ABSTRACT. The skulls of Japanese wolf (Canis hodophilax) were osteometrically examined and compared with those of Akita-Inu. The skull total length was not statistically different between two species. However, significant differences were demonstrated between two species in some ratios concerning the frontal bone. CT examination was carried out in the Japanese wolf skull. The data indicated that the frontal sinus is not be largely developed and compressed in the dorso-ventral direction in parasagittal area. The narrow frontal sinus fitted to external shape of the frontal bone. The cribriform plate had a well-developed complicated structure in a caudal part of the ethmoid bone. These data will be useful to examine the respiratory function and the olfactory sense in the Japanese wolf. -KEY WORDS: Akita-Inu, CT, Japanese wolf, osteometry, skull.

The modern-day Tarim Basin is covered almost entirely by the Taklimakan sand desert and is one of the most arid regions in the world. Unraveling the aridification history of the desert is important for understanding global climate changes during the Cenozoic, yet the timing and mechanisms driving its formation remain controversial. One of the leading hypotheses is that the uplift of the Pamir, located to the west of the Tarim Basin, blocked the intrusion of moist air and induced the aridification in the Tarim Basin. In this study, we explore the linkage between the uplift of the Pamir and the desertification in the Tarim Basin from the late Eocene to the middle Miocene in the Aertashi section, which is located at the southwestern edge of the Tarim Basin and offers the longest sedimentary record with a reliable age model. Provenance changes in fluvial deposits along the Aertashi section were examined using electron spin resonance (ESR) signal intensity and crystallinity index (CI) of quartz in the sand fraction of fluvial sandstones and clast counting based on the identification of clast types by thin section observation to identify timings of tectonic events in the Pamir, from which clastic materials were supplied to the Aertashi section by rivers. Our results suggest that major provenance changes in the drainage of the paleo-Yarkand river delivering clasts to the Aertashi section occurred at ca. 27, 20, and 15 Ma. These timings are mostly consistent with those observed in previous provenance studies in the Aertashi section and probably reflect tectonic events in the Pamir. On the other hand, according to the previous studies, the first occurrence of sand dune deposits indicates that the Tarim Basin was relatively arid after ca. 34 Ma. Hence, our result does not support the hypothesis that the initial aridification in the Tarim Basin was triggered by the uplift of the Pamir and the resultant blocking of moisture supply from the Paratethys Sea, although the subsequent intensification of tectonic events at ca. 27 Ma in the Pamir might have caused aridification indicated by the initiation of loess deposition.

The Tarim basin is one of the most arid areas in the world and its major part is occupied by the Taklimakan desert. Although unraveling the history of aridification of Taklimakan desert is important to understand the global climate change during the Cenozoic, the timing and the mechanism of its formation are still controversial. One of the hypotheses is that the uplift of the Pamir locating to the west of the Tarim basin blocked the intrusion of the moist air and induced the aridification in the Tarim basin. In this study, we explored the linkage between the uplift of the Pamir and the desertification in the Tarim basin during the period from the late Eocene to the middle Miocene. Provenance changes of the fluvial deposits along the Aertashi section, which is located in the southwestern edge of the Tarim basin and offers the longest record with the reliable age model, was examined using Electron Spin Resonance (ESR) signal intensity and crystallinity index (CI) of quartz in the sand fraction of fluvial sandstone and the thin section observation to identify the timings of tectonic events in the Pamir from which clastic materials were supplied by rivers. Our results suggest that major provenance changes in the drainage of the river delivering the clasts to the Aertashi section occurred at ca. 26 Ma, 20 Ma, and 15 Ma. These timings are mostly consistent with the timings observed in the previous provenance studies in the Aertashi section and probably reflect tectonic events in the Pamir. On the other hand, the Tarim basin was under the relatively arid condition after ca. 34 Ma based on the first occurrence of sand dune deposit. Hence, our result does not support the hypothesis that the onset of the aridification in the Tarim basin was caused by the uplift of the Pamir and consequent shut down of the moisture supply from the Paratethys Sea although the afterward intensification of tectonic events in the Pamir might be related to the phased uplift.

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