An Important Ornithischian Tracksite in the Early Jurassic of the Shenmu Region,Shaanxi,China

A large track site with multiple, well-preserved trackways of an Early Jurassic quadrupedal ornithischian dinosaur is the first report of Moyenisauripus-like trackways from Asia, herein named Shenmuichnus youngteilhardorum. The tracks occur in a clastic fluvial sequence in the Fuxian Formation in Shenmu County, Shaanxi Province, which is in the same general region as the discovery site of Sinoichnites, the first dinosaur track reported from China. Based on size and morphology, it is likely that Sinoichnites, which is now lost, also represents an ornithischian. The Shenmuichnus youngteilhardorum trackways show two modes of preservation： the first representing deeper tracks, with sediment rims, results in Deltapodus-like tracks, with indistinct pes digit traces and sub-circular manus traces, the second produces Moyenosauripus-like tracks, with clear tridactyl and pentadactyl digit traces in the pes and manus respectively. Thus the Shenmu trackways play a key role in resolving globally significant ichnotaxonomic problems surrounding the nomenclature of Sinoichnites, Moyenosauripus, Deltapodus and other named （Ravatichnus） and unnamed trackways from Asia, Africa and Europe. In addition they shed important light on the paleogeographical and paleoecological distribution of quadrupedal ornithischians in the Early Mesozoic. The track site has been the focus of a major excavation to transfer the trackways from their original remote location to the new Shenmu Museum, in Shenmu City. Other tracksites in the area which reveal Anomoepus, Grallator and the Deltapodus morphotype, together with Shenmuichnus and plant fossil evidence, suggest an Early Jurassic age for the tracksite.

Single-atom Pd anchored in the porphyrin-center of ultrathin 2D-MOFs as the active center to enhance photocatalytic hydrogen-evolution and NO-removal

Single-atom catalysts were widely used to treat atmospheric pollution and alleviate energy crises through photocatalysis.However,how to prevent the aggregation of single atoms during the preparation and catalytic processes remained a great challenge.Herein,a novel ultrathin two-dimensional porphyrin-based single-atom photocatalyst Ti-MOF(abbreviated as TMPd)obtained through a simple hydrothermal synthesis strategy was used for photocatalytic hydrogen evolution and NO removal,in which the singleatom Pd tightly anchored in the center of porphyrin to ensure single-atom Pd stable existence.Compared with most reported MOFs-based photocatalysts,the TMPd showed an excellent hydrogen evolution rate(1.32 mmol g^(-1)h^(-1))and the NO removal efficiency(62%)under visible light irradiation.Aberrationcorrected high-angle annular dark-field scanning transmission electron microscope(HAADF-STEM)and synchrotron-radiation-based X-ray absorption fine-structure spectroscopy(XAFS)proved that pd in TMPd existed in an isolated state,and the atomic force microscope(AFM)proved the ultrathin morphology of TMPd.DFT calculations had demonstrated that single-atom Pd could serve as the active center and more effectively achieve electron transfer,indicating that single-atom Pd played a vital role in photocatalytic hydrogen evolution.In addition,a possible photocatalytic pathway of NO removal was proposed based on ESR and in-situ infrared spectra,in which the catalysts anchored with single-atom Pd could produce more active substances and more effectively oxidize NO to NO_(2)^(-)or NO_(3)^(-).The results suggested that coordinating single-atom metal species as the active site in the center of porphyrin could be a feasible strategy to obtain various ultrathin porphyrin-based single-atom photocatalysts to acquire excellent photocatalytic performance further.

Distribution of sand dunes and sand shifts along the southern fringe of the Mu Us Desert since the Ming Dynasty

This article takes the two segments of the Ming Great Walls,Dabian and Erbian,and their associated barracks and forts as geographical references. Based on a detailed scrutiny of historical records of the Ming and Qing dynasties,and on field surveys,the southern boundaries of the sand dunes and sand shifts of the Mu Us Desert in the Ming and Qing dynasties are carefully reconstructed. A comparison of the southern boundaries of the sand dunes and sand shifts of the Mu Us Desert in Ming and Qing with the modern boundary revealed in remote sensing imagery clearly shows that the southern boundary of dunes and shifts in the Mu us Desert has expanded only in a few areas and on a small scale. In the area to the south of Changle Fort,along the direction of annually prevailing winds,sand drifts have pene-trated through the Jialu River valley into the loess region and have formed a sand strip of 32 km long and 3 km wide. To the east of Qingping Fort,sand drifts penetrated toward the eastern loess region through the Luhe River valley and have formed another sand strip of 8 km long and 2 km wide. Gener-ally speaking,though the intensity of human activity has been increasing in this area since the Ming Dynasty,the Mu Us Desert has not significantly expanded toward the southeast or southwest. The sand-loess boundary in the southern fringe of the Mu Us Desert has been almost unchanged since the Ming Dynasty.

