An Ossified Meckel's Cartilage in Two Cretaceous Mammals and Origin of the Mammalian Middle Ear Yuanqing Wang, Yaoming Hu, Jin Meng, and Chuankui Li

Supplemental Figure 1. Cheek teeth of Repenomamus robustus (holotype, IVPP V12549). (A) lateral view of left lower molariforms (m1-5; m1 broken); (B) crown view (stereo photographs) of right upper cheek teeth (P4-M5; M1 lost). Molariforms share basic structures and occlusal pattern with those of gobiconodontids in having main cusps of lower molariforms mesiodistally arranged with central cusp a tallest, and cusps b and c significantly reduced; upper molariforms transversely wider than lower teeth, with cusp A slightly more lingual than B and C; cusp a of lower molariform occluding between cusps C and D of upper molariform (shearing with cusp A also involved); and cusps e and f and embayment between them interlocking with cusp d of anterior tooth in m2-4. Differing from gobiconodontids in reduction of cingulae and cusp B but inflation of cusp A in upper molariforms, and in having incisors less enlarged.

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