. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 252 Bulletin Museum of Comparative Zoology, Vol. 151, No. 4 lANT BUG. 5 MM Figure 20. Right maxillary tooth row of Dinnebitodon ama- rali, MNA V3222 (holotype), in occlusal view. Hatching de- notes damaged areas. may, of course, further increase these ranges.) The posteriormost cheek-tooth is never fully eruptedr The buccolingual width of the postcanine teeth increases progressively in immature specimens (MCZ 8811) but in the largest known in- dividuals (MCZ 8812) the posterior teeth begin to decrease in width. A simi
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 252 Bulletin Museum of Comparative Zoology, Vol. 151, No. 4 lANT BUG. 5 MM Figure 20. Right maxillary tooth row of Dinnebitodon ama- rali, MNA V3222 (holotype), in occlusal view. Hatching de- notes damaged areas. may, of course, further increase these ranges.) The posteriormost cheek-tooth is never fully eruptedr The buccolingual width of the postcanine teeth increases progressively in immature specimens (MCZ 8811) but in the largest known in- dividuals (MCZ 8812) the posterior teeth begin to decrease in width. A similar on- togenetic change has also been observed in Bienotherium (Young, 1947: 553) and Oligokyphus (Kiihne, 1956: 76) as well as in more primitive Tritylodontoidea such as Scalenodon (Crompton, 1955: 651). As noted previously, new teeth were added at the back of the tooth row while teeth were lost in front. Toward the an- terior end of the tooth row in MCZ 8811 and 8812, the roots of the cheek-teeth be- come progressively more exposed through resorption of the surrounding alveolar bone. In none of the currently available specimens did I observe an empty alveo- lus anterior to the first functional postca- nine tooth but such alveoli do occur in Oligokyphus (Kuhne, 1956: pi. 2, fig. 3). Apparently the tooth was shed with its roots virtually intact and then the alveolus was very quickly filled with bone (Kiihne, 1956: 69). This loss of anterior teeth par- tially contributed to an ontogenetic in- crease in the relative length of the diaste- ma. New lower postcanine teeth were formed in a posterior extension of the tooth-bearing part of the dentary medial to the coronoid process ( Fig. 13B). The bone surrounding the new teeth was thin, much as that around the replace- ment teeth in the maxilla. The crowns of newly erupted lower postcanines initially are inclined lingually (MCZ 8837) but they increasingly turn buccally and anteriorly further forward along the tooth row. The pos
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