. Bulletin of the British Museum (Natural History). 224 P. H. GREENWOOD of a lateral ethmoid (Text-fig. 3). The median ethmoid cartilage barely touches the two frontals in the midline. There is a single, small cuboid and densely " toothed " supraorbital bone on each side. Medially the supraorbital is attached to the lateral ethmoid, and posteri- orly it articulates with the frontal. Clausen (1959) apparently interpreted the entire odontode-bearing margin of the frontal as a supraorbital bone (see his figure i). Since there is no indication of fusion between the supraorbital ledge and
. Bulletin of the British Museum (Natural History). 224 P. H. GREENWOOD of a lateral ethmoid (Text-fig. 3). The median ethmoid cartilage barely touches the two frontals in the midline. There is a single, small cuboid and densely " toothed " supraorbital bone on each side. Medially the supraorbital is attached to the lateral ethmoid, and posteri- orly it articulates with the frontal. Clausen (1959) apparently interpreted the entire odontode-bearing margin of the frontal as a supraorbital bone (see his figure i). Since there is no indication of fusion between the supraorbital ledge and the main body of the frontal, and because the element here identified as a supraorbital bone is readily separated from the frontal, I would dispute Clausen's identification. The large unpaired orbitosphenoid (Text-figs. 6 and g) is broadly U-shaped in cross-section, with a distinct median keel, low posteriorly but greatly expanded and ventrally produced anteriorly. Neither the main body of the bone nor its anteriorly directed keel contacts the ethmoid region. Soc. 1 mm. Fig. 6. Neurocranium in lateral view. The paired pterosphenoids (Text-figs. 6 and 9) are in contact with the posterior margin of the orbitosphenoid anteriorly, with the frontals dorsally, and with the prootics and basisphenoid posteriorly and posterolaterally. At no point are the two pterosphenoids in contact with each other. Each is a large, broadly concave bone almost square in outline. Near the posterolateral angle is a notch which contributes to the medial margin of the large foramen opening into the pars jugularis. Posterodorsally the bone is pierced by a foramen for the trochlear nerve (IV). Articulating with the ventromedial margin of each pterosphenoid is the unpaired, hexagonal and basisphenoid, its convex face directed anteroven- trally. No ventral limb is present. The ventiolateral margins of the basisphenoid. Please note that these images are extracted from scanned page images that m
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Keywords: ., 1968, boo, bookauthorbritishmuseumnaturalhistory, bookcentury1900
