Wahlert, John H.2005-10-062005-10-061983http://hdl.handle.net/2246/525723 p. : ill. ; 26 cm.Includes bibliographical references (p. 22-23)."The family Florentiamyidae is redefined based on derived cranial and dental characteristics that demonstrate monophyly. A unique process from the palatine, together with the alisphenoid, forms the edge of the anterior-alar fissure; the foramen for the descending palatine vein is lateral to the process. The optic foramen is larger than 1.0 mm. Masticatory and buccinator foramina are united with the accessory foramen ovale. The temporal foramen is large. The frontal is wide with roughly parallel, marginal flanges that project over the orbits. An anteriorly concave process on the petrosal descends posterior to the fenestra cochleae. The entostyle in the upper molars is elongated and blocks the lingual end of the transverse valley. The florentiamyids share primitive characters with eomyoids and Sciuravus that are modified in other geomyoids; these indicate that the family is the earliest branch in the phylogeny of geomyoid rodents. Cranial and dental morphology of florentiamyids is described. Variations in tooth crown patterns illustrate possible origin of the typical geomyoid pattern. Evidence of cusp height and wear facets supports the hypothesis that geomyoid teeth are widened by the addition of styles. Completeness of fossil material suggests that florentiamyids were burrowers. The genera Sanctimus and Florentiamys are redefined, and three new species of each genus are named and described. New specimens range in age from late Oligocene to early Miocene. Diagnoses of previously described species are revised. The species S. tiptoni is transferred to the genus Florentiamys; ?S. clasoni and ?F. agnewi are designated as Geomyoidea incertae sedis"--P. [1].4194006 bytesapplication/pdfen-USQL1 .A436 no.2769, 1983Florentiamyidae.Rodents -- Anatomy.Skull -- Anatomy.Teeth, Fossil -- West (U.S.)Rodents, Fossil -- West (U.S.)Mammals, Fossil -- West (U.S.)Paleontology -- Tertiary -- West (u.S.)Paleontology -- West (u.S.)text