When we repeated this analysis removing the fossil calibration date based on Stirtonia, estimated divergences among the atelids are shifted to be slightly more recent. With no Stirtonia calibration, the estimated age of the most recent common ancestor (MRCA) of the family Atelidae is inferred to be 11.1 Ma and that of Ateles to be 5.7 Ma (Table 6). Exclusion of the A. marginatus sequence from our dating analysis likewise yields slightly more recent divergence date estimates among the atelids. Here, the MRCA of atelids is esti- mated at 13.0 Ma and that of Ateles is inferred to be even more recent, at 4.4 Ma (Table 6).