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Large quadrupedal sauropod dinosaurs of the group Titanosauria were globally distributed in the Late Cretaceous. Many titanosaurian species have been discovered in eastern Asia, but most of them are controversial and represented by poorly preserved remains. Here, we describe a new titanosaur, Gandititan cavocaudatus gen. et sp. nov., based on a partial skeleton recovered from the lower Upper Cretaceous of Ganxian County, Ganzhou City, southern China, and comprising six articulated cervical vertebrae, two partial dorsal vertebrae, and a complete sacrum preserved in articulation with the first 17 caudal vertebrae and part of the right pelvis. Gandititan can be diagnosed on the basis of the following autapomorphies: long and narrow fossae present on the dorsal and ventral parts of the lateral surfaces of the cervical centra, sacral neural spines forming a dorsal platform with wave-shaped lateral margins, anteriormost six caudal vertebrae with bifurcated neural spines, the presence of prominent triangular flanges on the transverse processes of the anteriormost caudal vertebrae, a pair of slit-like foramina present on the ventral surface of each anterior caudal centrum, lateral surfaces of neural arches strongly excavated, additional spinoprezygapophyseal laminae present, and a prominent lamina extending horizontally between the bases of the pre- and postzygapophyses in some anterior caudal vertebrae. An expanded phylogenetic analysis places Gandititan as the sister taxon to Abdarainurus, within a clade of non-lithostrotian titanosaurs that also includes the Chinese titanosaurs Dongyangosaurus, Baotianmansaurus and Huabeisaurus, as well as the Argentine titanosaur Andesaurus. Such results imply the possible existence of a previously unrecognized group of titanosaurs in eastern Asia, and potential dispersal of titanosaurs between Asia and South America during the mid-Cretaceous. [ABSTRACT FROM AUTHOR]

The Upper Cretaceous Ganzhou Basin of Jiangxi Province, South China is among one of the richest egg fossil sites in the world and yields abundant exquisite egg clutches and embryonic eggs, especially in oviraptorosaurs. Hadrosaurian, troodontid, and potential dromaeosaurid egg fossils were also reported, though they were rare. All these reported eggs vary in morphology but have relatively large sizes. Here, we report a partial egg clutch with six complete small eggs from the Upper Cretaceous Tangbian Formation of Ganzhou City, Southeast China. The microstructure of the eggshell indicates that it can be assigned to Ovaloolithidae. Hence, we established a new ootaxon, Minioolithus ganzhouensis oogen. et oosp. nov. based on a unique combination of characters, including a small egg size, irregular egg arrangement, worm-like and nodular ornamentation, and a gradual boundary between two structural layers. The egg morphology and eggshell microstructure support it to be the smallest known non-avian theropod egg up to date. This discovery increases the diversity of dinosaur eggs in the Late Cretaceous and is significant for our understanding of the evolution of theropods in the Late Cretaceous. [ABSTRACT FROM AUTHOR]

Nanhsiungchelyidae are a group of large turtles that lived in Asia and North America during the Cretaceous. Here we report a new species of nanhsiungchelyid, Nanhsiungchelys yangi sp. nov., from the Upper Cretaceous of Nanxiong Basin, China. The specimen consists of a well-preserved skull and lower jaw, as well as the anterior parts of the carapace and plastron. The diagnostic features of Nanhsiungchelys include a large entire carapace length (~55.5 cm), a network of sculptures consisting of pits and ridges on the surface of the skull and shell, shallow cheek emargination and temporal emargination, deep nuchal emargination, and a pair of anterolateral processes on the carapace. However, Nanhsiungchelys yangi differs from the other species of Nanhsiungchelys mainly in having a triangular-shaped snout (in dorsal view) and wide anterolateral processes on the carapace. Additionally, some other characteristics (e.g., the premaxilla is higher than wide, the maxilla is unseen in dorsal views, a small portion of the maxilla extends posterior and ventral of the orbit, and the parietal is bigger than the frontal) are strong evidence to distinguish Nanhsiungchelys yangi from Nanhsiungchelys wuchingensis. A phylogenetic analysis of nanhsiungchelyids places Nanhsiungchelys yangi and Nanhsiungchelys wuchingensis as sister taxa. Nanhsiungchelys yangi and some other nanhsiungchelyids bear distinct anterolateral processes on the carapace, which have not been reported in any extant turtles and may have played a role in protecting the head. The Nanxiong Basin was extremely hot during the Late Cretaceous, and so we suggest that nanhsiungchelyids might have immersed themselves in mud or water to avoid the heat, similar to some extant tortoises. If they were capable of swimming, our computer simulations of fluid flow suggest the anterolateral processes could have reduced drag during locomotion. [ABSTRACT FROM AUTHOR]

