Macromesodon Blake, 1905 and Apomesodon Poyato-Ariza & Wenz, 2002 (Actinopterygii, Pycnodontiformes) from the Jurassic and lowermost Cretaceous of England, France, and Germany

The pycnodontiform genera Macromesodon and Apomesodon from the Upper Jurassic and lowermost Cretaceous of Central and Western Europe are described in detail and their union into one genus is rejected. Nomenclature problems are explained and the differences between these two genera are described, supplemented by new specimens and spectacular UV photos that show new characters like sclerites and spines of the skin along with known characteristics in much better detail than what has been previously published. Apomesodon differs from Macromesodon mainly in the dentition, the more prominent dorsal apex, the scale pattern, the shape and ornamentation of the body scales and the articulation of neural arches and spines. Further taxa are assigned to these two genera for the first time, and a comparison of these genera with closely related taxa is made. Additionally, a new phylogeny of the Pycnodontomorpha is presented, in which the families of the basal Pycnodontiformes, Macromesodontidae and Brembodontidae, are redefined.