Figure 9

Hypothetical relationships of the major clades of turtles and the evolution of the basipterygoid process and the carotid artery circulation system. The cladogram is the strict consensus tree of 9261 trees of 870 steps obtained after a parsimony analysis of 237 morphological characters and 84 extinct and extant turtle taxa. The relationships of Durocryptodira [1] were constrained after the molecular phylogeny of Barley et al. [79]. Note the unorthodox position of Xinjiangchelyidae outside of Testudines. The more traditional phylogenetic placement of Xinjiangchelyidae [3] is presented on the right for comparison. Taxa in bold are figured in Figures 10, 11, 12. Numbers correspond to nodes.