Figure 13 in A transitional species of Daspletosaurus Russell, 1970 from the Judith River Formation of eastern Montana

Figure 13 Time-calibrated sequence of Daspletosaurus chronospecies. Ages (left) are in Ma and are based on Carr et al. (2017) and Fowler (2017) for D. torosus and D. horneri. Representative skulls are, from top to bottom: D. horneri, MOR 590; D. wilsoni, BDM 107 (known material in white); D. torosus, CMN 8506. Stars represents the temporal position of adjacent specimens. Accompanying characters represent synapomorphies of progressively more exclusive clades represented by each taxon (e.g., D. wilsoni + more derived tyrannosaurines, D. horneri + more derived tyrannosaurines). No clear demarcations are drawn between taxa along the depicted lineage, given the relative paucity of specimens and the subjectivity intrinsic to species delineations of anagenetic lineages; ages of taxa are therefore imprecise. Scale is 10 cm. Full-size DOI: 10.7717/peerj.14461/fig-13