New findings of Changxingaspis(Xiushuiaspidae,Galeaspida)from the Silurian of Tarim Basin and Zhejiang Province,China

New discovery of the early Silurian fossil fish Changxingaspis(Xiushuiaspidae,Galeaspida),Changxingaspis nianzhongi sp.nov.and C.gui,are described from the Tataertag Formation in Tarim Basin and the Kangshan Formation in Zhejiang Province,respectively.C.nianzhongi mainly differs from C.gui in the shape of the median dorsal opening that is transverse elliptic with a width/length ratio of about 3.0,the long lateral transverse canals extending to the lateral margin of the headshield,and the second lateral transverse canal with dichotomous branchings.Discovery of C.nianzhongi from the Tataertag Formation and C.gui from the Kangshan Formation provide direct evidence on the specific level for the correlation between these two formations,which further supports the Silurian fish-bearing red beds in northwest Zhejiang belonging to the Silurian Lower Red Beds(LRBs)rather than the Upper Red Beds(URBs).Additionally,as the first record of the Changxingaspis in Tarim Basin,it extends the paleogeographical distribution of this genus from the South China Block to the Tarim Block,providing new evidence to support faunal exchanges between these two blocks and the hypothesis of a united Tarim-South China Block during the early Silurian.

Flat-footed Females and Missing Males:A New Genus and Species of Pleciofungivoridae(Diptera:Bibionomorpha)Represents the First Record of the Family from Mid-Cretaceous Kachin Amber

A new genus and species,Cretopleciofungivora simpsoni gen.et sp.nov.,from the extinct family Pleciofungivoridae(Diptera:Bibionomorpha),is discovered in mid-Cretaceous Kachin amber.Previously,this family was known only from imprints in sedimentary rocks of the Jurassic and the Lower Cretaceous.Discovery of a representative of Pleciofungivoridae in Kachin amber confirms the presence of the family in the Upper Cretaceous.The new species has a unique structure of fore tarsus,with lobed and extended tarsal segments Ⅱ to Ⅳ,a feature hitherto known only in a few species of extant Sciaroidea.Although not particularly rare,the new species is currently known only from female specimens.Possible reasons for this phenomenon,very unusual in Sciaroidea,are briefly discussed,including parthenogenesis as a potentially plausible hypothesis.

Enigmatic ribbon-like fossil from Early Cambrian of Yunnan, China

During the Late Neoproterozoic and Early Cambrian,a series of paleogeographic and paleoecological events occurred associated with deglaciations and the evolution of life.The appearance of fossils representing diverse phyla,novel body plans and complex ecologies in Ediacaran and Cambrian sedimentary successions has sparked diverse hypotheses about potential drivers for the radiation of early animals during this interval.Recently,new macroscopic fossils of carbonaceous compressions with unique features have been found in Anning,Yunnan,China.The fossils’bodies are ribbon-shaped and bilaterally symmetric,with dense longitudinal features and transversal features.The fossils occur 0.68 m below a bentonite interlayer which has been dated 535.2±1.7 Ma by Ri-xiang Zhu and his team in 2009.The relatively simply morphology of these fossils,coupled with a lack of preserved internal structures challenge efforts taxonomically identify the precursor organism and definitively ally it to a living group.However,the symmetry and unusual features of the body are analogous to members of Platyzoa.The presence of ribbon-shaped fossils in the Zhongyicun Member in Anning indicates that these organisms were at least a locally significant component of Cambrian seafloor ecosystems,and may hold important implications for our understanding of the early evolution of Bilateria.

Leaf fossils of Sabalites(Arecaceae)from the Oligocene of northern Vietnam and their paleoclimatic implications

Recent paleobotanical investigations in Vietnam provide a good opportunity to improve our understanding of the biodiversity and paleoclimatic conditions in the geological past of Southeast Asia.Palms(Arecaceae)are a diverse family of typical thermophilous plants with a relatively low tolerance for freezing.In this study,we describe well-preserved fossil palm leaves from the Oligocene Dong Ho Formation of Hoanh Bo Basin,northern Vietnam.Characters of the fossil leaves,such as a fan-shaped costapalmate lamina,an unarmed petiole,a costa slightly enlarged at the base that then tapers distally into the blade,and well-preserved amphistomatic leaves with cuticles,suggest that they represent a new fossil species,which we herein designate Sabalites colaniae A.Song,T.Su,T.V.Do et Z.K.Zhou sp.nov.Together with other paleontological and palaeoclimatic evidence,we conclude that a warm climate prevailed in northern Vietnam and nearby areas during the Oligocene.

Petrogenesis of the Early Cretaceous Tiantangshan A-type Granite in northwestern Guangdong province, SE China and tectonic implications

1 Introduction During the late Mesozoic times,the SE China is characterized by extensive magmatism and mineralization.The widely distributed granitoids with different(I-,S-and A-)types have been inferred to be closely related to the large-scale polymetallic mineralization.The Nanling tungsten-tin polymetallic belt is endowed with considerable

Petrogenesis of the Early Jurassic Longtang and Menglong Peraluminous Granites in Tengchong Terrane,and their Tectonic Implication

A comprehensive study of zircon U-Pb geochronology,in situ Hf isotopes,whole-rock major and trace element geochemistry,and Nd isotopes was carried out for two Early Jurassic two-mica granites(Longtang and Menglong)in the southern part of the Tengchong terrane,which is in the northern part of the larger Sibumasu terrane.We assess the origin of the granites and explore their possible genetic relationship to the Paleo-Tethyan regime.LA-ICP-MS zircon U-Pb dating shows that they were simultaneously emplaced in the Early Jurassic(ca.199 Ma).They have SiO2 contents of 69.7–75.1 wt%and are mainly strongly peraluminous with alumina saturation index(ASI)values ranging from 1.06 to 1.46.They show similar Mg#(0.29–0.42)to experimental partial melts of metasedimentary rocks under continental pressuretemperature(P-T)conditions.They are enriched in light rare earth elements(LREEs)relative to heavy rare earth elements(HREEs),with moderately negative Eu anomalies and flat HREEs patterns.They show negativeεNd(t)values(−9.0 to–12.4)andεHf(t)values(−8.0 to−9.1).Elemental and isotopic data suggest that they most likely to formed by muscovitedehydration melting of a metapelitic source at lower temperatures in the range of 700℃to 750℃.The granites might represent a post-collisional tectonic setting response to Paleo-Tethyan regime.

