Symmorium

Extinct genus of cartilaginous fishes

Symmorium
Temporal range: Devonian-Carboniferous, Famennian–Moscovian
PreꞒ
O
S
D
C
P
T
J
K
Pg
N
Fossil specimen (FMNH PF 2202) of S. reniforme, Field Museum of Natural History
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Symmoriiformes
Family: Symmoriidae
Genus: Symmorium
Cope, 1893
Species:
S. reniforme
Binomial name
Symmorium reniforme
Cope, 1893
Life restoration

Symmorium is a dubious genus of extinct stethacanthid cartilaginous fish from the Devonian and Carboniferous of the United States (Illinois)[1][2] and Russia.[3] The type species, Symmorium reniforme, was named by Edward Drinker Cope in 1893[4] and several other species were originally classed under this genus, but they have since been classified into other genera such as Petalodus. Symmorium bears close similarity in size and appearance to Stethacanthus[5] but the former is missing the "spine and brush" on its back.[6] Some paleontologists think that the two forms are simply the males and females of related species, while other scientists think they were distinct genera.[6][7]

  • Preserved S. reniforme specimen
    Preserved S. reniforme specimen
  • Tooth from an unnamed Symmorium species
    Tooth from an unnamed Symmorium species

References

  1. ^ E. D. Cope. 1894. New and little known Paleozoic and Mesozoic fishes. Journal of the Academy of Natural Sciences Philadelphia (Series 2) 9:427-448
  2. ^ M. E. Williams. 1985. The "Cladodont level" sharks of the Pennsylvanian black shales of central North America. Palaeontographica Abteilung A 190:83-158
  3. ^ A. Ivanov. 1999. Late Devonian - Early Permian chondrichthyans of the Russian Arctic. Acta Palaeontologica Polonica 49(3):267-285
  4. ^ E. D. Cope. 1893. On Symmorium, and the position of cladodont sharks. American Naturalist 27:999-1001
  5. ^ "Hierarchical Taxonomy of the Class Chondrichthyes". comenius.susqu.edu. Archived from the original on 27 September 2007. Retrieved 12 January 2022.
  6. ^ a b M. Ginter, O. Hampe, and C. J. Duffin. 2010. Chondrichthyes, Paleozoic Elasmobranchii: Teeth. In H.P. Schultze (ed.), Handbook of Paleoichthyology 3D:1-168
  7. ^ Coates, Michael I.; Gess, Robert W.; Finarelli, John A.; Criswell, Katharine E.; Tietjen, Kristen (2017). "A symmoriiform chondrichthyan braincase and the origin of chimaeroid fishes". Nature. 541 (7636): 208–211. Bibcode:2017Natur.541..208C. doi:10.1038/nature20806. ISSN 0028-0836. PMID 28052054. S2CID 4455946.
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Gnathostomata
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Chondrichthyes
    • see below↓
  • Cassidiceps
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  • Ramirosuarezia?
Sinacanthidae
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"Ischnacanthiformes"
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Acritolepidae
Ischnacanthidae
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Podoliacanthidae
Poracanthodidae
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Diplacanthidae
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Acanthodidae
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"Climatiiformes"
and related taxa
Climatiidae
Gyracanthidae
"Conventionally defined
chondrichthyans"
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Ischnacanthus gracilis

Diplacanthus sp. Acanthodes lopatini

Brochoadmones milesi
"Conventionally defined chondrichthyans"
"Conventionally defined chondrichthyans"
Antarctilamnidae
Mcmurdodontidae
Pucapampellidae
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Ctenacanthidae
Heslerodidae
Jalodontidae
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Phoebodontidae
Symmoriiformes
Cladoselachidae?
Falcatidae
Symmoriidae
Bransonelliformes
Xenacanthiformes
Diplodoselachidae
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Xenacanthidae
Crown-Chondrichthyes
Doliodus problematicus

Ctenacanthus concinnus Cobelodus sp.

Xenacanthus decheni
Incertae sedis scale-based taxa
Altholepidiformes?
Elegestolepidida?
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Shiqianolepidae
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Vesperaliidae
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Others
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Taxon identifiers
Symmorium


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