Plectronoceras
Genus of mollusc
From Wikipedia, the free encyclopedia
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 Temporal range: Cambrian | |
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| Life restoration | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | †Plectronocerida |
| Family: | †Plectronoceridae |
| Genus: | †Plectronoceras Ulrich & Foerste, 1933 |
| Species | |
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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]
