FIGURE 5. H. niobrarensis P4s from Valentine Railway Quarries (modified from Bair 2007). Wear series superimposed on plot showing correlation between crown height and occlusal dimensions, from left to right. Scale bar equals 1 mm; occlusal view above, posterior view below. 5.1, UNSM 122643. 5.2, UNSM 122648. 5.3, UNSM 122637. 5.4, UNSM 122645. 5.5, UNSM 122653. 5.6, UNSM 122939. 5.7. 'composite' P4 constructed by overlay of posterior view of 5.1, 5.4, and 5.6. Lines on plot show linear regressions; upper white circles for occlusal width, lower black circles for occlusal length. Gray width circles mark location on plot of specimens 5.1-5.6.