Figure 4. Phylogeny of Lower Jurassic plesiosaurians.
Temporally-calibrated strict consensus of 42 MPTs recovered from our phylogenetic analysis. Triangular symbols represent non-neoplesiosaurian plesiosaurians (mainly rhomaleosaurids), squares represent pliosaurids and circles represent plesiosauroids. Unfilled shapes represent British taxa whereas grey-filled shapes represent German and French taxa. Key localities yielding abundant remains from four narrow horizons are indicated by grey bands, although contemporaneous specimen are known from other localities: A, Street, Somerset, UK (lowermost Hettangian); B, Lyme Regis and Charmouth, Dorset, UK (late Hettangian–Sinemurian); C, Holzmaden and vicinity, Baden-Württemberg, Germany (H. falciferum Chronozone; lower Hettangian); D, Yorkshire, UK (H. bifrons Chronozone; lower Hettangian). Dashed lines indicate polytomy at base of Pistosauria prior to deletion of Pistosaurus from the set of MPTs.