Tsintaosaurus spinorhinus is famous for the unique rod-like nasal spine, but there has been a long debate about whether its nasal spine is hollow, since it is difficult to examine the nasal inside through direct observation. Here, we used a high-resolution CT scan to reveal the interior structure of the nasal spine and re-observed the holotype and paratype of Tsintaosaurus spinorhinus. By the direct observation and CT scan, we provide new information about the nasal spine of Tsintaosaurus spinorhinus, and our result shows the rod-like nasal spine of Tsintaosaurus spinorhinus is a solid sandwich structure, rather than a hollow tubular structure. There is a significant fracture between the rod-like process and the base of the nasal, and if the two processes fit together, the nasal spine would have been more inclined rostrally in life. The new cranial information collected through the direct observation and CT scan reveals that the narrow strip surrounded by the nasals and frontals is formed by a longitudinal median groove filled with sediment, indicating the possible presence of the frontal-nasal fontanelle in younger juveniles. [ABSTRACT FROM AUTHOR]

Turtle eggs containing embryos are exceedingly rare in the fossil record. Here, we provide the first description and taxonomic identification, to our knowledge, of a fossilized embryonic turtle preserved in an egg, a fossil recovered from the Upper Cretaceous Xiaguan Formation of Henan Province, China. The specimen is attributed to the Nanhsiungchelyidae (Pan-Trionychia), an extinct group of large terrestrial turtles (possibly the species Yuchelys nanyangensis). The egg is rigid, spherical, and is one of the largest and thickest shelled Mesozoic turtle eggs known. Importantly, this specimen allowed identification of other nanhsiungchelyid egg clutches and comparison to those of Adocidae, as Nanhsiungchelyidae and Adocidae form the basal extinct clade Adocusia of the Pan-Trionychia (includes living soft-shelled turtles). Despite the differences in habitat adaptations, nanhsiungchelyids (terrestrial) and adocids (aquatic) shared several reproductive traits, including relatively thick eggshells, medium size clutches and relatively large eggs, which may be primitive for trionychoids (including Adocusia and Carrettochelyidae). The unusually thick calcareous eggshell of nanhsiungchelyids compared to those of all other turtles (including adocids) may be related to a nesting style adaptation to an extremely harsh environment. [ABSTRACT FROM AUTHOR]

To investigate pore characteristics and the factors controlling lacustrine shales, geochemical, mineralogical and petrophysical experiments were performed on 23 shale samples from the Qingshankou Formation of the Songliao Basin, China. A comparison of mercury injection capillary pressure (MICP) and low‐temperature N2 adsorption pore‐size distribution showed that MICP has a higher pore‐size distribution (PSD) line in its overlapping pore diameter range, which may be elevated by the higher pressure of MICP. Therefore, in the overlapping range, low‐temperature N2 adsorption data were preferred in pore characterization. Negative correlations were observed between pore volumes and TOC content, indicating organic matter pores are not well‐developed in the studied samples. This may be related to their low grade of maturity and type I kerogens. There existed negative relationships between pore volumes and S1, which illustrated that liquid hydrocarbons occupied some pore space. Micropore volume had a better correlation with S1 than mesopore and macropore volumes, which suggests that liquid hydrocarbons preferentially occur in micropores. No obvious relationships between pore volumes and quartz or feldspar were observed, while pore volumes increased with the increasing clay mineral content. These relationships indicate that intraparticle pores in clay minerals represent the principal pore type. [ABSTRACT FROM AUTHOR]

Tyrannosaurids were the most derived group of Tyrannosauroidea and are characterized by having two body plans: gracile, long-snouted and robust, deep-snouted skulls. Both groups lived sympatrically in central Asia. Here, we report a new deep-snouted tyrannosaurid, Asiatyrannus xui gen. et sp. nov., from the Upper Cretaceous of Ganzhou City, southeastern China, which has produced the large-bodied and long-snouted Qianzhousaurus. Based on histological analysis, the holotype of Asiatyrannus xui is not a somatically mature adult, but it already passed through the most rapid growth stages. Asiatyrannus is a small to medium-sized tyrannosaurine, with a skull length of 47.5 cm and an estimated total body length of 3.5-4 m; or around half the size of Qianzhousaurus and other large-bodied tyrannosaurines in similar growth stages. Asiatyrannus and Qianzhousaurus are sympatric tyrannosaurid genera in the Maastrichtian of southeastern China. Asiatyrannus differs from Qianzhousaurus in that it has a proportionally deeper snout, longer premaxilla, deeper maxilla, and deeper dentary, and the cornual process of the lacrimal is inflated without developing a discrete horn. The different skull proportions and body sizes suggest that Asiatyrannus and Qianzhousaurus likely had different feeding strategies and occupied different ecological niches., (© 2024. The Author(s).)

