The name Chubutolithes was proposed by Ihering (1922) for an unknown type of fossil occurring in Eocene continental rocks of Patagonia, Argentina. Bown and Ratcliffe (1988) demonstrated that Chubutolithes is a trace fossil; specifically, it is the fossil nest of a mud-dauber. The latter authors also suggested that Chubutolithes was constructed by an insect belonging to the hymenopteran family Sphecidae, and coined the specific name C. gaimanensis for the unusual trace fossil. Comparison with a Recent nest of the mud-dauber Auplopus (Pompilidae; Figure 1.1) suggests that Auplopus is a much more likely candidate as the architect of Chubutolithes than are any sphecid mud-daubers.