Fossil record and evolution of Scarabaeoidea (Coleoptera: Polyphaga)

The fossil record of scarab beetles (Coleoptera: Scarabaeoidea) is reviewed and its relevance for the reconstruction of the evolutionary history of the taxon is explored. After a discussion of the different kinds of preservation of scarab fossils, including preservation of color, the richest scarab deposits are identified. From the fossil record, the minimum age of Scarabaeoidea is determined as 152 myr. To develop an idea about the appearance of the first scarab, the ground-pattern of Scarabaeoidea is reconstructed for the first time on the basis of published phylogenetic analyses. Extinct scarabaeoid family-group taxa are described and discussed. Cretocomini and Cretoglaphyrini are upgraded to subfamily rank for reasons of consistency. Most of their diagnostic character states are controverted or not polarized. The minimum age of extant scarabaeoid family-group taxa is deduced from the fossil record. Ancient feeding habits, particularly the development of coprophagy, are discussed. The youngest extinct species described are from the Pleistocene, whereas extant species have been recorded since the Pliocene.