The Upper Cretaceous Qingshankou Formation in the northern Songliao Basin was deposited in river‐dominated lacustrine delta systems. Three third‐order sequences and two types of sequence architecture were recognized using core observations, logging curve interpretations, and three‐dimensional (3‐D) seismic profiles in Qingshankou Formation. One type of sequence architecture was developed in a syndepositional flexural slope break, and the other was deposited on a gentle slope. The studied sequences were deposited in a high accommodation setting, which was due to the large rate of subsidence of the basin basement, and a tropical to semi‐tropical and a humid to semi‐humid climate. The episodic tectonic/thermal subsidence of the basin controlled the development of the sequence architecture. Turbidite bodies within transgressive systems tracts and early highstand systems tracts were deposited predominantly in the basinward part of the syndepositional flexural slope breaks, and they were favourable exploration targets, particularly for stratigraphic traps. [ABSTRACT FROM AUTHOR]

The Songliao Basin is one of the most important petroliferous basins in northern China. With a recent gradual decline in conventional oil production in the basin, the exploration and development of unconventional resources are becoming increasingly urgent. The Qingshankou Formation consists of typical Upper Cretaceous continental strata, and represents a promising and practical replacement resource for shale oil in the Songliao Basin. Previous studies have shown that low‐mature to mature Qingshankou shale mainly preserves type I and type II1 organic matter, with relatively high total organic carbon (TOC) content. It is estimated that there is a great potential to explore for shale oil resources in the Qingshankou Formation in this basin. However, not enough systematic research has been conducted on pore characteristics and their main controlling factors in this lacustrine shale reservoir. In this study, 19 Qingshankou shales from two wells drilled in the study area were tested and analyzed for mineral composition, pore distribution and feature evolution using X‐ray diffraction (XRD), scanning electron microscopy (SEM), low‐pressure nitrogen gas adsorption (N2‐GA), and thermal simulation experiments. The XRD results show that clay, quartz, and feldspar are the dominant mineral constituents of Qingshankou shale. The clay minerals are mostly illite/smectite mixed layers with a mean content of 83.5%, followed by illite, chlorite, and kaolinite. There are abundant deposits of clay‐rich shale in the Qingshankou Formation in the study area, within which many mineral and organic matter pores were observed using SEM. Mineral pores contribute the most to shale porosity; specifically, clay mineral pores and carbonate pores comprise most of the mineral pores in the shale. Among the three types of organic matter pores, type B is more dominant the other two. Pores with diameters greater than 10 nm supply the main pore volume; most are half‐open slits and wedge‐shaped pores. The total pore volume had no obvious linear relationship with TOC content, but had some degree of positive correlation with the content of quartz + feldspar and clay minerals respectively. However, it was negatively correlated with carbonate mineral content. The specific surface area of the pores is negatively related to TOC content, average pore diameter, and carbonate mineral content. Moreover, it had a somewhat positive correlation with clay mineral content and no clear linear relationship with the content of quartz + feldspar. With increases in maturity, there was also an increase in the number of carbonate mineral dissolution pores and organic matter pores, average pore diameter, and pore volume, whereas there was a decrease in specific surface area of the pores. Generally, the Qingshankou shale is at a low‐mature to mature stage with a TOC content of more than 1.0%, and could be as thick as 250 m in the study area. Pores with diameters of more than 10 nm are well‐developed in the shale. This research illustrates that there are favorable conditions for shale oil occurrence and enrichment in the Qingshankou shale in the study area. [ABSTRACT FROM AUTHOR]

