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Leaf stomata form an essential conduit between plant tissue and the atmosphere, thus presenting a link between plants and their environments. Changes in their properties in fossil leaves have been studied widely to infer palaeo‐atmospheric‐CO2 in deep time, ranging from the Palaeozoic to the Cenozoic. Epidermal cells of leaves, however, have often been neglected for their usefulness in reconstructing past‐environments, as their irregular shape makes the manual analyses of epidermal cells a challenging and error‐prone task. Here, we used machine‐learning (using the U‐Net architecture, which evolved from a fully convolutional network) to segment epidermal cells automatically, to efficiently reduce artificial errors. We furthermore applied minimum bounding rectangles to extract length‐to‐width ratios (RL/W) from the irregularly shaped cells. We applied this to a dataset including over 21 000 stomata and 170 000 epidermal cells in 114 Ginkgo leaves from 16 locations spanning three climate zones in China. Our results show negative correlations between the RL/W and specific climatic parameters, suggesting that local temperature and precipitation conditions may have affected the RL/W of epidermal cells. We subsequently tested this methodology and the observations from the modern dataset on 15 fossil ginkgoaleans from the Lower to the Middle Jurassic (China). It suggested that the RL/W values of fossil ginkgo generally had a similar negative response to warmer climatic backgrounds as modern G. biloba. The automated analyses of large palaeo‐floral datasets provide a new direction for palaeoclimate reconstructions and emphasize the importance of hidden morphological characters of epidermal cells in ginkgoaleans. [ABSTRACT FROM AUTHOR]

Fossil wood is a significant proxy for terrestrial palaeoclimate and palaeogeography. Abundant and diversified Mesozoic fossil wood has been documented in China. However, there are limited reports of Jurassic fossil wood records from northwest China. Herein, several calcified wood fossils are described in anatomical detail, from the Middle Jurassic (Bajocian to Callovian) Xinhe Formation in Gansu Province. They were identified as two species of the fossil wood genus Xenoxylon Gothan of Coniferales, namely X. latiporosum (Cramer) Gothan and X. peidense Zheng et Zhang. The newly collected material represents the first record of Jurassic petrified wood from Gansu Province. Based on the palaeoclimatic implication of Xenoxylon, we propose that the Baojishan Basin may have experienced a distinct short-term cooling during the Middle Jurassic. We analysed the fossil diversity and spatial-temporal distribution of Xenoxylon species in China. A total of 15 Xenoxylon species have been documented in China. These occurred from the Late Triassic to Late Cretaceous, but flourished from the Jurassic to Cretaceous intervals. Geographically, they are distributed across 13 provinces, mainly in northeast China. Significantly, this record expands the distribution of this important climate indicator taxon. [ABSTRACT FROM AUTHOR]

A fossil eudicot, Gansufructus saligna gen. et sp. nov. is reported from the Early Cretaceous (late Aptian–early Albian) of the Gansu Province, Northwest China, based on numerous well-preserved axes with attached leaves and infructescences. The leaves are alternate, short petiolate and linear-lanceolate with low rank pinnate to reticulate venation. The infructescences are loose panicles bearing fruits in different stages of maturity, each containing four partly free carpels borne in a whorled arrangement. Each carpel has three to five seeds borne along its ventral margin. The nature of the leaves and axes indicates a terrestrial, herbaceous habit. In general organization, Gansufructus is closely similar to the fruit-bearing axes of Sinocarpus decussatus from the Early Cretaceous Jehol Biota, as well as other more or less contemporaneous angiosperms from the Far East, which together provide evidence of diverse eudicot angiosperms of low stature colonizing areas close to environments of deposition. [ABSTRACT FROM AUTHOR]

Fossils are critical for understanding the environmental changes and uplift history of the Tibetan Plateau during the Cenozoic. As the largest inland basin located at the northeastern plateau, Qaidam Basin has been regarded as the key region to understand the climatic changes in the plateau during the Cenozoic. Herein, fossil legumes from the Oligocene Shangganchaigou Formation in northwestern Qaidam Basin have been reported and are assigned to Desmanthus cf. virgatus (L.) Willd. based on morphological comparison. Current materials represent the first megafossil record of this genus in the world. The living analogues of current fossils now live in regions with mean annual temperature values (MAT) ranging from 13.4 to 29.1°C and mean annual precipitation values (MAP) ranging from 36 to 2874 mm while the MAT and MAP of current northwestern Qaidam Basin is −1.03°C and 60.5 mm, respectively, and indicate that the Oligocene Qaidam was much warmer than today. We calculate that current fossils could grow no higher than 2492 m considering the climatic condition of the Oligocene Qaidam. The difference between estimated and modern elevation of the fossil site suggests that the elevation of the research area has increased by at least ≈1000 m since the Oligocene. [ABSTRACT FROM AUTHOR]

