Final answer:
The statement is false; birds evolved from theropod dinosaurs, not from the Ornithischia, despite the similar hip structure.
Step-by-step explanation:
The statement that the most primitive, plant-eating dinosaurs can be assigned to the Ornithischia is false. While Ornithischia, also known as "bird-hipped" dinosaurs, were primarily herbivores with a hip structure superficially resembling that of birds, they are not the ancestors of modern birds. Instead, it is the theropod dinosaurs from the saurischian, or "lizard-hipped," lineage that evolved into birds. This evolutionary relationship is supported by anatomical features such as the structure of the hip and wrist bones, as well as the presence of the wishbone formed by the fusion of clavicles, which are found in both theropods and birds.
Paleontological evidence shows the close relationship between theropods and birds, with Archaeopteryx serving as a famous example of an 'intermediate' form with characteristics of both dinosaurs and birds. Although the pelvis of Ornithischia dinosaurs resembles that of birds, the bird-like hip structure is a case of convergent evolution rather than a direct ancestral relationship.