Fig. 11 in Phylogenetic Studies On Didelphid Marsupials Ii. Nonmolecular Data And New Irbp Sequences: Separate And Combined Analyses Of Didelphine Relationships With Denser Taxon Sampling

Fig. 11. Unworn premaxillary dentitions of Marmosops pinheiroi (A, AMNH 267341) and Lutreolina crassicaudata (B, AMNH 210422) illustrating taxonomic differences in the shape of the incisor crowns. In Marmosops and many other small didelphines, the crowns of I2–I5 are symmetrically rhomboidal, with subequal anterior (mesial) and posterior (distal) cutting edges that converge to form a sharp central apex; a distinct posterior corner (distostyle) is always present on I5. By contrast, in Lutreolina (and certain other taxa), the crowns of I2–I5 are conspicuously asymmetrical, with longer anterior than posterior cutting edges; a distinct distostyle is usually absent on I5. Scale bars = 1 mm.