ΐῒ῏ῑῐ ῍῎῍῎ῌThe Quaternary Research.1 , p. 2+ 3, April ,**2 Small mammal fauna of Early Pleistocene age from the Xiaochangliang site in the Nihewan Basin, Hebei, northern China Yingqi Zhang*+,- , Yoshinari Kawamura*,a and Baoquan Cai* A large amount of sediments was taken from the horizon stratigraphically equiva- lent to the artifact layer in the Xiaochangliang site, an important archaeological site of Early Pleistocene age. The sediments were washed with fine-mesh screens to col- lect small mammal remains. The layer is dated as+4-0 Ma by paleomagnetic measure- ments. Small mammal remains are important for biostratigraphic and paleoenviron- mental studies, but they have been hardly collected from the site before the present study. A large number of the remains collected by the screen-washing have revealed the characteristics of the small mammal fauna of the site. The fauna is compared with those of the four well-dated localities in the adjacent area. On the basis of the faunal characteristics and comparisons, we discuss the biostratigraphy and faunal turnover in the Late Pliocene and Pleistocene. Furthermore, we reconstruct the paleoenviron- ment around the site in the Early Pleistocene. Keywords : small mammal fauna, biostratigraphy, Early Pleistocene, Xiaochangliang site, Nihewan Basin, China Since then, thousands of artifacts and more I. Introduction than+* forms of mammals have been exca- The Nihewan Basin situated about+/* km vated from the site (Tanget al., +33/ ; Chen et westo north o west of Beijing (Fig. + ) has beenal., +333 ), but the knowledge on small mammals well known for geologists and paleontologists has been quite limited in previous works. since the discovery of abundant mammalian Because the site is important for considering remains of Early Pleistocene age in the later human immigration into East Asia during the +3,*’s. The remains have occurred from fluvio- Early Pleisotcene, Zhuet al. (,**+ ) tried to de- lacustrine sediments called the Nihewan For- termine the detailed numerical age of the arti- mation. In spite of a piece of information on fact layer of the site by paleomagnetic meas- the occurrence of a “stone artifact” from the urements. They concluded that the layer was basin (Breuil,+3-/ ), archaeologists had paid dated as +4-0 Ma. Their conclusion is more de- little attention to the sediments of the basin, tailed and more reliable than the results of until paleolithic artifacts were discovered at faunal dating by previous authors. the Xiaochangliang site in+312 (Youet al., +32* ). In order to obtain su$ cient knowledge on Received July,+, ,**1. Accepted November +1 , ,**1 . * + Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences. P.O. Box0.- , Beijing, +***.., China (Present address : Graduate School of Science, Osaka City University.-ῌῌ - +-2 Sugimoto, Sumiyoshi-ku, Osaka,//2ῌ 2/2/ , Japan). *Dep,+artment of Earth Sciences, Aichi University of Education. Hirosawa, Igaya-cho,Kariya, Aichi Prefecture, ..2ῌ 2/.,,Japan. *Dep-artment of History, Xiamen University. Xiamen, Fujian, -0+**/,China. * a Corresponding author:[email protected]. ac. jp 82 Zhang, Y.Q., Kawamura, Y. and Cai, B.Q. April ,**2 Fig.+oo Map showing the topographynear the east north easternendof the Nihewan Basin, where the Xiaochangliang site (X) is situated AP : alluvial plain of the Sangganhe River,PS:plateau surface, M : another archaeological site at Majuangou (“new cultural layer”ofCai and Li,,**- ). small mammals of the paleomagnetically well- plateau surface about+/* m higher than the dated layer, a large amount of sediments was plain (Fig.+ ). Several paleolithic archaeologi- sampled from the layer, and was washed with cal sites found after the Xiaochangliang site fine-mesh screens. The screen-washing resulted are also distributed in the hilly area (for exam- in obtaining more than,** remains of small ple, the Donggutuo and Majuangou sites). Cai mammals assignable to+* forms, most of which et al. (,**. ) divided the sediments in the area were new to the mammalian fauna of this site. and in the neibourhood with the same topogra- Small mammals are generally more important phy into such four units as+ ) “Hipparion red for biostratigraphy and paleoenvironmental re- clay” of early Pliocene age,, ) red, gray and construction than large mammals. Thus in this grayish black fluvio-lacustrine silty clay of late paper, we describe the small mammal fauna of Pliocene age,- ) brownish yellow to grayish yel- the site, compare it with other faunas, and dis- low fluvio-lacustrine clay and gravel of Pleisto- cuss small mammal biostratigraphy, faunal turn- cene age, and. ) overlying loess forming the over and paleoenvironment. The systematic plateau surface, in ascending order. The unit - descriptions for each form of small mammals is sometimes subdivided into the Nihewan For- will be given in subsequent papers. mation of Early Pleistocene age and the Xiao- dukou Formation of Middle Pleistocene age II. Geological setting (Yanget al., +330 ; Wei, +331 , etc.). The Xiaochangliang site is situated near the The Xiaochangliang site was found on a eastoo north eastern end of the Nihewan Basin small ridge called Xiaochangliang which means which shows a slender shape extending from a small but long hill ridge in Chinese (Fig.,ῌ A). this end toward westoo south west along the The ridge extends north o westward from the Sangganhe River into Shanxi Province. Around plateau edge near Guanting (Fig.