it is not precisely known from which strata the first few remains of this bird were collected. they were formerly considered of early oligocene age—some 33-30 ma—but this is now assumed incorrect, as only the upper and not the entire jebel qatrani formation is of oligocene age. it is also possible that they are from the slightly older qasr el sagha formation, but as both this and the oligocene parts of the jebel qatrani formation were laid down in an ecosystem markedly different from that of the eocene jebel qatrani formation, it is now assumed that all material of "e. eocaenus" is from the lowest rocks of the jebel qatrani formation.