Ptomacanthus

Ptomacanthus Temporal range: 419–410 Ma PreꞒ Ꞓ O S D C P T J K Pg N Early Devonian (Lochkovian)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Acanthodii
Order:	Climatiiformes
Genus:	Ptomacanthus
Species
†P. anglicus †P. spp. indet.

Ptomacanthus (meaning thorny corpse) is an extinct genus of spiny shark,^[1] an early relative of living cartilaginous fishes (sharks, rays, and chimaeras).^[2]

Location found

Ptomacanthus is known mainly from the Old Red Sandstone of the United Kingdom.^[1] The most completely known species, P. anglicus is known from several articulated fossils from Wayne Herbert Quarry, Herefordshire, United Kingdom.^[1] Two indeterminate species are known from shoulder-girdles recovered from Castle Mattock Quarry, Herefordshire and Zaleszychi, Ukraine.^[1]

Description

The only species known in any detail, P. anglicus was a fish about 25 cm long.^[3] Like other acanthodians it had small, shark like scales, and a suite of fin-spines in front of its dorsal, pectoral, and pelvic fins.^[1]

Paleobiology

P. anglicus is important to our understanding of early vertebrate evolution as it preserves part of the braincase, a scientifically informative part of the skeleton.^[2] Because of the cartilaginous makeup of the acanthodian internal skeleton, it is very rarely preserved, and the braincase of Ptomacanthus is only the second acanthodian braincase known to science (the first being that of Acanthodes).^[4] The description of this braincase reignited debate over the relationships of acanthodians as well as those of early vertebrates more generally.^[2][4]

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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