Ostrich (Struthio camelus)

Along with tinamous, rheas, cassowaries and kiwis, ostriches belong to the primitive bird infraclass Paleognathae, distinguished by the structure of their skulls. In these birds, a weak carina sterni (or keel) evolved, resulting in underdeveloped flight muscles that prevent flight (with the exception of tinamous, which are still poor fliers). The ostrich is native to Africa, although small populations have been introduced in certain regions of Australia. Ostriches exhibit pronounced sexual dimorphism in coloration. For copulation, the male has a large penis within the cloaca. Typically, he mates with multiple females, but only one will assist him in raising offspring. Adult ostriches have very strong legs, making them potentially dangerous to humans. Nevertheless, they are often kept as farm animals for their valuable products, such as meat, eggs and feathers. ## Keywords Together with tinamous, rheas, casowaries and kiwis, the ostrich belongs to the most primitive bird superorder Paleognatha due to the construction of their skull. On their skeleton, a very weak crista sterni was evolved and then, as a consequence, they have very weak flight muscles and cannot fly (except of tinamous, which are, nevertheless, not very good fliers). Ostriches live in Africa, but small populations were also introduced to some particular areas of Australia. It has a very typical sexual dimorphism in colour. Male has a very big penis in his cloaca and uses it during copulation. He usually copulates with more than one female, but the only one assists him during breeding their chicks. Adult ostriches have very strong legs and so they can be dangerous also for the human. Despite it, they are frequently kept as farm animals and their products (meat, eggs, feathers) are further processed.