Therizinosauroidea Early Cretaceous-Late Cretaceous (Previously called segnosaurs)

Australia: The Land Where Time Began

This clade of theropods from Mongolia, China and western North America is often referred to as freaky and enigmatic, because they don't seem to fit comfortably in any group of dinosaurs. They were originally classified as saurischian dinosaurs, then as a separate group of saurischians, and now, after more recent detailed study they have been recognised as maniraptorans and placed in the Theropods, albeit bizarre theropods.

Among the characteristics of the group was an opisthopubic pelvis (the pubis pointed to the rear), as in birds, and a pneumatised hollow bones as in theropods and birds. With the exception of Beipiaosaurus inexpectus, the basal form, they were all large and bulky, with wide bodies. They appeared similar to prosauropods in having 4 main toes on their feet and a small head with large leaf-like teeth on long necks. Unlike most theropods, they appear to have been herbivores, based on the morphology of their jaws and teeth. A most distinctive feature were claws on the hand that grew up to 3 ft long.