Fig. 2

Bayesian maximum-clade-credibility tree based on the concatenated mitochondrial coding genes dataset in BEAST 2.5.1 with a strict clock, showing the estimated divergence time of Chelicerata species. Node shows the mean estimated divergence times in million years ago (MYA). Purple bars indicate 95% confidence levels. On the time axis, the green bar shows the divergence time for split of the scorpion from horseshoe crabs; the brown bar shows the inner split time of the three spiders; the blue bar shows the origin of the the last common ancestor of Asian horseshoe crabs (including T. tridentatus) and L. polyphemus; the red bar shows the inner split of C. rotundicauda and T. tridentatus