Extended Data Fig. 9: Comparison of hypotheses on lower molar cusp homologies of shuotheriids and docodontans.

A. Conventional interpretation of the lower molar structures of Shuotherium; the neomorphic pseudotalonid of the molars is marked in green. B. A hypothetical dental occlusal relationship in Shuotherium based on the conventional interpretation. In addition to what has been explained in the text and Fig. 3, an additional issue is that the ultimate upper premolar of Shuotherium would not have a pseudoprotocone because there is no area in px to receive it. This contradicts the fact that px is already submolariform (enlarged and widened). C. Dental structurers reinterpreted under the new hypothesis (see Fig. 3 and text). D. A hypothetical dental occlusal relationship in Shuotherium under the new hypothesis. The ultimate upper premolar (Px) and even the penultimate premolar may have the pseudoprotocone, as in Feredocodon. E-H. Comparison of cusp homology hypotheses in the lower molar of shuotheriids and docodontans. Abbreviations: c-g, cusp g; trd, trigonid; pad(b), paraconid (cusp b); phy, pseudohypoconid; ptad, pseudotalonid; ptrd, pseudotrigonid.