Ground squirrels, Interspecific hybridization, Pleistocene, Spermophilus elegans, Spermophilus richardsonii, Supernumerary teeth
A supernumerary distal upper molar, always expressed bilaterally, occurred in Pleistocene (one of 204) and Recent (five of 1,667) specimens of the Spermophilus richardsonii complex. Among Recent specimens with the abnormality, three of four with known provenance came from adjacent colonies with hybrids of S. richardsonii (Richardson's ground squirrel) and S. elegans (Wyoming ground squirrel). Elsewhere, the trait was rare in S. richardsonii (one of 947) and absent in S. elegans (out of 668). Affected individuals exhibited normal P3-M2, but two aberrant teeth distal to M2. Aberrant teeth exhibited a mosaic of features typical of M2, M3, and atypical of any normal tooth. The trait was inferred to be hereditary.
Journal of Mammalogy
Goodwin, H. Thomas, "Supernumerary Teeth in Pleistocene, Recent, and Hybrid Individuals of the Spermophilus richardsonii Complex (Sciuridae)" (1998). Faculty Publications. 2558.
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