The Lithornithiformes (Aves) from the early Eocene London Clay of Walton†on†the†Naze (Essex, UK)

We describe multiple partial skeletons and isolated bones of the palaeognathous Lithornithiformes from the early Eocene London Clay of Walton†on†the†Naze (Essex, UK). The well†preserved specimens are assigned to at least four species of the taxa and Two species of are identified as and cf. . The latter species, which was established for fossils from the North American Green River Formation, was initially assigned to the monotypic taxon , which is here considered synonymous with . Two further new species are tentatively referred to the taxon and are described as ? and ? . In previous analyses, lithornithiforms most often resulted as the sister taxon of either the Tinamiformes or all crown group Palaeognathae. We detail that current morphological evidence conforms best to a position of these birds outside crown group Palaeognathae and discuss previously unrecognized plesiomorphic features of the foot and pelvis, which support this phylogenetic placement.