FIGURE 2. Dental terminology and methodology for measuring Sigmodon m1. Length (A) and width (B) were measured on the occlusal surface. The enamel height (C) was measured on the lingual side of the tooth from the tip of the metaconid to the lower extent of the enamel, perpendicular to the straight portion of the linea sinuousa below the anteroconid, metaconid, and entoconid. Abbreviations: acd, anteroconid; BRA 1 and BRA2, first and second buccal reentrant angles; LRA1, LRA2, and LRA3, first, second, and third lingual reentrant angles; ent, entoconid; hyp, hypoconid; met, metaconid; pos, posterolophid; pro, protoconid (following Martin and Prince 1979).