. Breviora. 18 BREVIORA No. 255 type and MCZ 3656 and 7637, Pj is a large, single-rooted, re- curved, caniniform tooth laterally compressed and with blade- like anterior and posterior edges. In MCZ 3708, 7635, and 3655 the alveolus for the first premolar indicates a very tiny vestigial tooth which could not have been functional to any great extent in the living animal. In size and dental morphology these two groups are identical. Since dimorphs of this kind are known among artio- dactyls, and with no evidence to the contrary, it is preferable to consider these as sexual morphs rather than two
. Breviora. 18 BREVIORA No. 255 type and MCZ 3656 and 7637, Pj is a large, single-rooted, re- curved, caniniform tooth laterally compressed and with blade- like anterior and posterior edges. In MCZ 3708, 7635, and 3655 the alveolus for the first premolar indicates a very tiny vestigial tooth which could not have been functional to any great extent in the living animal. In size and dental morphology these two groups are identical. Since dimorphs of this kind are known among artio- dactyls, and with no evidence to the contrary, it is preferable to consider these as sexual morphs rather than two distinct taxa, the latter group being the females. A long diastema separates Pi and Po. The latter is a two-rooted, simple, robust tooth equal to P3 in length (Fig. 2). P3 is propor- tionately smaller than the corresponding tooth in S. rileyi rileyi, but similar to it in structure. The anterior edge is somewhat re- curved onto the internal face forming a moderate stylid. The high median cusp is connected with the anterior and posterior cusps by narrow crests. A posterior intermediate crest extends backward nearly to the edge of the tooth, but fails to fuse with the posterior crest, resulting in a partially closed lake which is open postero- medially. P4 is similar to Po with a stronger parastylid and a lake which is completely closed near the base of the crown. It differs from S. rileyi rileyi in having a narrower median cusp. The molars are indistinguishable from those of S. r. rileyi. M^ and Mo have narrow crescents, strong parastylids, and weak metastylids. The median ridges are well developed, especially on M2. M3 is similar but with the posterior edge of the metaconid slightly overlapping the entoconid. The hypoconulid is C-shaped forming two functional grinding surfaces, and is quite variable in MCZ 3660 MCZ 3656 Figure 2. Synthetoceras {Prosynthetoceras) rilexi anstralis, composite crown view of right lower cheek teeth, XI. In the upper dentition, the referred pal
Size: 3712px × 673px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorharvarduniversitymuseumofcomparative, bookcentury1900
