''Homaloceras'' is an extinct
nautiloid
Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and '' Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded specie ...
cephalopod from the Middle
Devonian with a strongly curved shell, included in the
nautilid family
Centroceratidae
The Centroceratidae is the ancestral family of the Trigonoceratoidea and of the equivalent Centroceratina; extinct shelled cephalopods belonging to the order Nautilida
Diagnosis
The Centroceratidae, which range from the Middle Devonian to the ...
.
''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. ( 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. ( 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
*
List of nautiloids
This list of nautiloids is a comprehensive listing of all genera that have ever been included in the subclass Nautiloidea, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered in ...
References
* , B. 1984; Nautiloidea -Nautilida;
Treatise on Invertebrate Paleontology
The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...
Part K, Geological Society of America and University of Kansas Press.
* Sepkoski, J.J. Jr. 2002. A compendium of fossil marine animal genera. D.J. Jablonski & M.L. Foote (eds.). ''Bulletins of American Paleontology'' 363: 1–560
Sepkoski's Online Genus Database (CEPHALOPODA)
{{Taxonbar, from=Q5887567
Nautiloids