There is a general relationship between the formation of terrestrial hydrocarbon source rocks and marine incursions during the Mesozoic–Cenozoic in China. To better understand this scientific issue, this study focused on the little-studied Upper Cretaceous Qingshankou Formation (early Late Cretaceous) in the Songliao Basin, China, which was investigated using organic petrological and organic and inorganic geochemical methods. The mudstone and shale in the Qingshankou Formation were deposited in an anoxic, reducing, slightly brackish water environment and contain benthic macroalgae, which is a typical marine fossil in Qingshankou Member I. The δ34S values are generally similar to those of Late Cretaceous marine sulfate, and the total N contents and isotopic compositions (δ15N) are both high, suggesting that the Qingshankou Formation was affected by marine incursions that triggered lake anoxia. The total organic carbon (TOC) contents of the mudstones and shales in the Qingshankou Formation are 0.21–3.86 wt%, with an average value of 1.91 wt%, which meet the criterion of a very good–excellent source rock. The organic matter varies from type I to III kerogen but is mainly types I and II, which generate oil. The hydrocarbon-generating bio-precursors are mainly planktonic and benthic algae. The hydrocarbon generation potential of the Qingshankou Member I is high, mainly due to the high productivity during its deposition. Increased productivity caused by marine intrusions, water stratification caused by high salinity, and reducing bottom-water environment provided favorable conditions for organic matter enrichment. The marine incursions during deposition of the Qingshankou Formation (especially Member I) improved the quality of the source rocks by enhancing the primary productivity, which might be a common feature of terrestrial source rocks affected by such incursions in general. • Benthic marcroalgae and C–N–S isotopes suggest marine incursions during the Upper Cretaceous Songliao Basin, China (Qingshankou Fm). • Lake anoxia triggered by marine incursions is conducive for organic matter accumulation. • Marine incursions improved the quality of the source rocks by enhancing the primary productivity. [ABSTRACT FROM AUTHOR]

The Upper Cretaceous Qingshankou Formation in the Songliao Basin, NE China is known to contain excellent petroleum source rocks. In addition, it serves as a valuable record to study depositional conditions within the water column and climatic change. In this study, a large set of organic petrography, major and trace element geochemistry, as well as bulk and molecular organic geochemistry data obtained on 38 core samples of the first Member of the Qingshankou Formation (K 2 qn1) in the south central depression is reported. All rocks are thermally oil-mature, reaching the early to peak oil generation stage, indicated by the vitrinite reflectance (VR r) of approximately 0.8%. Two different types of lacustrine source rocks (units I and II) and two OM-rich layers within unit I are identified in the studied well. Basically, there is a lower unit 1, characterized by lower total organic carbon (TOC) content and an upper unit 2 characterized by higher TOC content. Furthermore, within unit 1, thin marine transgressive layers of approximately 1–2 m were identified. Generally, unit 1 is characterized by the lowest TOC and sulfur contents with average values of 1.31 wt% and 0.56 wt%, respectively. By contrast, unit 2 samples have significantly higher TOC (avg. 2.39 wt%) and sulfur contents (avg. 1.24 wt%). Samples, which represent the postulated marine transgressive events show the highest TOC (avg. 2.82 wt%) and sulfur contents (avg. 2.01 wt%). Unit 1 was mainly deposited in oxic-dysoxic and freshwater-brackish water column conditions based on multiple organic and inorganic geochemical proxies. By contrast, unit 2 and marine transgressive layers were deposited in less oxygenated and more saline environments. Source rocks from the K 2 qn1 generally show only minor terrestrial organic matter input. However, unit 1, containing type II-III kerogen, shows indications for a slightly more pronounced contribution from terrigenous higher plants than unit 2 and the marine transgressive layers, where the kerogen is almost exclusively derived from planktonic/algal and microbial organic matter. The low TOC content in unit 1 is attributed to multiple adverse factors for organic matter accumulation, including a relatively shallow, oxic-dysoxic, and weakly stratified water column and high dilution by terrigenous mineral matter. By contrast, more favorable conditions persisted during the deposition of marine transgressive layers and unit 2, e.g., a more reducing and stratified water column and lower dilution by terrigenous mineral matter. • Characterization of the Upper Cretaceous K 2 qn1 source rocks in the Songliao Basin. • Results show evolution from fresh-brackish water to more saline lacustrine setting. • During late lake stages bottom waters were more reducing. • Geochemical data indicate short term marine ingressions during the early lake stages. • Hydrogen-rich, small-size algal, and microbial organic matters prevail. [ABSTRACT FROM AUTHOR]

