Xiao-Ju Yang's research while affiliated with Chinese Academy of Sciences and other places

Newly discovered foliage of Rhaphidopteris zhouii sp. nov from the Lower Jurassic Sangonghe Formation at the Haojiagou section in the Junggar Basin of Xinjiang, northwestern China is investigated on morphological characters and cuticular structure. The new species has anisotomically divided leaves, linear ultimate segments with a single vein; amphistomatic cuticle, epidermal cells that are similar both on the upper and lower surfaces but more regular on the upper surface; stomata distributed densely on the lower cuticle and sparsely and confined in two bands near the lateral margin on the upper cuticle; anomocytic stomata which are longitudinally oriented with 4-6 subsidiary cells of irregular shape and size. This is the first report of the genus Rhaphidopteris from Xinjiang. The gross morphology and epidermal characters of the new species improves our understanding on the morpho-heterogenus Rhaphidopteris .

With ca. 250 extant species, Radula is one of the largest genera of the Porellales and the sole extant genus of the leafy liverwort family Radulaceae, widely distributed around the world. The earliest fossils of Radula were described from mid-Cretaceous Kachin amber of Myanmar, namely R. cretacea and R. heinrichsii. Here, we report two new exquisitely preserved specimens of R. heinrichsii from Kachin amber, yielding new morphological characters for an extended description of this taxon. Cladistic analysis based on a matrix of fourteen morphological characters and a molecular backbone constraint suggests its close relationship with extant species of Radula subgenus Amentuloradula. But due to distinctive morphological characters in R. heinrichsii and the younger estimated age for the crown group, it is likely that R. heinrichsii represents a stem group of the subgenus. The genus Radula is characterized by a high degree of morphological homoplasy, which makes the assignment of fossils to this extant taxon difficult and requires profound knowledge of the morphology of fossils.

Stomata characteristics of two extinct conifer Cheirolepidiaceae species, Pseudofrenelopsis gansuensis and Pseudofrenelopsis dalatzensis were used to reconstruct the atmospheric carbon dioxide concentration levels during the late Albian of Cretaceous. A sequence of fossil samples was collected from 5 beds in the Dalazi Formation in Zhixin and Luozigou basins of Jilin Province, northeastern China. The stomatal index was used to estimate the palaeo- p CO 2 . The average stomatal index value of the two species was 4.1 and the atmospheric CO 2 content was ∼1200 ppmv by the average of Recent standardization and Carboniferous standardization. During the short interval of 104.8±0.5 Ma to 104.0±0.4 Ma in the late Albian, the atmospheric CO 2 contents present a deceasing tendency, and the highest value was ∼1300 ppmv in the Luozigou Basin. In addition, the higher atmospheric CO 2 values of late Albian likely linked to a “greenhouse climate” time of Oceanic anoxic event 1c (OAE1c).

A new species of conifer wood, Brachyoxylon lalongense sp. nov., was discovered from the Lower Cretaceous (Berriasian–Barremian) Duoni Formation of Bangoin County in the northern part of the Lhasa Block, Southwest China. The anatomical structure of the secondary xylem is characterized by the absence of growth rings, mixed type of radial tracheary pitting, araucarioid cross-field pits, uniseriate xylem rays, and the absence of resin canals. The absence of growth rings in the secondary wood indicates that this conifer was evergreen and the area was dominated by a hot climate during the Early Cretaceous. This conclusion is coincident with the coeval palaeobotanical and palynological evidence discovered in Tibet.

