December 1985
Vol. 15, Fasc. 3
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Print ISSN: 0031-0247
Online ISSN: 2274-0333
Frequency: biannual

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PalaeovertebrataVol. 15, Fasc. 3:129-138. 1985
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Evolution of the Rhizomyine zygoma
Lawrence J. Flynn, Mohammed Sarwar and Jean-Jacques Jaeger
Keywords: parallel evolution; Rhizomyidae; Rodentia; Siwalik; zygoma

Cite this article: Flynn L. J., Sarwar M., Jaeger J.-J., 1985. Evolution of the Rhizomyine zygoma. Palaeovertebrata 15 (3): 129-138.


Cranial anatomy of a late Miocene rhizomyid, Brafhyrhizomys cf. B. pilgrimi, provides new evidence on the origin of the dorsal, round infraorbital foramen of living rhizomyines. Primitive rhizomyids retain a myomorphous keyhole foramen with a long ventral slit that retracts upward during the evolutionary history of the Rhizomyidae. The primitive condition of the elongated ventral slit is represented by Kanisamys sivalensis. Among later burrowers the foramen shows progressive dorsal migration, the ventral slit terminating midway up the snout in B.tertracharax and B. choristos ; well above the midline of the snout in Brachyrhizamys cf. B. pilgrimi. Apparently this transformation began earlier among Rhizomyinae than among Tachyoryctinae and continued to a more derived stage in rhizomyines. ln living Rhizomyx the ventral slit is absent and only a high round hole remains at the anterior end of the zygomatic arch. 

Published in Vol. 15, Fasc. 3 (1985)