 The Romanian fossil "Grus miocaenicus" is sometimes considered a synonym of this species.Other, somewhat doubtful species described from the Late Oligocene to Early Miocene (c. 28-23 mya) of French inland sites are "P. gracilipes" and "P. crassipes" which are most common in the Late Oligocene and later are replaced by "P. ambiguus".From Late Oligocene to Middle Miocene (c. 28-12 mya) sites in Australia, two species, "P. pledgei" and "P. wilsoni" have been described.