Molecular Decay of the Tooth Gene Enamelin (ENAM) Mirrors the Loss of Enamel in the Fossil Record of Placental Mammals
Figure 4
A synthetic interpretation of the history of enamel degeneration in Pholidota (pangolins) based on fossils, phylogenetics, molecular clocks, frameshift mutations, and dN/dS ratios.
Estimates for the timing of the transition from functional gene to pseudogene are based on decomposition of mixed dN/dS history into two distinct episodes of evolution under purifying selection and neutral evolution, respectively. The divergence time between Pholidota and Carnivora (79.8 mya) is from Murphy and Eizirik [23]. The divergence time between Manis pentadactyla and M. tricuspis (27.9 mya) is based on molecular dating analyses with ENAM (see Methods). The age of the oldest pangolin, Eomanis from the Eocene Messel deposits of Germany, is ∼47 mya [29].