''Idoceras'' is a genus of perisphictacean

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

, belonging to the Perisphinctidae subfamily Idoceratinae. The genus is known from the Upper Jurassic, with a widespread distribution. Shells of ''Idoceras'' are evolute, with a wide umbilicus; ribbing strong, bifurcate high on flanks. Suture simpler than in the similar ''

Ataxioceras ''Ataxioceras'' is an extinct Ammonite cephalopod genus confined to the Upper Jurassic of Europe, included in the superfamily Perisphinctoidea. Previously ''Ataxioceras'' was assigned to the Perisphinctidae but has now been placed in the Ataxioc ...

''.

References

* Jurassic ammonites Ammonitida genera Perisphinctidae Ammonites of Europe {{ammonitina-stub