Nanhsiungchelyidae are a group of large turtles that lived in Asia and North America during the Cretaceous. Here we report a new species of nanhsiungchelyid, Nanhsiungchelys yangi sp. nov., from the Upper Cretaceous of Nanxiong Basin, China. The specimen consists of a well-preserved skull and lower jaw, as well as the anterior parts of the carapace and plastron. The diagnostic features of Nanhsiungchelys include a large entire carapace length (∼55.5 cm), a network of sculptures consisting of pits and ridges on the surface of the skull and shell, shallow cheek emargination and temporal emargination, deep nuchal emargination, and a pair of anterolateral processes on the carapace. However, Nanhsiungchelys yangi differs from the other species of Nanhsiungchelys mainly in having a triangular-shaped snout (in dorsal view) and wide anterolateral processes on the carapace. Additionally, some other characteristics ( e.g. , the premaxilla is higher than wide, the maxilla is unseen in dorsal views, a small portion of the maxilla extends posterior and ventral of the orbit, and the parietal is bigger than the frontal) are strong evidence to distinguish Nanhsiungchelys yangi from Nanhsiungchelys wuchingensis . A phylogenetic analysis of nanhsiungchelyids places Nanhsiungchelys yangi and Nanhsiungchelys wuchingensis as sister taxa. Nanhsiungchelys yangi and some other nanhsiungchelyids bear distinct anterolateral processes on the carapace, which have not been reported in any extant turtles and may have played a role in protecting the head. The Nanxiong Basin was extremely hot during the Late Cretaceous, and so we suggest that nanhsiungchelyids might have immersed themselves in mud or water to avoid the heat, similar to some extant tortoises. If they were capable of swimming, our computer simulations of fluid flow suggest the anterolateral processes could have reduced drag during locomotion., Competing Interests: The authors declare there are no competing interests., (©2023 Ke et al.)

The controlling factors of oil shale formation within the Upper Cretaceous Qingshankou and Nenjiang Formations of the Songliao Basin are investigated by petrological and geochemical methods. Sediment deposition was balanced by basin subsidence, resulting in the accumulation of Cretaceous strata of high thickness. Global sea level fluctuations have been related to periods of oil shale deposition within the basin. The results indicate a comparable depositional environment during oil shale formation within the two Upper Cretaceous strata with respect to palaeotectonic and palaeoclimate, but differences in the accommodation space during accumulation of the two formations. The larger accommodation space during deposition of the Nenjiang Formation resulted in the higher thickness and wider distribution of the oil shale members (total thickness: 11.2–32 m; distribution area 4.48 × 10 3 km 2 ) within the basin, as compared to the oil shale of the Qingshankou Formation (total thickness: 2–19.3 m; distribution area 1.3 × 10 3 km 2 ). Further differences exist with regard to the palaeoenvironment of oil shale formation and primary productivity. Deposition of the Qingshankou Formation 1st member and Nenjiang Formation 1st member took place within a saline-brackish lake under anoxic conditions in the bottom water. Preservation of organic matter is suggested to have been less favorable during deposition of the Nenjiang Formation 2nd member. Higher primary productivity is believed to be the responsible factor for the accumulation of organic-rich sediments in the Qingshankou Formation 1st member. The interplay of these two factors (i.e. preservation, productivity) leads to the formation of oil shale in the Qingshankou Formation (average TOC: 8.32%; TOC max : 13.52%; average oil yield: 5.57%/) with better hydrocarbon source rock potential and slightly higher oil yield during pyrolysis as in the Nenjiang Formation (average TOC: 7.76%; TOC max : 9.7%; average oil yield: 5.54%). Primary productivity is suggested as the main controlling factor on differences in oil shale quality and source rock potential between the two formations, whereas the variations in quality within each formation mainly depend on the preservation of organic matter. The high thickness, wide spatial distribution and excellent hydrocarbon potential of the Upper Cretaceous oil shales in the Songliao Basin are suggested to have been the result of large accommodation space, stable palaeoenvironmental conditions, and high primary productivity. [ABSTRACT FROM AUTHOR]

Some new palynological fossils were newly found from the lower part of Upper Cretaceous Yong'ancun Formation in Jiayin, China, nearby the Heilongjiang (Amur) River. 43 genera and 54 species of palynomorphs, and three palynological sub-assemblages have been recently identified in the lower Yong'ancun Formation. The palynomorphs are dominated by gymnosperms and ferns, angiosperm pollen not abundant. The fern spores are represented mainly by Cyathidites- Dictyotriletes, gymnosperms by Pinuspollenites- Podocarpidites, and angiosperms by Retitricolpites- Mancicorpus. The palynological assemblage is comparable in general to those from the Members 2-3 of Yaojia Formation and the Member 1 of Nenjiang Formation in Songliao Basin, China, indicating the Santonian age. The new palynological material provides supplementary evidence for better understanding of the Santonian palynoflora of the Yong'ancun Formation in Jiayin. [ABSTRACT FROM AUTHOR]

