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. 2017 Dec 13;3(12):e1701144. doi: 10.1126/sciadv.1701144

Fig. 3. Calibrated phylogenetic tree of Middle Triassic to Early Jurassic Eosauropterygia and evolution of key features of Plesiosauria.

Fig. 3

(A) Major features of the tree resemble topologies from previous analyses (4, 11) and uses the same clade names. Rhaeticosaurus mertensi is a sister to the main radiation of Pliosauridae. (B) Evolution of key features of plesiosaurians plotted on the phylogeny of Sauropterygia. Note that these key features were not necessarily recovered as synapomorphies in the phylogenetic analysis and that their arrangement on a specific branch does not imply the order of appearance. Asterisk indicates latest possible appearance of the feature. Lad., Ladinian; He., Hettangian; Pliens., Pliensbachian; Sinem., Sinemurian; Toarc., Toarcian. Geologic time is from Walker et al. (62). The horizontal gray bands indicate that stratigraphic position of the major plesiosaurian faunas in the Lower Jurassic. LR, Lyme Regis; H, Holzmaden; S, Street; Y, Yorkshire.