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Tubercular vs. Prismatic Teeth New World Rats & Mice (Peromyscus maniculatus shown) Old World Rats & Mice (Mus musculus shown) Prismatic cusp pattern in.

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Presentation on theme: "Tubercular vs. Prismatic Teeth New World Rats & Mice (Peromyscus maniculatus shown) Old World Rats & Mice (Mus musculus shown) Prismatic cusp pattern in."— Presentation transcript:

1 Tubercular vs. Prismatic Teeth New World Rats & Mice (Peromyscus maniculatus shown) Old World Rats & Mice (Mus musculus shown) Prismatic cusp pattern in murids, voles and lemmings ( note alternating triangles ) (Right upper molariform toothrow of Microtus ochrogaster shown) A = anterior, P = posterior, B = buccal surface, L = lingual surface A L P B Alternating enamel (white ridges) and dentin (light brown material) maintains occlusal surfaces as the tooth wears down; enamel is much harder than dentin ** In each of the following plates the upper right molariform toothrow is shown with the anterior- most tooth at the top and the last molar at the bottom of the photo. The buccal surface (adjacent to the cheek) is to the left and the lingual surface (adjacent to the tongue) is to the right. Plate 6 Tubercular

2 Southern red-backed vole (Clethrionomys gapperi) Meadow vole (Microtus pennsylvanicus) Abrupt palate - Transverse shelf Palate sloping downward Plate 7 Inferorbital foramen Genus Tamias (Tamias amoenus) Inferorbital foramen situated in the Zygomatic plate Black-tailed prairie dog (Cynomys ludoviscianus) Inferorbital foramen situated in projection on maxillary bone (Tree squirrels, ground squirrels, and prairie dogs)

3 Western harvest mouse (Reithrodontomys megalotis) Ventral view of upper grooved incisors Northern bog lemming (Synaptomys borealis) Very deep reentrant angles: (a) upper teeth cut inward from buccal surface, (b) lower teeth cut inward from lingual surface a b Sagebrush vole (Lemmicus curtatus) 3 lingual projections on last upper molar Northern red-backed vole (Clethrionomys gapperi) 4 lingual projections on last upper molar Prairie vole (Microtus ochrogaster) Reentrant angles of upper molariform teeth equal on lingual and buccal surfaces Heather vole (Phenocomys intermedius) Reentrant angles of both upper (a) and lower (b) molariform teeth much deeper on lingual surface than on buccal surface a b Plate 8

4 Meadow vole (Microtus pennsylvanicus) Water vole (Microtus richardsoni) Montane vole (Microtus montanus) M 2 4 closed triangles and posterior loop (arrow) M2M2 loop M 3 with 2 deep reentrant angles on lingual side M 3 with 3 deep reentrant angles on lingual side; no loop on M 2 M2M2 M3M3 Montane vole (Microtus montanus) Incisive foramina constrict abruptly and narrow posteriorly (bracket) Long-tailed vole (Microtus longicaudus) incisive foramina parallel throughout, only slighlty narrower posteriorly Red squirrel (Tamiasciurus hudsonicus) Anterior marginof orbit opposite P 4 (arrow) P4M1P4M1 Plate 9 M3M3

5 Plate 10 Columbian ground squirrel (Spermophilus columbianus) The thirteen-lined ground squirrel (S. tridecemlineatus) has similar characteristics; these two species can be separated by greatest length [GL] (SPCO > 45mm, SPTR < 45mm) Higher power P3P4M1 M2M3P3P4M1 M2M3 Pronounced anterior valley on P 4 - M 3 passes completely across the tooth (arrows) Higher power Golden-mantled ground squirrel (Spermophilus lateralis) Anterior valley on P 4 - M 3 does not pass completely across the tooth (arrows) Ridge of enamel rises up at lingual side of cusp No ridge of enamel rises up at lingual side of cusp


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