Baleiichthys Explained

Baleiichthys is a genus of extinct freshwater ray-finned fish, belonging to the teleosts. It lived in the Middle Jurassic, and its fossil remains have been found in northern Asia.^[1] Almost nothing is known about it.^{[2] [3]}

Description

Baleiichthys was small in size and had an elongated and slender body, up to 7 centimeters long. The head was low, with small eyes and rather large jaws. The dorsal fin was placed approximately halfway down the body, obliquely opposite the small anal fin, which was triangular in shape. The pectoral fins were small and fan-shaped. The caudal fin was slightly forked. The body was covered in rather thick scales, arranged in diagonal rows, with a serrated rear edge. There were numerous fringed fulcrums along the margins of the unpaired fins.

Classification

Baleiichthys was described by Rohon in 1890, based on fossil remains found in formations dating back to the early-middle Jurassic in the Baleysky District in Siberia; the type species is Baleiichthys graciosa, but the slightly larger species B. lata also comes from the same sediments. Another species, B. antingensis, is known from the Middle Jurassic Anting Formation in Shaanxi Province, China.^[4]

Baleiichthys was previously thought to be a member of the pholidophoriforms, a large group of fishes at the base of the teleosts that are known to have ganoid scales. Subsequent research has found substantial differences between Baleiichthys and the Pholidophorus genus and related forms; currently Baleiichthys is considered an archaic representative of teleosts, outside the group of pholidophoriforms proper. Sepkoski (2002) incorrectly referred to it as a pachycormiform.^[5]

References

• Rohon, J.V., 1890. Die Jura-Fische von Ust-Balei in Ost-Sibirien. Mémoires de l'Académie impériale des Sciences de St.-Pétersbourg, 7ème série, 38 (1): 1-15.
• Liu, H.-T., 1955. A new Baleichthys from Shensi. Aeta Paiaeontologica Sinica, 3 (4): 317-321
• Taverne, Louis. "Ostéologie et relations phylogénétiques de Steurbautichthys (‘Pholidophophorus’) aequatorialis gen. nov.(Teleostei,‘Pholidophoriformes’) du Jurassique moyen de Kisangani, en République Démocratique du Congo." Bulletin de l’Institut Royal des Sciences Naturelles de Belgique: Sciences de la Terre 81 (2011): 129-173.

Notes and References

1. Web site: PBDB . 2024-03-05 . paleobiodb.org.
2. Taverne . Louis . 2011 . Ostéologie et relations phylogénétiques de Steurbautichthys ("Pholidophophorus") aequatorialis gen. nov. (Teleostei, "Pholidophoriformes") du Jurassique moyen de Kisangani, en République Démocratique du Congo. . Bulletin de l'Institut Royal des Sciences Naturelles de Belgique - Bulletin van het Koninklijk Belgisch Instituut voor Natuurwetenschappen . 81 . 129–173.
3. Book: Chang, Meemann . Mesozoic Fishes 3 - Systematics, Paleoenvironments and Biodiversity . Miao . Desui . Verlag Dr. Friedrich Pfeil . 2004 . 3-89937-053-8 . Miinchen, Germany . 535-563 . An overview of Mesozoic fishes in Asia.
4. Zhang . Jiangyong . 2007-04-01 . Two shark finspines (Hybodontoidea) from the Mesozoic of North China . Cretaceous Research . Current Research on Cretaceous lake systems in northeast China . 28 . 2 . 277–280 . 10.1016/j.cretres.2006.05.005 . 0195-6671.
5. Sepkoski . Jack . A compendium of fossil marine animal genera . Bulletins of American Paleontology . 364 . 560 . 2002 . 2009-02-27 . dead . https://web.archive.org/web/20110723131237/http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class . 2011-07-23 .