Figure 3.

Morphology and temporal distribution of early artiodactyl endocasts. Endocasts are figured in dorsal view, anterior tip (olfactory bulbs) pointing upwards. Colour codes for stratigraphical ranges of each taxon coincide with their phylogenetic affinities among non-artiodactyls (black), stem artiodactyls (grey) and crown artiodactyls (see the phylogenetic tree for colour codes; phylogenetic relationships according to Asher & Helgen [35] and Meredith et al. [36]). The main neocortical sulci are highlighted in red; accessory sulci are figured in black. Each genus typifies an artiodactyl family: Diacodexeidae (Diacodexis), Homacodontidae (Homacodon), Helohyidae (Helohyus), Cebochoeridae (Cebochoerus), Dichobunidae (Dichobune), Choeropotamidae (Tapirulus), Dacrytheriidae (Dacrytherium), Protoceratidae (Leptotragulus), Oromerycidae (Protylopus [3]), Cainotheriidae (Robiacina), Agriochoeridae (Agriochoerus), Hypertragulidae (Hypertragulus), Mericoidodontidae (Bathygenys [23], fig. 4) and Entelodontidae (Entelodon). Pleuraspidotherium illustrates endocast morphology of an archaic ungulate (‘condylarth’) closely related to Artiodactyla [51]; Xenicohippus illustrates early equid endocast. The parts reconstructed after comparison to closely related taxa appear in light grey. Endocasts not to scale.