when described "pachycondyla petrosa" was known from a single fossil insect which is a compression-impression fossil preserved in layers of soft sedimentary rock. along with other well preserved insect fossils, the "p. petrosa" specimen was collected from layers of lutetian messel formation rock in the messel pit world heritage site. the messel formation is composed of brown coals, oil shales, and bituminous shale, which preserved numerous insects, fish, birds, reptiles, and terrestrial mammals as a notable lagerstätten. the area is a preserved maar lake which initially formed approximately 47 million years ago as the result of volcanic explosions.