FIGURE 6. H. niobrarensis M1s and M2s from Valentine Railway Quarries. Teeth are arranged in order of increasing wear stage, from left to right. Standard orientations as in Figure 2. Each lettered pair shows occlusal view (above) and posterior view (below). Scale bars for occlusal and posterior views next to 6.1 also indicate scale for all other specimens. 6.1-6.5, M1s. 6.1, UNSM 122519. 6.2, UNSM 122523. 6.3, UNSM 122707. 6.4, UNSM 122718. 6.5, UNSM 122704. 6.6-6.8, M2s. 6.6, UNSM 123097. 6.7, UNSM 12286. 6.8, UNSM 122811.