+ ). The sec- the site, Pliocene and Pleistocene sediments are tion of the sediments are observable along the well exposed in a hilly area between the allu- ridge. In the section, the units+, and of Cai et vial plain of the Sangganhe River and a flatal. (,**. ) are lacking, while the units - and . are ,**2῎῍ . Small mammal fauna from the Xiaochangliang site 83 Fig. , Sampling site in “Location A” of the Xiaochangliang site A:overall view from “Location B” showing the sampling site (arrow) on the westernslope of the ridge extending from the plateau surface (PS), B : close-up photo of the sampling site showing the sampling horizon (SH). present. The unit- overlies directly the Juras- chapter. Zhuet al. ( ,**+ ) estimated the age of sic basement rocks with an unconformity and the layer to be+4-0 Ma, because the average is covered by the unit. Zhuet al. ( ,**+ ) showed accumulation rate between the Jaramillo and a detailed stratigraphic sequence of the section Olduvai Subchrons was calculated at about .40 with a thickness of1- m, which was composed cm/ka in the “Donggou” section which interca- mainly of silt and/or clay (Fig.- ). They also lated a thin marker layer of black silty clay described a thicker sequence of the “Donggou”+-4. m below the Jaramillo onset ( +4*1 Ma), and section+oo km west south west of the Xiaochang- because the same layer was also found at the liang site (outside the map of Fig.+ ). Unfortu- top of the artifact layer of the Xiaochangliang nately, they did not show the exact position of site. this section, and “Donggou” by them is di#,40 er- In the present paper, we adopt Ma as the ent in position from the same place-name used boundary age of the Pliocene and Pleistocene by other authors, as discussed in the subse- instead ofca. +42 Ma, the end of the Olduvai quent chapter. The “Donggou” section is cor- Subchron, as generally done among Chinese relative with the Xiaochangliang section, be- scientists. cause the sequences of the two sections are III. Sampling site and horizon almost identical, and contain sedimentological marker layers. Zhuet al. (,**+ ) carried out de- Since the first excavation, the Xiaochang- tailed paleomagnetic measurements, and deter- liang site has been divided into Locations A mined two normal and two reversed magneto- and B (Fig.. ). The geographic coordinates are zones in the Xiaochangliang section (N+ , N , ++.ῌῌ -341/,ῌῌ E and .* +-4+2+ N for A, and ++. ῌ and R+, , R ), and three normal and two reversed -3403,ῌῌE and .*ῌ +-4+22 N for B (Chenet al., +333 ). magnetozones in the “Donggou” section (N+ , The excavations of the site have been conduct- N,- , N and R +, , R ). They correlated the mag- ed in many grids as shown in Figure. We de- netozones with the standard geomagnetic time- cided the sampling site on the western slope near scale, as shown in Figure-- . N correlative with the most southo western grid of Location A (Figs. the Olduvai Subchron is recognized only in the,.ῌ A and ), because each layer of the sediments “Donggou” section, while N, correlative with are horizontal and the artifact layer is expected the Jaramillo Subchron is found in both of to expose in the sampling site. As a result of the sections. The sampling horizon of the pre- our excavation, the marker layer of black silty sent study (SH in Fig.-, ) is identical with the clay with a thickness of cm was found in the artifact layer of the site as stated in the next lower part of the section of the sampling site. 84 Zhang, Y.Q., Kawamura, Y. and Cai, B.Q. April ,**2 Zhuet al. (,**+ ) already described the marker screen-washing. layer lying just above the artifact layer of the IV. Screen-washing Xiaochangliang site. Thus the sediments just below the marker layer in our section is stra- The excavation, sampling and screen-washing tigraphically equivalent to those of the artifact were conducted by one of us (Zhang, Y.Q.) with layer (SH in Fig.,ῌ B). They were sampled for assistance of two employed villagers in the summer of,**/ . More than +40 tons of raw sediments taken from the sampling horizon were transported to the riverbed of the Sang- ganhe River near Xiaodukou (Fig.+ ). A double- layered screen box was used for washing the sediments. The box comprises the upper part with,4* mm mesh screen and the lower part with*4/ mm mesh screen.