And though it served as the namesake for a popular alternate common name of the pseudotooth birds – "pseudodontorns" or "pseudodontornids" – that was extensively used in the 20th century, current authors prefer "pelagornithids" because this is less fraught with taxonomic dispute.

The presumed family "Pseudodontornithidae", deemed invalid nowadays, had been recognized as pseudotooth birds all along, as they were established based on skull fossils preserving parts of the "toothed" beak.

[3] The type species P. longirostris (initially placed in Odontopteryx) is known from an incomplete but quite well preserved[4] fossil skull of unknown age and origin; it was bought from a merchant who had acquired it from a sailor returning from Brazil, but the specimen is widely presumed to be actually from the North Sea region.

A pseudotooth bird's lower right dentary piece (specimen YPM 4617) from near Charleston, South Carolina (United States) – apparently dredged up from near the source of the Stono River – was provisionally assigned to P. longirostris as it closely matches the holotype in size and appearance.

Its paroccipital process is not as markedly elongated back- and downwards as in the Ypresian (Early Eocene) Dasornis and Odontopteryx and seems to be in a more apomorphic condition, which would agree with a late Paleogene, possibly even (like Pelagornis) Neogene age for the holotype.

P. tenuirostris was proposed for a Late Paleocene-Early Eocene[7] pseudotooth bird from Herne Bay, Kent (England), and P. tshulensis[verification needed] is an approximately contemporary species from Zhylga (Kazakhstan) that is sometimes placed in Odontopteryx.

The Motunau Beach skull resembles the roughly contemporary Osteodontornis of the North Pacific in having a jugal arch that is short and very stout behind the orbital process of the prefrontal bone – apparently unlike in P. longirostris.