A diminutive euphyllophyte, Douaphyton levigata, from the Middle Devonian of Xinjiang, the vegetitave and fertile speicmens. The grid in the upper right corner of the left fig is 1 mm wide. Devonian (420-360 Ma) witnessed a serial of dramatic landscape changes. A variety of land plants, including early ferns, lycopsids and zosterophylls, appeared in the lands of Devonian world. The first forest also occurred in the Devonian. The West Junggar, Xinjiang, China, with well-developed Devonian sequences and abundant plant fossils, has become a representative and significant area working on Middle Devonian flora. Diminutive Devonian plants (axis width less than 2 mm), for a long time were neglected for the reason of small size and that it is hard to fine organic connected specimens of vegetative and fertile organ. As a result, few study was carried on diminutive Devonian plants, which, however, act as a significant group to study plant and flora evolution, diversity and palaeophytogergraphy. Recently, a diminutive euphyllophyte, Douaphyton levigata gen. et sp. nov., is described from the upper Middle Devonian (Givetian) Hujiersite Formation of West Junggar, Xinjiang, China, by Prof. XU Honghe from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and his collegues. The plant consists of more than three orders of axis branching, each axis being less than 2 mm wide. The second-order axes are short, laterally and alternately attached to the main axis. The third-order axes are paired and anisotomously divided, bearing the vegetative appendages or the fertile units. The fertile unit consists of a short recurved axis giving off up to four short pedicels along one side, each of which bears one to four pairs of terminal sporangia. The plant was named after the geologist Mr. DOU Yawei, who worked on geologic survey to Xinjiang in 1970-1980s. Douaphyton has a three-dimensional branching system that has an intermediate form in the evolutionary context of euphyllophytes and lignophytes. It is also proposed that complex branching developed in multiple groups in the Middle Devonian. Reference: Xu, H.-H., Wang, Y., Tang, P., Wang, Y., 2017. A new diminutive euphyllophyte from the Middle Devonian of West Junggar, Xinjiang, China and its evolutionary implications. Alcheringa.
Ankitokazocaris chaohuensis. scale bars equal 5 mm Thylacocephala, though only been recognized for 25 years, has been considered a peculiar group worthy of detailed anatomical and phylogenetic studies. They are benthic arthropods showing large, laterally flattened ovoid/sub-trapezoidal bivalved carapace that encompasses the entire body and have a typical anterior rostrum-optic notch complex. Generally they have large compound eyes, three large raptorial appendages, 8 gills and numerous posterior appendages. Their long temporal distribution, from the early Palaeozoic to the Late Cretaceous, is furnished by patchy records that clearly reflect the availability of Fossil-Lagerst？tten. The taxonomy and ecology of this group has been controversial due to the low diversity and lack of complete specimens. In the Chaohu Area of Anhui Province, a complete strata of the Early Triassic can be observed. The Chaohu Fauna, represented by the diversified marine reptiles and fishes from the upper part of Nanlinghu Formation (Spathian, Olenekian), has been regarded as a marker of the full recovery of marine ecosystem after PTME. Recently, Dr. JI Cheng from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and her collegues discovered new material of thylacocephalan from the Chaohu Fauna and it is also the first report of this group in the Triassic of South China. More than one species can be recognized but majority belongs to a new species, Ankitokazocaris chaohuensis, suggesting a close geographic correlation with Madagascar and Japan during the Spathian of Early Triassic. From the bed yielding A. chaohuensis, we also found some coprolite fossils, some of which contain conodonts inside. The size and structure of these coprolites can rule out the marine reptiles and fish from the same fauna as producers. Dr. JI compared the relative size of gut and carapace of Silurian thylacocephalan Thylacares brandonensis and their coprolites and found that these thylacocephalans from the same bed could possibly have produced the coprolites after eating conodont animal. This is the first report of the predation between thylacocephalan and conodont animal. On the other hand, thylacocephalans have large compound eyes and large raptorial appendages, suggesting they are capable of detecting and grasping small prey like shrimp or maybe even conodont animal of similar size. Dr. JI also have a few specimens that preserve conodonts inside the partial carapace where the latter was broken. They might be related with gut remains but still need further evidence. reconstruction of Ankitokazocaris chaohuensis (By YANG Dinghua from NIGPAS) This research has been recently published on-line in Pal？ontologische Zeitschrift, founded by National Science Foundation of China, CAS Key Laboratory of Economic Stratigraphy and Palaeogeography and State Key Laboratory of Palaeobiology and Stratigraphy (NIGPAS). Reference: Cheng Ji, Andrea Tintori, Dayong Jiang and Ryosuke Motani, 2017. New species of Thylacocephala (Arthropoda) from the Spathian (Lower Triassic) of Chaohu, Anhui Province of China. Pal？ontologische Zeitschrift, DOI: 10.1007/s12542-017-0347-7.
