page_title: Therizinosaurus
section_title: Description
hierarchical_section_title: Therizinosaurus / Description
caption_attribution_description: English: Life restoration of the gigantic, Late Cretaceous therizinosaurid Therizinosaurus cheloniformis. Claws and arms based on holotype PIN 551-483 and specimens IGM 100/15, 100/16 and 100/17. Русский: Реконструкция гигантского верхнемелового теризинозаврида Therizinosaurus cheloniformis. Когти и передние конечности основаны на голотипе PIN 551-483 и образцах IGM 100/15, 100/16 и 100/17.
context_page_description: Therizinosaurus is a genus of very large therizinosaurid dinosaurs that lived in Asia during the Late Cretaceous period in what is now the Nemegt Formation around 70 million years ago. The first remains of Therizinosaurus were found in 1948 by a Mongolian field expedition at the Gobi Desert. Fossils of this species were first described by Evgeny Maleev in 1954 and originally thought to belong to a turtle-like reptile. It is known only from a few bones, including gigantic hand claws, from which it gets its name. Additional findings compromising forelimb and hindlimb elements have been discovered during the 1960s-1980s.
  Therizinosaurus comprises the single species T. cheloniformis, which could grow up from 9 to 10 m long and weigh possibly over 5 t. They had the longest known claws of any land animal, reaching up to 1 m in length. Unlike other therizinosaurs, the claws were very stiff and elongated. But like other members, they would have been slow, long-necked/high browser herbivores equipped with a keratinous beak and wide torsos. The feet were equipped with four weight-bearing toes, resembling a little bit the unrelated sauropodomorphs.
context_section_description: 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.
caption: Life restoration
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