Figure 5. Ancestral state reconstruction of the patella in Mesozoic mammals (see Fig. S4 for alternative tree topology).

The main tree shows a parsimony reconstruction using unordered character states, where branch colour indicates reconstructed state. Maximum likelihood gives similar results to parsimony, and likelihood values for numbered nodes are displayed (inset). Crown Metatheria and Eutheria are further explored in Figs. 6 and 7. Our results suggest that the ossified patella has evolved at least five times within Mammaliaformes.