Research on this taxon is however difficult as the current whereabouts of the fossil material are unknown, limiting data to the description and illustrations of Milne-Edwards.

The name Elornis was first coined by Auguste Aymard in a report on the paleontology of the French Haute Loire region, which was presented on two occasions to the Congres Seientifique de France in 1855.

The nomenclature of Elornis was eventually covered in greater detail by Storrs Olson, who wrote that due to Aymard's names being nomina nuda, the status of his taxa was entirely dependent on Milne-Edwards description.

Elornis antiquus was intended to be based on a humerus by Aymard, however this idea was immediately discarded by Milne-Edwards who considered it to be synonymous with E. littoralis.

The material of Elornis grandis received less attention, the humerus Aymard intended as the holotype only mentioned to be "as big as that of a flamingo" by Milne-Edwards and not illustrated at all.

Milne-Edwards later agreed with the assignment and Olson, although incapable of studying the fossil material itself, concurred with the identification on the basis of the illustrations.