Fig. 1 Some charophytes from the Pingyi Basin. A-C. Feistiella anluensis; D-I. Peckichara varians. var ss="图1. 山东平邑盆地部分轮藻化石属种"; if(ss=="") document.getElementById("d0").style.display="none";
The Cretaceous-Paleogene boundary (K/Pg boundary) marks the beginning of the Cenozoic, and is one of the most important geological boundaries. The end-Cretaceous extinction is one of five mass extinction events, leading to the extinction of ammonites and belemnites in the sea. Also it is the end of dinosaur’s age. The K/Pg boundary is recognized as the boundary clay and the GSSP for the base of Danian stage is at the base of the clay. However, it is difficult to find the boundary clay in non-marine strata. Charophytes are usually very abundant in the non-marine strata near the K/Pg boundary, and the significant changes of charophyte flora can help to recognize the K/Pg boundary. Recent investigation conducted by the Dr. LI Sha from “Modern terrestrial ecosystems origin and early evolution research team” at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, cooperated with Carles Martín-Closas from the University of Barcelona, studied the change of charophyte floras from the Cretaceous–Paleogene transition in the Pingyi Basin, China and correlated it with European charophyte floras under the same age. The Cretaceous–Paleogene boundary was raised in the Pingyi Basin and the results were published on the Journal of Cretaceous Research. Traditionally, the identification of charophytes in China is usually based on individual or a few gyrogonites but not the whole population. Such studies lack statistical measurements of the population and a uniform taxonomic standard, and do not consider the population characteristics and intraspecific variation. So it is difficult to make an intercontinental charopyhte biostratigraphic correlation and calibrate the K/Pg boundary in China. In study of the Pingyi Basin, Shandong Province, both traditions of identification from China and Europe were combined. For example, Porochara anluensis used in China was in fact belonged to the genus Feistiella according to observing the sections of basal plates. The intraspecific variations Peckichara varians was recognized based on population measurement and analysis. The abundant species Gobichara deserta around the Cretaceous–Paleogene boundary is in fact a younger synonym of Microchara cristata. (Fig. 1). Fig. 2 Paleobiogeography of Microchara cristata in the Maastrichtian and early Paleocene, showing its Eurasian distribution. Paleogeography modified from Blakey (2006) with data plotted on a map at 65 Ma. var ss="图2. 山东平邑盆地马斯特里赫特期至古新世早期Microchara cristata的地理分布，显示其欧亚分布。古地理图改自Blakey（2006），65Ma"; if(ss=="") document.getElementById("d1").style.display="none";
Based on a concensus of identification standard, a new biozonation is proposed which encompasses two biozones based on species with broad paleoecological requirements and a Eurasiatic distribution (Fig. 2, 3). European terrestrial Cretaceous–Paleogene boundary is mainly studied based on charophyte biozonations, the results can also be used in the research of Chinese terrestrial Cretaceous–Paleogene boundary. These are the Microchara cristata biozone starting in the latest Campanian and lasting at least until the earliest Danian and the Peckichara varians biozone encompassing the late Danian–earliest Eocene. The former can be correlated with biozones established by Galbrun et al. (1993) and Vicente et al. (2015) and calibrated to the GPTS, and the latter was correlated with Paleocene larger foraminifera in the Northern Pyrenees (Massieux et al., 1981). Therefore, the Cretaceous–Paleogene boundary from the Pingyi Basin was proposed to be in the first member (upper sub-member) of the Bianqiao Formation. Reference: Li, Sha, Wang, Qifei, Zhang, Haichun, Lu, Huinan, Martín-Closas, Carles* (2016) Charophytes from the Cretaceous–Paleogene transition in the Pingyi Basin (Eastern China) and their Eurasian correlation. Cretaceous Research, 59: 179-200
Fig. 3 Paleoenvironmental models summarizing the paleoecological distribution of charophyte floras in the Pingyi Basin (Gucheng and Bianqiao Formations) during the Maastrichtian and Paleocene.
