Fig. 1 in Reexamination of the mandibular and dental morphology of the Early Jurassic mammaliaform Hadrocodium wui

Fig. 1. Lower jaws of comparative mammaliaforms. A. Hadrocodium wui Luo, Crompton, and Sun, 2001 (holotype, IVPP 8275), from the Lower Lufeng Formation, Lower Jurassic of Yunnan, China. Right mandible in lingual (A1) and labial (A2) views. B, C. Morganucodontan Dinnetherium nezorum Jenkins, Crompton, and Downs, 1983, from the Kayenta Formation, Lower Jurassic of Arizona, USA. B. An older adult (MCZ 20910). C. A young adult (MCZ 20870); modified from Crompton and Luo 1993). Younger individuals of D. nezorum have a full set of five premolars, while older individuals have lost up to two anterior premolars without replacement. The postcanine diastema developed by shedding premolars without replacement is an aging-related character of many mammaliaforms including Hadrocodium.