Protolira thorvaldssoni is in the Skeneidae family, within the Trochoidea superfamily, and under the Vetigastropoda subclass (neither a major taxonomic group of sea snails nor a marine gastropod mollusks that form a very ancient lineage).
Vetigastropoda is a major taxonomic group of sea snails, marine gastropod mollusks that form a very ancient lineage. 
