Bamnet Narong is located in northeastern Thailand (Chaiyaphum Province). It is the largest salt mine in the country and has been mined for decades. The landscape in this part of Thailand is characterised by a low plat...Bamnet Narong is located in northeastern Thailand (Chaiyaphum Province). It is the largest salt mine in the country and has been mined for decades. The landscape in this part of Thailand is characterised by a low plateau, which is called the Khorat Plateau. The plateau is divided into two basins by the Phu Phan Range, the Sakhon Nakhon Basin in the north and the Khorat Basin in the south. The analysed potashes and rock salts are deposited in the Maha Sarakham Formation, which represents the salt-bearing strata of the Khorat Basin. The stratigraphic age of this deposit has been debated since the late 1960’s. The assigned ages range from Mid-Cretaceous to Late Cretaceous and up to the Eocene. In this study different isotopic dating systems (Rb-Sr, Sr-Sr, K-Ar and K-Ca) were applied. The stratigraphic age for the time of deposition was confirmed to be Mid Cretaceous (Cenomanian). Furthermore, the homogeneity of the carnallites was investigated in order to trace a possible redistribution of rubidium.展开更多
A new hadrosauroid dinosaur, Shuangmiaosaurus gilmorei gen. et sp. nov., is described based on a complete left maxilla with articulated premaxilla and lacrimal fragments, and a complete left dentary from the mid-Creta...A new hadrosauroid dinosaur, Shuangmiaosaurus gilmorei gen. et sp. nov., is described based on a complete left maxilla with articulated premaxilla and lacrimal fragments, and a complete left dentary from the mid-Cretaceous Sunjiawan Formation of Beipiao, Liaoning, northeastern China. Cladistic analysis shows that Shuangmiaosaurus is a basal hadrosauroid, and comprises the sister taxon to Hadrosauridae. In both Shuangmiaosaurus and Hadrosauridae, the maxilla-jugal suture is butt-jointed, rather than finger-in-recess articulation as in other basal hadrosauroids. However, Shuangmiaosaurus does not possess such hadrosaurid synapomorphies as the diamond-shaped maxillary crowns with reduced primary ridges and reduced marginal denticles.展开更多
The amber deposits from the Albian-Cenomanian in Myanmar have emerged as a pivotal source for exceptionally abundant fossil insect fauna since their initial discovery. Recent studies have increasingly focused on eluci...The amber deposits from the Albian-Cenomanian in Myanmar have emerged as a pivotal source for exceptionally abundant fossil insect fauna since their initial discovery. Recent studies have increasingly focused on elucidating the fern inventory and examining newly available fossils from Myanmar amber, suggesting a diverse fern flora that once thrived in Cretaceous forests. Through investigations of amber collections, with particular emphasis on sporangium structures—especially the annulus types preserved in amber inclusions—this study revealed additional novelties within the Cyatheales and Schizaeales in mid-Cretaceous Myanmar amber forests. The described specimens and newly discovered fossils provide compelling evidence that Polypodiales were not only diverse and abundant but also that other fern lineages, such as Cyatheales and Schizaeales, coexisted in these ancient forest ecosystems. This study reveals the high diversity of ferns in the mid-Cretaceous Myanmar area, while also implying the paleoecological and paleogeographical significance of the Mesozoic Burmese amber forests.展开更多
According to the most recent Pteridophyte Phylogeny Group (PPG), eupolypods, or eupolypod ferns, are the most differentiated and diversified of all major lineages of ferns, accounting for more than half of extant fern...According to the most recent Pteridophyte Phylogeny Group (PPG), eupolypods, or eupolypod ferns, are the most differentiated and diversified of all major lineages of ferns, accounting for more than half of extant fern diversity. However, the evolutionary history of eupolypods remains incompletely understood, and conflicting ideas and scenarios exist in the literature about many aspects of this history. Due to a scarce fossil record, the diversification time of eupolypods mainly inferred from molecular dating approaches. Currently, there are two molecular dating results: the diversification of eupolypods occurred either in the Late Cretaceous or as early as in the Jurassic. This study uses the Bayesian tip-dating approach for the first time to infer the diversification time for eupolypods. Our analyses support the Jurassic diversification for eupolypods. The age estimations for the diversifications of the whole clade and one of its two subclades (the eupolypods II) are both in the Jurassic, which adds to the growing body of data on a much earlier diversification of Polypodiales in the Mesozoic than previously suspected.展开更多
