Maniraptors are characterized by elongated arms and hands, as well as a semi-lunate carpal in the wrist. Other basal maniraptor traits include the presence of a furcula, a distally shortened and stiffened tail, feathers, and an elongated, backwards-pointing pubis. The "killer claw" which characterizes dromaeosaurs may also be a basal trait.
In the therezinosaurs, however, the divergence from the carnivore root stock is carried to extremes; they have abandoned all of the tendencies that their ancestors have held for over a hundred million years, and have become herbivores.
The hips of a therezinosaur are much wider then is normal for a maniraptor, and the pubis is swept backward in the manner of a bird or ornithischian dinosaur, to accommodate the large belly needed to digest plant matter.
The partial thawing of Earth's polar reaches has allowed orithscian herbivores, such as the formosicorns, the cenoceratopsians, and the viriosaurs to expand northward, chewing away at the therizinosaurs' strongholds.
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