Lebachacanthus Explained

Lebachacanthus is a genus of extinct xenacanth cartilaginous fish known from the late Carboniferous-Early Permian of Europe.^[1] Well-preserved specimens, originally identified as Orthacanthus, are known from Meisenheim Formation in Germany.^[2] During the late Paleozoic, xenacanths were the apex predators of freshwater ecosystems, preying on small amphibians.^[3]

Description

Like most other xenacanthids, this genus possessed an array of spines arising from the dorsal fins. It exceeded 3m (10feet) and even could reach 3.5m (11.5feet).^[4] The genus is often confused with the similar genus Orthacanthus; the two genera belong to entirely separate families.^[5] The teeth of this fish were multi-cusped, with the central cusp flanked by two sharp accessory "tines" on which its prey would be impaled and trapped, in preparation for being swallowed whole.^[6] It had an abundance of pectoral fins, two next to the head, two in the middle, one near the end, and one under the caudal fin.

Paleobiology

Lebachacanthus patrolled both fresh and marine waters, possibly preying on larvae of the temnospondyli and acanthodians. The genus displays sexually dimorphic features; females had longer fin spines than males. Histological and biometric analyses of the spines of specimens provides information on the development and age at death of the fish and the environmental conditions in which they lived.^[7]

Further reading

• Long . John A. . Young . Gavin C. . Sharks from the Middle-Late Devonian Aztec Siltstone, southern Victoria Land, Antarctica . Records of the Western Australian Museum . May 1995 . 17 . 287–308 . 10 March 2022.

Notes and References

1. Ivanov. Alexander. 30 August 2005. Early Permian chondrichthyans of the Middle and South Urals. Revista Brasileira de Paleontologia. 8. 2. 127–138. 10.4072/rbp.2005.2.05. 1519-7530. free.
2. Luccisano . Vincent . Pradel . Alan . Amiot . Romain . Pouillon . Jean‐Marc . Kindlimann . René . Steyer . Jean‐Sébastien . Cuny . Gilles . 2022 . Cavin . Lionel . Systematics, ontogeny and palaeobiogeography of the genus Orthacanthus (Diplodoselachidae, Xenacanthiformes) from the lower Permian of France . Papers in Palaeontology . en . 8 . 6 . 10.1002/spp2.1470 . 2056-2799.
3. First direct evidence of a vertebrate three-level trophic chain in the fossil record. 2007. 2596183. Kriwet. J.. Witzmann. F.. Klug. S.. Heidtke. U. H.. Proceedings. Biological Sciences. 275. 1631. 181–186. 10.1098/rspb.2007.1170. 17971323.
4. Soler-Gijón . R. . 2004 . Development and growth in xenacanth sharks: new data from Upper Carboniferous of Bohemia. . G. Arratia, M.V.H. Wilson, and R. Cloutier (eds.), Recent Advances in the Origin and Early Radiation of Vertebrates . 533–562 .
5. Soler-Gijón . Rodrigo . Phylogenetic relationships of Lebachacanthidae [Soler-Gijón 1997] (Xenacanthiformes; Elasmobranchii) . PalZ . December 2000 . 74 . 3 . 363–377 . 10.1007/BF02988107.
6. Jaws and Teeth of American Xenacanth Sharks. Journal of Paleontology. 1299956. Hotton. Nicholas. 1952. 26. 3. 489–500.
7. Morphology and histology of dorsal spines of the xenacanthid shark Orthacanthus platypternus from the Lower Permian of Texas, USA: Palaeobiological and palaeoenvironmental implications. Acta Palaeontologica Polonica. 2014. 10.4202/app.00126.2014. Beck. Kimberly. Soler-Gijon. Rodrigo. Carlucci. Jesse. Willis. Raymond. 53979047.