The remarkable transition of early angiosperms from a small to a dominant group characterized the terrestrial ecosystem of the Cretaceous. This transition was instigated and promoted by environmental changes. Mid-Cret...The remarkable transition of early angiosperms from a small to a dominant group characterized the terrestrial ecosystem of the Cretaceous. This transition was instigated and promoted by environmental changes. Mid-Cretaceous is characterized by major geological events that affected the global environment. δ^18O, palaeothermometer TEX86, and other climatic indices from marine sediments suggest rapid temperature increase during mid-Cretaceous despite occasional short cooling events. Simultaneously, terrestrial deposits in East Asia changed from coal-bearing to shale, then to red beds and evaporites. Plant assemblages and other paleoclimate indicators point to rapid aridification for midCretaceous terrestrial environments. In addition, the wildfires were frequently spread all over the earth by the numerous charcoal evidence during the Mid-Cretaceous. Thus, we speculate that the seasonally dry and hot conditions of mid-Cretaceous created a fiery hothouse world. Early angiosperms increased in abundance and diversity and evolved from a few aquatic species to terrestrial herbaceous and then to the diversified flora of today. Angiosperms showed rapid physiological evolution in vein density and leaf area that improved photosynthesis and water absorption. These ecophysiological changes made early angiosperms well adapted to the hot and dry environment in mid-Cretaceous. Moreover, these physiological changes facilitated the fire–angiosperm cycles in mid-Cretaceous that likely further stimulated the early angiosperm evolution.展开更多
The Dabie Orogenic Belt, located in east-central China, is known for the greatest outcrop area of the ultrahigh-pressure metamorphic rocks in the world and is typical for studying deep continental subduction and conti...The Dabie Orogenic Belt, located in east-central China, is known for the greatest outcrop area of the ultrahigh-pressure metamorphic rocks in the world and is typical for studying deep continental subduction and continent-continent collision. However, since lower-grade metamorphic rock occurrence in the core of the ultrahigh-pressure terrane was reported, it has become a new point of concern. This study reported new results. The so-called lower-grade metamorphic rocks are divided into sedimentary rocks and meta-volcanics.The sedimentary rocks consist mainly of fine-grained turbidites formed under an anoxic deep-water lacustrine basin. Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry U-Pb detrital zircon dating indicates that their maximum deposit age is 119.0 ± 1.1 Ma belonging to the mid-Cretaceous Aptian. U-Pb detrital zircon ages from the sedimentary rocks cluster in three age groups: 1) 2773.8-1550.0 Ma(45.0%);2)868.8-622.3 Ma(23.0%);3) 147.0-100.0 Ma(31.5%). And the provenance and tectonic settings of these sedimentary rocks are discussed by synthesizing U-Pb detrital zircon ages, initial Hf isotope ratios, and trace elements of the zircons. Source rocks of the first group were mainly composed of the Paleoproterozoic basement derived from the reworking of the Paleoarchean-Neoarchean Yangtze continental crust. For the second group, its source rocks consisted of Neoproterozoic volcanics mainly from an island arc system, which derived from the reworking of older continental crust in the northern Yangtze Block. The third group’s source rocks were chiefly composed of Cretaceous rift igneous rocks derived from the derivation through melting of middle-aged continental crust in the Dabie Orogenic Belt. The meta-volcanics have weighted mean U-Pb ages from 751.0 ± 16 Ma to 786.3 ± 5.9 Ma, and their protoliths formed under a Middle Neoproterozoic island arc system in the northern Yangtze Block. The meta-volcanics underwent a Triassic subduction of different depths and then an exhumation, but the sedimen展开更多
A new specimen of ankylosaurine dinosaur Crichtonpelta benxiensis is described. The new specimen is based on a nearly completely preserved skull from the same quarry as the holotype of the mid-Cretaceous Sunjiawan For...A new specimen of ankylosaurine dinosaur Crichtonpelta benxiensis is described. The new specimen is based on a nearly completely preserved skull from the same quarry as the holotype of the mid-Cretaceous Sunjiawan Formation in Shuangmiao, Beipiao City, Liaoning Province, China. Cladistic analysis incorporating new information from the new specimen resolves Crichtonpelta benxiensis is more advanced than basal members of Ankylosauridae （Kunbarrasaurus, Liaoningosaurus, Chuanqiiong, Cedarpelta, Gobisaurus and Shamosaurus） and represents the first diverging branch of Ankylosaurinae. Comparisons to other mid-Cretaceous ankylosaurid-bearing dinosaur assemblages in northern China indicate a late Early Cretaceous to early Late Cretaceous age for the Shuangmiao dinosaur assemblage.展开更多
