Ancyloceras

Belongs within: Ancyloceratidae.

Ancyloceras is a Lower Cretaceous (Lower Barremian to Lower Aptian) genus of heteromorph ammonites with an open initial spiral leading to a long shaft and terminal hook (Wright et al. 1996).

Characters (from Wright et al. (1996): Open, plane spiral followed by long shaft and terminal hook; ribs straight, radial or prorsiradiate, with periodic, enlarged trituberculate ribs at least on early whorls and hook. Known with Praestriaptychus.

<==Ancyloceras d’Orbigny 1842EK02 [incl. Hoplancyloceras Nowak 1913 (n. n.)WCH96]
    |  i. s.: A. durrelliK79
    |         A. flindersiF71
    |         A. innexumK79
    |         A. mosellense Terquem 1857DCH81
    |         A. vandenheckiiWCH96
    |--*A. (Ancyloceras) matheronianum Orbigny 1842WCH96
    |--A. (Audouliceras Thomel 1964)WCH96
    |    `--A. (*A.) audouli Astier 1851WCH96
    |--A. (Jaubertites Sarkar 1955)WCH96
    |    `--A. (*J.) dubium (Sarkar 1955) [=*Jaubertites dubius]WCH96
    `--A. (Tonoceras Hyatt 1900)WCH96
         `--A. (*T.) duvalianum Orbigny 1842WCH96

*Type species of generic name indicated

References

[DCH81] Donovan, D. T., J. H. Callomon & M. K. Howart. 1981. Classification of the Jurassic Ammonitina. In: House, M. R., & J. R. Senior (eds) The Ammonoidea: The evolution, classification, mode of life and geological usefulness of a major fossil group pp. 101–155. Academic Press.

[EK02] Engeser, T., & H. Keupp. 2002. Phylogeny of the aptychi-possessing Neoammonoidea (Aptychophora nov., Cephalopoda). Lethaia 35: 79–96.

[F71] Fletcher, H. O. 1971. Catalogue of type specimens of fossils in the Australian Museum, Sydney. Australian Museum Memoir 13: 1–167.

[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).

[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).