Typhlomys hipparionum QIU , 1989

Qiu, Zhuding & Ni, Xijun, 2019, Platacanthomyids (Rodentia, Mammalia) From The Late Miocene Yuanmou Hominoid Locality Of Yunnan, China, Fossil Imprint 75 (3 - 4), pp. 383-396 : 389-390

Typhlomys hipparionum QIU, 1989

Text-figs 6 , 7

H o l o t y p e. Right M 1 (IVPP V 8820).

T y p e l o c a l i t y. Shihuiba, Lufeng, Yunnan Province,

China.

R e f e r r e d m a t e r i a l. Yuanmou: 1 M 2, 1 M 3, 1 M 3 ( IVPP V 25885.1 – 3 ) from Loc. 9904; 1 M 1 ( IVPP V 25885.4 ) from Loc. 9905; 3 M 1, 2 M 2, 2 M 3, 4 M 1, 4 M 2, 2 M 3 ( IVPP V 25885.5 – 21 ) from Loc. 9906 .

M e a s u r e m e n t s. M 1: 1.75–1.90 × 1.15–1.30 mm; M 2: 1.60–1.65 × 1.00– 1.10 mm; M 3: 1.15–1.25 × 0.90–1.00 mm; M 1: 1.90–2.10 × 1.00– 1.10 mm; M 2: 1.50–1.55 × 1.05– 1.10 mm; M 3: 1.20–1.35 × 0.88–1.00 mm (length × width).

D e s c r i p t i o n. Typhlomys hipparionum from Leilao is larger than T. aff. T. primitivus in size, but closely matches in morphology and dimensions T. hipparionum from Shihuiba of Lufeng ( Text-fig. 6 ), the type locality of this species. However, minor differences between the two forms can be observed, which should not be overemphasized in view of the rather limited amount of material from the two sites.

All 4 M 1 s from Yuanmou are relatively wide and short in comparison with the holotype. Syncline Ia is slightly smaller than or equal to syncline IV, rather than slightly larger than syncline IV, as in the holotype. All 3 M 2 s show distinctly and laterally closed synclines Ia and IV, and continuous endoloph and ectoloph in this stage of wear. All 3 M 3 s have a distinct mesoloph and show a smaller syncline Ia at the anterobuccal corner of the tooth and a longer syncline IV at the posterobuccal corner .

The M 1 has a continuous endolophid, even in the fresh specimens. As in Typhlomys hipparionum from Lufeng and other species of the genus, the mesial angle of diagonal ridge/synclines to the longitudinal axis gradually increases toward the back. In 1 of 2 identifiable M 1 s, syncline Ia is long and narrow, and the other is short and separated by a crest. All 4 M 2 s have small and shallow synclines Ia and IV. All 3 M 3 s show discernable synclines Ia, but no hypolophid and synclines IV.

Figures

Text-fig. 6. Scatter diagrams (length and width) of Typhlomys aff. T. primitivus measurements from Leilao, Yuanmou in comparison with those of T. hipparionum and T. storchi from Leilao, and of T. primitivus and T. hipparionum from Shihuiba, Lufeng.

Text-fig. 7. Typhlomys hipparionum Q, 1989 from Leilao, Yuanmou. a) left M1 (IVPP V 25885.4), b) right M1 (IVPP V 25885.5), IU c) left M2 (IVPP V 25885.6), d) left M2 (IVPP V 25885.7, reversed), e) left M3 (IVPP V 25885.8), f) right M3 (IVPP V 25885.9), g) left M1 (IVPP V 25885.10), h) right M1 (IVPP V 25885.11), i) left M2 (IVPP V 25885.12), j) right M2 (IVPP V 25885.13), k) left M3 (IVPP V 25885.1), l) left M3 (IVPP V 25885.14, reversed).