Fig. 1. Phylogeographic relationships of American mastodons.

a Locations of specimens included in this study. Circles indicate specimens for which complete mitochondrial genomes were obtained, coloured according to their clade assignment. Stars indicate previously sequenced specimens (EF632344, Alaska; NC_035800, Massachusetts). The locations of specimens from Alberta and eastern Beringia have been jittered to aid visualisation (see Supplementary Fig. 2 for an unmodified version). b Phylogenetic tree inferred by the Joint analysis. Median posterior ages are given for major nodes in the tree. Support values for each node represent posterior probabilities from the Joint (PP_JT) and Individually Dated (PP_ID) analyses. The δ¹⁸O record for the last 3.5 million years is shown below the tree⁷, with the approximate extent of the MIS 5 interglacial period shaded in grey. Clades identified in this study are designated by colour and named where possible by the geographic provenance of their members (i.e., A Alaska, Y Yukon, G Great Lakes, M Mexico, N Nova Scotia, L Alberta/Missouri). Specimens with finite radiometric or geological ages are indicated with asterisks.