Ichthyodectidae

Abstract: The author describes briefly the osteology of the three valid species of the Late Cretaceous genus Chirocentrites. He shows that only the type species, C. coroninii, belongs to this genus. He creates the new genus Heckelichthys for the two other species, C. microdon and C. vexillifer, with the latter as type species. The phylogeny of the Ichthyodectidae is studied. The systematic position of Chlrocentrites and Heckelichthys is specified.

Abstract: The osteology and the phylogenetic relationships of three ichthyodectids from the Aptian bituminous shales of Equatorial Guinea and Gabon are studied. The first species was already known as Chirocentrites guinensis. It is a valid species but its skeleton shows that it does not belong to Chirocentrites but to Chiromystus, a genus characterized by its enlarged and branched pectoral rays and a short vertebral axis. The differences between Chiromystus and Cladocyclus are brought to light to demonstrate the validity of Chiromystus. The second species is only known by some cranial fragments, particularly the jaws. It is a new genus and species, Africathrissops weileri, which seems primitive and close to Thrissops. Its articulation facet for the quadrate is formed by the retroarticular and the articular without a participation of the angular. The third species Verraesichthys bloti is new and represents a new genus too, also characterised by a short axial skeleton, but its skull and its pectoral girdle strongly differ from those of Chiromystus. The caudal skeleton of an unnamed but specialised ichthyodectid is also described.

Abstract: Actinopterygian remains have been recovered from Upper Cretaceous (uppermost lower to lowermost upper Campanian) marine strata of the Kristianstad Basin, southern Sweden. This is the first record of Upper Cretaceous bony fish from the Fennoscandian shield. The fauna consists of higher taxa including Pachycormiformes (Pachycormidae), Elopiformes (Pachyrhizodontidae), Pycnodontiformes (Pycnodontidae), Aulopiformes (Enchodontidae), Ichthyodectiformes (Ichthyodectidae), and indeterminable teleost fish. The ichthyofauna comprises a relative vast number of disarticulated meso-to macroscopic bony elements (e.g. vertebrae, isolated teeth, cycloid scales, coprolites, otolithes and fin spines). All major groups are so far only recognized by a few numbers of isolated dental remains suggesting major taphonomic losses prior to preservation. The total amount of recovered bony fish elements indicates the presence of a diverse teleostean/actinopterygian fauna, although taxonomic assessments of the material are severely hampered by the low preservational degree. In addition, previous works on the vertebrate assemblage of the Kristianstad Basin have resulted in major collection biases towards larger marine vertebrates which has led to an under-representation of the actinopterygian fauna. The ichthyofauna of the Kristianstad Basin bears compositional resemblance towards those in the North American Western Interior Seaway suggesting palaeobiogeographical communication.