The Qaidam Basin, lying in the north-eastern Tibetan Plateau, China, is key to understanding the Cenozoic climatic and biological changes that have occurred on the plateau; however, information from a palaeontological perspective on this Palaeogene basin is scant. Recently, fossil cyprinids were found in the middle portion of the Shangganchaigou Formation (= Upper Ganchaigou Formation; Oligocene) in the north-western Qaidam Basin. These share many osteological characters with barbines and 'morphologically primitive clade schizothoracines' (= primitive schizothoracines; i.e. Schizothorax and Aspiorhynchus), and they closely resemble the latter in the size and shape of the scales: body scales are small and oval; the number of lateral line scales exceeds 100; and the long-oval scales from the pre-anal region are very similar to the 'anal scales', which are unique to schizothoracines. Compared with another fossil fish, Paleoschizothorax qaidamensis, from the same formation, the major differences are: (1) the posterior part of the entopterygoid in the new material is normal and not expanded while that of P. qaidamensis is obviously expanded; and (2) the premaxilla process of maxilla is well developed in P. qaidamensis but weak in the new specimens. Therefore, they are described as a new species of the fossil genus Paleoschizothorax (subfamily Schizothoracinae): Paleoschizothorax diluculum sp. nov. A phylogenetic analysis, which included 13 extant genera and three fossil forms of barbines and schizothoracines and 70 morphological characters, also supports the close relationship between P. diluculum and primitive schizothoracines. A preliminary correlation analysis suggests that the degree of reduction of body scale size is negatively correlated with habitat mean temperatures among most Chinese cyprinids. Moreover, we speculate that the 'primitive schizothoracines' likely originated in the north-eastern–central Tibetan Plateau based on the fossil records and molecular phylogeny of the extant taxa. [ABSTRACT FROM AUTHOR]

As the largest inland basin in the northeastern Tibetan Plateau, Qaidam Basin has traditionally been thought of as the key region to study the Cenozoic climatic changes in the plateau; however, the information from a palaeobotanic respect is still lacking because of the paucity of the fossil plants. Fossil fruits and foliage of Ailanthus (Simaroubaceae) are reported from the Oligocene Shangganchaigou Formation in the northwestern Qaidam Basin, Qinghai Province, China. All the characters suggest that the fossil materials should be assigned to A. confucii, which is one widely distributed fossil species in the Cenozoic, regarded as the analogue of extant A. altissima. Current materials represent the first fossil record of Simaroubaceae in the northern Tibetan Plateau. Based on the climate requirements of the living A. altissima, the ranges of mean annual temperature (MAT) and mean annual precipitation (MAP) reflected by current fossils from Qaidamare 6.9–17.0°C, and 376–1,383 mm, respectively, compared with the current climate at the fossil site with MAT of −1.03°C and MAP of 60.5 mm. The results indicate that the climate conditions of the fossil site during the Early Oligocene were much warmer and more humid than that of the current. We hereby suggest the warm and moist air could approach the northwestern Qaidam and to accommodate the ecological environment in Early Oligocene. [ABSTRACT FROM AUTHOR]

The fossil record of Lauraceae can be traced back to the Early Cretaceous of eastern Asia based on fossil flowers. Here, we refer a number of new occurrences of leaf and fruit fossils of Lauraceae from the Middle Miocene of Zhangpu, Fujian, China, to seven species. These data provide evidence supporting the fact that a diverse subtropical, or tropical, Lauraceae-dominated evergreen forest surrounded this region 15 million years ago (Mya). The Lauraceae fossils presented in this paper provide evidence for the evolution of this group as well as new materials that enable the study of the Fujian Province Neogene flora. The fossils described in this paper fill in the gaps in studies about Lauraceae pollen in the Middle Miocene from Fotan, Fujian, China. In addition, these fossils also enrich the Middle Miocene fossil records of Lauraceae in eastern Asia, especially improving the study of the macrostructures and reproductive organs of fossil Lauraceae from southern China. The similarity between fossil and modern fruits shows that during the Middle Miocene the fruit morphological of Lauraceae have changed very little. We also identify families where the fossils we report belong to their closest relatives and can be used to reconstruct the paleoenvironment of Fujian in the Middle Miocene. [ABSTRACT FROM AUTHOR]

