Therizinosaurids descend from carnivorous theropod ancestors but evolved toward a herbivorous or omnivorous diet, and their anatomy shows it: small, leaf-shaped teeth suited to processing plants, a wide, potbellied torso presumably housing a long digestive tract, and enormous, slightly curved hand claws -- among the longest of any known animal relative to body size -- whose exact function (defense, foraging, or display) is still debated.
The family's namesake genus, Therizinosaurus, is known mostly from its dramatic claws, among the longest ever found on any animal, while more complete skeletons of relatives like Nothronychus have filled in the rest of the family's genuinely bizarre body plan. Therizinosaurids are known from Cretaceous Asia and North America and remain one of the clearest examples of a meat-eating dinosaur lineage evolving away from carnivory entirely.