Article: The coelacanth Rhabdoderma in the Carboniferous of the British Isles

Several points in the anatomy of Rhabdoderma are reinterpreted based on three-dimensional specimens from the Upper Carboniferous of Great Britain. It is shown that Rhabdoderma does not possess a basipterygoid process, and that the otico-occipital division of the braincase is completely ossified, with no trace of separate ossification centres. Rhabdoderma is distinguished from other coelacanths by the shape of the first dorsal fin support and the pattern of ornament on the scales. Emended diagnoses are given of the five British species considered as valid. R.(?) abdenense (Traquair) and R.(?) davisi Moy-Thomas are considered as belonging to Diplocercides. Species from the Carboniferous of North America and the Triassic of Madagascar are reviewed. The phylogenetic position of Rhabdoderma is discussed. The stratigraphical distribution of species of Rhabdoderma occurring in the British Isles is given. It is suggested that Rhabdoderma was euryhaline.