The evolutionary history of Eupolypods still remains unclear, especially on its diversification scenarios. In recent years, it has been found that approximately 100 million-year-old Myanmar amber provides a unique sou...The evolutionary history of Eupolypods still remains unclear, especially on its diversification scenarios. In recent years, it has been found that approximately 100 million-year-old Myanmar amber provides a unique source of polypod fossils. Different families and numerous sporangia, spores, and scales have been found in Myanmar amber. These discoveries are nevertheless important because they provided the first unequivocal fossil evidence that the diversity of eupolypod ferns was present already in the mid-Cretaceous Myanmar amber forest. This clearly shows that Eupolypods originated before mid-Cretaceous, probably as early as the Early Jurassic, which is consistent with the recent divergence time estimate based on molecular dating.展开更多
文摘Bamnet Narong is located in northeastern Thailand (Chaiyaphum Province). It is the largest salt mine in the country and has been mined for decades. The landscape in this part of Thailand is characterised by a low plateau, which is called the Khorat Plateau. The plateau is divided into two basins by the Phu Phan Range, the Sakhon Nakhon Basin in the north and the Khorat Basin in the south. The analysed potashes and rock salts are deposited in the Maha Sarakham Formation, which represents the salt-bearing strata of the Khorat Basin. The stratigraphic age of this deposit has been debated since the late 1960’s. The assigned ages range from Mid-Cretaceous to Late Cretaceous and up to the Eocene. In this study different isotopic dating systems (Rb-Sr, Sr-Sr, K-Ar and K-Ca) were applied. The stratigraphic age for the time of deposition was confirmed to be Mid Cretaceous (Cenomanian). Furthermore, the homogeneity of the carnallites was investigated in order to trace a possible redistribution of rubidium.
文摘A new hadrosauroid dinosaur, Shuangmiaosaurus gilmorei gen. et sp. nov., is described based on a complete left maxilla with articulated premaxilla and lacrimal fragments, and a complete left dentary from the mid-Cretaceous Sunjiawan Formation of Beipiao, Liaoning, northeastern China. Cladistic analysis shows that Shuangmiaosaurus is a basal hadrosauroid, and comprises the sister taxon to Hadrosauridae. In both Shuangmiaosaurus and Hadrosauridae, the maxilla-jugal suture is butt-jointed, rather than finger-in-recess articulation as in other basal hadrosauroids. However, Shuangmiaosaurus does not possess such hadrosaurid synapomorphies as the diamond-shaped maxillary crowns with reduced primary ridges and reduced marginal denticles.
文摘The amber deposits from the Albian-Cenomanian in Myanmar have emerged as a pivotal source for exceptionally abundant fossil insect fauna since their initial discovery. Recent studies have increasingly focused on elucidating the fern inventory and examining newly available fossils from Myanmar amber, suggesting a diverse fern flora that once thrived in Cretaceous forests. Through investigations of amber collections, with particular emphasis on sporangium structures—especially the annulus types preserved in amber inclusions—this study revealed additional novelties within the Cyatheales and Schizaeales in mid-Cretaceous Myanmar amber forests. The described specimens and newly discovered fossils provide compelling evidence that Polypodiales were not only diverse and abundant but also that other fern lineages, such as Cyatheales and Schizaeales, coexisted in these ancient forest ecosystems. This study reveals the high diversity of ferns in the mid-Cretaceous Myanmar area, while also implying the paleoecological and paleogeographical significance of the Mesozoic Burmese amber forests.
文摘According to the most recent Pteridophyte Phylogeny Group (PPG), eupolypods, or eupolypod ferns, are the most differentiated and diversified of all major lineages of ferns, accounting for more than half of extant fern diversity. However, the evolutionary history of eupolypods remains incompletely understood, and conflicting ideas and scenarios exist in the literature about many aspects of this history. Due to a scarce fossil record, the diversification time of eupolypods mainly inferred from molecular dating approaches. Currently, there are two molecular dating results: the diversification of eupolypods occurred either in the Late Cretaceous or as early as in the Jurassic. This study uses the Bayesian tip-dating approach for the first time to infer the diversification time for eupolypods. Our analyses support the Jurassic diversification for eupolypods. The age estimations for the diversifications of the whole clade and one of its two subclades (the eupolypods II) are both in the Jurassic, which adds to the growing body of data on a much earlier diversification of Polypodiales in the Mesozoic than previously suspected.