Abstract: The abundance and composition of total organic carbon, aliphatic and aromatic hydrocarbons including biomarkers, and the δ13C composition of total organic matter and individual compounds in core samples of the Nenjiang Formation from the SK-1 borehole of the Songliao Basin provide information on the paleoenvironmental conditions of lacustrine sediments formed during the Upper Cretaceous. The distribution of n-alkanes, and their δ13C composition, and 4-methylsteranes and dinosteranes in the first member of the Nenjiang Formation (K2n1) indicate that the organic matter largely originated from algal organisms and is dominated by types I and II kerogen. The occurrence of gammacerane, aryl isoprenoids isorenieratane and low pristane/phytane and diasterane/sterane ratios further suggest a salinity stratified water column associated with anoxic bottom waters, as well as possible photic zone oxygen depletion conditions during major source rock deposition of the K2n1. The organic geochemical data also indicate significantly different depositional environments for the second member of the Nenjiang Formation (K2n2) sediments, which are interpreted to have been deposited under a uniform salinity (non-stratified) oxic water column. Consequently, although the organic matter in the K2n2 sediments was largely derived from algal and bacterial sources, the kerogen types are dominantly IIb and III due to the oxidative degradation of organic matter, combined with a gradual increase in land–plant input. Furthermore, the occurrence and shift of two saw-toothed distribution patterns of the δ13C composition of C29 to C33 n-alkanes, with “W” and “M” patterns being isotopically heavy odd- and even-numbered alkanes, respectively, is suggestive of organic input shift or an unknown mechanism of carbon uptake or isotopic fractionation. In particular, the heavy even carbon numbered high molecular weight n-alkanes is rare and needs further investigation. [Copyright &y& Elsevier]

A new oviraptorid dinosaur Jiangxisaurus ganzhouensis gen. et sp. nov., is erected based on a partial skeleton from the Upper Cretaceous Nanxiong Formation of Ganzhou City, Jiangxi Province. The new taxon differs from other oviraptorids in the weakly downturned rostrum of the lower jaw, much-elongated mandible with a height-to-length ratio being about 20% and the length ratio of radius to humerus of about 0.70. This species not only adds a new member to oviraptorid dinosaurs, but also provides more information about oviraptorid paleogeographical distribution in southern China. [ABSTRACT FROM AUTHOR]

Here we describe new types of dinosaur eggs found from the Late Cretaceous Chichengshan Formation in the Tiantai Basin, Zhejiang Province. On the basis of such characters as small spheroid or near-spheroid, columnar layer composed of three zones, the outer zone consisted of stalagmite-like or coralliform secondary shell units, we established two new oogenera, one new and one combination oospecies: Stalicoolithus shifengensis oogen. et oosp. nov. and Coralloidoolithus shizuiwanensis oogen. et comb. nov. In addition, re-examination of the holotype of Shixingoolithus erbeni from the Upper Cretaceous Pingling Formation, Guangdong Province reveals that it was erroneously attributed to Spheroolithidae, and should be transferred to stalicoolithid. Consequently, we established a new oofamily: Stalicoolithidae oofam. nov. Stalicoolthids represents a new model of dinosaur eggshell and thus sheds new light on the formation and evolution of amniotic eggshells. [ABSTRACT FROM AUTHOR]

High-resolution biostratigraphy has been established on the basis of fossil ostracodes from cores of the Cretaceous Continental Scientific Drilling borehole-Songke 1 (south) (SK1(s)) in the Songliao Basin, northeast China. More than 80 species belonging to 13 genera have been identified and 15 ostracode assemblage zones have been recognized. On the basis of ostracode paleoecological analysis, paleoenvironments, for example lake levels and salinity, have been reconstructed. Two inferred deep-water phases occurred during the deposition of the lower Qingshankou and lower Nenjiang formations, whereas shallower water phases probably occurred during deposition of the upper Quantou and uppermost Qingshankou to Yaojia formations. The salinity of paleo-Songliao lake is interpreted as predominantly freshwater to oligohaline. Oligohaline to mesohaline water environments may have occurred during the first and middle third members of the Qingshankou formation and the lower first and lower second members of the Nenjiang formation. [ABSTRACT FROM AUTHOR]

