Fig. 22 in Braincase Of The Upper Devonian Shark Cladodoides Wildungensis (Chondrichthyes, Elasmobranchii With Observations On The Braincase In Early Chondrichthyans

Fig. 22. Otic region of the Cladodoides braincase (surface rendering), oblique perspective detail views. (A) Anteromedial view; (B) anterolateral view; (C) posterior view; (D) posteromedial view. This block overlaps slightly with that depicted in figure 17, repeating the exit of the hyomandibular trunk. Note the absence of a medial wall to the saccular chamber, utricular recess, and crus commune, although the semicircular canals are almost completely enclosed by cartilage. The position of the octaval (acusticovestibular) nerve is indicated, but is more clearly seen in sections (see fig. 18E). The hypotic lamina extends beneath the otic capsule, forming a wide glossopharyngeal canal and a short metotic fissure. The lateral dorsal aorta is enclosed by cartilage posteriorly, then emerges ventrally. The uneven internal floor and thickened cranial roof in front of the posterior dorsal fontanelle are artifacts of digital interpretation, as the braincase wall is poorly calcified in these areas; it is unlikely that the synotic tectum was originally as thick as shown here.