Age, origin, and biogeography: Unveiling the factors behind the diversification of dung beetles

11 The remarkable diversity and global distribution of dung beetles has long attracted the interest of 12 researchers. However, there is still an ongoing debate on their origin, the reasons behind their 13 diversity, and their path to global distribution. The two most prominent hypotheses regarding 14 their origin and biogeographic history involve either vicariance events after the breakup of 15 Gondwana, or an African origin and subsequent dispersal. One of the key reasons why the 16 question is still disputed is a dependence on knowing the age of the dung beetles-a Mesozoic 17 origin would favor the scenario of Gondwanan vicariance, a Cenozoic origin would suggest the 18 out-of-Africa scenario. To help settle this longstanding question, we provide a taxonomically 19 expanded phylogeny, with divergence times estimated under two calibration schemes suggesting 20 an older or younger origin respectively. Using model-based inference, we estimate the ancestral 21 area of the group and test for the influence of ranges on diversification rates. Our results support 22 the hypothesis of an old age for Scarabaeinae and Gondwanan origin but remain ambiguous 23 about the exact relation of range on lineage diversification.