Figure 1:2 Tree of Ursid Ancestors (Cladogram)
Phylogenetic trees for ursids have been proposed by Erdbrink (1953??), Thenius (1979), and Wayne et al. (1989). The latter paper is based on molecular and biochemical data; I assume it to be most accurate for the limited range of species it addresses. I have incorporated data from all 3 sources, and others cited in the foregoing narrative, to construct the phylogenetic tree shown in 
Fig. 2:1.
Fig. 2:1.