Fig. 2

The Paleozoic age of the hagfish radiation. Boxplots (A) generated using the R package ggplot2 for divergence times of major hagfish lineages under different fossil calibration schemes and those reported in a previous study. Note the similar ages estimated for these lineages regardless of the inclusion of †Myxinikela siroka as a fossil tip calibration, and the much older ages for all major hagfish clades except Rubicundinae estimated in this study compared to previous estimates based on smaller molecular datasets and less-inclusive taxon sampling. Panel (B) shows the ages of major vertebrate crown groups. Hagfishes are the third oldest, exceeded only by the far more species rich and morphologically disparate lissamphibians (frogs, salamanders, and caecilians) and chondrichthyans (sharks, rays, skates, and chimaeras). Silhouettes are public from phylopic.org, Wikimedia commons, and by CDB