stem-group bilaterians Hatschek, 1888 - bilaterians see Subkingdom Bilateria Hatschek, 1888
   Family †Siphusauctidae O'Brien & Caron, 2012
     Genus †Siphusauctum O'Brien & Caron, 2012
       1 †Siphusauctum gregarium O'Brien & Caron, 2012