of the three digits of their front limbs. These were common among therizinosaurs but particularly large in Therizinosaurus, and they are considered as the longest known from any terrestrial animal.
Therizinosaurus