镰刀龙超科（Therizinosauroidea）是群兽脚亚目恐龙。镰刀龙类的化石发现于蒙古、中国、以及北美洲西部等地的白垩纪早期到晚期沉积层。牠们拥有类似的前肢、头颅骨、以及骨盆特征。镰刀龙超科属于手盗龙类，牠们与鸟类有接近亲缘关系。

镰刀龙超科的名称衍化自希腊文，therizo意为「切割」或「砍断」，而sauros意为「蜥蜴」。而镰刀龙超科的旧称慢龙下目（Segnosauria），segnis在拉丁语意为「缓慢的」或「迟钝的」。

Therizinosaurs (or segnosaurs) were theropod dinosaurs belonging to the clade Therizinosauria. Therizinosaur fossils have been found in Early through Late Cretaceous deposits in Mongolia, the People's ***************** and western North America. Various features of the forelimbs, skull and pelvis unite these finds as both theropods and as maniraptorans, close relatives to birds.