 Apart from the giant teratorn "Argentavis magnificens", the biggest of the pseudotooth birds were the largest flying birds known.Almost all of their remains from the Neogene are immense, but in the Paleogene there were a number of pelagornithids that were around the size of a great albatross (genus "Diomedea") or even a bit smaller.The undescribed species provisionally called "Odontoptila inexpectata" – from the Paleocene-Eocene boundary of Morocco – is the smallest pseudotooth bird discovered to date and was just a bit larger than a white-chinned petrel ("Procellaria aequinoctialis").