Table 5. Wear pattern of the upper and lower molars of Abdounodus hamdii: attritional wear facets and related occluding structures.
C1-6 primitive shearing facets of tribosphenic molars following the nomenclature of Crompton [31], B1-B10 shearing facets of lophodont molars described by Butler [32].
| Attritional wear facets (all phase I) | Shearing occlusal structures (Table 4) | Specimen | Comments | ||
|---|---|---|---|---|---|
| Tribosphenic molars (Crompton 1971) | Lophodont molars (Butler 1952) | upper molars | lower molars | ||
| C1 | B2 | 1: Preparacrista-preprotocrista / protocristid | MHNM.KHG.154 | Holotype, OCP DEK/GE 308, MNHN PM35, OCP DEK/GE 310, PM67, PM68, MNHN PM92 | Predominant attritional wear and function in Abdounodus |
| C2 | B1 | 2: Postmetacrista / paracristid | Absent or weak | Weak, except MNHN PM35, PM67 | Reduced attritional wear and function in Abdounodus |
| C3 | B6 | 3: Postparacrista / cristid obliqua | Weak | Weak: PM68 | Reduced attritional wear and function in Abdounodus |
| C4 | B7 | 4: Premetacrista / Hypoconid-postcristid | MHNM.KHG.154 | Holotype, OCP DEK/GE 308, MNHN PM35, OCP DEK/GE 310, PM67, PM68 | C4 > C3 and extended lingually to metacone—possibly related to metaloph development |
| C5 | B3 | Preprotocrista-protocone mesial / protocristid-metaconid distal | MHNM.KHG.154 | PM67, PM68,? MNHN PM92 | In continuity with C1; protoloph / protolophid shearing pair |
| (modified C61) | B9 | 6: Protocone distal / entoconid mesial-hypolophid | MHNM.KHG.154 | OCP DEK/GE 308, MNHN PM35, PM67 | Interloph / hypolophid occlusion |
| (modified C9? 2) | B10 | 5: Protocone lingual / hypoconid apex-hypolophid | MHNM.KHG.154 | Holotype, OCP DEK/GE 308, MNHN PM35, OCP DEK/GE 310, PM67, PM68 | Interloph / hypolophid occlusion |
| - | B8 | 7: Metaconule mesial / entoconid distal | MHNM.KHG.154 | PM68 (M3), MNHN PM92 | Metaconule-Interloph / hypolophid occlusion (= posterior loph shearing) |
| - | B5? | 8: Metaconule distal / postentoconulid-hypoconulid mesial | MHNM.KHG.154 (M3) | OCP DEK/GE 308, MNHN PM35, OCP DEK/GE 310, PM67, PM68, MNHN PM92 | Homology with facet B5 of Butler (1952)? |
(1) resulting from the regression of the postprotocrista and the development of the hypolophid by comparison to the tribosphenic pattern
(2) possible modification the grinding occlusal contact 9 (facet C9) of the tribosphenic molars for shearing with the hypolophid (see text)