Pachystruthio
Pachystruthio is a genus of extinct bird which lived in Eurasia from the Late Pliocene to the Middle Pleistocene. Its fossils have been found in Hungary, Greece Crimea, Georgia, and China. The genus contains three species: P. pannonicus, P. dmanisensis, and P. transcaucasicus, which were all formerly placed with the ostrich genus, Struthio. An incomplete femur from the Nihewan Formation has been assigned to Pachystruthio indet. P. dmanisensis has been estimated standing 3.5 meters tall and weighing up to 450 kg, making it much larger than the modern ostrich and one of the largest known birds.
Although P. dmanisensis is known as the giant ostrich, its relationship to the extant ostriches of the genus Struthio is not clear.
Some authors have suggested placing the large extinct ostrich species Struthio anderssoni from the Late Pleistocene of China in the genus.