A possible hatchling of a jumping bristletail in 50 million years old amber

Haug, Joachim T.; Hädicke, Christian W.; Haug, Carolin; Hörnig, Marie K.


We describe a small fossil wingless ectognathan insect preserved in Baltic amber. The specimen possesses an enlarged maxillary palp and enlarged appendages of the ninth abdominal segment, which identify the fossil as a representative of Archaeognatha. The specimen is small (body without terminal filament < 5 mm) and pale in colour. The appendages, especially the thoracic ones, appear quite stout. The antennae and the terminal filament have comparably few elements. Especially weakly developed are the cerci, they are small and cone-shaped and appear to lack subdivisions, besides a single proximal ring. In addition, the tarsi of the thoracic appendages appear to lack subdivisions, although this aspect remains difficult to judge due to preservation. Together all these characters indicate that the specimen is an early developmental post-embryonic stage, possibly a hatchling. This is the oldest fossil find of such an early instar among "apterygote" insects; only one comparable specimen of Miocene age has been described so far. The differences of early post-embryonic stages compared to their corresponding adults of archaeognathans seem to be as profound as in many "hemimetabolous" insects, with the exception of the development of the wings. Hence, we question the value of the classification of non-holometabolous insect developmental patterns into "ametaboly" and "hemimetaboly".


baltic ambereoceneametabolypost-embryonic ontogenyarchaeognatha