Recently, ZENG Han (PhD student) and his colleagues from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences described in detail the appendages of an early Cambrian trilobite Hongshiyanaspis yiliangensis Zhang & Lin in Zhang et al., 1980 (Redlichiida, Metadoxididae) from the Cambrian Xiazhuang fossil assemblage at the suburban of Kunming, Yunnan. This is the seventh trilobite species with complete appendages described and reconstructed in the world, and the second one in China after Eoredlichia intermedia from the Chengjiang Lagerst？tte. The new data supports the mandibulate affinities of trilobites. Trilobites are one of the most diverse extinct groups of arthropods that inhabited Paleozoic seas from the Cambrian explosion to the end-Permian mass extinction (~ 520–250 Ma). So far, more than 20,000 trilobite species have been discovered. However, nearly 99% trilobite species are named based on morphology of exoskeletons, the soft bodies of trilobites are poorly known. In particular, complete walking limbs of trilobites have only been reconstructed in six species from exceptionally preserved fossil deposits. This limited knowledge of the trilobite soft anatomy, especially appendages, has long constrained our understanding on the evolutionary position of trilobites on the arthropod tree of life. Owing to increasing numbers of exceptionally well-preserved arthropods from the Cambrian Chengjiang (Yunnan, China) and the Burgess Shale (British Columbia, Canada) during the last two decades, the artiopods (meaning bearing a complete set of similar appendages), a miscellaneous group of Cambrian arthropods possessing similar body plans and appendage structures with trilobites, are widely accepted as the closest relatives of trilobites. However, no consensus has been reached on the closest extant arthropod group of trilobites and artiopods, as either Chelicerata or Mandibulata. The appendages of H. yiliangensis exhibit the common architecture revealed by other trilobites and artiopods by consisting of a pair of uniramous antennae followed by a series of paired homonomous biramous limbs. The antennae in holaspid individuals comprise up to 27 spinous podomeres and their ontogeny occurs by lengthening of the podomeres. The post-antennal biramous limbs are similar to those in other trilobites and artiopods by having a single-segmented protopodite and an endopodite comprising seven segments, but possess a unique wide tripartite exopodite with long setae. Appendages of trilobites, artiopods and other upper stem-group euarthropods are compared and summarized. The H. yiliangensis appendages highlight the high morphological disparity of exopodites and the conservativeness of endopodites in trilobites and artiopods. This morphological pattern, together with similar body patterning seen in crustaceans but not in chelicerates, supports the mandibulate affinities of trilobites and at least some artiopods. This research was funded by the National Natural Science Foundation of China, the Ministry of Science and Technology of China, and the Chinese Academy of Sciences. Article information: Han Zeng, Fangchen Zhao*, Zongjun Yin, Maoyan Zhu. 2017. Appendages of an early Cambrian metadoxidid trilobite from Yunnan, SW China support mandibulate affinities of trilobites and artiopods. Geological Magazine: 1–23. doi: 10.1017/S0016756817000279. (*corresponding author)
Early Cambrian trilobite Hongshiyanaspis yiliangensis preserved with complete appendages (Image by Zeng et al.) Reconstruction of limbs of early Cambrian trilobite Hongshiyanaspis yiliangensis (Image by Zeng et al.)
