Figure 8. Fetal skull of Maiacetus inuus (GSP-UM 3475b).

(A)–Photograph showing bones (shaded white) and teeth (shaded brown) in lateral view. (B)–CT image overlain on tooth-bearing part of fetal skull in lateral veiw. Abbreviations: left frontal (L. Front.), left jugal (L Jug.), occipital (Occip.) with left and right condyles flanking the foramen magnum, and left and right dentaries (L dent., R dent.). Teeth are shaded brown, with darker brown representing enamel, and lighter brown representing roots and exposed dentine. White and black labels identify teeth of the left and right sides, respectively. Dotted lines trace outlines of fully formed crowns of left dP³ and dP⁴. These crowns are visible on the surface (A) where thin bone of the maxilla is pressed over more rigid underlying crowns, and as denser masses in the CT scan (B). Remaining teeth are identified by size and position relative to dP³ and dP⁴. Note presence of the developing crown of permanent left M¹ posterodorsal to the crown of left dP⁴ (dorsal to the left jugal and posterior to the left frontal). Partial crown of right M¹ (unlabeled) is visible just below and posterior to left M¹.