With over 300 extant species, the nearly worldwide‐distributed genus Frullania is one of the most species‐rich genera of leafy liverworts and the sole extant genus of Frullaniaceae. Amber fossil record of Frullania is also rather diverse, with inclusions known from several amber deposits. The earliest fossils are F. baerlocheri, F. cretacea, and F. partita from the mid‐Cretaceous Kachin amber, Myanmar. Here, we describe a new fossil species of Frullania as F. kachinensis sp. nov., based on seven sterile gametophyte fragments from three pieces of Kachin amber. This new species is characterized by leaf dorsal lobes mostly with rounded apexes, leaf ventral lobules inserted in approximately 30–90 μm distance to stem, lanceolate styli, and deeply bilobed underleaves with entire‐margined to toothed lobes and V‐shaped sinuses. Morphological comparisons indicate that F. kachinensis shows mosaic character combinations of two coeval species F. cretacea and F. partita. The leaf lobes of F. kachinensis resemble those of F. cretacea, while the underleaves are more similar to those of F. partita. But in taphonomy, F. kachinensis is preserved together with Protofrullania cornigera or F. baerlocheri in the same amber, which could indicate that these three species might live in the same habitat and even on the same tree. The fossils presented in this study provide additional evidence for the presence of a diverse liverwort flora, mostly composed of Frullaniaceae lineages in the mid‐Cretaceous Kachin amber forest. Here, we describe some liverwort inclusions within mid‐Cretaceous Kachin amber as Frullania kachinensis sp. nov. (Frullaniaceae). It combines key morphological features of two coeval species Frullania cretacea and Frullania partita, while cluster analysis has F. kachinensis as more similar to F. cretacea.

The data presented in this article are related to the research paper entitled “Cuticle ultrastructure of Baiera furcata from Northeast China and its implication in Taxonomy and Palaeoenvironment” (Guignard et al. 2019 [1]. The data correspond to a study of the ultrastructural fine cuticle details of fossil Baiera furcata (Ginkgoales) from the Lower Cretaceous Huolinhe Formation in Holingola of East Inner Mongolia, Northeast China. Two sets of data are provided here: 1/ thickness measurements of the layers of four types of cuticles, i.e. ordinary epidermal cells and stomatal apparatus, 2/ ten EDS element analysis of ordinary epidermal cell cuticle layers; the latter data also contain cuticle layers values of Sphenobaiera huangii from the Lower Jurassic Xiangxi Formation in Zigui of Hubei Province, Central China used for comparison in the research article; EDS cell remnant values of Baiera furcata are also included. Some of these data have been used efficiently for taxonomy and palaeoenvironment topics. As they are the first data for genera Baiera and Sphenobaiera of the Ginkgoales, they can serve in the future for considerations of taxonomical comparisons, palaeoreconstructions, palaeoenvironment and evolution.

A new species of Ginkgo L., G. pediculata sp. nov., is described from the Lower Cretaceous of Liaoning Province, Northeast China, on the basis of a well-preserved ovule-bearing organ. The cuticles of the integument and peduncle are generally similar to those of the lamina and petiole of the associated Ginkgoites manchurica (Yabe et Ôishi) Cao, which is among the most widely distributed Ginkgo-like leaves in the Lower Cretaceous of Northeast China. The new species is close to the Jurassic Ginkgo yimaensis Zhou et Zhang and clearly distinguished from the Paleogene species Ginkgo cranei Zhou et al. and the extant Ginkgo biloba. Although the coeval Ginkgo apodes Zheng et Zhou and G. neimengensis Xu et al. from Northeast China bear more ovules, they both have no pedicel when matured as the living species. The associated Ginkgoites-type leaves morphologically also resemble those of the Jurassic species. Therefore, Ginkgo pediculata sp. nov. appears to be closely related to the Jurassic species and is the latest representative of the group with primitive type ovulate organs and vegetative leaves so far known of Ginkgo. Since there co-exist two different types of ginkgoes, one with primitive characters (Ginkgo pediculata) and the other such as Ginkgo apodes and G. neimengensis which resemble the extent species G. biloba, the Lower Cretaceous is a critical time in the morphological evolution of the genus Ginkgo, roughly corresponding to the major global floristic transformation marked by the rapid decline of gymnosperms and drastic rise of flowering plants.

