Figure 3: Morphological character evolution mapped onto the phylogenetic tree derived in this study (a) and structure of jaw suspension of C. anguineus (b). (a) Divergence time for each node of Selachii was estimated by the divergence time of Selachii and Batoidea (213.4 Mya (203.3~228.8 Mya in the 95% confidence intervals)) [24]. The red line extending from the circled node indicates the evolutionary time (115.4 Mya) of the divergence of Hexanchiformes from the other Squalomorphi lineages. Numbers above the branches indicate the gill cleft numbers, and numbers above the nodes indicate range of the divergence time. The schematic diagrams of jaw suspension were based on previous reports [3, 13, 25]. (b) Vertical, horizontal, and grid-lined areas and black and white areas indicate lower jaws (Meckel’s cartilage), upper jaws (palatoquadrate), hyomandibular and ceratohyal cartilages, and cranium, respectively. Red and orange arrows in the schematic diagram of the jaw suspension apparatus indicate orbital and postorbital articulations, respectively.