Search

From the late Carboniferous to the early Permian, multiple pulses of glaciation and deglaciation have been caused by the LPIA. The Pennsylvanian period experienced phases of recovery, proliferation, and decline, ultimately forming a reef system distinctly different from that of the Mississippian period. During the late Bashkirian to Moscovian, the metazoan reef experienced a limited resurgence, with reef predominantly formed by chaetetid developing in the United States, northern China, and Japan. During the Kasimovian to Gzhelian, the phylloid algal reef dominated the global reef systems. In the late Pennsylvanian, bioconstruction cases and paleoenvironmental proxies in southern Guizhou Province were studied to investigate the composition, recovery, and evolutionary processes of the bioconstructions as well as their response to environmental variations during this period. Several bioconstructions have been reported in the Lumazhai section of Houchang Town, Guizhou Province, southern China, from the Moscovian to the Gzhelian. The upper Carboniferous strata are well-preserved and continuously exposed. The continuous strata, abundant fossils, and diverse bioconstructions provide excellent research materials for exploring the mutual constraints between organisms and their environment. This study identified ten microfacies, whose vertical evolution indicated significant changes in the depositional environment related to relative sea-level fluctuations. Skeletal grains are widely present in these facies. Among them, foraminifera, algae, bryozoans, crinoids, and Tubiphytes are the most common and exhibit distinct distribution characteristics in various environments. Quantitative statistics, CCA and theoretical ecospace have been utilized to examine and interpret environmental impact factors. Quantitative analysis of their relative abundance and distribution patterns provides insights into the complex interactions between organisms and environmental factors. The relative abundances of different organisms and factors controlling their bioconstructions are influenced by relative sea-level changes. CCA analysis reveal that hydrodynamic conditions are the primary influencing factor. Variation trends in average tiering and motility reveal the characteristics of biological communities during environmental changes in phylloid algae and microbial bioconstructions. These bioconstructions are not directly correlated with changes in environmental factors, and the biological communities in phylloid algae mounds and biostromes exhibit similar organism compositions and ecological niches across different environments. [ABSTRACT FROM AUTHOR]

Liaoceratops is a small basal neoceratopsian dinosaur from the Early Cretaceous Jehol Biota of western Liaoning, China. Because its postcranial skeleton is lacking, its behaviour and palaeoecology remain poorly understood. By using computed tomography (CT), we reconstructed the cranial endocast and endosseous labyrinths of an adult individual of Liaoceratops yanzigouensis (PMoL-AD00097). Analysis and comparisons indicate that the brain, olfactory bulb and inner ear of adult Liaoceratops more closely resemble those observed in adult specimens of the basal ceratopsian Psittacosaurus than those in more derived ceratopsians. The relatively large olfactory bulb, discernible floccular lobes, and relatively long semicircular canals suggest that the adult Liaoceratops had a keen sense of smell, a well-developed sensory input for the reflexive stabilisation of gaze and posture, and a nearly horizontal head posture. Based on its relatively short cochlear ducts, adult Liaoceratops likely vocalised at and heard more efficiently to relatively high frequencies than the derived ceratopsian Pachyrhinosaurus and Triceratops. The relatively well-developed semicircular canals suggest that adult Liaoceratops was agile biped and had a similar locomoter mode with adult Psittacosaurus. [ABSTRACT FROM AUTHOR]

The Carboniferous period was a unique period for reef developments during the Late Paleozoic; however, in past years, studies dealing with the Carboniferous reefs in China were very rare. In recent years, the Carboniferous reefs were studied in detail and diverse types of reefs have been discovered in different areas of China. In these areas, the Mississippian reefs were primarily built of bryozoans and rugose corals, which were associated with various kinds of calcareous algae. During the Pennsylvanian, in South China, the reef builders were composed of the rugose coral Fomichevella and phylloid algae, whereas in North China, the reef builders were composed of Chaetetes, bryozoans and corals. There are two main reef-building communities within Carboniferous reefs in China; an algal reef-building community and a reef-building community dominated by colonial coral. No evolutionary relationships between these two types of communities can be detected, thus indicating that two different linerages of reef-building communities evolved during the Carboniferous; the former community consists of cyanobacteria, bacteria and calcareous algae, while the latter one consists of various skeletal metazoan organisms. Through careful study of the developments of Chinese Carboniferous reefs, the evidence indicates that various communities of organisms played important reef-building functions during this period. The occurrence of these metazoan framework reefs also indicates that, during the Carboniferous, most areas in China would have been dominated by the environments with a tropical or subtropical climate.

