Young bivalves on insect wings: A new taphonomic model of the Konservat-Lagerstätte Hagen-Vorhalle (early Late Carboniferous; Germany)

Taphonomic conditions of insects from the Late Carboniferous (Pennsylvanian) Konservat-Lagerstätte Hagen-Vorhalle (western Germany) are remarkably unique but have not been the focus of detailed work thus far. Their particular preservation is conspicuous and furthermore shows significant differences between “Palaeoptera” and Neoptera. The first are almost always completely preserved while the latter invariably lack an abdomen. Furthermore all Neoptera bear tiny bivalve prodissoconchs (~ 0.8–1.2 mm) or few dissoconchs (~ 1.3–1.4 mm) exclusively on the dorsal wing membrane.Taking into account geological, sedimentological, paleontological and paleo-oceanological data a novel taphonomic model is presented here. After a short period of drifting along the water/air contact layer “Palaeoptera” sank directly to the bottom whereas the soft-tissued abdomens of Neoptera began to decay under these oxic conditions. After loosing their abdomen the corpses sank to a pycnocline in a strongly stratified water body where a second period of drifting took place. At this stage the wings were settled by attaching bivalve larvae derived from a river. When the weight of the shells increased the insect/bivalve association broke through the pycnocline and sank to the bottom where they were finally embedded and fossilized.

► Young bivalves are attached to Fossil Neoptera wing surfaces from Hagen-Vorhalle. ► They lack in corresponding “Palaeoptera” from the same strata. ► Bivalve larvae affected Neoptera during intra-water drifting along a pycnocline.