Coelacanth

This article is about the order of fish. For the living species of coelacanths, see Latimeria.

Coelacanth
Temporal range: Early Devonian – Recent,[1] 409–0 Ma
Live coelacanth seen off Pumula on the KwaZulu-Natal South Coast, South Africa, 2019
Specimen of Axelrodichthys araripensis from the Early Cretaceous of Brazil (Mawsoniidae)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Sarcopterygii
Class: Actinistia
Cope, 1871
Order: Coelacanthiformes
Huxley, 1861
Type species
†Coelacanthus granulatus
Agassiz, 1839
Families and genera

Others, see text

Coelacanths (/ˈsiːləkænθ/ ⓘ SEE-lə-kanth) (order Coelacanthiformes) are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia.[2][3] As sarcopterygians, they are more closely related to lungfish and tetrapods (which includes amphibians, reptiles, birds and mammals) than to ray-finned fish.

Well-represented in both freshwater and marine fossils since the Devonian, they are now represented by only two extant marine species in the genus Latimeria: the West Indian Ocean coelacanth (Latimeria chalumnae), primarily found near the Comoro Islands off the east coast of Africa, and the Indonesian coelacanth (Latimeria menadoensis).[4] The name coelacanth originates from the Permian genus Coelacanthus, which was the first scientifically named coelacanth.[5]

The oldest known coelacanth fossils date back more than 410 million years. Coelacanths were thought to have become extinct in the Late Cretaceous, around 66 million years ago, but were discovered living off the coast of South Africa in 1938.[6][7]

The coelacanth was long considered a "living fossil" because scientists thought it was the sole remaining member of a taxon otherwise known only from fossils, with no close relations alive,[8] and that it evolved into roughly its current form approximately 400 million years ago.[1] However, several more recent studies have shown that coelacanth body shapes are much more diverse than previously thought.[9][10][11]

  1. ^ a b Johanson, Z.; Long, J. A; Talent, J. A; Janvier, P.; Warren, J. W (2006). "Oldest coelacanth, from the Early Devonian of Australia". Biology Letters. 2 (3): 443–6. doi:10.1098/rsbl.2006.0470. PMC 1686207. PMID 17148426.
  2. ^ Nelson, Joseph S. (16 March 2016). Fishes of the World. John Wiley & Sons. ISBN 978-1-119-22081-7. OCLC 951128215.
  3. ^ "Order Summary for Coelacanthiformes". www.fishbase.se. Retrieved 13 March 2023.
  4. ^ Yokoyama, Shozo; Zhang, Huan; Radlwimmer, F. Bernhard; Blow, Nathan S. (1999). "Coelacanths, Coelacanth Pictures, Coelacanth Facts – National Geographic". Proceedings of the National Academy of Sciences. 96 (11): 6279–84. Bibcode:1999PNAS...96.6279Y. doi:10.1073/pnas.96.11.6279. PMC 26872. PMID 10339578.
  5. ^ Agassiz, L. 1839. Recherches sur les poissons fossiles II. Petitpierre, Neuchâtel.
  6. ^ Smith, J. L. B. (1956). Old Fourlegs: the Story of the Coelacanth. Longmans Green. p. 24.
  7. ^ Lavett Smith, C.; Rand, Charles S.; Schaeffer, Bobb; Atz, James W. (1975). "Latimeria, the Living Coelacanth, is Ovoviviparous". Science. 190 (4219): 1105–6. Bibcode:1975Sci...190.1105L. doi:10.1126/science.190.4219.1105. S2CID 83943031.
  8. ^ Forey, Peter L (1998). History of the Coelacanth Fishes. London: Chapman & Hall. ISBN 978-0-412-78480-4.[page needed]
  9. ^ Friedman, Matt; Coates, Michael I.; Anderson, Philip (2007). "First discovery of a primitive coelacanth fin fills a major gap in the evolution of lobed fins and limbs". Evolution & Development. 9 (4): 329–37. doi:10.1111/j.1525-142X.2007.00169.x. PMID 17651357. S2CID 23069133.
  10. ^ Friedman, Matt; Coates, Michael I. (2006). "A newly recognized fossil coelacanth highlights the early morphological diversification of the clade". Proceedings of the Royal Society B: Biological Sciences. 273 (1583): 245–50. doi:10.1098/rspb.2005.3316. JSTOR 25223279. PMC 1560029. PMID 16555794.
  11. ^ Wendruff, Andrew J.; Wilson, Mark V. H. (2012). "A fork-tailed coelacanth, Rebellatrix divaricerca, gen. Et sp. Nov. (Actinistia, Rebellatricidae, fam. Nov.), from the Lower Triassic of Western Canada". Journal of Vertebrate Paleontology. 32 (3): 499–511. Bibcode:2012JVPal..32..499W. doi:10.1080/02724634.2012.657317. S2CID 85826893.