Tropaeum

Belongs within: Ancyloceratidae.

Tropaeum is a Lower Cretaceous (Aptian) genus of large ammonites in which ribs become larger and coarser in the final whorl (Wright et al. 1996).

Characters (from Wright et al. 1996): Very large; earliest whorls with some trituberculate ribs; then all ribs fine and dense, normally no more than slightly angulate on shoulders, until last whorl, on which they may become coarse and distant.

<==Tropaeum Sowerby 1837WCH96
    |  i. s.: T. arcticumK79
    |         T. australeK79
    |         T. jackiK79
    |         T. leptum (Etheridge 1909) [=Crioceras leptum]F71
    |         T. (Ancylotropaeum Casey 1980)WCH96
    |           `--T. (*A.) baylissi Casey 1980WCH96
    |--T. hillsiW69
    `--+--T. (Tropaeum) [incl. Australotropaeum Urreta 1985]WCH96
       |    |--*T. (T.) bowerbanki (Sowerby 1840)WCH96, W69, WCH96 [=Crioceratites bowerbankiWCH96]
       |    |--T. (T.) drewiWCH96
       |    `--T. (T.) magnum Urreta 1985 [=T. (*Australotropaeum) magnum]WCH96
       `--T. (Epitropaeum Kakabadze 1977)WCH96
            `--T. (*E.) subarcticum Casey 1960WCH96, W69, WCH96

*Type species of generic name indicated

References

[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).

[W69] Wiedmann, J. 1969. The heteromorphs and ammonoid extinction. Biological Reviews 44: 563–602.

[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).