Cribriform plate and olfactory bulb in extinct cetaceans.
a. Skull of the pakicetid cetacean Ichthyolestes pinfoldi (H-GSP 98134, described by Nummela et al. ) in ventral view, rectangle indicates detail shown in (b). b. Detail of (a), showing the dorsal side of the cribriform plate with some of its perforations encircled, and the lateral wall (LW) of the olfactory chamber. c. ventral view of the endocast of the cranial cavity of the remingtonocetid cetacean Remingtonocetus (IITR-SB 2770, described by Bajpai et al. ) based on 3D reconstruction of CT-scans, showing impressions of olfactory tract (OT) and olfactory bulb (OB), area in box is enlarged in (d). d-g. impression of olfactory bulb in ventral, dorsal, lateral, and cranial view respectively, dorsal and rostral view show midline dorsal crest (DC), and lateral view shows the contrast between convex ventral side where cranial nerve I pierces the cribriform plate (CP), and flat dorsal side.