The fossil evidence is reviewed in Carpenter, F.M. 1992. Geological Society of America. Odonata Predatory palaeopterous insects with well-developed eyes and four pairs of similar membranous wings. Wings with a dense and characteristic pattern of venation. Thoracic structure of adult stage highly skewed through development of hypertrophied mesanepisternum.
Debate abounds both on relationships among the suborders and within the suborders.
The extant Epiophlebiidae can be closely allied with the Anisoptera on the basis of larval morphology. Associated larvae are not available for the various fossil 'Anisozygoptera'. Larva lacks ability to jet-propel. After second instar larvae can convulsively expell water from rectum and jet-propel.