Acanthodiscus

Acanthodiscus; Temporal range: Hauterivian; ~133–130 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	†Ammonoidea
Order:	†Ammonitida
Family:	†Neocomitidae
Subfamily:	†Berriasellinae
Genus:	†Acanthodiscus; Uhlig 1905
Type species
	Acanthodiscus radiatus;
Species
	A. magnificus Imlay 1938; A. octagonus; A. ottmeri; A. radiatus Bruguiére 1792; A. rollieri; A. schmidtii; A. subradiatus Uhlig 1910;

Acanthodiscus is an extinct ammonoid cephalopod genus from the order Ammonitida and included in the persphinctacean family Berriasellidae. The type species, named by Bruguière, 1792, is Acanthodiscus radiatus.^[1]

Description

The shell of Acanthodiscus (A. radiatus) is of modest size, slightly more than 14 centimetres (5.5 in) in diameter, coiled with the outer whorl covering about a third of the next inner whorl. The lower (2/3) flanks bear strong, wide spaced, radial ribs with large nodes at either end, and become weaker on the mature body chamber. Outer flanks (approx. 1/3) slope toward a narrow, flat to concave venter lined on either side by a series of smaller nodes. the mature whorl section is higher than wide.

Biostratigraphic significance

Acanthodiscus is found in shallow water sediments in both the Tethyan and Boreal realms where it is used as an index fossil. In fact, the International Commission on Stratigraphy (ICS) has assigned the First Appearance Datum of Acanthodiscus radiatus, the first species of the genus, as the defining biological marker for the start of the Hauterivian stage of the Cretaceous, ~132.9 million years ago.

Species

A. radiatus; type species
A. octagonus
A. ottmeri
A. rollieri
A. schmidtii; Found on the Antarctic Peninsula
A. subradiatus

Distribution

Acanthodiscus fossils can be found in the Agrio Formation of the Neuquén Basin, Argentina. Also in the Macanal Formation of the Eastern Ranges of the Colombian Andes, fossils of Acanthodiscus have been found.^[2]

Other occurrences of the genus are in:^[1]

Abundancia Formation, Chile
Guchuochun Formation, China
Kaliste Formation, the Czech Republic
France
Giumal Sandstone Formation, India
Chia Gara Formation, Iraq
Sardinia, Italy
Sabinal Formation and Barril Viejo Shale Member, Mexico
Myrtle Formation, Oregon, United States

References

^ ^a ^b Acanthodiscus at Fossilworks.org
^ Piraquive et al., 2011, p.204

Bibliography

Piraquive, Alejandro; Díaz, Juan Sebastián; Cuéllar, Tomas; Pardo, Germán; Kammer, Andreas (2011), "Reactivación Neógena de estructuras de rift del Cretácico Temprano asociadas con la Falla de Chámeza, Pajarito, Boyacá (Colombia): evidencias tectónicas y bioestratigráficas" (PDF), Geología Colombiana, 36: 197–216, retrieved 2017-08-04

External links

Acanthodiscus-Paleodb
Acanthodiscus radiatus Archived 2015-04-13 at the Wayback Machine in French
T. Birkelund, et al.: Cretaceous Stage Boundaries - Proposals. Bulletin of the Geological Society of Denmark, vol. 33 1984 [1]

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[FW-1] Acanthodiscus at Fossilworks.org

[Piraquive_p204-2] Piraquive et al., 2011, p.204

[1]

[2]