| The nature of mass extinctions in particular has been distorted by a combination of post-extinction sampling bias and associated pseudoextinction of paraphyletic groups. |
| The taxonomy of the group is not well resolved, with many family-group taxa considered paraphyletic or polyphyletic, and several subfamilies are unplaced at the family level. |
| Parsimony analyses recover a paraphyletic Rotifera, where a bdelloid rotifer and acanthocephalans form a monophyletic clade. |
| The Galaxoidea, in turn, are paraphyletic and contain the Stomiiformes which are often regarded as part of the Stenopterygii. |
| These taxa together form a paraphyletic group at the base of the clade of biramous arthropods. |
| In traditional classifications, the hagfish, lampreys, and extinct armored jawless fish are grouped together in the paraphyletic Class Agnatha. |
