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Parasemionotiformes

Extinct order of ray-finned fishes From Wikipedia, the free encyclopedia

Parasemionotiformes
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Parasemionotiformes is an extinct order of neopterygian ray-finned fish that existed globally during the Triassic period. It comprises the families Parasemionotidae and Promecosominidae. Many of the included genera are monotypic and most species lived during the Early Triassic epoch.[1][2]

Quick facts Scientific classification, Families ...

Parasemionotiforms were normally small to medium-sized fishes. They were predominantly marine.[3]

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Evolutionary relationships

Parasemionotiformes are neopterygians, which is the clade that encompasses the vast majority of living ray-finned fishes (Actinopterygii) and about half of all living species of vertebrates.[4] Neopterygii are divided into Teleostei and Holostei. The latter represents a depauperate group today but used to be a diverse clade especially during the Mesozoic Era. The only surviving members of the Holostei are the gars (Ginglymodi) and the bowfin (Halecomorphi).[4]

Parasemionotiformes belong to Holostei and are one of the earliest clades of the Halecomorphi (bowfin and its extinct relatives).[5] Parasemionotiformes are the sister group to all other halecomorphs according to cladistic analyses.[6]

The following tree summarizes the evolutionary relationships of the Parasemionotiformes. Names accompanied by a dagger (†) represent extinct groups.

Neopterygii

Teleostei

Holostei

Ginglymodi (gars and their extinct relatives)

Halecomorphi

Parasemionotiformes

Panxianichthyiformes

Ionoscopiformes

Amiiformes (bowfin and its fossil relatives)

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Classification

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Parasemionotus labordei was the first described parasemionotiform
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Albertonia cupidinia from the Early Triassic of Canada had large pectoral fins
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Jacobulus novus was a small parasemionotiform
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Watsonulus eugnathoides from the Early Triassic of Madagascar is one of the best known parasemionotiforms
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Candelarialepis argentus from the Early Triassic of Nevada was a medium-sized parasemionotiform
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See also

References

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