''Spitidiscus'' is a genus of

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

s placed in the family Holcodiscidae. with and (1996), ''Mollusca 4 Revised , Cretaceous Ammonoidea'', vol. 4, in ''Treatise on Invertebrate Paleontology'', Part L (Roger L. Kaesler et el. eds.), Boulder, Colorado: The Geological Society of America & Lawrence, Kansas: University of Kansas Press, at 69.

Species

List of species within ''Spitidiscus'':''Spitidiscus''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org * ''Spitidiscus hugii'' * ''Spitidiscus kilapiae'' Rawson and Aguirre-Urreta, 2012 - Argentina * ''Spitidiscus oregonensis'' Imlay, 1960 - Oregon * ''Spitidiscus riccardii'' Leanza, and Wiedmann, 1992 - Argentina * ''Spitidiscus rotulia'' - England * ''Spitidiscus simitiensis'' Haas, 1960 - Colombia * ''Spitidiscus vandeckii'' (d'Orbigny, 1847)

Description

Member species have a rather evolute shell in which the whorl section is more or less circular, venter broadly rounded and dorsum fairly deeply impressed. Close, fine low, single or rarely branching ribs are interspersed by frequent straight or slightly sinuous, moderately deep but wide constrictions. The type species ''S. rotulia'' is from the

Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.9 ± 2 Ma and 129.4 ± 1.5 Ma (million years ago). The Hauterivian is preceded by the Va ...

of England.

Biostratigraphic significance

The first appearance of the species '' Spitidiscus hugii'' or ''

Spitidiscus vandeckii ''Spitidiscus'' is a genus of ammonites placed in the family Holcodiscidae. with and (1996), ''Mollusca 4 Revised , Cretaceous Ammonoidea'', vol. 4, in ''Treatise on Invertebrate Paleontology'', Part L (Roger L. Kaesler et el. eds.), Boulde ...

'' are proposed to be the marker for the beginning of the

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...

Distribution

''Spitidiscus'' has been found in: *

Agrio Formation The Agrio Formation is an Early Cretaceous geologic formation that is up to thick and is located in the southern Mendoza Province and northern-central Neuquén Province, in the Neuquén Basin of northwestern Patagonia, Argentina.Weaver, C. E. (1 ...

, Argentina *

Magdalena Valley The Magdalena River Valley ( es, Valle del Río Magdalena) is a valley in Colombia located within the Colombian Andes. The valley is specifically situated between the Central and Eastern Ranges and crossed by the river of the same name, the Magdale ...

, Simití and Cáqueza, Colombia * Kaliste Formation, Czech Republic * France * Gagra, Georgia, Caucasus * Maiolica Formation, Italy * Subbetics, Spain * Foggy Creek, Oregon * Bulgaria * Portugal * Russia * Morocco * Mexico

References

Bibliography

* * * W.J. Arkell ''et al.'', (1957). Mesozoic Ammonoidea in Treatise on Invertebrate Paleontology, Part L, Ammonoidea. Geological Society of America and Univ Kansas Press. Desmoceratoidea Ammonitida genera Index fossils Cretaceous ammonites Barremian life Hauterivian life Ammonites of Europe Fossils of the Czech Republic Cretaceous France Fossils of France Fossils of Georgia (country) Cretaceous Italy Fossils of Italy Cretaceous Spain Fossils of Spain Ammonites of North America Paleontology in Oregon Fossils of the United States Ammonites of South America Cretaceous Argentina Fossils of Argentina Cretaceous Colombia Fossils of Colombia Fossil taxa described in 1910 {{ammonitina-stub