Location map of Site U1391, and distribution of main ocean water masses in the northeastern Atlantic and western Mediterranean Sea After the Strait of Gibraltar re-opened at 5.33 million years ago, warm high-salinity Mediterranean outflow water (MOW) showered into the Gulf of Cadiz, north Atlantic, penetrating north along the Portuguese slope, even to the Norwegian- Greenland Sea region, which enhances the North Atlantic deep water density and helps drive Atlantic Meridional Overturning Circulation (AMOC). Due to the stronger current in the west Iberian margin, most study were limited to the last glacial- interglacial periods before the long term continuous sediments retrieved from the IODP339 cruise during November, 2011-January, 2012. As part of the post cruise scientific research, this study, supported by National Natural Science Foundation of China, Chinese Academy of Sciences and IODP-China, and lead by Prof. LI Baohua from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, performed large amount of micropaleontological work on core sediments from Site U1391 off the Portuguese margin. Quantitative benthic foraminifera, detailed stable isotope of both planktonic and benthic foraminiferal shells, and Mg/Ca ratios of benthic foraminiferal shells were used to reconstruct the long-term variation of Mediterranean outflow water with continuous record for the first time. Benthic foraminiferal faunal data from Site U1391 disclose the bottom water property over the last ~0.9 Ma. Variations of the index species or assemblages, such as Planulina ariminensis and the “elevated epibenthos” group suggest that the MOW intensity has typical glacial-interglacial cycles, an active MOW current during the interglacial periods and a sluggish MOW current during the glacial periods. Over the last ~0.9 Ma, the strength of MOW reached its peak at MIS 11, when the sea level was considered to rise up to ~20 m above the present high-stand, which confirms the influence of climate on the MOW current by waving the sea level stands. The above results was recently published in Global and Planetary Change: Qimei Guo, Baohua Li, Jin-Kyoung Kim, IODP Expedition 339 Scientists, 2017. Benthic foraminiferal assemblages and bottom water evolution off the Portuguese margin since the Middle Pleistocene. Global and Planetary Change, http://dx.doi.org/10.1016/j.gloplacha.2016.11.004
Although a majority of biologists are convinced that a mass extinction is underway on earth today, the human history with direct observatory data is too short to predict its future trend. At least five great mass extinctions occurred during the Phanerozoic and they caused at least 75% marine species rapidly to go extinct; they also seriously affected the species diversity on land once the terrestrial ecosystem developed. The causes and consequences of these mass extinctions have become the most useful analogs to understand whether the current global ecosystem is experiencing extinction or not. Recently, Prof. SHEN Shuzhong and Dr. ZHANG Hua from Nanjing Insititute of Geology and Palaeontolgy, Chinese Academy of Sciences reviewed previous multidisciplinary studies of the extinction patterns of fossil groups and their concurrent environmental changes of the five mass extinctions during the past 500 million years suggested that no catastrophic event wiped out all organisms on earth. However, all five mass extinctions were associated with serious environmental deteriorations and major palaeoclimatic changes. They thought that global changes of atmospheric CO2 and palaeotemperatrue (both icehouse and greenhouse), oceanic acidification, sea-level changes, and anoxia triggered by massive volcanisms were the most plausible causes of the past extinctions. Massive volcanism not only ejected a huge amount of CO2 and volcanic sulfates, but also caused a massive release of thermogenic CO2 and methane stored in the deposits of inland basins and continental shelf. Extraterrestrial impact, supernova explosion, and solar flares could instantaneously wipe out all organisms on earth, but they are not the main causes of the five mass extinctions during the earth history. This paper was published in Chinese Science Bulletin and financially supported by the National Natural Science Foundation of China and the Strategic Priority Research Program (B) of Chinese Academy Sciences. Reference: Shen S Z, Zhang H. What caused the five mass extinctions (in Chinese)? Chin Sci Bull, 2017, 62: 1119–1135, doi: 10.1360/N972017-00013.
