Xenacanthus

Xenacanthus Temporal range: Carboniferous–Permian PreꞒ Ꞓ O S D C P T J K Pg N
Skeletal reconstruction of Xenacanthus decheni
Life restoration of Xenacanthus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Order:	†Xenacanthida
Family:	†Xenacanthidae
Genus:	†Xenacanthus Beyrich, 1848
Type species
Xenacanthus decheni
Species
See text
Synonyms
Pleuracanthus Agassiz 1837

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 relatively small member in its order.^[1] X. decheni reached about 1 m (3.3 ft),^[2] X. meisenheimensis reached up to 1.2 m (3.9 ft),^[3] X. (Expleuracanthus) gaudryi reached 58 cm (1.90 ft).^[4] X. parallelus is one of the smallest xenacanth, male reached 20 cm (0.66 ft) and female reached 34 cm (1.12 ft), both are fully grown.^[5]

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.^[6]

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.^[7][8][9]

Species

• 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

References

External links

• Data related to Xenacanthus at Wikispecies
• Media related to Xenacanthus at Wikimedia Commons

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Total group Chondrichthyes (including "acanthodians")

Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Infraphylum: Gnathostomata
Gnathostomata see Gnathostomata Chondrichthyes see below↓

Chondrichthyes

Chondrichthyes †Cassidiceps †Euthacanthus †Latviacanthus †Ramirosuarezia? †Sinacanthidae Hunanacanthus Neosinacanthus Sinacanthus Tarimacanthus †"Ischnacanthiformes" Acanthospina Campylodus Granulacanthus Machaeracanthus? Onchus Serradentus Acritolepidae Acritolepis Monospina Nerepisacanthus Pechoralepis Ischnacanthidae Arcticacanthus Arenaceacanthus Atopacanthus Bracteatacanthus Cacheacanthus Erymnacanthus Euryacanthus Gomphonchus Grenfellacanthus Ischnacanthus Marsdenius? Persacanthus Plectrodus Rockycampacanthus Rohonilepis Taemasacanthus Tricuspicanthus Xylacanthus Podoliacanthidae Drygantacanthus Kasperacanthus Podoliacanthus Poracanthodidae Gomphonchoporus Machaeraporus Obruchevacanthus? Poracanthodes Radioporacanthodes Taimyrolepis Trundlelepis Zemlyacanthus †Diplacanthiformes Bryantonchus Culmacanthus? Devononchus Striacanthus Tetanopsyrus Uraniacanthus Diplacanthidae Diplacanthus Milesacanthus Ptychodictyon Rhadinacanthus †Acanthodiformes Halimacanthodes Howittacanthus Acanthodidae Acanthodes Acanthodopsis Traquairichthys Cheiracanthidae Cheiracanthus Fallodentus Ginkgolepis Homalacanthus Markacanthus Mesacanthidae Lodeacanthus Melanoacanthus Mesacanthus Orcadacanthus Promesacanthus Teneracanthus? Triazeugacanthus "Climatiiformes" and related taxa †Brochoadmones †Dobunnacanthus †Fanjingshania? †Kathemacanthus †Lupopsyroides †Lupopsyrus †Obtusacanthus †Paucicanthus †Ptomacanthus †Qianodus? †Vernicomacanthus †Climatiidae Brachyacanthus Climatius Erriwacanthus Nodocosta? Parexus Sevyacanthus †Gyracanthidae Aganacanthus? Ankylacanthus Gyracanthides Gyracanthus Oracanthus? "Conventionally defined chondrichthyans" see below↓

"Conventionally defined chondrichthyans"
"Conventionally defined chondrichthyans" †Carcharopsis †Celtiberina †Gladbachus? †Gogoselachus †Karksiodus †Leonodus †Plesioselachus †Polymerolepis †Protodus †Samarodus †Shenacanthus? †Squatinactis †Antarctilamnidae Antarctilamna Wellerodus? †Mcmurdodontidae Maiseyodus Mcmurdodus †Pucapampellidae Gydoselache Pucapampella †Omalodontiformes Siberiodus Aztecodontidae Aztecodus Manberodus Omalodontidae Doliodus? Omalodus Portalodus †"Ctenacanthiformes" Neosaivodus Saivodus Sculptospina Tamiobatis Ctenacanthidae Arduodens? Cladodoides Cladodus Ctenacanthus Goodrichthys Natarapax? Troglocladodus Heslerodidae Avonacanthus Bythiacanthus Dracopristis Glencartius Glikmanius Heslerodoides Heslerodus Kaibabvenator Nanoskalmae †Jalodontidae Adamantina Isacrodus Jalodus Keuperodus Texasodus †Phoebodontidae Diademodus? Phoebodus Thrinacodus †Symmoriiformes Dwykaselachus Ferromirum Kawichthys Kungurodus? Maiseyacanthus Cladoselachidae? Cladoselache Maghriboselache Falcatidae Cosmoselachus Cretacladoides? Damocles Denaea Falcatus Ozarcus? Stethacanthulus Symmoriidae Akmonistion Cobelodus Crioselache? Stethacanthus Symmorium †Bransonelliformes Barbclabornia Bransonella †Xenacanthiformes Orthacanthus Tikiodontus Diplodoselachidae Decentrodus Diplodoselache Hagenoselache Hokomata Lebachacanthus Taquaralodus Xenacanthidae Mooreodontus Plicatodus Triodus Wurdigneria Xenacanthus Crown-Chondrichthyes Holocephali Elasmobranchii

Incertae sedis scale-based taxa

†Altholepidiformes? Altholepis Tezakia †Elegestolepidida? Kannathalepis Elegestolepididae Deltalepis Elegestolepis Ellesmereia †Mongolepidida? Solinalepis Mongolepididae Mongolepis Rongolepis Sodolepis Taklamakanolepis Teslepis Shiqianolepidae Chenolepis Shiqianolepis Tielikewatielepis Xiaohaizilepis Xinjiangichthys †Tchunacanthidae Fecundosquama Lenacanthus Tchunacanthus †Vesperaliidae Acanthacanthus Vesperalia Others †Canyonlepis? †Frigorilepis? †Funicristata †Gualepis †Ivanelepis †Jolepis †Karksilepis †Lunalepis †Nobilesquama †Nostolepis †Nostovicina †Ohiolepis †Seretolepis †Tuvalepis †Wellingtonella? †Yuanolepis

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