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Xenacanthus

( Xenacanths )

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Fish Reached Species Xenacanthus

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Xenacanthus (from Ancient Greek , xénos, 'foreign, alien' + , akanthos, 'spine') is an extinct genus of Xenacanthida cartilaginous fish. It lived in freshwater environments, and fossils of various species have been found worldwide.

Description

Xenacanthus is a relatively small member of its order.Beck, Kimberley G.; oler-Gijón, Rodrigo; Carlucci, Jesse R.; Willis, Ray E. (December 2014). "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. 61 (1): 97–117. X. decheni reached about , X. meisenheimensis reached up to , X. ( Expleuracanthus) gaudryi reached . X. parallelus is one of the smallest xenacanths, males reached and females reached , both are fully grown.

The dorsal fin was ribbonlike and ran the entire length of the back and round the tail, where it joined with the anal fin. This arrangement resembles that of modern , and Xenacanthus probably swam in a similar manner. A distinctive spine projected from the back of the head and gave the genus its name. The spike has even been speculated to have been venomous, perhaps in a similar manner to a sting ray. The teeth had an unusual "V" shape, and it probably fed on small and heavily scaled palaeoniscid fishes.

(1999). 9781840281521, Marshall Editions. ISBN 9781840281521

As with many xencanths, Xenacanthus is mainly known because of fossilised teeth and spines.

Fossils are known from the Carboniferous-Permian of North America, Europe, and South America. Triassic species have been moved into the separate genus Mooreodontus.