FIG. 4 in The Serrialis Bone, Interparietals, "X" Elements, Entotympanics, And The Composition Of The Notoungulate Caudal Cranium

FIG. 4. Caudal cranium of adult Nesodon ovinus, as illustrated and interpreted by Roth (1903: pl. III, fig. 2; original magnification, cited as approximately one-third natural size); lateral aspect. The label "serrial" is simply floated over the external acoustic meatus, with no bounding sutures indicated, making it impossible to evaluate Roth's (1903) reason for discriminating it as such. Roth's key (terminology translated, updated, and annotated as in fig. 3): 3, occipital condyle; 4, paroccipital process; 5, retrotympanic process; 6a, "pars mastoidea" (= caudal section of pars canalicularis, exposed on margin of posttemporal canal); 7, crista meatus; 9, glaserian fissure; 11, retroarticular process; 12, mandibular fossa; 13, articular tubercle; 14, "incisura mastoidea" (= cleft between crista meatus and retrotympanic process); 21, external acoustic meatus.