Orthacanthus

Orthacanthus
Temporal range: Upper Carboniferous - Lower Permian[1]
Fossil interpretation of juvenile specimen of O. platypternus (top) and skeletal reconstruction of juvenile specimen of O. bohemicus (bottom)
Front view of skull, American Museum of Natural History
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Order: †Xenacanthida
Family: †Orthacanthidae
Heyler and Poplin, 1989
Genus: †Orthacanthus
Agassiz, 1843
Species
  • Orthacanthus cylindricus (Agassiz, 1843)
  • Orthacanthus adamas Babcock, 2024
  • Orthacanthus arcuatus (Newberry, 1857) [2]
  • Orthacanthus buxieri (Heyler and Poplin, 1989)
  • Orthacanthus compressus (Newberry, 1857)
  • Orthacanthus donnelljohnsi (Johnson and Thayer, 2009)
  • Orthacanthus gibbosus (Agassiz, 1843)
  • Orthacanthus gracilis (Giebel, 1848)
  • Orthacanthus lintonensis Babcock, 2024
  • Orthacanthus milleri (Agassiz, 1843)
  • Orthacanthus minor (Agassiz, 1843)
  • Orthacanthus platypternus (Cope, 1884)
  • Orthacanthus pustulosus (Agassiz, 1843)
  • Orthacanthus texensis (Cope, 1888)

Orthacanthus is an extinct genus of fresh-water xenacanthiform cartilaginous fish, named by Louis Agassiz in 1843,[3][4] ranging from the Upper Carboniferous[3] into the Lower Permian.[1] Orthacanthus had a nektobenthic life habitat, with a carnivorous diet.[5] Multiple authors have also discovered evidence of cannibalism in the diet of Orthacanthus and of "filial cannibalism" where adult Orthacanthus preyed upon juvenile Orthacanthus.[6] Synonyms of the genus Orthacanthus are Dittodus Owen, 1867, Didymodus Cope, 1883, Diplodus Agassiz, 1843,[5] Chilodus Giebel, 1848 (preoccupied by Chilodus Müller & Troschel, 1844).[3]

During the Late Carboniferous-Early Permian, Orthacanthus was an apex predator of freshwater swamps and bayous in Europe and North America.[6] Mature Orthacanthus reached nearly 3 meters (10 feet) in length.[6] Orthacanthus teeth have a minimum of three cusps, two principal cusps, and an intermediate cusp, where the principal cusps are variously serrated, with complex base morphology.[7][4] Additionally, Orthacanthus can be diagnosed by major transverse axes of proximal ends at a 45-degree angle to and often almost parallel to the labial margin of the base between the cusps.[4] Deformed teeth are characteristic of the xenacanthiform sharks and of Orthacanthus.[8]

  1. ^ a b Hampe, O. "On the Dentition of Orthacanthus (Chondrichthyes, Xencanthida) Upper Carboniferous-Lower Permian." Palaont Z 62.3-4 (1988).
  2. ^ Baird, Donald; Hook, Robert W. (1986). "The Diamond Coal Mine of Linton, Ohio, and Its Pennsylvanian-Age Vertebrates". Journal of Vertebrate Paleontology. 6 (2): 174–190. Bibcode:1986JVPal...6..174H. doi:10.1080/02724634.1986.10011609. JSTOR 4523086.
  3. ^ a b c Babcock, L. E. (2024). ""Replacement names for two species of Orthacanthus Agassiz, 1843 (Chondrichthyes, Xenacanthiformes), and discussion of Giebelodus Whitley, 1940, replacement name for Chilodus Giebel, 1848 (Chondrichthyes, Xenacanthiformes), preoccupied by Chilodus Müller & Troschel, 1844 (Actinopterygii, Characiformes)."". ZooKeys (1188): 219–226. doi:10.3897/zookeys.1188.108571. PMC 10790574. PMID 38230382.
  4. ^ a b c Johnson, Gary D.; Thayer, David W. (2009). "Early Pennsylvanian Xenacanth Chondrichthyans from the Swisshelm Mountains, Arizona, USA". Acta Palaeontologica Polonica. 54 (4): 649–668. doi:10.4202/app.2008.0051. ISSN 0567-7920. S2CID 54093505.
  5. ^ a b "PBDB". paleobiodb.org. Retrieved 2020-03-04.
  6. ^ a b c Gogáin, Aodhán Ó; Falcon-Lang, Howard J.; Carpenter, David K.; Miller, Randall F.; Benton, Michael J.; Pufahl, Peir K.; Ruta, Marcello; Davies, Thomas G.; Hinds, Steven J.; Stimson, Matthew R. (11 August 2016). "Data from: Fish and tetrapod communities across a marine to brackish salinity gradient in the Pennsylvanian (early Moscovian) Minto Formation of New Brunswick, Canada, and their palaeoecological and palaeogeographical implications" (PDF). Palaeontology. doi:10.1111/pala.12249. ISSN 1475-4983. S2CID 132845922.
  7. ^ Johnson, Gary D. (2012). "Possible origin of the xenacanth sharksOrthacanthus texensisandOrthacanthus platypternusin the Lower Permian of Texas, USA". Historical Biology. 24 (4): 369–379. Bibcode:2012HBio...24..369J. doi:10.1080/08912963.2012.669128. ISSN 0891-2963. S2CID 128880622.
  8. ^ Johnson, G. D. (2018). "Orthacanthus platypternus (Cope, 1883) (Chondrichthyes: Xenacanthiformes) teeth and other isolated vertebrate remains from a single horizon in the early Permian (Artinskian) Craddock Bonebed, lower Clear Fork Group, Baylor County, Texas, USA". Acta Geologica Polonica. 68 (3). doi:10.1515/agp-2018-0025 (inactive 1 November 2024). ISSN 0001-5709.{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)