We generated a unique timescale for primates by predicting molecular rates from the reconstructed phenotypic values for a large phylogeny of living and extinct primates.
This analysis suggests that crown primates originated close to the K–Pg boundary and possibly in the Paleocene, largely reconciling the molecular and fossil timescales of primate evolution.
Nevertheless, the application of these methods still results in large differences between paleontological and molecular estimates for many primate groups (Fig. This discordance is particularly striking for the origin of the primate crown group, because recent molecular studies suggest a Late Cretaceous estimate (an average of ∼82 Ma) for this event and yet the oldest crown primate fossils are ∼56 Ma old (15)—a difference of ∼45%.
–7), and this phenomenon can lead to inaccurate or biased molecular clock estimates.This problem has precipitated the development of methods that model rate variation across lineages to date phylogenies when rates vary (8–11).