A research entitled “Precarious ephemeral refugia during the earliest Triassic” has published in GEOLOGY on May 1. Their findings highlight an assemblage including microbial mats, trace fossils, bivalves, and echinoids that represent a refuge in a moderately deep-water setting. A refuge describes an ecosystem that acts as a sanctuary for organisms during and immediately following times of environmental stress. The culprit was global warming associated with massive volcanic eruptions in Siberia, but modern-day events may lead to similar changes in today’s oceans. An international team of researchers at the University of Calgary and the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Science have shown just how precarious the recovery of life was following Earth’s greatest extinction event, about 251.9 million years ago. A site near Shangsi in Sichuan Province, China highlights a short-lived community of organisms that may hold clues to forces shaping our planet today and into the future. Graduate student Amanda Godbold, Postdoctoral Fellow Shane Schoepfer, and Professors Shuzhong Shen and Charles Henderson are co-authors on a paper published online May 1, 2017 in Geology entitled “Precarious ephemeral refugia during the earliest Triassic”. Their findings highlight an assemblage including microbial mats, trace fossils, bivalves, and echinoids that represent a refuge in a moderately deep-water setting. A refuge describes an ecosystem that acts as a sanctuary for organisms during and immediately following times of environmental stress. The echinoids normally live in shallow-water environments, but in this case they sought refuge from lethally hot surface waters. The culprit was global warming associated with massive volcanic eruptions in Siberia, but modern-day events may lead to similar changes in today’s oceans. The community was short-lived, and was extinguished by a relatively minor ecologic disturbance as determined from the geochemistry of the host rocks, only to be replaced by a low-diversity community of ‘disaster taxa’, opportunistic organisms that thrive while others go extinct. The team envisages the earliest Triassic ocean floor as a shifting patchwork of temporary or ephemeral refugia, in which some communities survived and others died off depending on local conditions. As conditions improved throughout the Early Triassic these communities no longer had to cling to life in ephemeral refugia, but could expand into normal habitats around the world. The echinoids at this site are the ancestors of a diverse group of modern echinoids or sea urchins that live in reef communities, rocky shorelines and sandy shelves today. The study will help bring about a deeper understanding of how modern oceans might respond to intense global warming due to natural or anthropogenic effects. It could inform the management of our oceanic resources as they continue to be affected by environmental stressors. The rock record is cryptic, but it records events that have run their full course. If we can decipher the story, then it is possible to inform us better as to what might happen in the future as changes to our environment continue to occur. This study was supported by the National Science Foundation of China, the Strategic Priority Research Program (B) of the Chinese Academy of Sciences, and a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant. Contact: Charles Henderson; cmhender@ucalgary.ca Shuzhong Shen; szshen@nigpas.ac.cn
Auroradiolites biconvexus in Sangzugang Formation photographed in the field Diagnostic characters of the recently established new genus of radiolitid rudist Auroradiolites include an entirely compact outer shell layer, a distinctly convex upper (left) valve and a robust myocardinal apparatus surrounding a strongly internally projected ligamentary infolding. Until now, A. biconvexus (previously considered as exclusively Late Albian in age) has been reported only from the Langshan Formation, which crops out along the northern portion of the Lhasa block, Tibet. Here, Dr. RAO Xin from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and her colleagues reported new Auroradiolites fossils for the first time in addition from the Sangzugang Formation of the Xigaze Forearc Basin, situated on the southern margin of the Lhasa block. A. biconvexus differs from the southwest Asian type species A. gilgitensis (Late Aptian to Albian) by its relatively larger size, more strongly domed left valve and distinct radial undulations of the outer shell layer. The characters of A. gilgitensis are further clarified from archived material from central Afghanistan, also newly identified and described herein. All Auroradiolites records to date are revised. The recognition of examples of A. biconvexus from Upper Aptian strata increases both the stratigraphical and geographical ranges of the species, indicating that it had already branched off from A. gilgitensis in the Late Aptian. Some new radiolitid specimens that combine both compact and cellular calcitic outer shell layer structures are also described from the Langshan Formation, but a number of internal differences from Auroradiolites cast doubt on their constituting a sister group to the latter and we assign