. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. 310 Bulletin Museum of Comparative Zoology, Vol. 158, No. 6 1 mm. Figure 16. The braincase of Eocaecilia micropodia (MNA V8063) in ventral view (stereophotographs). For labeled drawings of this specimen, see Figure 15A, B. and Typhlonectes compressicauda (MCZ 24524). A fourth difference is that the ventral aspect of the os basale of Eocaecilia mi- cropodia lacks any indication on its ventral surface of the attachment of subvertebral cranial depressor musculature, specifically the longus capitis. In many Recen
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. 310 Bulletin Museum of Comparative Zoology, Vol. 158, No. 6 1 mm. Figure 16. The braincase of Eocaecilia micropodia (MNA V8063) in ventral view (stereophotographs). For labeled drawings of this specimen, see Figure 15A, B. and Typhlonectes compressicauda (MCZ 24524). A fourth difference is that the ventral aspect of the os basale of Eocaecilia mi- cropodia lacks any indication on its ventral surface of the attachment of subvertebral cranial depressor musculature, specifically the longus capitis. In many Recent caeci- lians, a pair of facetlike depressions ante- rior to the foramen magnum, separated in the median plane by a low ridge, mark this attachment site (cf. Figs. 3, 6B-D). The muscle flexes the skull ventrally, a move- ment that Bemis et al. (1983) suggested would be employed in both feeding and burrowing. Pleurosphenoid. Anteromedial to the otic capsule a large pleurosphenoid forms the lateral wall of the braincase, extending anteriorly along the lateral margin of the parasphenoid portion of the os basale to- ward the sphenethmoid (Fig. 16), as in modern caecilians. The pleurosphenoid does appear to have been fully fused to the parasphenoid (Figs. 15, 16). In MCZ 9167, the pleurosphenoid is approximately mm long and mm high. The anterior margin of the pleurosphenoid is recessed, and a small gap, estimated to be mm in width, separates the anterior margin of this bone from the posterior margin of the sphenethmoid (Fig. 17A). This gap is likely to have accommodated the egress of cra- nial nerves II, III, and IV. Sphenethmoid. The sphenethmoid of Eocaecilia micropodia, which is not well preserved or visible in its entirety in any one specimen, is reconstructed (Fig. 17) on the basis of the holotype, MNA V8066, and MNA V8059 (Fig. 7). The spheneth- moid appears to conform generally to the pattern in modern caecilians (Fig. 18). In the holotype, the sphenethmoid is es
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