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

  1. Sepkoski, Jack (2002). "Sepkoski's Online Genus Database". Retrieved 2014-05-28.
  2. 1 2 The Paleobiology Database
This article is issued from Wikipedia - version of the Friday, January 29, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.