File:Erythrotherium, Morganucodon & Megazostrodon occlusion.png

English: Comparison of the occlusal hypothesis for m2–m3 and M1–M2 of morganucodontan mammaliaforms Erythotherium parringtoni (Crompton, 1964), SAM-PK-K00359; Late Triassic, South Africa, Mafeteng locality, Upper Red Beds (A), Morganucodon watsoni (Kühne, 1949), UMZC Eo.CR.1; Early Jurassic, United Kingdom, Glamorgan fissure systems, Pontalun 3 (B), and m1–m2, P5 and M1 of Megazostrodon rudnerae (Crompton and Jenkins, 1968), NHMUK PV M26407; Early Jurassic, South Africa, Lesotho, Red Bed Series (C). Lingual view of Erythrotherium embrasure occlusion and Morganucodon-like occlusion, compared in early (A1, A5), middle (A2, A6), and late (A3, A7) stages of the power stroke. Occlusal view of late stages of the power stroke of Erythrotherium with embrasure occlusion (A4) with Morganucodon-like occlusion (A8), Megazostrodon (B) and Morganucodon (C), note sufficient space between cusps a and c to accommodate cusp A. Additionally, the upper molars are angled to provide space for cusp a, especially the very large cusp a of m2. In comparison, the space between cusps a and c in Erythrotherium is much smaller and both lower and upper molars are aligned in a straight line, similar to Megazostrodon (A4 , B). Therefore, Morganucodon-like occlusion in Erythrotherium lacks contact for the b/B and d/D cusps (A8). Embrasure occlusion on the other hand results in collision detection on all major cusps and correlates with observed wear facets (A4). This becomes most apparent in the later stages of the power stroke (A3 ), where embrasure occlusion results in well-aligned teeth with the a/A cusps utilizing the space between two antagonists. With Morganucodon-like occlusion the direct contact of the a/A cusps prevents close contact of the smaller cusps (A 7, A8). Colored regions represent contact areas during the OFA analysis, for comparison see Jäger et al. (2019). Mesial is to the left. Not to scale.