them to Eoradiolites cf. hedini. Rather, the evolution of Auroradiolites directly from the ancestral radiolitid genus Agriopleura is favoured on the grounds of parsimony. So far, the genus Auroradiolites has been recorded from Iran, central and eastern Afghanistan, the type locality of Yasin in northwestern Pakistan, southern and northern Ladakh, the Lhasa block, as well as Hokkaido in northern Japan. During the Late Aptian to Albian interval, all these localities were associated with terranes and blocks that were limited to the northeastern margin of Tethys and the western Pacific margin, making Auroradiolites an indicator of a SW Asian to Pacific faunal province. Related information of this paper:：Rao Xin, Skelton W. Peter, Sano Shin-ichi, Li Cai, Pan Yanhong, Luo Hui, Cai Huawei, Peng Bo, Sha Jingeng, 2017. Evolution and palaeogeographical dispersion of the radiolitid rudist genus Auroradiolites (Bivalvia: Hippuritida), with descriptions of new material from Tibet and archived specimens from Afghanistan，Papers in Palaeontology, DOI:10.1002/spp2.1076
Living seed plants consist of Cycadales, Ginkgoales, Coniferales, Gnetales and angiosperms. The origin and phylogenetic relationships of these five group of living seed plants are poorly understood, in large part because of very imperfect knowledge of extinct seed plant diversity. Recently, Dr. SHI Gongle from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and colleagues from US, Mongolia, Japan and Russia studied three-dimensionally preserved, lignite plant fossils from the Early Cretaceous of Mongolia. Leaves of Podozamites and Pseudotorellia are dominant in the Early Cretaceous lignite floras of Mongolia. Podozamites and Pseudotorellia are common in Late Triassic to Early Cretaceous floras from Laurasia. Both are typically strap-shaped with parallel veins, and the two genera are often confused with each other if the leaves are found detached and their cuticles are not preserved. Podozamites is thought to be the leaf of a voltzialean conifer, but its epidermal features are poorly understood because its cuticle is extremely delicate. Pseudotorellia is commonly thought to be the leaf of an extinct ginkgoalean. It has a thick cuticle with stomatal complexes that have been described as haplocheilic. In one study the leaf morphology, cuticle, and stomata of Podozamites and Pseudotorellia are described based on excellently preserved material from the Early Cretaceous of central Mongolia. Podozamites harrisii has transversely oriented, paracytic (probably syndetocheilic) stomata that are regularly arranged in longitudinal files. Pseudotorellia resinosa and Pseudotorellia palustris have scattered, longitudinally oriented stomata in which the two guard cells are sunken and surrounded by 2–5 specialized lateral subsidiary cells and 1–3 unspecialized polar cells. Association evidence and similarities in cuticular structure suggest that Po. harrisii was produced by the same plant as the seed cone Krassilovia. The distinctive stomatal pattern of Po. harrisii and Krassilovia, is also seen in some species of Swedenborgia and Cycadocarpidium, suggesting these plants may all belong to the same natural group. Cycadocarpidium, Krassilovia and Swedenborgia have previously been treated as conifers, but their transversely oriented, paracytic stomata hint instead at a possible relationship with Bennettitales and Gnetales.
Transversely oriented, paracytic stomata of Podozamites Pseudotorellia has been long considered a ginkgoalean leaf based on its venation and features of the cuticle. Like extant Ginkgo, Pseudotorellia has two veins that enter the leaf base and stomata that are sparsely scattered in ill-defined stomatal bands on the presumed abaxial surface. Pseudotorellia was also thought to be produced by the same plant as the ovulate organ Umaltolepis Krassilov based on their repeated association, similarities in the structure of their cuticles, and similarities between the scale leaves at the base of the stalk of Umaltolepsis and the scale leaves on dwarf shoots that bore Pseudotorellia. However, Abundant new material from the Early Cretaceous of Mongolia shows that Umaltolepis is a seed-bearing cupule that was borne on a stalk at the tip of a short shoot. Each cupule is umbrella-like with a central column that bears a thick, resinous, four-lobed outer covering, which opens from below (Fig. 2). Four, pendulous, winged seeds are attached to the upper part of the column and are enclosed by the cupule. In spite of the similarity of Pseudotorellia leaves to those of living Ginkgo. Umaltolepis seed-bearing structures are very different from those of Ginkgo but very similar to fossils described previously as Vladimaria. Umaltolepis and Vladimaria do not closely resemble the seed-bearing structures of any living or extinct plant, but are comparable in some respects to those of certain Peltaspermales and Umkomasiales (corystosperms). Vegetative similarities of the Umaltolepis plant to Ginkgo, and reproductive similarities to extinct peltasperms and corystosperms, support previous ideas that Ginkgo may be the last survivor of a once highly diverse group of extinct plants, several of which exhibited various degrees of ovule enclosure.
