Plectronoceras

Plectronoceras
Temporal range: Cambrian
Life restoration
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Nautiloidea
Order: †Plectronocerida
Family: †Plectronoceridae
Genus: †Plectronoceras
Ulrich & Foerste, 1933
Species
  • †Plectronoceras cambria
    Walcott, 1905

Plectronoceras is an extinct genus of early shelled cephalopod, dating to the Late Cambrian.[1][2][3] None of the fossils are complete, and none show the apex or aperture of the shell.[3] Around half of its shell was filled with septa; 7 were recorded in a 2 centimetres (0.79 in) shell.[4] Its shell contains transverse septa separated by about half a millimetre, with a siphuncle on its concave side.[3] It is among the oldest known shelled cephalopods (the Early Cambrian Eoceras being older),[5] and its morphology matches closely that hypothesised for the last common ancestor of all cephalopods.[3]

Plectronoceras is the type genus of the family Plectronoceratidae. Fossils of Plectronoceras have been found in the San Saba Limestone of Texas, United States and in Yunnan, China.[2]

Several species have been included in the genus Plectronoceras, though a 2024 review reorganized their taxonomy; P. exile and P. gracile were synonymyzed with Palaeoceras mutabile, while P. huaibeiense and P. liaotungense were synonymyzed with P. cambria, the type species of Plectronoceras.[6]

References

  1. ↑ Dzik, J. (1981). "Origin of the cephalopoda" (PDF). Acta Palaeontologica Polonica. 26 (2): 161–191.
  2. 1 2 Plectronoceras at Fossilworks.org
  3. 1 2 3 4 Clarke, M.R. (1985), "Main features of cephalopod evolution", in Wilbur, Karl M.; Clarke, M.R.; Trueman, E.R. (eds.), The Mollusca, vol. 12. Paleontology and neontology of Cephalopods, New York: Academic Press, ISBN 0-12-728702-7
  4. ↑ Webers, G. F.; Yochelson, E. L. (1989). Crame, J. A. (ed.). "Late Cambrian molluscan faunas and the origin of the Cephalopoda". Geological Society, London, Special Publications. 47 (1): 29–42. Bibcode:1989GSLSP..47...29W. doi:10.1144/GSL.SP.1989.047.01.04.
  5. ↑ Song, Zuchen; Pan, Bing; Guo, Junfeng; Vinther, Jakob; Li, Guoxiang; Han, Jian; Van Iten, Heyo; Zhao, Xiaofang; Pei, Xianzhi; Peng, Jiaxin; Qiang, Yaqin; Zhang, Boyao; Wen, Hanjie (2026-07-31). "Earliest siphuncle-bearing cephalopod from the early Cambrian". Nature. doi:10.1038/s41586-026-10868-y. ISSN 0028-0836. PMID 42527604.
  6. ↑ Pohle, Alexander; Jell, Peter; Klug, Christian (2024-02-29). "Plectronoceratids (Cephalopoda) from the latest Cambrian at Black Mountain, Queensland, reveal complex three-dimensional siphuncle morphology, with major taxonomic implications". PeerJ. 12 e17003. Bibcode:2024PeerJ..1217003P. doi:10.7717/peerj.17003. ISSN 2167-8359. PMC 10909373. PMID 38436030.


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