| 词条 | Homaloceras |
| 释义 |
| fossil_range = M Devonian | image = | taxon = Homaloceras | authority = Whiteavus (1891) }} Homaloceras is an extinct nautiloid cephalopod from the Middle Devonian with a strongly curved shell, included in the nautilid family Centroceratidae. Homaloceras is characterized by a smooth, exogastrically curved and laterally compressed, cyrtoconic to gyroconic, shell with the ventral margin the outer rim. The venter is narrow and concave with a groove running down the middle; the dorsum on the inner rim, rounded; the sides broadly convex and convergent. The suture is only slightly sinuous, the siphuncle tubular and near the venter. ({{Not a typo|Kummel}} 1964) Homaloceras, named by Whiteavus in 1891, and found in North America, in Canada, is the most primitive and one of the earliest genera assigned to the Centroceratidae. ({{Not a typo|Kummel}} 1964) The Nautiloidea, in which Homaloceras is included, is a subclass of once diverse and numerous shelled cephalopods characterized by a retrochoantic siphuncle in which the septal necks point back toward the apex. See also{{Portal|Paleontology|Marine life}}
References
1 : Nautiloids |
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