Figure 4

Morphospace positions for Mesozoic mammals and the extant and “archaic” ungulates. Mesozoic mammals (coloured in blue) are found near the centre (1,1) of the morphospace, closer to the plesiomorphic conditions of equal-sized molars. “Condylarths”, coloured black, are found mostly in the region of the morphospace where m2 is the largest molar, and are separate from Artiodactyla (dark green) and Perissodactyla (light green), with the exceptions of Hyopsodus, Anisonchus and Lambertocyon, all of which possess molars that increase in size posteriorly. Artiodactyla show the most extreme increase in molar size, with Uintacyon, Elomeryx and Merycoidodon exhibiting six-fold or more increases in molar area from m1 to m3.