Figure 3. Dating genetic divergence times and speciation events in early marsupials.

(A) The reconstructed evolutionary history of the three-lineage bifurcation among the six extant marsupials using three types of concatenated alignments. The Dipr_Dasy alignment (red) containing the type0 loci, where ILS was assumed to be absent, were supported by all four species combinations. The Dipr_Micr ILS alignment (blue) and the Dasy_Micr ILS alignment (green) contained the loci identified as, respectively, type2 and type3 in all four combinations. Names were labeled with plate colors.

(B) The known movements of the South American, Antarctic, and Australian continental plates during the crucial time window of ca. 84–35 mya. The sea-floor spreading began between Australia and Antarctica at ca. 84 mya (left panel). The final separation of Australia and Antarctica along the South Tasman Rise at ca. 45 mya created a shallow marine crust region between Australia and Antarctica that gradually opened further (gray area in middle panel). This process resulted in Australia and Antarctica being fully separated ca. 35 mya at which point also the connection between South America and Antarctica was severed (right panel). This pattern of continental drift excludes the possibility of continuing hybridization between monito del monte and Australian marsupials after their divergence had been completed. South America, Antarctica, and Australia are represented in blue, yellow, and brown, respectively. The contours represent the reconstructed continental plate and the black lines outside the plates represent the submerged continental plate crust areas (Vizcaíno et al., 1998; Williams et al., 2019).

See also Table S3.