in most members, particularly on Therizinosaurus. The reduced carpal block on therizinosaurids enabled an enhanced hand flexion. Manual phalanges are relatively standard in shape among maniraptorans with a formula of digits I, II and III. The manual unguals (claw bones) are proportionally larger than the phalanges, strongly flattened from side to side, and recurved with more degrees of specialization than therizinosauroids. Most therizinosaurids had sharply pointed and recurved unguals with very robust tubercles (flexor tendons attachment). These traits are better seen on Nothronychus and Segnosaurus. In Therizinosaurus, however, the manual unguals were extremely elongated and straight with poor curves. Although most of them are incomplete, if restored, they would measure about long, which make them the largest hand claws of any known terrestrial animal. The tubercles are not as strongly developed as in other therizinosaurids though, in addition, Therizinosaurus had some of the longest forelimbs known for any bipedal dinosaurs: the preserved right arm in specimen IGM 100/15 has a total length of . The vertebral column was highly pneumatized (air-spaced) and is relatively well documented from several badly to well-preserved elements among genera but specimens of Nanshiungosaurus and Nothronychus preserve the most complete series of vertebrae. Therizinosaurids had large and robust cervical vertebrae with relatively short neural spines and platycoelous (concave at both ends) to opisthocoelus (concave posterior ends) centra that were elongated and had some degree of pneumacity. In dorsal vertebrae the neural spines are more elongated and stiff. Several pneumatopores (small openings leading to air pockets) are present on the dorsolateral surfaces of the centra and they progressively reduce in size. Some species like N. graffami had a narrow hump-like structure on their back as indicated by the very elongated neural spines of the first dorsals. In therizinosaurids, the sacrum was composed by about six sacral vertebrae with broad centra that have rounded facets. The caudal vertebrae were stocky with stiff and rounded transverse projections. When compared to early members, therizinosaurids had a reduction in the number of caudals and a minor chevron constriction, which indicates a shorter and flexible tail. Therizinosaurids had wide torsos supported by a broad, sloth-like pelvis. The ribcage was very round and composed by elongated ribs with fairly robust capitula. The most modified element within the therizinosaurid build was the possession of a unique opisthopubic pelvis (pubis and ischium extending backwards), a feature known otherwise only in birds and ornithischians. The ilium