This would then be an example of convergent evolution: avialans, therizinosaurians, and ornithischian dinosaurs all developed a similar hip anatomy independently of each other, possibly as an adaptation to their herbivorous or omnivorous diets.
Convergent evolution: similar hip anatomy in aviaians, therizinosaurians, and ornithischian dinosaurs, possibly due to their herbivorous or omnivorous diets.