Fig. 27 in Phyletic Diversification Of The Cormohipparion Occidentale Complex (Mammalia; Perissodactyla, Equidae), Late Miocene, North America, And The Origin Of The Old World Hippotherium Datum

Fig. 27. Cladogram of species of Cormohipparion, with outgroups of Parahippus leonensis, ''Merychippus'' primus, M. insignis. Tree length is 93; Consistency Index is 0.849; Retention Index is 0.770; Homoplasy Index is 0.208. Bootstrap values are in boldface. Based on a character distribution analysis via MacClade 4.08. Node 1 is the outgroup, Parahippus leonensis. Node 2 shows that ''M.'' primus can be distinguished by the lacrimo-jugal and maxillo-lacrimal sutures forming a right angle (15:0). At Node 3, the mesodont taxa M. insignis + Cormohipparion are distinguished by having an anteriorly oriented nasomaxillary fossa (5:1); maxillo-lacrimal and naso-lacrimal sutures form an acute angle (14:2); P2 protocone connecting to the protoloph in late wear (50–60%; 20:4); premolar anterior postfossette plis are 2–3 (25:1); molar anterior postfossette plis are 2–3 (26:1); molar pli caballin is usually single (30:1); protocone is isolated from, rather than connected to, the protoloph (34:1); and the orbit is positioned above M3 (38:1). Merychippus insignis is distinguished by having the IOF above P4 (10:2); the length ratio of dP1–P2 is about 50% (17:1); the hypoconal groove in the cheek teeth has 1–2 plis (33:1). At Node 4 (Cormohipparion), the lacrimal fossa is absent (1:1); the anterior end of the lacrimal fossa thus is absent (4:2); the IOF is aligned with the lower one-third of the orbit (12:1); the lacrimal is pointed anteriorly (13:1); the upper premolars have 4–5 plis in the posterior border of the prefossette (23:2); the upper molars have 4–5 plis in the posterior border of the prefossette (24:2); the lower premolar ectoflexid retracts from the metaconid/metastylid in early wear (31:1); and the IOF is located below the anterior end of the nasomaxillary fossa (37:1) C. goorisi is distinguished by having the P2 protocone connect to the protoloph within 40–50% wear (20:3); the lower premolar isthmus is not developed in early wear (32:1). At Node 5, there are 4–5 plis in the premolar anterior border of the postfossette (25:2); the premolar pli caballin is usually double (29:2); and the protocone lacks a spur (35:1).