Ratite - Physical Characteristics

Physical Characteristics

Ratites in general have many physical characteristics in common, which are often not shared by the family Tinamidae, or tinamous. First, the breast muscles are underdeveloped. They do not have keeled sterna. Their wishbones (furculae) are almost absent. They have a simplified wing skeletons and musculature. Their legs are stronger and do not have air chambers, except the femurs. Their tail and flight feathers have retrogressed or have become decorative plumes. They have no feather vanes, which means they do not need to oil their feathers, hence they have no preen glands. They have no separation of pterylae and apteria, and finally, they have palaeognathous palates.

Ostriches have the greatest dimorphism, rheas show some dichromatism during the breeding season. Emus, cassowaries, and kiwis show some dimorphism, predominantly in size.

While the ratites share a lot of similarities, they also have major differences. Ostriches have only two toes, with one being much larger than the other. Cassowaries have developed long inner toenails, used defensively. Ostriches and rheas have prominent wings; although they don't use them to fly, they do use them in courtship and predator distraction.