. Bulletin. Natural history. THE POSTCRANIAL SKELETON OF AFRICAN CYNODONTS 63 third cervical. In fact the reverse is true; as in Thrinaxodon, the articulation of the zygapophyseal facets of the axis and third cervical makes an angle of approximately 45° with the horizontal and between the third and seventh cervical vertebrae the angle increases to about 55°. On UMC the articulations show the same fea- tures, although they are somewhat obscured by breakage. Thoracic Series morphology. In the 13 thoracic vertebrae of UMC no substantial differ- ences from Thrinaxodon are apparent al
. Bulletin. Natural history. THE POSTCRANIAL SKELETON OF AFRICAN CYNODONTS 63 third cervical. In fact the reverse is true; as in Thrinaxodon, the articulation of the zygapophyseal facets of the axis and third cervical makes an angle of approximately 45° with the horizontal and between the third and seventh cervical vertebrae the angle increases to about 55°. On UMC the articulations show the same fea- tures, although they are somewhat obscured by breakage. Thoracic Series morphology. In the 13 thoracic vertebrae of UMC no substantial differ- ences from Thrinaxodon are apparent although the specimen is only partially pre- pared and somewhat damaged. The morphological gradient of facets for the tubercu- lum is evident. In the anterior thoracic vertebrae the capitular fovea is composed of two separate demifacets borne on the adjacent rims of successive vertebrae. These demifacets, located on the dorsolateral aspect of the rim below the pedicle-centrum suture, together form a wedge-shaped fovea. The caudal demifacet is partially formed on the base of the pedicle projecting anteriorly beyond the rim of the centrum. To- ward the posterior thoracic vertebrae, the fovea progressively increases in size and shifts its position caudally, , by increasing the demifacet size of the caudal half and decreasing the demifacet size of the cranial half. In the most anterior thoracics the transverse process is crescentic in cross-section (tr p, Fig. 13A). An anteroventral extension of the process almost reaches the pedicle-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Peabody Museum of Natural History. New Haven, Peabody Museum of Natural History, Yale University
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