It consisted of a single forewing[5] collected from the Taynton Limestone Formation (Stonesfield Slate) of Oxfordshire, England by the English natural historian Edward Charlesworth.

[9] They possessed an inflated frons and a long rostrum (piercing and sucking mouthpart), indicating that they fed on xylem fluids like some other modern hemipterans,[10] including living cicadas to which they have often been compared.

[9] Numerous newly evolved insectivorous animals (feathered theropods, primitive mammals, and early birds) may have also contributed significantly to their extinction.

[15] In contrast, later palaeontinids like the Upper Jurassic Eocicada and Early Cretaceous Ilerdocossus had triangular forewings with the flexion line closer to the base.

These indicate that they were highly versatile fliers, able to fly with a wide range of speeds and agility like modern wasps and sphinx moths.

[11] The trend of forewing elongation is most evident in members of the family Mesogereonidae, an early offshoot and close relatives of palaeontinids.

[17] The English entomologist Edward Meyrick supported the lepidopteran conclusion, though he believed they belonged to the family Hepialidae (ghost moths) instead.

"[5] The Belgian entomologist Auguste Lameere challenged this conclusion, claiming palaeontinids were more closely related to the extant family Cicadidae (cicadas).

The English-Australian entomologist and geologist Robert John Tillyard supported Lameere's conclusion, noting that the wings of palaeontinid fossils lacked the characteristic scales of lepidopterans but instead had tubercules, pits, and cross-ridges like those found in modern cicadas.

Within Palaeontinoidea, the family Dunstaniidae (Upper Permian to Lower Jurassic of Australia, South Africa, and China) is ancestral to palaeontinids.

Both are distinct from the only other member of the superfamily, the more primitive and specialized family Mesogereonidae (Upper Triassic of Australia and South Africa).

[14] Fossils have been recorded in Brazil, China, Russia, Germany, the Transbaikal region, Tajikistan, Turkmenistan, Kyrgyzstan, Kazakhstan, Spain, and the United Kingdom.