Six
species have been recognized in modern times; undescribed ones are also likely to exist. The supposed
tarsometatarsus piece from which
"Lithornis" emuinus was described is actually a
humerus fragment of the giant
pseudotooth bird Dasornis.
Lithornis celetius L. celetius is from the Bangtail Quarry, Sedan Quadrangle,
Park County, Montana, and was described by Peter Houde (1988). It is from the
Fort Union Formation, which is earliest
Tiffanian, Late
Paleocene. The type fossil is USNM 290601.
L. hookeri is the smallest of the Lithornithidae. Mayr and Kitchner (2025) disagreed with the proposed synonymy based on their notable size difference. from the holotype fossil 955 738 - TM 024 717. The fossilized bones include an almost complete sternum and parts of the coracoid, a dorsal vertebra, a left femur and tibia and rib fragments. They were collected from
Early Eocene London Clay deposits on the Isle of Sheppey, Kent, England and held in the collections of
John Hunter and a Mr Bowerbank. The collection date of the fossils are uncertain, but as Hunter died in 1793, it can be presumed that it is before this data. This fossil was destroyed by bombing in
World War II. Numerous isolated fossil bones of
Lithornis vulturinus were incorrectly described anew, such as
Parvigyps praecox and
Promusophaga magnifica - the supposed earliest vulture and turaco, while others were referred to existing families of neognathous birds. A
neotype (BMNH A 5204) was erected to replace the holotype in 1988 by Houde, who for the first time diagnosed it as a paleognath based on complete three-dimensional skulls and skeletons of congeners from North America. An exceptionally preserved specimen was collected from Denmark and cataloged as MGUH 26770. ==Palaeobiology==