| Acanthodiscus Temporal range: Hauterivian( L Cret) |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Ammonoidea |
| Order: | Ammonitida |
| Superfamily: | Perisphinctaceae |
| Family: | Berriasellidae |
| Genus: | Acanthodiscus Bruguière, 1779 |
Acanthodiscus is an extinct ammonoid cephalopod genus from the order Ammonitida and included in the persphinctacean family Berriasellidae. The type, named by Bruguière ,1779, is Acanthodiscus radiatus.
Contents |
The shell of Acanthodiscus (A. radiatus) is of modest size, slightly more than 14 cm (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.
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 first appearance of Acanthodiscus radiatus, as well as that of allied species, currently defines the base of the Hauterivian stage (L Cret)
Acanthodiscus fossils can be found in Argentina's Neuquén Basin