Compressed fossil plants were found in the gypsum beds of the Zhoujiadian Formation in Guixi City, Jiangxi Province, China. The cuticular features of two species of Pseudofrenelopsis (Cheirolepidiaceae) were examined by scanning electron microscopy in this study: Pseudofrenelopsis papillosa Cao ex Zhou and Pseudofrenelopsis guixiensis Bainian Sun et Dai, sp. nov. A detailed analysis of the internode epidermis, and the adaxial and abaxial leaf cuticles of the two species, was performed, extending our knowledge of the morphological and anatomical characteristics of the extinct Pseudofrenelopsis. A new species, Pseudofrenelopsis guixiensis sp. nov., is proposed based upon comparison of its cuticular features. It differs from previously published species in that it has hairs on the abaxial surfaces of its leaves, sometimes shares subsidiary cells on the surfaces of internodes, lacks a hypodermis, and has no papillae on its epidermal cells. Because the distribution of fossil Pseudofrenelopsis is restricted to the Lower Cretaceous, the Early Cretaceous age of the Zhoujiadian Formation is affirmed. The fossils of Pseudofrenelopsis show obvious xeromorphic characteristics, such as apparent thickening of the cuticles, subsidiary cells with obvious papillae, and anticlinal walls with strong cutinization, and they are found associated with gypsum beds and close to red beds. All of these features indicate an arid climate. [ABSTRACT FROM AUTHOR]

Solenites vimineus (Phillips) Harris (Ginkgophyta) specimens with well-preserved cuticles were collected from five different beds in the oil shale member of the Middle Jurassic Yaojie Formation in the Yaojie Basin, Gansu Province, northwestern China. Gross morphology and fine structures of the fossil leaves were studied, and stomatal parameters were analyzed, according to which, the paleoatmospheric CO2 concentration can be deduced as 1512–1896 ppm that would have caused an increase in mean temperature of about 6.5–7.4°C. Carbon isotopes from the fossils indicate that the carbon isotopic discrimination and water use efficiency (WUE) of S. vimineus were raised nearly obtaining the ideal physiologic state in increased CO2 concentrations and temperature conditions, suggesting that S. vimineus records the paleoenvironmental information of the Middle Jurassic Yaojie Basin and can be used for environmental reconstruction. [ABSTRACT FROM AUTHOR]

A new species Theronia qaidamensis sp. nov. (Ichneumonidae, Pimplinae) is described from the Oligocene Shangganchaigou Formation of the northwestern Qaidam Basin (Huatugou area), northeast of the Tibetan Plateau (TP). The new species represents the first report of the Ichneumonidae from the Qaidam Basin, which reveals an insect linkage between the Qaidam Basin and Europe. In addition, the study of associated fossils from the Shangganchaigou Formation shows that the palaeoenvironment of the northwestern Qaidam Basin during the Oligocene was warm and moist, which provided suitable living conditions for the current fossil. [ABSTRACT FROM AUTHOR]

A fossil eudicot, Gansufructus saligna gen. et sp. nov., is reported from the Early Cretaceous (late Aptian-early Albian) of the Gansu Province, Northwest China, based on numerous well-preserved axes with attached leaves and infructescences. The leaves are alternate, short petiolate and linear-lanceolate with low rank pinnate to reticulate venation. The infructescences are loose panicles bearing fruits in different stages of maturity, each containing four partly free carpels borne in a whorled arrangement. Each carpel has three to five seeds borne along its ventral margin. The nature of the leaves and axes indicates a terrestrial, herbaceous habit. In general organization, Gansufructus is closely similar to the fruit-bearing axes of Sinocarpus decussatus from the Early Cretaceous Jehol Biota, as well as other more or less contemporaneous angiosperms from the Far East, which together provide evidence of diverse eudicot angiosperms of low stature colonizing areas close to environments of deposition., (© The Author(s) 2021. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

The genus Dactylis , an important forage crop, has a wide geographical distribution in temperate regions. While this genus is thought to include a single species, Dactylis glomerata , this species encompasses many subspecies whose relationships have not been fully characterized. In this study, the genetic diversity and phylogenetic relationships of nine representative Dactylis subspecies were examined using SSR and IT-ISJ markers. In total, 21 pairs of SSR primers and 15 pairs of IT-ISJ primers were used to amplify 295 polymorphic bands with polymorphic rates of 100%. The average polymorphic information contents (PICs) of SSR and IT-ISJ markers were 0.909 and 0.780, respectively. The combined data of the two markers indicated a high level of genetic diversity among the nine D. glomerata subspecies, with a Nei's gene diversity index value of 0.283 and Shannon's diversity of 0.448. Preliminarily phylogenetic analysis results revealed that the 20 accessions could be divided into three groups (A, B, C). Furthermore, they could be divided into five clusters, which is similar to the structure analysis with K = 5. Phylogenetic placement in these three groups may be related to the distribution ranges and the climate types of the subspecies in each group. Group A contained eight accessions of four subspecies, originating from the west Mediterranean, while Group B contained seven accessions of three subspecies, originating from the east Mediterranean.