Ataxioceras
| Ataxioceras Temporal range: Kimmeridgian[1] | |
|---|---|
 | |
| Fossil shell of Ataxioceras conditum from Germany, on display at Galerie de paléontologie et d'anatomie comparée in Paris | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Ammonoidea |
| Order: | Ammonitida |
| Superfamily: | Perisphinctaceae |
| Family: | Ataxioceratidae |
| Genus: | Ataxioceras |
Ataxioceras is an extinct Ammonite cephalopod genus confined to the Upper Jurassic of Europe, included in the superfamily Perisphinctaceae.
Previously Ataxioceras was assigned to the Perisphinctidae but has now been placed in the Ataxioceratidae for which it is the type genus.
These fast-moving nektonic carnivores lived during the Jurassic period, from 161.2 to 150.8 Ma. [2]
Description
The shell is evolute, strongly ribbed and miderately umbilicate. Primary ribs, on the order of 32 -36 per whorl, are sharp and widely spaced, originate at the unbilical shoulder. Secondary ribs form about mid flank, generally by trifurcation, but sometimes quadrafurcation (splitting into threes or sometimes fours) of the primaries. The umbilicus is about 0.4 the shell diameter.
Distribution
Fossils of species within this genus have been found in the Jurassic sediments in Germany, France, India and Romania. [2]
References
- ↑ Sepkoski, Jack (2002). "Sepkoski's Online Genus Database". Retrieved 2014-05-28.
- 1 2 The Paleobiology Database
- D.T. Donovan et al. Classification of the Jurassic Ammonitina, in The Ammonoidea, M.R. House and J.R. Senior (eds); Academic Press 1981. Systematics Association Special Volume. 18.