Sayimys, WOOD, 1937

Hartman, Julian, Van De Weerd, Andrew A., Bruijn, Hans De & Wessels, Wilma, 2019, An Exceptional Large Sample Of The Early Miocene Ctenodactyline Rodent Sayimys Giganteus, Specific Variation And Taxonomic Implications, Fossil Imprint 75 (3 - 4), pp. 359-382 : 371-372

Sayimys minor DE BRUIJN, HUSSAIN et LEINDERS, 1981

H o l o t y p e. A left m1–2 no 313.

Ty p e l o c a l i t y. H.-GSP116, Murree Formation near Banda Daud Shah, Pakistan; age of the site: 18.5–19.5 Ma ( Baskin 1996).

P a r a t y p e s. One damaged dp4, one m3 and one M1–2.

D i s c u s s i o n. A well-developed mesolophid is present in the dp4, but absent in the m1–2 and m3. The sizes of the specimens are like those of Sayimys flynni, or slightly larger.

This small collection of only four molars has been the subject of some discussion. Baskin (1996) suggested that the rather worn M1–2 is too large to fit in the same species as the other three teeth, without testing the homogeneity of the sample. The m1–2 and M1–2 of all large Sayimys populations have a large size variability if first and second molars are not separated ( Tab. 2). This M1–2 may very well be a large second molar belonging to the same species as the other three teeth. Wang (1997) suggested that Sayimys minor could be a junior synonym of S. intermedius ( Sen and Thomas 1979) , because these species are similar in size, the only difference being the presence of a mesolophid in the single dp4 of S. minor and absence of this lophid in the single known dp4 of S. intermediu s. But, as Baskin (1996: 41) mentioned: “persistence of a rodent species over 5 million years and 3,500 km distance would be highly unusual”, and we therefore hesitate to follow Wang. López- Antoñanzas and Sen (2003, 2004) subdivided the sample of S. minor from the type locality (only four teeth) into two or three species. The holotype (the m1–2, no 313) was included in S. intermedius ( Sen and Thomas 1979) because “this molar cannot be differentiated from the equivalent tooth of S. intermedius ”. The dp4 and m3 were separated from the m1–2 for unknown reasons, and included into S. baskini LÓPEZ- ANTOÑANZAS et SEN, 2003, see below. It is not clear in this publication how to classify the fourth tooth in the sample from the type locality (the large M1–2). The clear remark by Munthe (1980) on the large variability in Sayimys was here completely forgotten or ignored. In our opinion, the assemblage from H.-GSP116 (Murree Formation) is homogenous, and there is no valid reason to split up the small collection of S. minor and include the holotype in S. intermedius , and thus to synonymize S. minor and S. intermedius .