Plectronoceras
Genus of molluscs
From Wikipedia, the free encyclopedia
Plectronoceras is the earliest known 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] Its morphology matches closely to that hypothesised for the last common ancestor of all cephalopods.[3]
| Plectronoceras Temporal range: Cambrian | |
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| Life reconstruction of Plectronoceras cambria | |
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 and in Yunnan, China.[2]
Species
- †Plectronoceras cambria (Walcott, 1905)
- †Plectronoceras exile (Flower, 1964)
- †Plectronoceras gracile (Flower, 1964)
- †Plectronoceras huaibeiense (Chen & Qi, 1979)
- †Plectronoceras liaotungense (Kobayashi, 1935)
