Nautiloceras
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| Nautiloceras Temporal range: Upper Tournaisian | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | Nautilida |
| Genus: | †Nautiloceras D'Orbigny, 1849 |
Nautiloceras is an extinct genus from the nautiloid order Nautilida,[1] which includes the living Nautilus and its close relative Allonautilus.
Nautiloceras is a poorly known genus that probably belongs to the Trigonoceratidae. According to Kummel (1964)[2] Nautiloceras is a jr synonym for Trigonoceras which was named by M'Coy in 1948. Different ages are given for the two however,[3] with Nautiloceras being from the Upper Tournesian, about 352-345 Ma, (Lower Osage) and Trigonoceras somewhat younger, Upper Visean - Lower Serpukhovian, (Upper Meremec - Chester) with the span from about 340 to 322 Ma.
Nautiloceras [2] may have been cyrtconic to loosely gyroconic, coiled without whorls being in contact with one another. Gyroconic forms may have had a subtriangular cross section with a broad concave venter, occupying the outer rim.
