A new Crossognathus (Actinopterygii, Teleostei) from the Lower Cretaceous of Romania with comments on Crossognathidae relationships

Crossognathus danubiensis n. sp., known by a single specimen from the middle Albian of the vicinity of Giurgiu, south Romania, is described. The new species differs from other Crossognathus by the very elongated posterior infraorbitals covering the vertical limb of the preopercle and part of the opercle and by the bones of the opercular series with fine posterior radiating ridges. Some of its characters, such as the presence of numerous well developed branchiostegal rays, are unusual for crossognathids and are discussed. We discuss the phylogenetic relationships of crossognathids and we point out several characters indicating possible relationships with the Late Jurassic Varasichthyidae. This possible sister-group relationship is regarded as a working hypothesis for further studies on basal teleosts phylogeny.