Calycoceras spinosum, from here.

Belongs within: Acanthoceratidae.

Calycoceras is a genus of evolute ammonites with depressed whorls known from the Upper Cretaceous (Cenomanian) (Wright et al. 1996).

Characters (from Wright et al. 1996): Rather evolute, with whorl section depressed and subcircular, oval, polygonal, or subquadrate; ribs strong, generally straight, continuous over rounded or flat but not concave venter; on early whorls at least umbilical, ventrolateral, siphonal, and, in most specimens, midlateral tubercles; in multituberculate forms umbilical tubercle more prominent than midlateral; tubercles may disappear with age and may or may not be rejuvenated on last part of shell. Marked dimorphism in size apparently general.

Calycoceras Hyatt 1900WCH96
|--*C. (Calycoceras) naviculare (Mantell 1822)WCH96 (see below for synonymy)
|--C. (Gentoniceras Thomel 1972) [incl. Subeucalycoceras Thomel 1972]WCH96
| |--C. (*G.) gentoni (Brongniart in Cuvier & Brongniart 1822) [=Ammonites gentoni]WCH96
| `--‘Acanthoceras’ sarthacense Bayle 1878 [incl. A. baylei Pervinquière 1907, *Subeucalycoceras baylei]WCH96
|--C. (Hourcqiceras Collignon 1939)WCH96
| `--C. (*H.) hourcqi Collignon 1939WCH96
|--C. (Newboldiceras Thomel 1972)WCH96
| |--C. (N.) asiaticum (Jimbo 1894) (see below for synonymy)WCH96
| |--‘Newboldiceras (*Mourreiceras)’ mourrei Thomel 1972WCH96
| `--‘Acanthoceras’ tapara Wright 1963 [=*Pseudacanthoceras tapara]WCH96
`--C. (Proeucalycoceras Thomel 1972) [incl. Haugiceras Thomel 1972]WCH96
|--C. (*P.) besairiei Collignon 1937 [=C. (Eucalycoceras) besairiei]WCH96
`--‘Acanthoceras’ haugi Pervinquière 1907 [=*Haugiceras haugi]WCH96

Calycoceras incertae sedis:
C. andranovaritelenseK79
C. bouleiK79
C. canitaurinumK79
C. guerangeriWCH96
C. jeannetiK79
C. latelobatumK79
C. leonenseK79
C. orientaleK79
C. spinosumK79
C. stoliczkaiK79
C. tarrantenseK79

*Calycoceras (Calycoceras) naviculare (Mantell 1822)WCH96 [=Ammonites navicularisWCH96, Acanthoceras naviculareKK08, *Metacalycoceras naviculareWCH96]

Calycoceras (Newboldiceras) asiaticum (Jimbo 1894) [=Acanthoceras asiaticum; incl. A. newboldi Kossmat 1897, Calycoceras (*Newboldiceras) newboldi]WCH96

*Type species of generic name indicated


[K79] Kauffman, E. G. 1979. Cretaceous. In: Robison, R. A., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt A. Introduction. Fossilisation (Taphonomy), Biogeography and Biostratigraphy pp. A418–A487. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[KK08] Kennedy, W. J., & H. C. Klinger. 2008. Hypermorphosis in Salaziceras, a Cretaceous ammonite, from Madagascar. African Natural History 4: 113–116.

[WCH96] Wright, C. W., J. H. Calloman & M. K. Howarth. 1996. Treatise on Invertebrate Paleontology pt L. Mollusca 4, revised vol. 4. Cretaceous Ammonoidea. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

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