A new oviraptorid is described on the basis of a partial forelimb collected from the Upper Cretaceous redbeds of Bayan Mandahu, Inner Mongolia. Machairasaurus leptonychus, gen. et sp. nov. is diagnosed by slender, weakly curved manual unguals, reduced flexor tubercles, penultimate phalanges that are subequal in length to the preceding phalanges, and short, robust manual digits. Machairasaurus is found to be a member of the Ingeniinae, along with Ingenia yanshini, Heyuannia huangi, Conchoraptor gracilis, and Nemegtomaia barsboldi. Machairasaurus exhibits unusual proportions of the manus, suggesting that the manus was not primarily used to grasp prey. Instead, Machairasaurus and other oviraptorids are likely to have fed largely on plant material. The recognition of a previously unknown oviraptorid at Bayan Mandahu provides further evidence that the Bayan Mandahu dinosaur assemblage is distinct from that found at the Djadokhta Formation exposures at Bayn Dzak, Tugriken Shireh, and Ukhaa Tolgod. Given that these localities are separated by just a few hundred kilometres and represent similar palaeoenvironments, marked differences in the fauna suggest that the Bayan Mandahu Formation of Inner Mongolia is not coeval with the known Djadokhta localities in Mongolia. [ABSTRACT FROM AUTHOR]

Abstract: The spinicaudatan genus Tenuestheria was originally described from the Upper Cretaceous Lanxi Formation in Jinhua, Zhejiang Province, China. Its frequent occurrence in contemporaneous strata elsewhere makes it an important index fossil for correlating non-marine red beds in southern China. Its discovery in the Zhutian Formation of the Nanxiong Group makes it possible to correlate the formation more accurately with the Tenuestheria-bearing beds elsewhere. Previously the whole of the Nanxiong Group was correlated with Maastrichtian formations whereas now only the Zhenshui Formation is considered to be of this age. The Zhutian Formation, which underlies it, correlates with early Santonian–Campanian formations. The age of the red beds in south-east China is also adjusted to take into account radiometric age determinations from the volcanic and sedimentary succession in eastern Zhejiang. [Copyright &y& Elsevier]

Abstract: The Upper Cretaceous dinosaur egg-bearing deposits in Henan Province, central China are divided into three formations in ascending order: Gaogou, Majiacun and Sigou. The Gaogou Formation belongs to alluvial fan deposits containing the fossil dinosaur egg assemblage of Faveoloolithus, Dendroolithus, Dictyoolithus, Paraspheroolithus and Longiteresoolithus. The Majiacun Formation is interpreted as braided stream to meandering stream deposits with assemblage of Ovaloolithus, Paraspheroolithus, Placoolithus, Dendroolithus, Prismatoolithus, rare Youngoolithus and Nanhiungoolithus. The Sigou Formation is shallow lacustrine/palustrine to low-sinuosity river sedimentary rocks with assemblage of Macroolithus, Elongatoolithus, Ovaloolithus and Paraspheroolithus. To date, 37 oospecies, 13 oogenera and 8 oofamilies of dinosaur eggs have been distinguished. Autochthonous dinosaur eggs are preserved in the floodplain deposits, whereas allochthonous and parautochthonous dinosaur eggs are preserved in the alluvial fans. This suggests that river floodplains are the best environments for the preservation of numerous autochthonous dinosaur eggs. The preservation of most dinosaur eggs in brown to red calcic palaeosoils, muddy siltstones or mudstones suggests that the paleoclimate of the nesting area was semiarid. The presence of gray and green mudstone and coal layers, however, indicates that there existed an ephemeral subhumid climate during the middle and Late Cretaceous. It is suggested that such a climate was favorable for the development of meandering streams in a vegetated environment. [Copyright &y& Elsevier]

Abstract: Planktonic foraminiferal fossil assemblages identified from the Bolinxiala Formation in Bolin, Zanda, southwestern Tibet of China, determine its age from latest Albian to Maastrichtian. The fossil contents of the Bolinxiala Formation allow its correlation with successions across a platform-to-basin transect of the Late Cretaceous Tethyan Himalaya passive margin. The ocean anoxic event at the Cenomanian–Turonian transition (OAE2) is located at the Whiteinella archaeocretacaea biozone in Zanda, but lithologically it is characterized by grey and bioturbated limestone, implying that during the OAE2 the shallow-water environments of the Tethyan Himalayan carbonate platform remained oxic. Paleogeographic reconstruction indicates that the Upper Cretaceous Oceanic Red Beds (CORBs) in southern Tibet are restricted to the slope and basinal environments but they are entirely missing in the shelf environments. This phenomenon suggests the formation of CORBs by oxidation of Fe(II)-enriched anoxic deep ocean seawater at the chemocline that separated the oxic surface ocean from anoxic deep ocean. For depositional environments above the chemocline, no CORBs would be expected. Because of the chemocline instability across different sedimentary basins, CORBs may be significantly diachronous, consistent with the occurrence of CORBs documented from global sedimentary basins. [Copyright &y& Elsevier]

