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 : 373

Sayimys sivalensis ( HINTON, 1933)

O r i g i n a l c o m b i n a t i o n. Pectinator sivalensis

HINTON, 1933.

H o l o t y p e. A left partial mandible with m2 and m3, see Black (1972) for a good illustration.

Ty p e l o c a l i t y. Surface find near Chinji village ( Pakistan), Chinji Formation; the age of the formation near Chinji village ranges from 14.3 to 10.8 Ma ( Johnson et al. 1985).

D i s c u s s i o n. Munthe (1980) allocated a fine collection of isolated Sayimys teeth from the upper part of the Chinji Formation near Daud Khel (age approximately 11–10 Ma; Jacobs et al. 1989) to S. sivalensis. He provided an emended diagnosis of S. sivalensis based on the Daud Khel assemblage.

Baskin (1996) recognized two species of Sayimys from the area near Chinji. He allocated the older relatively lowcrowned to S. sivalensis and described the younger relatively high-crowned as S. chinjiensis. This S. sivalensis material comes from thirteen small assemblages in the Kamlial and the lower Chinji Formations (age range 15.1–13 Ma), while eight small collections from the upper Chinji and Nagri Formations (age range 12.1–9.1 Ma) were included in S. chinjiensis. The Daud Khel assemblage described by Munthe was allocated to S. chinjiensis. Baskin (1996) considered the holotype of S. sivalensis primitive because of the position of its masseteric crest. He therefore assumed that it came from the lower Chinji beds. We consider Sayimys sivalensis a nomen dubium; its holotype is of unknown location and lacks diagnostic criteria, whereas the intraspecific variability of masseteric crest is not known. We therefore restrict the name S. sivalensis to the holotype, and create a new species to house the assemblages with relatively low-crowned molars.