The study of the palaeoenvironment of the Early Cretaceous has been a significant research topic, largely due to the "Jehol Biota" in western Liaoning and the important prospect of fossils in Dakangpu Layer. Based on the sedimentology of Dakangpu Layer, it is helpful to get a deeper understanding of the living environment of the "Jehol Biota." Varves are highly developed in the Dakangpu Bed of lower Cretaceous Yixian Basin in western Liaoning, China, supplying reliable and high‐quality proxies to explore the palaeoclimate. This paper reconstructs the palaeo‐lake environment and palaeoclimate, using petrography, facies associations, varves components, and geochemistry. Detailed petrographic studies helped to recognize 11 lithofacies which were grouped into two facies associations: Shallow lake and deep to semi‐deep lake sequences. The delicate structure of varves in the Dakangpu Bed were divided into two categories: Clastic and endogenic. Additionally, two sub‐types of clastic varves have been discovered, with distinct components, thickness, and distribution in vertical sequence. Nineteen representative samples of varves reveal that rare earth and trace elements have a similar change trend. The composition, formation, and preservation of the varves in the Dakangpu Bed depicted a deep lake, with stratified water and oxygen‐depleted bottom layer environment. The U/Th ratios and V/Cr ratios are in the ranges of 0.37–1.55 and 0.97–10.47 respectively, supporting the redox environment's minor fluctuation. The varve thickness, flood frequency, sporopollenin collections, and geochemical data indicated that precipitation and humidity decreased gradually in the sedimentary period, and the climate changed to warmer and drier, with fluctuations in the middle to later periods. [ABSTRACT FROM AUTHOR]

This study focuses on the Tianshifu Basin, eastern Liaoning, China, which is filled with Lower–Middle Jurassic fluviolacustrine sediments rich in macroplants. Our aim is to explore the continental climate features of the late Early Jurassic period. The composition of the Early–Middle Jurassic flora and the carbon isotopic ratios of organic matter, total organic carbon, total organic nitrogen and sulphur of the rock samples from the Changliangzi section (the upper part of the Lower Jurassic deposits) have been investigated. Based on the flora, eastern Liaoning was generally characterized by temperate and humid conditions during the Early–Middle Jurassic period, but with rising temperatures during late Early Jurassic time. The sediments of the Changliangzi section show a transformation from shallow-lake facies to deep-lake facies. A positive organic carbon isotope excursion correlates with the deepening of this palaeolake, considered to be caused by climate warming. The late Early Jurassic climate warming indicated by floral and isotopic evidence corresponds to the climatic events recorded elsewhere in marine and continental sequences during the Toarcian Age, the so-called Toarcian Anoxic event, and may be associated with enhanced global greenhouse warming. This study provides new continental data supporting global warming during the late Early Jurassic period. [ABSTRACT FROM AUTHOR]

Principal component analysis has been used to test for similarities in ecology and life habit between modern and fossil birds; however, the two main portions of the hind limb—the foot and the long bone elements—have not been examined separately. We examine the potential links between morphology, ecology, and phylogeny through a synthesis of phylogenetic paleoecological methods and morphospace analysis. Both hind limb morphologies and species' ecologies exhibit extreme phylogenetic clumping, although these patterns are at least partially explainable by a Brownian motion style of evolution. Some morphologies are strongly correlated with particular ecologies, while some ecologies are occupied by a variety of morphologies. Within the morphospace analyses, the length of the hallux (toe I) is the most defining characteristic of the entire hind limb. The foot and hind limb are represented on different axes when all measurements are considered in an analysis, suggesting that these structures undergo morphological change separately from each other. Early birds tend to cluster together, representing an unspecialized basal foot morphotype and a hind limb reliant on hip-driven, not knee-driven, locomotion. Direct links between morphology, ecology, and phylogeny are unclear and complicated and may be biased due to sample size (~60 species). This study should be treated as a preliminary analysis that further studies, especially those examining the vast diversity of modern birds, can build upon. [ABSTRACT FROM AUTHOR]

