Ctenurella
Ctenurella (from , 'comb' and , 'tail') is an extinct genus of ptyctodont placoderm from the Late Devonian of Germany. The first fossils were found in the Strunde valley in the Paffrather Kalkmulde. Description. As with other ptyctodonts, the armor of "Ctenurella" was reduced to a few thin plates on the head and shoulder region. It was also relatively small for a placoderm, at just in length. "Ctenurella" had two dorsal fins and the rear of the body was relatively long and low. Most ptyctodonts are presumed to have fed on the ocean floor, but the well-developed fins of this  genus indicate that it probably also swam in open waters. "Ctenurella" had a long, whip-like tail, large eyes, and robust upper and lower jaw tooth plates. Males also had hook-shaped sex organs, known as claspers. Since analogous features are also found in the unrelated living chimaeras, chimaeras and ptyctodonts are thought to be an example of convergent evolution. Etymology. The specific name of the type species, "C. gladbachensis", is a reference of the place Bergisch Gladbach, where it was founded. Taxonomy and evolution. The species "Ctenurella gardineri" was split off into the new genus "Austroptyctodus" by Long (1997 ) in his review of the Gogo ptyctodontid species, stipulating that the genus "Ctenurella" as only coming from the German sites. A new description of "Ctenurella gladbachensis" by Long (1997) showed that the original restoration had wrongly restored the skull-roof as the central bones do not in fact meet each other behind the nuchal plate. Ptyctodontid placoderms recently have been shown to give birth to live young, with specimens of pregnant females from two genera, "Materpiscis" and "Austroptyctodus", both from the Gogo Formation of Western Australia, showing the presence of unborn embryos within the mother fishes (Long et al. 2008