Struthio

Struthio is a genus of bird in the order Struthioniformes. There are two living species, the common ostrich and the Somali ostrich. There are nine known species from this genus, of which seven are extinct. Three additional species, S. pannonicus, S. dmanisensis (the giant ostrich), and S. transcaucasicus, were transferred to the genus Pachystruthio in 2019. Several additional fossil forms are ichnotaxa (that is, classified according to the organism's trace fossils such as footprints rather than its body) and their association with those described from distinctive bones is contentious and in need of revision pending more good material.