Keasius

Keasius Temporal range: 41.2–11.63  Ma Middle Eocene–Middle Miocene PreꞒ Ꞓ O S D C P T J K Pg N
Restoration, with Austromola
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Division:	Selachii
Order:	Lamniformes
Family:	Cetorhinidae
Genus:	† Keasius Welton, 2013 [1]
Type species
†Keasius taylori Welton, 2013
Other species
†Keasius parvus (Leriche, 1908) [2] †Keasius septemtrionalis Reinecke, von der Hocht, & Dufraing, 2015 [3] †Keasius rhenanus Reinecke, von der Hocht, & Dufraing, 2015
Synonyms
Genus synonymy "Praecetorhinus" von der Hocht, 1978 ( nomen nudum ) [4] Species synonymy K. parvus Cetorhinus parvus Leriche, 1908

Keasius is an extinct genus of basking sharks that lived during the Cenozoic. It contains four valid species, which have been found in North America, Europe, and Antarctica. ^{[1] [3]}

Taxonomy

History

It was previously thought that the basking shark (Cetorhinus maximus) would be the only representative of the genus Cetorhinus , that is, a monotypic genus.^{[ citation needed ]} Therefore, in 1908, the paleontologist Maurice Leriche described Cetorhinus parvus, considering it an extremely close relative of the modern basking shark. In 1978, a group of paleontologists changed this view, suggesting a new genus called "Praecetorhinus". However, the genus was never formally described and is considered a junior synonym of C. parvus. ^[1]

In 2013, the paleontologist Welton described a new genus, the genus Keasius, placing it in the family Cetorhinidae (the same family as the modern basking shark). He described its type species, K. taylori, and included C. parvus as part of the genus (now K. parvus). ^{[1] [3]}

References

1. Welton, B.J. (2013). "A new archaic basking shark (Lamniformes: Cetorhinidae) from the late Eocene of western Oregon, U.S.A., and description of the dentition, gill rakers and vertebrae of the recent basking shark Cetorhinus maximus (Gunnerus)". New Mexico Museum of Natural History and Science Bulletin. 58: 1–48.
2. Leriche, M. (1908). "Sur un appareil fanonculaire de Cetorhinus trouvé à l'état fossile dans le Pliocène d'Anvers". Comptes rendus hebdomadaires des séances de l'Académie des sciences. 146 (16): 875–878.
3. Reinecke, T.; von der Hocht, F.; Dufraing, L. (2015). "Fossil basking shark of the genus Keasius (Lamniforme, Cetorhinidae) from the boreal North Sea Basin and Upper Rhine Graben: evolution of dental characteristics from the Oligocene to late Middle Miocene and description of two new species". Palaeontos. 28: 39–98.
4. von der Hocht, F. (1978). "Bestandsaufnahme der Chondrichthyes-Fauna des unteren Meeressandes (Oligozän, Rupelium) in Mainzer Becken". Mededelingen van de Werkgroep voor Tertiaire en Kwartaire Geologie. 15 (3): 77–83.