. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Oligocene Rodexts of Bolivia • Patterson and Wood 381. Figure 3. Teeth and jaw of Migraveramus beatus, gen. et sp. nov., PU no. 21948, type. A. RPi-Mj, xlO. B. Cross section of Rl,, beneath diastema, xlO. C. Lateral view of right lower jaw, x5. terior and posterior cusps of each side. The base of the enamel is nearly horizon- tal around the teeth. The anterior root of dm4 is still present in front of P4 (Fig. 3C). The incisor has a flat anterior face, with the enamel extending fairly far around on both sides (Fig. 3B)
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Oligocene Rodexts of Bolivia • Patterson and Wood 381. Figure 3. Teeth and jaw of Migraveramus beatus, gen. et sp. nov., PU no. 21948, type. A. RPi-Mj, xlO. B. Cross section of Rl,, beneath diastema, xlO. C. Lateral view of right lower jaw, x5. terior and posterior cusps of each side. The base of the enamel is nearly horizon- tal around the teeth. The anterior root of dm4 is still present in front of P4 (Fig. 3C). The incisor has a flat anterior face, with the enamel extending fairly far around on both sides (Fig. 3B). The pulp cavity, be- low the diastema, is small and oval. The mandible is badly damaged. No features of any significance were ob- served on the medial side. The mental foramen (Fig. 3C) is about half way up the side of the mandible, a short distance in front of the anterior root of P4, and faces forward and downward. The ante- rior tip of the masseteric crest lies on the upper third of the mandible, beneath the rear of P4, whence it curves posteroven- trad and increases rapidly in prominence. Only the beginning of the coronoid pro- cess is visible, but it passed the alveolar border near the front of M3 (Fig. 3C). Relationships. The mandible agrees with that of the Deseadan octodontid Platypittamys (Wood and Patterson, 1959: 298) in the absence of any distinct scar for the M. masseter medialis, pars anterior, suggesting that this muscle was poorly developed. The pattern of the lower molars agrees with that of Platypittamys alone among Deseadan rodents—there are four trans- verse crests, the two anterior and the two posterior being widely separated by the deep mesoflexid (Wood, 1949: Fig. 3C,D). As in Platypittamys (Wood, 1949: Fig. 3C; M2), the metaconid is somewhat isolated from the metalophid. The Table 1. Measurements, ln mm, of teeth of Migraveramus beatus, TYPE, PU NO. 21948, right. ?polophid ratio .70. Please note that these images are extracted from scanned pag
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