A preliminary study of chronology for a newly-discovered ancient city and five archaeological sites in Lop Nor, China

In the past century, it has long been debated in the archeological, historical, geographical, and many other related communities where the capital of the Luolan and Shanshan states was in the Lop Nor region. This paper presents three AMS radiocarbon ages from a newly-discovered ancient city at about 6.3 km to the northwest of the Xiaohe Graveyard, and fifteen new radiocarbon ages from the Loulan (LA), LE, Qieerqiduke, Milan, and Tuyin sites in Lop Nor. The new investigation shows that the age of newly-discovered ancient city is at ca. 440–500 AD, belonging to the Northern Wei Dynasty (386–534 AD). This is about 100–300 years younger than Loulan (ca. 100–230 AD), LE (ca. 230–300 AD), Qieerqiduke (ca. 200 AD), and Tuyin (ca. 100 AD). A wooden beam from Milan fortress is dated to ca. 370 AD, while the age on north wall at west gate of the fortress is younger, around 770 AD, suggesting that its construction time might be at the Tang Dynasty. According to 14C ages, cultural relic style, and the geographical location, the newly-discovered ancient city is probably attributed to "Zhubin City", as documented in the historical literature. Temporally, we name the city "ancient Zhubin River City". However, the characteristics and functions of this ancient city are largely unknown and need more detailed archaeological excavation and investigation in the future. Given its location near the ancient postal relay of Alagan on the crossroad, there is no doubt that the newly-discovered city was at an important geographical position on the Silk Road, no matter whether it was called "Zhubin City", or "Lielo City", or the capital of Loulan state–"Yuni City". Our findings provide new evidence for the temporal and spatial distribution of ancient relic sites and the development of civilization in western China, thus contributing to our understanding of the relationship between human activities and environmental change in the Lop Nor region.

Animal diversities and characteristics of environmental change revealed by skeletons unearthed at Zhongba Site of Chongqing City,China

Nearly 200000 animal skeletons are unearthed in the Unit T0202 from Zhongba Site of Zhongxian County.According to the analysis of 129165 specimens,these skeletons may be classified into 5 kinds, namely,Mammalia,Osteichthys,Aves,Amphibian and Reptilia,which belong to 13 orders,28 families and 42 genera.In this paper,based on archeological dating and AMS 14 C data,through statistically analyzing the unearthed skeletons and studying the change of the smallest individual numbers,these research results detected the following:1)In almost all the time of 2370―200 BC,in Zhongba region, some animals distributed widely,such as Muntiacus sp,Elaphodus cephalophus and Muntiacus sp. inhabiting in glade and grassland,Scrofa sp.and Canis familiaris raised by the ancient people,rodentia rabbit and Rattus rattus,which suggested that a fairly good ecological environment of forest and grassland was preserved at that period and the predecessors began to raise domestic animals from 1750 to 1000 BC,which has lasted until today.2)Rhinoceros only lived during 2000―1750 BC,1000― 700 BC and 700―500 BC,which indicates that the ecological environment of grassland and wetland might be better in these phases.3)Macaca sp.and Ursus arctos appeared only after 1750―1000 BC, which may show that the forest condition is better for animals to live during 1750―200 BC.4)The smallest individual numbers of Bublus sp.,bos sp.and otters emerged during about 2370―1750 BC, which perhaps infers that water area during the early period was wider than that of the late period.5) Since skeletons of rhinoceros are discovered in strata of Zhongba Site during 2000―1750 BC and 1000―500 BC,according to the climate and ecology environment which rhinoceros live in now,the average annual temperature and precipitation during 2000―1750 BC and 1000―500 BC are supposed to be probably higher than that of today.Although Zhu Kezhen considered that the first low temperature period in the past 5000 years of China was between 1100 BC and 850 BC,massive pollen of Morus, Ulmus,Fagus,Quercus,Castanea,etc.were found in Dajiuhu peat at that time,which should indicate that the climate was still moderate for living things to live at least in Dajiuhu basin and Zhongba Site.6) Because skeletons of Gervus albirostris were unearthed during 310―200 BC at Zhongba Site,based onthe climate and the ecological environment those animals live in now,the average annual temperature and the average annual precipitation in Zhongba area between 310 BC and 200 BC should be lower than those of today,which is confirmed by the TOC research of Zhongba Site strata.

Extreme flood events and climate change around 3500 aBP in the Central Plains of China

The Xinzhai Period (35503400 aBP) belongs to Late Neolithic Culture, which bridges the Longshan Culture and the Xia Culture in the Central Plains of China. By studying the living environment of ancient human beings at the Xinzhai site, Henan Province, this paper pre-sents the discovery of extreme floods which threatened and destroyed the living environment of the ancient human beings during the Xinzhai Period. Pollen analysis and carbon-oxygen isotope measurement suggest that the climate was warm and wet during the Xinzhai Period, in contrast to the warm and arid climate during the Longshan Culture Period. The frequent flood events were the response of abrupt climate change during the Xinzhai Period. The conclusions drawn from this study not only help better understand the environmental change in the Central Plains of China around 3500 aBP, but also provide important clues to the environmental background for the origin of Chinese civilization.