albertonykus
Well-known member
Mayr, G. and A.C. Kitchener (2024)
Two distinctive, but difficult-to-classify, avian species and a new trogon (Trogoniformes) from the early Eocene London Clay
Neues Jahrbuch für Geologie und Paläontologie (advance online publication)
doi: 10.1127/njgpa/2024/1216
We describe three new bird species from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). Sulcitarsus aenigmatus, gen. et sp. nov., is known from hindlimb elements; even though we note resemblances to the Leptosomiformes and Accipitriformes, the species defies a well-founded phylogenetic placement. Another species, Xenavicula pamelae, gen. et sp. nov., is represented by two partial skeletons and is characterised by an autapomorphic morphology of the pectoral girdle, which suggests locomotory specialisations not found in extant birds. The scapula of X. pamelae differs from that of all extant birds in the very long and pointed acromion and in that the articular facet for the humerus is strap-like and forms a ventrally facing concavity. Further distinctive derived features concern the morphologies of the coracoid and tarsometatarsus. The new species resembles phylogenetically disparate taxa of the Telluraves (“higher land birds”), but an unambiguous phylogenetic placement is not possible and it is assigned to a monotypic higher-level taxon, Xenaviculidae, fam. nov. A new trogoniform species, ?Masillatrogon incertus, sp. nov., is based on hindlimb bones, which exhibit an intact hypotarsus and reveal this structure to be different from the hypotarsus of extant Trogoniformes.
Two distinctive, but difficult-to-classify, avian species and a new trogon (Trogoniformes) from the early Eocene London Clay
Neues Jahrbuch für Geologie und Paläontologie (advance online publication)
doi: 10.1127/njgpa/2024/1216
We describe three new bird species from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). Sulcitarsus aenigmatus, gen. et sp. nov., is known from hindlimb elements; even though we note resemblances to the Leptosomiformes and Accipitriformes, the species defies a well-founded phylogenetic placement. Another species, Xenavicula pamelae, gen. et sp. nov., is represented by two partial skeletons and is characterised by an autapomorphic morphology of the pectoral girdle, which suggests locomotory specialisations not found in extant birds. The scapula of X. pamelae differs from that of all extant birds in the very long and pointed acromion and in that the articular facet for the humerus is strap-like and forms a ventrally facing concavity. Further distinctive derived features concern the morphologies of the coracoid and tarsometatarsus. The new species resembles phylogenetically disparate taxa of the Telluraves (“higher land birds”), but an unambiguous phylogenetic placement is not possible and it is assigned to a monotypic higher-level taxon, Xenaviculidae, fam. nov. A new trogoniform species, ?Masillatrogon incertus, sp. nov., is based on hindlimb bones, which exhibit an intact hypotarsus and reveal this structure to be different from the hypotarsus of extant Trogoniformes.
