Dung-Beetle Fossil Brood Balls: The Ichnogenera Coprinisphaera Sauer and Quirogaichnus (Coprinisphaeridae)

Coprinisphaera is one of the most common trace fossils in South American paleosols from the Eocene to the Recent. Nevertheless, an ichnotaxonomical review of this ichnogenus has been lacking until now. The revision of hundreds of specimens of Coprinisphaera from numerous formations in Argentina, Uruguay and Ecuador has resulted in the recognition of two ichnogenera. One of them, Coprinisphaera, includes isolated, spherical, subspherical, pear-shaped and bispherical structures grouped in five ichnospecies: C. ecuadoriensis Sauer, C. murguiai (Roselli), C. kraglievichi (Roselli), C. tonni isp. n., and C. kheprii isp. n. The new ichnogenus and ichnospecies, Quirogaichnus coniunctus, consists of Coprinisphaera-like structures clustered in a common excavated chamber. The ichnotaxobases for the taxonomical arrangement of Coprinisphaera are mostly related to the presence and position of a small chamber (interpreted as the original egg chamber) with respect to a large chamber (provision chamber) and emergence hole. The egg chamber may be included in (1) the provision chamber, leaving no remains in the trace fossils and resulting in cylindrical emergence holes; (2) the wall of the provision chamber, without additional structures; and (3) a mamillate to spherical additional structure, external to the provision chamber, resulting in pear-shaped to bispherical trace fossils.