described Mesocetus schweinfurthi based on a dorsoventrally compressed skull with only I2 in situ, a specimen supposedly originating from a 40 Ma Tethyan deposit at Mokattam. Fraas also referred two isolated teeth, P4 and M1, to the skull and the most important of his specimens is not the deformed skull, but the upper molar which retains three roots and a worn but well-developed protocone. Georg August Schweinfurth, a German palaeontologist who explored Mokattam in the 1880s, mentioned the quarriers there very eagerly offered shark teeth to tourists and that scientists and fossil collectors regularly bought their specimens from this source. There is reason to assume that Fraas were among them and that at least his two isolated teeth were described without direct knowledge of their original locality and stratigraphic context. Notwithstanding that the stratigraphic information supplied by Fraas and his contemporaries can be difficult to interpret, the geology of Egypt is well-studied, and both the skull and the accompanying teeth are most likely Bartonian in age — older and significantly more primitive than any other cetacean specimen known from Egypt at that time. Fraas soon discovered that the name Mesocetus was already occupied, and changed the name of his Urform Protocetus to Eocetus.