Qualitative and quantitative comparisons with extant and extinct species allowed taxonomic assignment of most specimens. Most quantitative comparisons were based on the following variables:

1. Length of the maxillary alveolar row (LMAX). Front edge of alveolus of P3 to back edge of alveolus of M3.

2. Length of lower alveolar row (LMAND). All but Cynomys: front surface of anterior root on p4, in line with alveolar border (lateral view), to back edge of alveolus of m3. For Cynomys: same except anterior boundary was front edge of alveolar row of p4, to be consistent with Goodwin (1995b). In both cases, recorded length is the average of two replicates.

3. Dimensions of p4 length (Lp4), trigonid width (WTrp4), and talonid width (WTlp4). Lengths and widths of upper cheek teeth, and lengths and trigonid widths of other lower cheek teeth, were taken in selected cases.

In selected cases, quantitative variation within and across taxa was explored graphically and statistically (ANOVA) using Systat 5 for the Macintosh (Systat, Inc., Evanston, Illinois). For Cynomys, quantitative comparisons were done with all lower cheek teeth. Adult specimens with unworn to moderately worn teeth were measured. Relative abundances were estimated using minimum numbers of individuals per taxon (MNI), calculated separately for each site (small sites and MS), individual level (in the Pit), or horizon (VR-DMNH). Variation in relative abundance was examined graphically.

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