Article

On the genus Dikkomys (Geomyoidea, Mammalia)

Morton Green and Philip R. Bjork

Cite this article: Morton Green and Philip R. Bjork, 1980. On the genus Dikkomys (Geomyoidea, Mammalia). PalaeoVertebrata 9 (ext): 343-353.

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Abstract

The geomyoid genus Dikkomys is well represented in a sample from the Black Bear Quarry Il local fauna of Early Hemingfordian age in Bennett County, South Dakota. Isolated unworn P/4's of Dikkomys matthewi WOOD have a prominent median cristid (sagicristid) with a connection to the metaconid and the hypolophid. With wear, P/4 does not become as molariform as P/4 because of this cristid.
A large sample of the Whitneyan beteromyid Proheteromys nebraskensis WOOD contains variants of the P/4 with on incipient sagicristid in approximately 18 percent of the population. The upper dentition and lower molars of Proheteromys nebraskensis are sufficiently generalized to indicate probable ancestry to Dikkomys.