Harpoceras
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| Fossil shell of Harpoceras subplanatum from Isère (France), on display at Galerie de paléontologie et d'anatomie comparée in Paris | |
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| Genus: | Harpoceras Waagen 1869
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Harpoceras is an extinct genus of cephalopod belonging to the family Hildoceratidae. These cephalopods existed in the Jurassic period, during Toarcian age from Falciferum zone to Commune subzone of Bifrons zone. [2] They were fast-moving nektonic carnivores. [3]
Species
- Harpoceras eseri Oppel, 1856
- Harpoceras falciferum Sowerby, 1820
- Harpoceras kisslingi Hug, 1898
- Harpoceras lassum Buckman, 1927
- Harpoceras mediterraneum Pinna, 1968
- Harpoceras pseudoserpentinum Gabilly, 1973
- Harpoceras rulleaui Bécaud, 2006
- Harpoceras serpentinum Schlotheim, 1813
- Harpoceras strangewaysi Sowerby, 1820
- Harpoceras subexaratum Bonarelli, 1899
- Harpoceras subplanatum Oppel, 1856
Description
Shells of Harpoceras species show strong dimorphism in their size. While microconchs reach 24-51 mm in diameter, macroconchs shells width is 115-430 mm. They are moderately evolute to involute and compressed. Whorl sides are flat and there is strong keel. Ribs are falcoid or falcate and thus biconcave, strong and projected. Sometimes, ribs can be broad and flat topped on outer part of whorl and in some species they can be striate on inner part of whorl. Some species have midlateral groove, or series of undulating depressions on inner half of whorl.[1]
Distribution
Fossils of species within this genus have been found in the Early Jurassic rocks of Europe, northern Africa, Russia, Japan, Borneo, New Zealand, North and South America.[1]
References
- ^ a b c M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea.
- ^ Sepkoski, Jack Sepkoski's Online Genus Database – Cephalopoda
- ^ a b The Paleobiology Database
External links
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