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

Abstract

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.

Keywords:

• Ichnotaxonomy
• Coprinisphaera, Quirogaichnus, dung-beetle brood balls

ACKNOWLEDGEMENTS

The author gives thanks to Jorge F. Genise and Eduardo S. Bellosi for fruitful ideas, comments, and the English translation of the first version of the manuscript.

Thanks also to Alberto Riccardi, Chief of the División Paleozoología Invertebrados of the Museo de La Plata, to Wilfredo Fernandez and Jorge Frogoni of the Museo Municipal “Lucas Roselli” of Nueva Palmira, Uruguay, and to Roberto Scaglia of the Museo Municipal de Mar del Plata “Lorenzo Scaglia” for allowing the examination and borrow of material. To Renato Serna of Repsol Ecuador for providing Ecuadorian specimens. To Ichnos reviewers Chris Baldwin and Alfred Uchman and co-editor Andrew Rindsberg. To Angel Fusaro, photographer of the Museo Argentino de Ciencias Naturales, to Mirta González and María Victoria Sanchez of the División Icnología of the same museum for collaboration in handling the material, and to Federico Laza for his help with drawings. This research was partially supported by grants PICT 13286 to Jorge F. Genise; and US NSF EAR-00-87636 to R. Kay and R. Madden.