Earliest record of exophytic insect oviposition on plant material from the latest Pennsylvanian (Gzhelian, Stephanian C) of the Saale Basin, Germany

Abstract

The Late Palaeozoic fossil record of plant-insect interactions contains few records of oviposition. Here we report the earliest evidence of exophytic oviposition, where eggs are laid directly on the outer surface of plants. The fossil structures consist of small, circular impressions on plant fossils from the late Pennsylvanian (Gzhelian, Stephanian C) of the Saale Basin in Germany. Their interpretation as exophytic insect eggs is supported by the oviposition pattern, their three-dimensional preservation and the undamaged nature of the plant host tissue. The tight arrangement of the eggs in curved arcs suggests a producer with a short abdomen such as roachoids, the ancestral group of the Dictyoptera sensu stricto. A diagnostic feature of roachoids is their long ovipositor, which was well suited for deposition of single eggs in a distinct pattern.