. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Oligocene Rodents of Bolivia • Patterson and Wood 433. Figure 22. Lateral view of skull, Branisamys lun'bayensis, PL) no. 20914, x3. Part of orbital region restored from right side. Abbreviations: AEF—anterior ethmoid foramen; F—foramen into nasolacrimal canal; L—lacrimal foramen; N—nutritive foramina; OF—optic foramen; OSPH—orbitosphenoid; RLA—right lacrimal, reversed from opposite side; RMX—part of right maxillary, reversed from opposite side; SPF—sphenopalatine foramen. Dotted areas are matrix. cheek teeth, not so
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Oligocene Rodents of Bolivia • Patterson and Wood 433. Figure 22. Lateral view of skull, Branisamys lun'bayensis, PL) no. 20914, x3. Part of orbital region restored from right side. Abbreviations: AEF—anterior ethmoid foramen; F—foramen into nasolacrimal canal; L—lacrimal foramen; N—nutritive foramina; OF—optic foramen; OSPH—orbitosphenoid; RLA—right lacrimal, reversed from opposite side; RMX—part of right maxillary, reversed from opposite side; SPF—sphenopalatine foramen. Dotted areas are matrix. cheek teeth, not so much as in Dinomys but in striking contrast to the condition in the dasyproctids. Most of the lateral surface of the snout is occupied by the very large fossa for M. masseter medialis, pars anterior, which extends far forward onto the premaxilla. The fossa is compa- rable in extent, except anterodorsally, to that of Dinomijs but is more deeply in- cised and is bounded anteriorly and dor- sally by a much more prominent bony rim (Fig. 22). As in Incamys, the nasals are very long for caviomorphs, extending back to a point above M*. In Branisamys these bones are narrow. Bluntly pointed, they increase somewhat in width posteriorly for slightly less than half their lengths and then decrease evenly toward the frontals. In contour, therefore, they re- semble the shorter and wider nasals of Dinomys, and differ from the posteriorly tapering ones of Neoreomys or the more parallel-sided ones of Incamys and the living dasyproctids. The premaxillaries are large and ro- bust. Ventrally, they are relatively wider and the lateral margins are more conver- gent anteriorly than in Dinomys and, as already noted, they are more excavated laterally for the reception of the anterior portion of M. masseter medialis. The in- cisive foramina are kidney-shaped (Fig. 23A), much broader in proportion to length than in Dinomys or the living das- yproctids; in contrast to Incamys and oth- e
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