FIGURE 3. Morphology of the earliest northeast Siberian steppe and woolly mammoth third molars. a, upper molar from Chukochya (PIN-3341-737); b, upper molar from Krestovka (PIN-3491-3, flipped horizontally); c, partial lower molar from Adycha (PIN-3723-511), occlusal view flipped horizontally. Note the more closely spaced lamellae and thinner enamel in a (primigenius-like) than b and c (trogontherii-like). d, hypsodonty index vs lamellar length index of upper M3s; e, Enamel thickness index vs basal lamellar length index of lower M3s. Olyorian specimens that yielded DNA are labelled by site name. Green dashed line: convex hull summarising Early to early Middle Pleistocene (ca. 1.5–0.5 Ma) North American Mammuthus samples (data points not shown). Green and blue squares: Early and Late Olyorian North-East Siberian samples, respectively; red and green circles: European M. meridionalis and M. trogontherii, respectively; blue circles, M. primigenius from North-East Siberia and Alaska. Note (i) similarity of Krestovka and Adycha to other Early Olyorian molars and to European steppe mammoths (M. trogontherii), (ii) similarity of early North American mammoths to these (Early Olyorian in particular), and (iii) similarity of Chukochya to M. primigenius. From van der Valk et al. (2021), with permission.