Contribution
The Vastanavidae and Messelasturidae (Aves) from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK)
Mayr, Gerald; Kitchener, Andrew C.
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 307 Heft 2 (2023), p. 113 - 139
36 références bibliographiques
publié: Feb 28, 2023
manuscrit accepté: Feb 21, 2023
manuscrit reçu: Feb 3, 2023
ArtNo. ESP155030702005, Prix: 29.00 €
Abstract
We describe multiple specimens of the avian taxa Vastanavidae and Messelasturidae from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). The material includes a new species of the vastanavid taxon Avolatavis, the only previously named species of which is from the early Eocene of North America. The messelasturid fossils represent ten individuals, which belong to at least three species of the taxon Tynskya; two species are newly described in the present study. As partial skeletons with three-dimensionally preserved bones, the fossils provide new data on the skeletal anatomy of messelasturids. Still, the relationships of vastanavids and messelasturids are not well resolved. Our primary analysis showed both taxa to be early diverging stem group representatives of Pan-Psittaciformes, but concerning the extant taxa this analysis did not recover clades that are well-supported by molecular sequence data. An analysis employing a molecular backbone constraint identified vastanavids and messelasturids as stem group representatives of the Psittacopasseres, the clade including the Psittaciformes and Passeriformes. This phylogenetic placement is only weakly supported and there exists some character evidence for alternative phylogenies. The skeletal morphology of messelasturids indicates that these birds were raptorial, which documents a high diversity of feeding adaptations in stem group Psittacopasseres. Because all representatives of the Cariamiformes and Falconiformes are raptorial birds, a carnivorous ecology may be plesiomorphic for the Psittacopasseres. However, there appears to have been much morphological homoplasy in the evolution of the Psittacopasseres and some shared derived features of messelasturids and falconiforms are likely to have evolved convergently.
Mots-clefs
Aves • evolution • fossil birds • phylogeny • Psittacopasseres • taxonomy