An Issue on the Date of Fossil Human Remains from Salawusu, Inner Mongolia
SHANG Hong1,WEI Qi1,WU Xiao-hong2(1Institute of Vertebrate Paleontology and Paleoanthropology,Chinese Academy of Sciences,Beijing 100044;2School of Archaeology and Museology,Peking University,Beijing 100871)
Salawusu site from Inner Mongolia represents a typical profile of the Upper Pleistocene in North China. It is also one of the sites yielding the first evidence of the presence of Homo sapiens in Pleistocene Asia.The present paper reviews the results of chronometric studies of Salawusu Formation from which the “Ordos man” and Salawusu culture have been found. Qiu Zhonglang (1955) compared the Fluorine content between Salawusu PA.62 femur bone and other mammalian fossils from Salawusu Formation and indicated that the age of PA.62 is much younger than the other mammalian remains. Yuan Sixun (1983) et al collected some fossilized mammalian teeth and antlers from various stratigraphical position of primary Salawusu sediment and dated with Uranium series method. The result is that the lower Salawusu Formation was accumulated between 30000? ?0000 BP. Li Xingguo et al(1984) suggested that the date of “Ordos Man” and Salawusu culture should be 35340± 1900 BP according to the 14C date of the carbon particles collected from Salawusu Formation of Fanjiagouwan. Dong et al (1998) compared the fluvio-lacustrine-aeolian sand sequence from the Dishaogouwan section with loess, deep-sea core records and climatic fluctuations of glacial period according to the stratigraphic subdivision and dating of the Dishaogouwan section. According to their opinions the fluviolacustrine facies of Salawusu Formation was formed in the last interglacial period from 140000 to 70000 BP, roughly corresponding to the fifth stage of deep-sea oxygen isotope record, and developed in the same period as the palaeosol S1 on the Loess Plateau.Yin Gongming et al(2004) collected three samples for IRSL dating from the Paleolithic Culture layer of Fanjiagouwan locality, Salawusu site. The IRSL ages indicate that this is older than 61000± 4900 BP and younger than 68000± 7300 BP.Fan et al (2002) have collected 140 samples from the profile of Dishaogouwan for paleomagnetic dating. The distance between two samples is 20cm. The result is the Salawusu Formation is 180000? ?0000 BP, or roughly corresponding to the period between Late Middle Pleistocene and Late Pleistocene.Wei Qi sent a piece of specimen of PA.62 femur found on the earth surface of Salawusu in 1923 to the AMS laboratory of School of Archaeology and Museology,Peking University as well as Arizona University, USA for radiocarbon dating. The results from these laboratories are similar, i.e. 200—300 BP. These results confirm the assertion made by Qiu (1955) based on fluorine content of this specimen that it is not associated with the fauna of Salawusu Formation.Many human fossil remains have been found in the area of Salawusu valley in past years. Some of them are found in situ, others are surface findings. In recent years, come chronometric dating have been done for this Formation. Most of the dates obtained are consistent with the geological age of the mammal fossils belonging to the Upper Pleistocene. Generally speaking,the human fossil remains found in situ could be regarded as belonging to this age range. However in terms of the human remains collected from the surface we should not estimate their date only based on its fossilization, colour and contrasting with the other fossils from the stratum. PA.62 is a prominent example as that. For surface findings only the date from direct dating would have the creditability.