Protolira thorvaldssoni is in the Skeneidae family, within the Trochoidea superfamily, and under the Vetigastropoda subclass (a major taxonomic group of sea snails, marine gastropod mollusks that form a very ancient lineage).
Family: Skeneidae Superfamily: Trochoidea Subclass: Vetigastropoda Vetigastropoda is a major taxonomic group of sea snails, marine gastropod mollusks that form a very ancient lineage. 
