Although Lithornis was able to fly well, their closest relatives are the extant tinamous (which are poor flyers) and ratites (which are flightless birds).

The supposed tarsometatarsus piece from which "Lithornis" emuinus was described is actually a humerus fragment of the giant pseudotooth bird Dasornis.

[3] W. George collected the original fossil in the Division A London Clay, North Sea Basin at Walton on the Naze, Essex, England.

[3] In 2015, L. nasi was proposed to be a junior synonym of L. vulturinus because its differences in shape and size from the latter species were concluded to more likely represent intraspecific variation.

The fossil was collected from Early Eocene London Clay deposits on the Isle of Sheppey, Kent, England by J.

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.

[6] Lithornis' wing bones are similar to those of storks and vultures, meaning that unlike modern tinamous it was capable of soaring flight.