Harpoceratinae
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Harpoceratinae Temporal range: Upper Pliensbachian to lower Bajocian |
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| Fossil shell of Harpoceras subplanatum from Isère (France), on display at Galerie de paléontologie et d'anatomie comparée in Paris | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Ammonoidea |
| Order: | Ammonitida |
| Suborder: | Ammonitina |
| Superfamily: | Hildoceratoidea |
| Family: | Hildoceratidae |
| Subfamily: |
Harpoceratinae Neumayr 1875 |
| Genera | |
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at least 9, see text |
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| Synonyms | |
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Polyplectinae Venturi, 1981 |
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at least 9, see text
Polyplectinae Venturi, 1981
Harpoceratinae is an extinct subfamily of cephalopods belonging to the family Hildoceratidae. Ammonites of this subfamily had involute and compressed shells with strong keels. Keel might be rarely missing, but this is considered to be an abnormality. This has been observed both in Cleviceras and Harpoceras and called as genus Monestieria, which is now known to be invalid (into this invalid genus were added also abnormal unkeeled specimens of genus Protogrammoceras). Another example is Pseudolioceras, whose unkeeled specimen was used as type for description of invalid genus Praehaploceras. Oxyconic forms of this subfamily (Polyplectus and Sphenarpites) does not have any keel. Ribs were single, but in some genera also bifurcating with shapes from sigmoidal to falcate. Sometimes, shell can have only striate ribs or is smooth (Sphenarpites and older specimens of Eleganticeras and Ovaticeras). Tubercules are rare. Dimorphism is known in some genera and it is observable mostly in size. Macrochons can be 4, to 6 times larger than microconchs. As an example, macroconchs of Pseudolioceras are more than 150mm in diameter, while adult microconchs are only 35-50mm. There are big size differences even within dimorphs. Specimens ca be 2, or sometimes even 3 times bigger than other specimens of same dimorph.
At least 9 genera is considered to be members of this subfamily. This number can be increased, as some authors might consider valid some genera, which are by other authors considered to be synonyms of these 9. For example, Maconiceras is sometimes listed within this subfamily, while by other authors, it is considered to be a synonym of Harpoceras.
Sometimes, more genera is referred to this subfamily, as some authors does not recognize validity of subfamily Protogrammoceratinae.Neolioceratoides, which has been included within Protogrammoceratinae and was also considered to be a synonym of Lioceratoides is now member of Hildoceratinae, which is reason why it is not listed bellow. This would include genera:
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Wikipedia