structural:expansion, information:classification, linguistic:voice_change
Classification

The Zygoptera are an ancient group, with the earliest fossils dating to the Kimmeridgian age of the Late Jurassic, around 152 million years ago. Well-preserved Eocene damselfly larvae and exuviae are known from fossils preserved in amber in the Baltic region.

Molecular analysis in 2021 confirms that most of the traditional families are monophyletic, but shows that the Amphipterygidae, Megapodagrionidae and Protoneuridae are paraphyletic and will need to be reorganised. The Protoneuridae in particular is shown to be composed of six clades from five families. The result so far is 27 damselfly families, with 7 more likely to be created. The discovered clades did not agree well with traditional characteristics used to classify living and fossil Zygoptera such as wing venation, so fossil taxa will need to be revisited. The 18 extant traditional families are provisionally rearranged as follows (the 3 paraphyletic families disappearing, and many details not resolved):