FIG. 7 in The Serrialis Bone, Interparietals, "X" Elements, Entotympanics, And The Composition Of The Notoungulate Caudal Cranium

FIG. 7. Oldfieldthomasia cf. debilitata AMNH-VP 28600, left hemicranium, virtual coronal section; for approximate location see figure 1B; lateral to right. In this section, the only suture found on preserved part of lateral wall of auditory region is the squamoso-ectotympanic suture; retroarticular process formed jointly by squamosal and ectotympanic, with no evidence of additional element Xa. Petrosal material contributes modestly to medial margin of aditus to epitympanic sinus and therefore to thecal wall. Matrix (see fig. 1) filling epitympanic sinus has been partially removed to facilitate labeling. Auditory ossicles—fragments of malleus and incus—are out of position in aditus to epitympanic sinus.