Fig. 3. Micromorphology of brood balls made by Sulcophanaeus menelas and Sulcophanaeus imperator. A) Brood ball of S. menelas showing the wall (between white arrows) mostly composed of soil material and scarce dung fibers, the intermediate zone composed of elongated dung fibers, which are oriented parallel to the wall, and subordinated minerals, and the central part of the provision (black arrows) (scale bar = 1 mm), B) Spherical egg chamber in the brood ball of S. menelas lined by brown, amorphous organic matter (white arrows); the egg chamber roof shows an aeration conduit filled with longitudinal dung fibers (black arrows) (scale bar = 2.5 mm), C) Protuberance on the brrod ball of S. imperator showing similarity between external wall (white arrows) and the egg chamber wall (black arrows); note the coarse grains included in the provisioned dung between both walls (scale bar = 1.5 mm), D –E) Detail of the egg chamber wall of S. imperator showing parallel alignments of elongated mica grains (D taken with parallel light, E taken with polarized light) (scale bars = 1.5 mm).