Ainoceras

Taxobox
name = "Ainoceras"
status = fossil
fossil_range = Campanian
regnum = Animalia
phylum = Mollusca
classis = Cephalopoda
subclassis = Ammonoidea
ordo = Ammonitida
subordo = Ancyloceratina
subordo_authority = Wiedmann, 1966
superfamilia = Turrilitaceae
familia = Nostoceratidae
genus = "Ainoceras"
genus_authority =
subdivision_ranks =
subdivision =

"Ainoceras" ("Ainu's Horn") is a genus of extinct, aberrantly coiled ammonite cephalopod that live in the Pacific Ocean during the Campanian division of the Cretaceous, where Japan is today. Their shells were coiled very similarly to the related "Anaklinoceras", in that, when young, the shell coiled helically, and then upon reaching adulthood, the shell then bent over the older coils. However, "Ainoceras" differed in this respect in that, whereas in "Anaklinoceras", the youngest coil wrapped very closely around the older coils, while in "Ainoceras", the youngest coil bent over the older coils in a wide loop or oxbow.