基金supported by the National Natural Science Foundation of China(No.41602023,41402007)the Key Laboratory Project of Gansu Province(Grant No.1309RTSA041)
文摘The remarkable transition of early angiosperms from a small to a dominant group characterized the terrestrial ecosystem of the Cretaceous. This transition was instigated and promoted by environmental changes. Mid-Cretaceous is characterized by major geological events that affected the global environment. δ^18O, palaeothermometer TEX86, and other climatic indices from marine sediments suggest rapid temperature increase during mid-Cretaceous despite occasional short cooling events. Simultaneously, terrestrial deposits in East Asia changed from coal-bearing to shale, then to red beds and evaporites. Plant assemblages and other paleoclimate indicators point to rapid aridification for midCretaceous terrestrial environments. In addition, the wildfires were frequently spread all over the earth by the numerous charcoal evidence during the Mid-Cretaceous. Thus, we speculate that the seasonally dry and hot conditions of mid-Cretaceous created a fiery hothouse world. Early angiosperms increased in abundance and diversity and evolved from a few aquatic species to terrestrial herbaceous and then to the diversified flora of today. Angiosperms showed rapid physiological evolution in vein density and leaf area that improved photosynthesis and water absorption. These ecophysiological changes made early angiosperms well adapted to the hot and dry environment in mid-Cretaceous. Moreover, these physiological changes facilitated the fire–angiosperm cycles in mid-Cretaceous that likely further stimulated the early angiosperm evolution.
基金supported by the National Natural Science Foundation of China(Grant Nos.41772098,41172097)the China Geological Survey(Grant No.12120113094300)the Public Welfare Project of Geological Survey of Anhui Province,China(Grant Nos.2015-g-24,2014-g-9).
文摘The Dabie Orogenic Belt, located in east-central China, is known for the greatest outcrop area of the ultrahigh-pressure metamorphic rocks in the world and is typical for studying deep continental subduction and continent-continent collision. However, since lower-grade metamorphic rock occurrence in the core of the ultrahigh-pressure terrane was reported, it has become a new point of concern. This study reported new results. The so-called lower-grade metamorphic rocks are divided into sedimentary rocks and meta-volcanics.The sedimentary rocks consist mainly of fine-grained turbidites formed under an anoxic deep-water lacustrine basin. Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry U-Pb detrital zircon dating indicates that their maximum deposit age is 119.0 ± 1.1 Ma belonging to the mid-Cretaceous Aptian. U-Pb detrital zircon ages from the sedimentary rocks cluster in three age groups: 1) 2773.8-1550.0 Ma(45.0%);2)868.8-622.3 Ma(23.0%);3) 147.0-100.0 Ma(31.5%). And the provenance and tectonic settings of these sedimentary rocks are discussed by synthesizing U-Pb detrital zircon ages, initial Hf isotope ratios, and trace elements of the zircons. Source rocks of the first group were mainly composed of the Paleoproterozoic basement derived from the reworking of the Paleoarchean-Neoarchean Yangtze continental crust. For the second group, its source rocks consisted of Neoproterozoic volcanics mainly from an island arc system, which derived from the reworking of older continental crust in the northern Yangtze Block. The third group’s source rocks were chiefly composed of Cretaceous rift igneous rocks derived from the derivation through melting of middle-aged continental crust in the Dabie Orogenic Belt. The meta-volcanics have weighted mean U-Pb ages from 751.0 ± 16 Ma to 786.3 ± 5.9 Ma, and their protoliths formed under a Middle Neoproterozoic island arc system in the northern Yangtze Block. The meta-volcanics underwent a Triassic subduction of different depths and then an exhumation, but the sedimen
基金provided by the National Natural Science Foundation of China(Grant No.41688103 and 41472020)
文摘A new specimen of ankylosaurine dinosaur Crichtonpelta benxiensis is described. The new specimen is based on a nearly completely preserved skull from the same quarry as the holotype of the mid-Cretaceous Sunjiawan Formation in Shuangmiao, Beipiao City, Liaoning Province, China. Cladistic analysis incorporating new information from the new specimen resolves Crichtonpelta benxiensis is more advanced than basal members of Ankylosauridae （Kunbarrasaurus, Liaoningosaurus, Chuanqiiong, Cedarpelta, Gobisaurus and Shamosaurus） and represents the first diverging branch of Ankylosaurinae. Comparisons to other mid-Cretaceous ankylosaurid-bearing dinosaur assemblages in northern China indicate a late Early Cretaceous to early Late Cretaceous age for the Shuangmiao dinosaur assemblage.
文摘The evolutionary history of Eupolypods still remains unclear, especially on its diversification scenarios. In recent years, it has been found that approximately 100 million-year-old Myanmar amber provides a unique source of polypod fossils. Different families and numerous sporangia, spores, and scales have been found in Myanmar amber. These discoveries are nevertheless important because they provided the first unequivocal fossil evidence that the diversity of eupolypod ferns was present already in the mid-Cretaceous Myanmar amber forest. This clearly shows that Eupolypods originated before mid-Cretaceous, probably as early as the Early Jurassic, which is consistent with the recent divergence time estimate based on molecular dating.
