Class Cephalopoda Rank Genus | Phylum Mollusca Superfamily Perisphinctaceae | |
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Similar Macrocephalites, Orthosphinctes, Hemiaster, Aspidoceras, Aulacostephanus | ||
Ataxioceras is an extinct Ammonite cephalopod genus confined to the Upper Jurassic of Europe, included in the superfamily Perisphinctoidea.
Contents
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.
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.