The adakitic dikes with zircon ages of ~120–118 Ma are identified in the Xiejiagou gold deposit, Jiaobei terrain. The Early Cretaceous intermediate-acidic dikes include monzonite, quartz monzonite, and monzogranite, which have SiO2, Al2O3, K2O, Na2O contents ranging from 61.01 to 74.72 wt. %, 14.42 to 17.28 wt.%, 2.55 to 4.45 wt.%, and 3.09 to 4.64 wt.%, respectively. The dikes are enriched in large ion lithophile elements (LILEs) (e.g., Rb, Sr, and Ba) and light rare earth elements (LREEs), but are depleted in high field strength elements (HFSEs) (e.g., Nb, Ta) and heavy rare earth elements (HREEs). They are also characterized by continental crust-like isotopic compositions: whole-rock δ18O = 7.6–9.9‰, (87Sr/86Sr)i = 0.70893–0.71036, and εNd(t) = −13.16 to −17.06. Assimilation and fractional crystallization are limited, and partial melting of source rock is the main mechanism in controlling the compositional variation. The high Sr/Y (41.51–93.25) and (La/Yb)N (22.9–44.7) ratios imply that the dikes have affinities similar to adakitic rocks. The regional geological setting, coupled with the geochemical and isotopic data, indicate that the adakitic dikes were unlikely produced by partial melting of a subducted oceanic slab or a thickened/delaminated lower crust, or AFC processes of mantle-derived magmas. We conclude that the adakitic dikes are generated by partial melting of lower crust which was triggered and modified by underplating of the lithospheric mantle. We also propose that the eastern part of the North China Craton experienced severe thinning in the Early Cretaceous (~135–120 Ma), and the lithospheric thinning is related to delamination of the lower crust. [ABSTRACT FROM AUTHOR]

The particle interaction behavior is important in flotation process, and the interaction energy calculation is helpful for evaluating this behavior. This study investigates and compares the floatability of magnesite, dolomite, and quartz in single mineral flotation and artificial mixture flotation with dodecylamine (DDA) as collector. The results showed that while the pH, dissolved ions, and competitive adsorption had a minor influence on their floatability, fine magnesite and dolomite largely decreased the recovery of quartz. Scanning electron microscope (SEM) analysis on the flotation products demonstrated severe masking of fine particles on the surface of quartz. The extended-DLVO (Derjaguin–Landau–Verwey–Overbeek) theory was applied to calculate the interaction energy between the mineral particles, and the results showed that the interaction force between magnesite and quartz and between dolomite and quartz was attractive; therefore, fine magnesite and dolomite particles were easily masked on the surface of quartz. The calculation results agree with the experiment results and explain the mechanism of particles’ interaction and the reasons for the differences in single mineral flotation and artificially mixed minerals flotation. [ABSTRACT FROM PUBLISHER]

Fossils of the remarkable dromaeosaurid Microraptor gui and relatives clearly show well-developed flight feathers on the hind limbs as well as the front limbs. No modern vertebrate has hind limbs functioning as independent, fully developed wings; so, lacking a living example, little agreement exists on the functional morphology or likely flight configuration of the hindwing. Using a detailed reconstruction based on the actual skeleton of one individual, cast in the round, we developed light-weight, three-dimensional physical models and performed glide tests with anatomically reasonable hindwing configurations. Models were tested with hindwings abducted and extended laterally, as well as with a previously described biplane configuration. Although the hip joint requires the hindwing to have at least 200 of negative dihedral (anhedral), all configurations were quite stable gliders. Glide angles ranged from 3° to 21° with a mean estimated equilibrium angle of 13.7°, giving a lift to drag ratio of 4.1:1 and a lift coefficient of 0.64. The abducted hindwing model's equilibrium glide speed corresponds to a glide speed in the living animal of 10.6 m∙s-1. Although the biplane model glided almost as well as the other models, it was structurally deficient and required an unlikely weight distribution (very heavy head) for stable gliding. Our model with laterally abducted hindwings represents a biologically and aerodynamically reasonable configuration for this four-winged gliding animal. M. gui's feathered hindwings, although effective for gliding, would have seriously hampered terrestrial locomotion. [ABSTRACT FROM AUTHOR]