Gyrosteus

Gyrosteus
Temporal range: Lower Toarcian 181 Ma
↓
 Possible Bathonian record
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: †Chondrosteiformes
Family: †Chondrosteidae
Genus: †Gyrosteus
Agassiz, 1843
Type species
†Gyrosteus mirabilis
[2] Agassiz 1844
Species
  • †"Gyrosteus" subdeltoideus[1]

Gyrosteus is an extinct genus of very large ray-finned fish belonging to the family Chondrosteidae.[3] It comprises the type species, Gyrosteus mirabilis, which lived during the early Toarcian (Late Early Jurassic) in what is now northern Europe. A possible second species, "Gyrosteus" subdeltoideus, is known from otoliths.

Fossil remains of G. mirabilis have been recovered from the Whitby Mudstone Formation, United Kingdom, and from Ahrensburg erratics assemblage in Schleswig-Holstein, northern Germany.[4] It was mentioned but not formally described in subsequent publications and was left as a nomen nudum for more than 25 years.[5] Then in 1889 it was featured and formally described by Arthur Smith Woodward.[6] Gyrosteus was thought to be exclusive of the “British faunal province” and separated from the “Germanic faunal province” until the discovery of a hyomandibula in the baltic realm, mostly populated by Germanic fauna, which possibly implicates that Baltic region represented an interdigitating zone between both regions.[4]

The members of the genus Gyrosteus were massive fishes, with a maximum calculated standard length of 6 metres (20 ft) to 7 metres (23 ft), and with a reported hyomandibula reaching 50 centimetres (20 in).[7]

  1. ^ Stinton, F.C.; Torrens, H.S. (1968). "Fish otoliths from the Bathonian of southern England. Palaeontology". 11 (2): 246–258. Retrieved 21 November 2021.
  2. ^ Agassiz L. 1834. Recherches sur les Poissons Fossiles: Tome I. Neuchatel: Imprimerie de Petitpierre. 188
  3. ^ Bemis, William E.; Findeis, Eric K.; Grande, Lance (1997). "An overview of Acipenseriformes". Environmental Biology of Fishes. 48 (1–4): 25–71. doi:10.1023/A:1007370213924. S2CID 24961905.
  4. ^ a b Hornung, J. J.; Sachs, S. (2020). "First record of Gyrosteus mirabilis (Actinopterygii, Chondrosteidae) from the Toarcian (Lower Jurassic) of the Baltic region". PeerJ. 1 (1): 1–10. Retrieved 16 July 2021.
  5. ^ Egerton, P. G.; Cole, E. W. W. (1837). "A Systematic and Stratigraphical Catalogue of the Fossil Fish in the Cabinets of Lord Cole and Sir Philip Grey Egerton: Together with an Alphabetical and Stratigraphical Catalogue of the Same Species, with References to Their Published Figures and Descriptions". Richard and John e. Taylor. 1 (1): 45–89.
  6. ^ Woodward, A. S. (1889). "On the paleontology of sturgeons". Proceedings of the Geologists' Association. 11 (1): 24–32. doi:10.1016/S0016-7878(89)80044-6.
  7. ^ Woodward, A.S. (1890). "The fossil sturgeon of the Whitby Lias". Naturalist. 15 (177): 101–107.