Parexus

Parexus Temporal range: Early Devonian
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	†Acanthodii
Order:	†Climatiiformes
Family:	†Climatiidae
Genus:	†Parexus Agassiz, 1845
Species:	†P. recurvus
Binomial name
†Parexus recurvus Agassiz, 1845
Synonyms[1]
Parexus falcatus Farnellia tuberculata Traquair

Parexus is an extinct genus of acanthodian fish. Acanthodians are often referred to as ‘spiny sharks’, although acanthodians are not true sharks and evolved perhaps 50 million years earlier than sharks. Acanthodians share several features with bony fish and cartilaginous fish; they often have spines supporting their fins.

Parexus is recognised by its large anterior dorsal fin spine. Several fossils have been discovered from the Early (Lower) Devonian Period of Tillywhandland, Scotland. Two species were described, P. recurvus and P. falcatus, both from Scotland; according to Burrow et al. (2013) P. falcatus is in fact a junior synonym of P. recurvus.^[1]

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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