[1][4] When originally defined in 2013, Multiceratoidea included four nautiloid orders: Ellesmerocerida, Oncocerida, Discosorida, and Ascocerida.

The order Tarphycerida was considered a potential member of the subclass, though their larger body chamber and specialized muscle attachments lent uncertainty to this idea.

Nautilida (the order containing the modern nautilus) was allied with multiceratoids in a broader group termed "Nautilosiphonata", defined by its namesake connecting ring structure.

[4] Multiceratoidea would be an equivalent term to Nautiloidea sensu stricto if nautilids are confirmed to be within the group, though molecular divergence timing disagrees with this assessment.

[4] A 2022 bayesian phylogenetic analysis supports the existence of Multiceratoidea as a valid monophyletic clade (discounting the question of nautilus origins), with a membership that includes Tarphycerida and excludes most ellesmerocerids.