A study on the leaf cuticle ultrastructures of Baiera furcata from the Lower Cretaceous Huolinhe Formation in East Inner Mongolia, Northeast China, was conducted with transmission electron microscopy (TEM) and elements analysis by Energy Dispersive Spectroscopy (EDS). TEM observation revealed the ultrastructural details from ordinary epidermal cells for both upper and lower cuticles, and stomatal apparatus, which were all made with A2 (granular) and B1 (fibrilous) layers. Additionally, well-preserved cell remnants were also observed. Comparisons with other cuticles of the Ginkgoales were made using statistical measurements and evaluations of some potential Order characteristics, and genus–species characteristics were also emphasized. Two potential ultrastructural groups can be recognized: Baiera–Sphenobaiera and Ginkgo–Ginkgoites–Pseudotorellia. This is reinforced by EDS element analysis, whereby ratios could also be compared with another closely related Ginkgoalean taxon Sphenobaiera huangii. The paleoenvironment significances is discussed, and it seems to support the TEM and EDS results. It indicates a signature in the cuticle fine details of Sphenobaiera, which has experienced a putatively warmer paleoenvironment than that of Baiera.

Premise of research. Discovery of abundant leafy twigs with attached pollen cones and seed cones of Austrohamia acanthobractea from the Middle Jurassic Daohugou Lagerstätte in Inner Mongolia, Northeast China, provides detailed morphological and anatomical features of the species, permitting a whole-plant reconstruction and a more detailed evaluation of the affinities of this extinct plant within the Cupressaceae. Methodology. All fossil plants were studied with standard paleobotanical preparations and descriptive terminology. Pivotal results. Austrohamia acanthobractea has leafy twigs consisting of helically arranged, linear leaves with two narrow stomatal bands on the abaxial surface. Pollen cones are borne in the axil of a lanceolate bract, subterminally on shoots in clusters of four, with peltate microsporophylls. Seed cones are borne terminally or laterally, solitary or in a pair, with numerous spirally arranged bract-scale complexes. The bract-scale complex apparently lacks a free ovuliferous scale. Seeds are obovate and inverted, with two narrow lateral wings. Austrohamia acanthobractea bears a close resemblance to extant Taiwania and Cunninghamia. Conclusions. The morphological cladistic analysis suggests that the two species of Austrohamia form a polytomy with the expanded Cunninghamioideae clade, which includes extant Cunninghamia and Cunninghamia-like fossils from the Jurassic, Cretaceous, and Cenozoic. It supports the original interpretation that the genus is closely related to Cunninghamia and Cunninghamia-like fossils based on material from the Early Jurassic of Patagonia in Argentina.

New fossil plants are reported from the lower part of the Linbuzong Formation at Qubsang, Doilungdeqen, Lhasa, Tibet. The assemblage comprises Neocalamites sp., Ptilozamites tibetica Yang, Ptilozamites sp., ?Ptilozamites sp., Zamites sp. 1, Zamites sp. 2, ?Zamites (?Otozamites) sp. 1, ?Zamites sp. 2., Ptilophyllum sp. 1, Ptilophyllum sp. 2, Ptilophyllum sp. 3, Geinitzia sp. and Elatocladus (?Torreyites) sp. Among these plants at least two of them, Ptilozamites tibetica and Elatocladus (?Torreyites) sp. are firstly discovered in this area, and the others occured frequently in the Mesozoic flora in Tibet. Associated miospores suggests an Early Cretaceous age for the assemblage. The abundance of Ptilophyllum and conifer Geinitzia sp. and the absence of Ginkgoales might indicate a palaeoenvironment with both a low latitude and high temperatures, and a tropical arid to semi-arid climate predominating in this coastal area. The Qubsang assemblage, composed mainly of Bennettitales and Coniferopsida, does not resemble any contemporaneous ones known from Gondwanaland or Eurasia. Although the flora lacks characteristic Wealden ferns, such as Weichselia, the plant assemblage shows a general relation to Tethyan floras of the area and might roughly correspond in age to the Wealden floras of Western Europe.