Reconstruction of Umaltolepis mongoliensis.
The two studies were recently published in Journal of Systematic Palaeontology and PNAS. The studies have benefited from Professor ZHOU Zhiyan from NIGPAS and supported by the NSFC, the Youth Innovation Promotion Association, CAS and Nanjing Institute of Geology and Palaeontology. Reference: Shi Gongle, Herrera F., Herendeen P.S., Leslie A.B., Ichinnorov N., Takahashi M., Crane P.R., 2017. Leaves of Podozamites and Pseudotorellia from the Early Cretaceous of Mongolia: stomatal patterns and implications for relationships. Journal of Systematic Palaeontology, DOI: 10.1080/14772019.2016.1274343. Herrera F., Shi Gongle, Ichinnorov N., Takahashi M., Bugdaeva E., Herendeen P.S., Crane P. R., 2017. The presumed ginkgophyte Umaltolepis has seed-bearing structures resembling those of Peltaspermales and Umkomasiales. PNAS 114, E2385–E2391.
Stratigraphic distribution of geochemical results in this study The major diversification of animal life known as the Cambrian explosion commenced at the end of the Ediacaran Period, but did not reach its peak until Stage 3 of Cambrian Series 2. This remarkable escalation of biological complexity has long inspired hypotheses about the potential intrinsic or extrinsic catalysts driving early animal evolution. Environmental free oxygen is essential for the maintenance of many metabolic and physiological processes in metazoans, and low atmospheric oxygen content has often been viewed as a barrier to the evolution of large, metabolically active animals. Existing studies have found some evidence for oxygenation events in Cambrian Series 1-2, but the temporal relationship between Cambrian oxygenation and the Cambrian biological explosion remains controversial. For this study, XIANG Lei from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences and his colleagues conducted a series of geochemical analyses on the upper Lantian, Piyuancun, and Hetang formations in a drill well, part of the lower Yangtze Block in western Zhejiang. Iron speciation results indicate that the entire studied interval was deposited under anoxic conditions, with three intervals of persistent euxinia occurring in the uppermost Lantian Fm., the lower Hetang Formation (Fm.), and the upper Hetang Fm. Molybdenum (Mo) and uranium (U) contents and Mo/TOC and U/TOC ratios from the anoxic/euxinic intervals in this study, combined with published data from the sections in the middle and upper Yangtze Block, suggest that the oceanic Mo reservoir declined consistently from the Ediacaran to Cambrian Stage 3, while the size of the oceanic U reservoir remained relatively constant. Both metals were depleted in the ocean in lower Cambrian Stage 4, before increasing markedly at the end of Stage 4. The lack of an apparent increase in the size of the marine Mo and U reservoir from the upper Ediacaran to Cambrian Stage 3 suggests that oxic water masses did not expand until Cambrian Stage 4. The increase in marine Mo and U availability in the upper Hetang Fm. may have been due to the expansion of oxic water masses in the oceans, associated with oxygenation of the atmosphere during Cambrian Stage 4. This expansion of oxic waters in the global ocean postdates the main phase of Cambrian diversification, suggesting that pervasive oxygenation of the ocean on a large scale was not the primary control on animal diversity following the Ediacaran-Cambrian transition. Reference: Xiang, L., Schoepfer, S. D., Shen, S. Z., Cao, C. Q., Zhang, H. *, 2017. Evolution of oceanic molybdenum and uranium reservoir size around the Ediacaran-Cambrian transition: evidence from western Zhejiang, South China. Earth and Planetary Science Letters 464, 84-94.
