Spitidiscus

Spitidiscus is a genus of ammonites placed in the family Holcodiscidae.

Spitidiscus Temporal range: Hauterivian - Barremian [1] PreꞒ Ꞓ O S D C P T J K Pg N
Fossil shell of Spitidiscus species from Alpes-de-Haute-Provence, on display at Galerie de paléontologie et d'anatomie comparée in Paris
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Ammonitida
Family:	Holcodiscidae
Genus:	Spitidiscus Kilian, 1910

Species

List of species within Spitidiscus:[2]

• 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

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.

Geologic Time Scale

The first appearance of the species Spitidiscus hugii or Spitidiscus vandeckii are proposed to be the marker for the beginning of the Barremian.[3]

Distribution

Spitidiscus has been found in the Lower Cretaceous of Europe (Bulgaria, Czechoslovakia, France, Italy, Portugal, Spain, Russia), as well as of Morocco, Argentina, Colombia and Mexico.[2] The type species S. rotulia is from the Hauterivian of England.

Notes

1. Sepkoski, Jack Sepkoski's Online Genus Database – Cephalopoda
2. Spitidiscus at Fossilworks.org
3. "GSSP Table - Mesozoic Era". Geologic Time Scale Foundation. Retrieved 15 January 2014.

References

• W.J. Arkell et al., (1957). Mesozoic Ammonoidea in Treatise on Invertebrate Paleontology, Part L, Ammonoidea. Geological Society of America and Univ Kansas Press.