Upper pleistocene blow flies (Diptera: Calliphoridae) trapped in fossilized crania of large mammals discovered from gravel pits in the rhine rift valley from hesse (Germany)

Abstract

Fossil blow fly remains, discovered from cranial fragments of four Upper-Pleistocene large mammals (two Mammuthus primigenius, one Megaloceros giganteus and one Bos primigenius), could be identified as puparia of Protophormia terraenovae (Robineau-Desvoidy). The material was discovered from fluvial deposits of the ancient Rhine near Darmstadt (Hessen, Germany). The preservation of the puparia is exceptional. The four individuals of large mammals died separately, but all cadavers lay for a certain time likely on dry ground or were sitting by or in shallow water or sediments in an approximated temperature of 10°C or higher (based on current data). During the decomposition, the cadavers were colonized by gravid blow flies, which deposited eggs on natural body orifices and open wounds. Larvae hatched, fed on moist tissue, passed all larval stages and pupated. Shortly after the emergence of the fully developed blow flies, mammal remains were submerged and embedded. Thus they were trapped for fossilisation. Most individuals of Protophormia terraenovae found inside the cranial fragments of Megaloceros giganteus had died inside their puparia maybe as a consequence of freezing, drowning or smothering.