Sayimys

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

Sayimys aff. giganteus LÓPEZ- ANTOÑANZAS, SEN et SARAÇ, 2004

Text-figs 9 , 10

L o c a l i t i e s a n d f o r m a t i o n s.Yapıntı(Derinçay

Formation) and Horlak 2 (Yeniçubuk Formation).

A g e r a n g e. MN 4, possibly also late MN 3 ( Ünay et al. 2001, Sümengen et al. 1990).

M a t e r i a l a n d m e a s u r e m e n t s. See Tab. 4.

D i s c u s s i o n. The Yapıntı and Horlak material has been compared with early and middle Miocene species Sayimys flynni BASKIN, 1996, S. minor DE BRUIJN, HUSSAIN et LEINDERS, 1981, S. giganteus, S. obliquidens BOHLIN, 1946, S. assarrarensis LÓPEZ- ANTOÑANZAS et SEN, 2004 and S. intermedius ( SEN et THOMAS, 1979) . The Yapıntı and Horlak material is smaller than S. giganteus or overlaps with the smaller specimens of Keseköy ( Text-figs 12 , 13 ). Sayimys flynni, S. minor, S. assarrarensis and S. intermedius are considerably smaller, but S. obliquidens is about of the same size. The dental morphology of the specimens from Yapıntı and Horlak is very similar to the material from Keseköy, and therefore not described in detail. There are morphological differences in the dp4 and lower molars, in the mesolophid, with S. flynni, S. obliquidens and S. minor. Considering the size differences and agreement in dental morphology, the assemblages from Yapıntı and Horlak material are classified as S. aff. giganteus.

López-Antoñanzas et al. (2005) described Sayimys intermedius from the early Miocene of Chios ( Greece). The Yapıntı dp4 resembles one of the three figured specimens from Chios in having a rounded, isolated anteroconid; the other two Chios specimens have an elongate transverse anteroconid. The Chios dp4 do not show a clear mesolophid, but the area of the mesolophid basin is less deep than the mesoflexid. Text-figs 12 and 13 suggest that the Chios material is too large to be included in S. intermedius ; noteworthy is the long m3 from Chios. In dental morphology and size, the Chios material is close to that of Yapıntı, and should be classified as Sayimys aff. giganteus.

Figures

Text-fig. 9. Lower molars and premolars of Sayimys giganteus from Keseköy and Yapıntı (= YAP numbers) shown as right specimens. Left side specimens are shown in mirror image, these have underlined specimen numbers.

Text-fig. 10. Upper cheek teeth of Sayimys giganteus from Keseköy and Yapıntı (= YAP numbers) shown as right specimens. Left side specimens are shown in mirror image, these have underlined specimen numbers.

Text-fig. 12. Ranges of the length of the dp4 based on data from the literature. Vertical scale in Ma, the samples are from the Siwaliks (black) and Turkey, Greece and Arabia (red). Type localities of species are indicated with an asterisk. The Y and Z sites are from Baskin (1996), its size ranges are composed of data from several localities and the vertical arrowed broken line indicates the age range of these sites.

Text-fig. 13. Ranges of the length of the m3 based on data from the literature, see Text-fig. 12 for explanation.