. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Oligocene Rodents of Bolivia • Patterson and Wood 419. Figure 18. Right upper cheel< teeth of Incamys bolivianus, anterior ends to the right, x5. A. PL) no. 20947, RP*-M^. Part of zygomatic root added from PU no. 20938; anterior part of maxillary-palatine suture from PU no. 20954. B. PL) no. 20955, RP*-!^. C. PU no. 20943, RP*-M=. D. PU no. 20939, RP*. E. PU no. 20956, RP-M'. lated P^, and thus its size cannot be com- pared with that of M' or M^. In the lower teeth, P4 is longer than the rest, and M2 is the widest
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Oligocene Rodents of Bolivia • Patterson and Wood 419. Figure 18. Right upper cheel< teeth of Incamys bolivianus, anterior ends to the right, x5. A. PL) no. 20947, RP*-M^. Part of zygomatic root added from PU no. 20938; anterior part of maxillary-palatine suture from PU no. 20954. B. PL) no. 20955, RP*-!^. C. PU no. 20943, RP*-M=. D. PU no. 20939, RP*. E. PU no. 20956, RP-M'. lated P^, and thus its size cannot be com- pared with that of M' or M^. In the lower teeth, P4 is longer than the rest, and M2 is the widest of the molars (Table 4). The most variable factor in the lower cheek teeth is the length of M3. The length of the wear surface is to a great extent dependent on age, and is (otherwise) essentially meaningless. We have therefore taken the greatest extra- alveolar length of the crown as the anteroposterior diameter of the tooth. In cases where the entire alveolar border is preserved, we believe this measurement to be a homologous one. However, M3 is implanted at an angle (Fig. 16B,C), so that the crown of the tooth extends a con- siderable distance behind the rear of the alveolus, within that cavity. A recheck of a number of specimens with unusually large anteroposterior diameters for M3 showed that in most cases the unusually long measurements resulted from the fact that the posterior margins of the alveolus were damaged or destroyed. Because of the element of uncertainty as to the length of M3 and the variation of transverse diameters of M^~^ with age, we have prepared Tables 3-4 both to in- clude all specimens as originally mea- sured and to exclude the anteroposterior diameters of M3 where the location of the posterior margin of the alveolus is uncer- tain and the transverse diameters of all specimens of M^~^ where the buccal mar- gin of the crown extends 1 mm or more beyond the labial margin of the roots (Fig. 15D). Lavocat (1976: 42^3) discussed the homologies of the vari
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Keywords: ., bookauthorharvarduniversity, bookcentury1900, booksubjectzoology