New Phenotypes of Limnocythere inopinata from Lakes in Badain Jaran Desert,Northern China

Objective Limnocythere inopinata(Baird,1843)is an ostracod widely distributed in recent non-marine waters and in Quaternary sediments,where it comprises various phenotypes(Yin et al.,1999;Zhang et al.,2015).Based on the nodation patterns,five phenotypes were described in previous publications,namely,the unnoded,the phenotype with one node in the postero-ventral part of the valve,one with two nodes in the antero-ventral and postero-ventral parts of the valve,another with three nodes in the antero-ventral,postero-ventral and postero-dorsal parts of the valve.

SIMS U-Pb zircon age of a tuff layer in the Meishucun section, Yunnan, southwest China: Constraint on the age of the Precambrian-Cambrian boundary

Determination of the age of the Precambrian-Cambrian boundary is critical in understanding early evolution of life on Earth. SIMS U-Pb zircon analyses of the Bed 5 tuff layer of the Meishucun section were carried out closely following the guidance of cath

Noeggerathiales as coal-forming plants in Cathaysia:conclusions from an Early Permian vegetational Pompeii in Inner Mongolia

Noeggerathiales are an extinct group of sporebearing plants of uncertain systematic position that are known from Carboniferous and Permian age Euramerican and Cathaysian floras that occurred in present-day Europe,North America,and East Asia.The order Noeggerathiales includes over 50 species of more than 20 fossil genera,but their paleoecology is not well understood yet.Previously this group had been found only in extrabasinal floras or those inhabiting clastic wetlands.Noeggerathiales have never been recorded in coal ball floras.Thus,it is up to now uncertain whether this group has contributed to the formation of coal.Recent investigations of an Early Permian peat-forming flora of the Taiyuan Formation near Wuda,Inner Mongolia,which was preserved in a volcanic ash fall has provided evidence that noeggerathialean plants not only existed in the peat-forming vegetation but could even be the dominant group in some areas of the coal swamp.The Noeggerathiales in this particular peat-forming forest include Tingia unita,Paratingia wudensis,and a new species of Paratingia.Exceptionally well-preserved specimens indicate that these noeggerathialean plants are small trees with a canopy of compound leaves and strobili near the top of an unbranched(monocaulous)stem.

The redox structure of Ediacaran and early Cambrian oceans and its controls

The rapid diversification of early animals during the Ediacaran(635–541 Ma) and early Cambrian(ca.541–509 Ma) has frequently been attributed to increasing oceanic oxygenation. However, the pattern of oceanic oxygenation and its relationship to early animal evolution remain in debate. In this review,we examine the redox structure of Ediacaran and early Cambrian oceans and its controls, offering new insights into contemporaneous oceanic oxygenation patterns and their role in the coevolution of environments and early animals. We review the development of marine redox models which, in combination with independent distal deep-ocean redox proxies, supports a highly redox-stratified shelf and an anoxia-dominated deep ocean during the Ediacaran and early Cambrian. Geochemical and modeling evidence indicates that the marine redox structure was likely controlled by low atmospheric O2 levels and low seawater vertical mixing rates on shelves at that time. Furthermore, theoretical analysis and increasing geochemical evidence, particularly from South China, show that limited sulfate availability was a primary control on the attenuation of mid-depth euxinia offshore, in contrast to the existing paradigm invoking decreased organic carbon fluxes distally. In light of our review, we infer that if oceanic oxygenation indeed triggered the rise of early animals, it must have done so through a shelf oxygenation which was probably driven by elevated oxidant availability. Our review calls for further studies on EdiacaranCambrian marine redox structure and its controls, particularly from regions outside of South China, in order to better understand the coevolutionary relationship between oceanic redox and early animals.

When horsetails became giants

Horsetails arose in the Late Devonian,evolved a greater diversity and forming fast growing bamboo-like thickets in the Carboniferous lowland swamp forest ecosystems.However,the diversity of this group drastically declined during the Permian while the climate became more dynamic and arid.Today only a single surviving genus exists,the herbaceous Equisetum.Here we report an exceptional large horsetail tree from the Early Permian Petrified Forest of Chemnitz.This fossil horsetail tree is assigned to Arthropitys bistriata (Cotta) Goeppert.It is 15 m high and over 25 cm in diameter,with thick wood and at least 3 orders of woody branching system formed a big canopy,and is morphologically very comparable with the living woody higher plants.This suggests that the plasticity mechanism of Permian calamitaleans enabled novel growth strategies when they competed with the rising gymnosperms during the environmental changes.

The first shrimp preserved in mid-cretaceous Kachin amber:systematics,palaeoecology,and taphonomy

Amber from Kachin,Myanmar offers a unique window into mid-Cretaceous ecosystems because it provides large sample sets that span a wide range of taxa preserved in exquisite detail at approximately 99 Ma[1].A fringe benefit of such extensive sampling is that inclusions rarely captured in other amber deposits are represented in Kachin amber—even subaquatic taxa.Recent studies have documented inclusions of fully marine groups,such as ammonites[2]and bivalves[3].