“Palaeocycloceras”的意思、由来-开放百科全书

词条

Palaeocycloceras

释义

Taxonomy
Morphology
References

{{Italic title}}{{Taxobox
| fossil_range = Middle Ordovician
| image =
| image_caption =
| regnum = Animalia
| phylum = Mollusca
| classis = Cephalopoda
| subclassis = Nautiloidea
| ordo = Orthocerida
| familia = Orthoceratidae
| genus = Palaeocycloceras
| genus_authority = Shimizu & Obata, 1934
}}

Palaeocycloceras is a genus of Middle Ordovician orthocerids from the Baltic region of Europe, China, and Brazil.

Taxonomy

Walter Sweet in 1964 assigned Palaeocycloceras to the orthocerid superfamily Orthocerataceae and to the subfamily Orthocerinae, noting that it is probably synonymous with Ctenoceras.

Morphology

The shell of Palaeocycloceras (=?Ctenoceras) is straight or faintly curved upwardly (exgastric) and somewhat compressed in cross section (slightly higher than wide). The surface has prominent sinuous annulations and growth lines. The siphuncle is small, subcentral or between the center and venter. Necks are short and straight, connecting rings thin and slightly expanded at the anterior ends of the segments. In some the siphuncle has an apparently continuous parietal lining. No cameral deposits are known.

References

Walter C. Sweet, 1964. Nautilodea - Orthocerida. Treatise on Invertebrate Paleontology Part K, Mollusca 3. Geological Society of America and University of Kansas Press.
Paleobiology Database Paleocycloceras entry
Paleobiology Database Ctenoceras entry

4 : Prehistoric nautiloid genera|Ordovician cephalopods|Ordovician cephalopods of Europe|Ordovician cephalopods of South America

随便看

开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。