Palaeocentroscymnus
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| Palaeocentroscymnus Temporal range: | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Division: | Selachii |
| Order: | Squaliformes |
| Family: | Somniosidae |
| Genus: | †Palaeocentroscymnus Pollerspöck et al., 2018 |
| Species | |
| |
Palaeocentroscymnus is an extinct genus of small sleeper shark from the late Cretaceous to the Neogene of Eurasia. The fish is only known from teeth though based on the regions where the genus has been found, it has been suggested that it wound have lived in deeper water. Along with this, comparisons in the presence of the animal suggest that it was most common in low oxygen environments. Two species are currently recognized: P. horvathi and P. bavaricus.
Classification
The type species of Palaeocentroscymnus, P. horvathi, would first be named by Pollerspöck et al. in 2018 based on widespread material with the holotype being found about 10 kilometres (6.2 mi) from Wels during excavations done in 2013 and 2015. Other specimens of the species would be noted from multiple other sites including one the Gunma Prefecture of Japan along with the Cerová-Lieskové locality in the Slovak Republic.[1] A second species, P. bavaricus, would later be named in 2025 by Feichtinger et al. based on specimens collected from an exposure located southeast of village Bergen. This species would expand the temporal range of the genus, with the most recent range suggesting a range from the Late Cretaceous to the earliest Neogene.[2]
The name Palaeocentroscymnus derives from the Ancient Greek prefix "palaeo", which means old or ancient along with Centroscymnus, an extant genus of shark that the animal is most likely related to.[1] The species name of the type species horvathi honors Juraj and Tereza Horvath along with their children.[3] The species name of the second species references the district of Bavaria, the area in which the specimens where found.[2]
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Before the 2018 paper describing the genus, the material that would be assigned to the genus Palaeocentroscymnus was originally assigned to a number of other genera with the first assignment being to Centroscymnus sp. by Barthelt et al. in 1991. This genus assignment would continue until 2013 where the lower teeth of the genus would be named as Paraetmopterus horvathi by Underwood and Schlögl. A single tooth would be assigned to the genus Etmopterus within the same paper. The current genus is placed within the family Somniosidae based on a number of features of the teeth of the lower jaw with a phylogenic analysis suggesting a placement of the genus close to multiple genera the material was originally assigned to. Within this analysis, Palaeocentroscymnus was suggested to be the sister taxon of a group containing Scymnodalatias cigalafulgosii and Centroscymnus cf. owstonii.[1] Another analysis containing the genus would be done by Flammensbeck et al. in the same year would also place the genus as a member of Somniosidae along with suggesting a close relationship to Centroscymnus and Scymnodalatias.[4]
Below is a section of the cladogram in Flammensbeck et al. (2018) focusing on the family Somniosidae.[4]
