Diplacanthus

Diplacanthus Temporal range: Eifelian–Famennian PreꞒ Ꞓ O S D C P T J K Pg N
Fossil specimen of D. crassissimus (=D. striatus)
Life restoration
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	†Acanthodii
Order:	†Diplacanthiformes
Family:	†Diplacanthidae
Genus:	†Diplacanthus Agassiz, 1843
Species
see text

Diplacanthus is an extinct genus of Mid to Late Devonian fish in the class Acanthodii, known as spiny sharks.

Classification

The genus was named by Louis Agassiz in 1843.^[1] It was formerly regarded as belonging to the Climatiformes but recently reassigned to the Diplacanthiformes, in which it is united with, amongst others, Rhadinacanthus, Uraniacanthus, and Culmacanthus. Diplacanthiforms were widespread during the Middle and early Late Devonian. They are best represented in the Middle Devonian, by articulated fossils, fin spines, and abundant scales, the latter particularly from northern Europe.^[2]

In a latest revision of the genus Diplacanthus, a large number of species from Europe were synonymized with earlier Scottish species, and these too were redefined. D. crassisimus was taken to have precedence over D. striatus as the name of the type specimen. Diplacanthus longispinus was reassigned to Rhadinacanthus longispinus, within which were also included Diplacanthus horridus (Woodward, 1892) and Diplacanthus ellsi. Diplacanthus tenuistriatus and Diplacanthus kleesmentae were however retained. Non-Laurussian species such as Diplacanthus acus from South Africa were not considered in this review.^[2]

Species

• †D. acus Gess, 2001
• †D. crassisimus Duff, 1842 (type species)
• †D. gravis? Valiukevičius, 1986
• †D. kleesmentae? Valiukevičius, 1988
• †D. poltnigi? Valiukevičius, 2003
• †D. solidus? Valiukevičius, 1986
• †D. tenuistriatus Traquair, 1844

Fossil (left) and life restoration of D. acus

Diplacanthus acus is described from a near complete whole-bodied impression discovered in 1999 during roadworks cutting the Waterloo Farm lagerstätte in South Africa.^[3] The type specimen of Diplacanthus acus is approximately 100 mm long and has exceptionally long and thin ribbed spines. The intermediate spines are, conversely, extremely reduced.^[4] Unusually it preserves complete outlines of many of the fins.

Diplacanthus is most commonly associated with deposits traditionally interpreted as fresh water. However, Waterloo Farm is interpreted as estuarine in origin, as is the Canadian Miguashaia lagerstätte from which two species of Diplacanthus have been described.^[5] The description of Diplacanthus acus provided the first record of a diplacanthid from the Famennian, with diplacanthids having previously been thought to have gone extinct by the end of the Frasnian.^[6]

References

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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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