Figure 4.

Change in sea-surface temperatures in the South Atlantic Ocean and hypsodonty in ungulate mammals between 39 and 19 Ma. Solid line, foraminiferal ¹⁸O isotope data from K. G. Miller (personal communication), calibrated to the GPTS of Berggren et al. (18). Hypsodonty is expressed as an “Ungulate Hypsodonty Index” (UHI), the weighted sum of bunodont (weight = 1), lophodont (weight = 2), and hypsodont (weight = 3), taxa. If all taxa are bunodont, UHI = 100; if all are hypsodont, UHI = 300. Faunas: A, Barrancan; B, Mustersan; C, Tinguiririca and Astraponotéen plus Supérieur; D, Deseadan of Patagonia; E, Salla, Deseadan; and F, Colhuehuapian.