Xenacanthus

Template:Short description Template:Automatic taxobox Xenacanthus (from Ancient Greek ξένος, xénos, 'foreign, alien' + ἄκανθος, akanthos, 'spine') is an extinct genus of xenacanth 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. 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 conger eels, 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 crustaceans and heavily scaled palaeoniscid fishes. 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.

Species

File:Xenacanthus sp skull Harvard.jpg

A skull of Xenacanthus sp. on display at Harvard, shown in anterior view

• X. texensis
• X. atriossis
• X. compressus
• X. indicus
• X. decheni
• X. denticulatus
• X. erectus
• X. gibbosus
• X. gracilis
• X. howsei
• X. laevissimus
• X. latus
• X. luedernesis
• X. ossiani
• X. ovalis
• X. parallelus
• X. ragonhai - Rio do Rasto Formation, Brazil
• X. robustus
• X. serratus
• X. slaughteri
• X. taylori

External links

• Template:Sister-inline
• Template:Sister-inline