the classification of the apterygota changed over time. by the mid 20th century, the subclass included four orders (collembola, protura, diplura, and thysanura). with the advent of a more rigorous cladistic methodology, the subclass turned out to be paraphyletic. the first three groups formed a monophyletic group, the entognatha. the thysanura is more closely related to winged insects. thus rendering even the amyocerate apterygotes paraphyletic.