Figure 44 in The scorpion sternum: structure and phylogeny (Scorpiones: Orthosterni)

Figure 44: Charogram showing hypothesized evolution of the scorpion sternum for infraorder Orthosterni. Character derivations are depicted on the bottom of the branches (enclosed in rectangles) and subclades and taxa are shown on the top of branches or as terminal nodes. Type 1 sterna is considered plesiomorphic to all Recent scorpions being established for the palaeopisthacanthids; all type 1 sterna Recent taxa are depicted as "primitive" and type 2 sterna taxa, globally identified as those scorpions complying to Type C orthobothriotaxy, are considered "non-primitive". We suggest all buthoid scorpions exhibit some degree of horizontal compression, but in highly variable degrees. It is unknown whether the bothriurid genus Lisposoma shows vertical compression, so it is depicted separate from the bothriurids proper which exhibit vertical compression.