The Rodrigues solitaire shared traits with the dodo, its closest relative, such as size and features in the skull, pelvis, and sternum. It differed in other aspects; it was taller and more slender than the dodo and had a smaller skull and beak, a flatter skull roof, and larger orbits. Its neck and legs were proportionally longer, and the dodo did not possess an equivalent to the carpal knob of the Rodrigues solitaire. Many skeletal features of the Rodrigues solitaire and dodo that are unique among pigeons have evolved to adapt to flightlessness. Their pelvic elements were thicker than those of flighted birds (to support their greater weight), and their pectoral region and wings were paedomorphic (underdeveloped, retaining juvenile features). However, the skull, trunk, and pelvic limbs were peramorphic, which means they changed considerably with maturity.