''Eupachydisus'' is a large, coarse-ribbed Pachydiscid ammonite genus from the Upper Cretaceous, found in

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by ...

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

age strata in Europe, Madagascar, Japan, and British Columbia. The whorl section in ''Eupachydiscus'' is inflated and depressed, almost round in the later growth stages. Ribs are narrow but prominent in the early whorls, becoming thick and strong in the later. ''Eupachydiscus'' is distinct from the mostly later, Campanian -

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

, compressed and high-whorled ''

Pachydiscus ''Pachydiscus'' is an extinct genus of Ammonitina, ammonite from the Late Cretaceous and Early Paleocene with a worldwide distribution, and type (biology), type for the desmoceratacean family Pachydiscidae. The genus' type species is ''P. neuberg ...

'', but somewhat similar to the coeval, inflated and coarse ribbed, Coniacian-

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

, '' Pachydiscoides''.

Species

* '' Eupachydiscus isculensis'' † Redtenbacher 1873 * '' Eupachydiscus macoveii'' † Szaisz 1981 * '' Eupachydiscus pseudogrossouvrei'' † Collignon 1955

References

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

, Part L, Mollusca 4, R.C. Moore, ed. Geological Soc. of America and Univ. Kansas Press. p L377-L380.
Paleodb-Pachydiscidae
5/01/11 Cretaceous ammonites Ammonites of Europe Desmoceratoidea Ammonitida genera {{Ammonitina-stub