Abstract: The spinicaudatan (conchostracan) Dictyestheria, originally recovered from the Yaojia Formation, is recognized to occur also in the basal part of the overlying Nenjiang Formation. This means that the Dictyestheria elongata (= D. ovata) Zone extends from the Yaojia Formation into the upper Turonian basal part of the First Member of the Nenjiang Formation and underlies the Halysestheria yui Zone at Yaojia Railway Station, Dehui City, Jilin Province, northeast China. The fossil record shows that the basal part of the Halysestheria yui Zone is dominated by Plectestheria songhuaensis in the study area. The diagnoses of Dictyestheria and Plectestheria are revised on the basis of an examination of specimens under a scanning electron microscope. In both genera the radial lirae on the growth bands near the umbo are long and relatively widely spaced. There is a fine reticulum between them in the umbonal part of the carapace and cross-bars occur on the ventral surface. The ornament of both genera indicates that they can be assigned to the family Halysestheriidae rather than to the Jilinestheriidae, in which they have been placed previously. The discovery of serration along the lower margins of growth lines in Plectestheria indicates its close relationship with Orthestheria (Migransia), supporting an interpretation of parallel evolution of O. (Migransia) to Plectestheria in East Asia and Bauruestheria in South America. [Copyright &y& Elsevier]

Abstract: The diagnosis of Estherites corrugatus from the basal part of the Coniacian Second Member of the Nenjiang Formation in Nenjiang County, north-east China is revised following the application of a new preparation technique to some of the carapaces and an examination of specimens under a scanning electron microscope, both of which revealed morphological features on the carapace that had not been recognized previously. Restudy of the type species of the two subgenera Estherites (Euestherites) and Estherites (Parestherites) also revealed details of carapace features not seen hitherto. These indicate that they should be separated from Estherites. As a result, Euestherites is upgraded to genus level and Parestherites is placed in synonymy. The importance of Estherites and Euestherites is considered in the context of Late Cretaceous assemblages of these crustaceans and the three conchostracan provinces (South-West, South-East and North China) that are recognized to have been present in China during the Turonian–Santonian period. [Copyright &y& Elsevier]

Abstract: Cretaceous strata, spanning the Berriasian to Maastrichtian, crop out widely in southern Tibet. The sedimentary sequence can be divided into the Gyabula, Chuangde and Zhongzuo formations. The Gyabula Formation, which is Berriasian–Coniacian in age, is composed mainly of black shales characterized by relatively high total organic carbon (TOC) levels and a positive organic carbon isotope excursion near the Cenomanian/Turonian boundary, which can be correlated to oceanic anoxic events (OAE2) or with the so-called Bonarelli Horizon in the western Tethys. The oceanic sediments of the Chuangde Formation are represented by red beds of Santonian–Campanian age, and are characterized by low TOC values, a negative organic carbon isotope excursion, and low nC17/nC27 and nC17/hopane ratios, which indicate that the primary production and burial of organic matter during this period was low. We suggest that the climate at the time was cool and the oceanic water oxygen-rich. [Copyright &y& Elsevier]

Background: Dinosaur eggs containing embryos are rare, limiting our understanding of dinosaur development. Recently, a clutch of subspherical dinosaur eggs was discovered while blasting for a construction project in the Upper Cretaceous red beds (Hekou Formation) of the Ganzhou Basin, Jiangxi Province, China. At least two of the eggs contain identifiable hadrosauroid embryos, described here for the first time., Results: The eggs, attributable to Spheroolithidae indet., are thin-walled and small (~ 660 mL) compared to those of Lambeosaurinae. The shape of the embryonic squamosal is reminiscent of that seen in the Late Cretaceous hadrosauroids Levnesovia transoxiana, Tanius sinensis, and Nanningosaurus dashiensis, suggestive of possible affinities., Conclusion: The small size of the eggs and embryos, similar to those of Hadrosaurinae, indicates that the larger eggs and hatchlings typical of Lambeosaurinae are evolutionarily derived., (© 2022. The Author(s).)