New Discovery of Calamitaceae from the Cisuralian in Northwest China: Morphological Evolution of Strobilus.

Calamitaceae was the predominant arborescent element of the Late Paleozoic plant assemblages. However, there is currently controversy surrounding the evolutionary relationships of their four reproductive organs, and there is no unified understanding of the geographical distribution and species richness characteristics. This paper is based on the detailed description of the macro- and microstructures of Calamites and Macrostachya discovered in the Shanxi Formation of the Cisuralian in the eastern Hexi Corridor of northwestern China, and it discusses the evolutionary patterns of calamitean reproductive organs. The results indicate that the current specimens can be identified as the Calamites cistii and Macrostachya sp., and the in situ spores should exhibit distinct trilete marks, indicating that they belong to the Punctatisporites punctatus. The abundant fossil records suggest that the "Calamostachys" type should be considered as the ancestral type of strobili. Additionally, Calamitaceae was widely distributed in mid to low latitudes globally from the Pennsylvanian to the Cisuralian and coupled with paleogeographic distribution characteristics.

New Fossil Evidence Suggests That Angiosperms Flourished in the Middle Jurassic.

Angiosperms are a group of plants with the highest rate of evolution, the largest number of species, the widest distribution and the strongest adaptability. Needless to say, angiosperms are the most important group for the humans. The studies on the origin, evolution and systematics of angiosperms have been the major challenges in plant sciences. However, the origin and early history of angiosperms remains poorly understood and controversial among paleobotanists. Some paleobotanists insist that there were no angiosperms in the pre-Cretaceous age. However, this conclusion is facing increasing challenges from fossil evidence, especially Early Jurassic Nanjinganthus, which is based on over two hundred specimens of fossil flowers. Studying more fossil plants is the only reliable way to elucidate the origin and early evolution of angiosperms. Here, we document a new species of angiosperms, Qingganninginfructus formosa gen. et sp. nov, and provide the first detailed three-dimensional morphology of Qingganninginfructus gen. nov from the Middle Jurassic of Northwest China. A Micro-CT examination shows that the best-preserved fossil infructescence has eleven samaroid fruits, each with a single basal ovule. Since these fossils are distinct in morphology and organization from all organs of known gymnosperms and angiosperms (the latter are defined by their enclosed ovules), we interpret Qingganninginfructus as a new genus of angiosperms including a new species, Q. formosa gen. et sp. nov., and an unspecified species from the Middle Jurassic of Northwest China. The discovery of this new genus of angiosperms from the Middle Jurassic, in addition to the existing records, undermines the "no angiosperms until the Cretaceous" stereotype and updates the perspective on the origin and early history of angiosperms.

A New Fossil Species of Nothotsuga from the Mula Basin, Litang County, Sichuan Province and Its Paleoclimate and Paleoecology Significance.

In this paper, we describe a new fossil species, Nothotsuga mulaensis Z. Li & J.L. Dong sp. nov. The discovery of the fossil species was based on well-preserved fossil seed cones that were found in the Mula Basin in Xiamula village, Litang County, Sichuan Province, southwestern China. The shapes of these fossils were characterized by ovate seed cones, rhombic or suborbicular scales with auriculate bases, and the bracts were ligulate-spathulate in shape. This finding suggests that Nothotsuga once had a wide distribution range in China and that it also inhabited the eastern Tibetan Plateau (TP). Nothotsuga mulaensis was distributed in an intermountain lake basin, at altitudes from 2000 to 2300 m, in a warm and humid environment. This finding also suggests that the eastern TP may have provided good habitat for Nothotsuga during the Miocene. In addition, we propose that the uplift, accompanied by the severe cooling and aridification that occurred after the Miocene, caused the disappearance of this species of Nothotsuga in the eastern TP.

An exceptionally well-preserved herbaceous eudicot from the Early Cretaceous (late Aptian-early Albian) of Northwest China.

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.

Identification of two new species of Meliolinites associated with Lauraceae leaves from the middle Miocene of Fujian, China.

Several studies have investigated both the paleoclimate and the well-preserved fossil remains from the middle Miocene found in China's Fujian Province. This study describes two new species of Meliolinites, including their fungal hyphae, reproductive structures, and spores. The distribution of modern Meliolaceae indicates that they live in warm, humid, subtropical to tropical climates. Moreover, the fossil leaves and the epiphyllous fungal remains, indicate the prevalence of a warm, humid, subtropical to tropical climate in this area during the middle Miocene. In addition, it was observed that the surrounding cells of the fungi found on the uninfected host leaves were normal, whereas the infected host leaves themselves were abnormally dim. These features are a reflection of self-protection, and it can, therefore, be inferred that the host leaves were alive when they were infected. The present study used fossil angiosperm leaves with cuticles obtained from the Fotan sediments from Fujian to investigate not only the taxonomy of the fossils but also to interpret the paleoclimate and paleoecology.

Paliurus Fruits from the Oligocene of South China and Their Phytogeographic Implications.

Paliurus favonii Unger is recognized and described based on fruits from the Oligocene Ningming flora of Guangxi, South China. Characteristics of the present specimens include circular winged fruits that are 10.0-11.5 mm in diameter with a central endocarp at 3.0 to 4.0 mm in diameter. The specimens fall into the morphological range of the fossil species P. favonii, which has been observed in other Cenozoic sites in the Northern Hemisphere. The present discovery represents the lowest latitude distribution of P. favonii in the world, and we are presenting the first P. favonii fossil described with detailed cuticular characteristics from China. Further, this finding demonstrates that the genus existed in the Oligocene Ningming region, South China, and provides new information for understanding the fossil history. The dispersal mode for winged fossils demonstrates that wind dispersal is well-represented in the Oligocene Ningming flora.

A new species of Meliolinites associated with Buxus leaves from the Oligocene of Guangxi, southern China.

A new species of Meliolinites (fossil Meliolaceae), M. buxi sp. nov., is reported from the Oligocene Ningming Formation of Guangxi, South China. The fungus has hyphopodia characteristics of extant Meliolaceae, such as thick-walled, branching hyphae with appressoria and phialides. However, these fossils entirely lack mycelial or perithecial setae and have only a few phialides, thereby distinguishing the new species from most known species. The fungus was discovered on the adaxial and abaxial cuticles of several fossilized Buxus leaves. Thickening and twisting of cell walls in the Buxus leaf cuticle, along with the parasitic feeding strategy of the extant Meliolaceae, suggest that a parasitic interaction between Buxus and M. buxi seems feasible. The distribution of modern Meliolaceae suggests that they live in warm, humid subtropical-tropical climates. It is possible that the presence of M. buxi indicates a similar climatic condition. The co-occurrence of large-leaf Buxus and floristic comparisons of the Ningming assemblage also corroborate this conclusion.

First occurrence of Platycladus from the upper Miocene of Southwest China and its phytogeographic implications.

Platycladus Spach is native to Central China, but its natural occurrences are very difficult to establish. According to molecular phylogenetic data, this genus might have originated since the Oligocene, but no fossil record has been reported. Here, we describe eight foliage branches from the upper Miocene in western Yunnan, Southwest China as a new species, P. yunnanensis sp. nov., which is characterized by foliage branches spread in flattened sprays, and leaves decussate, imbricate, scale-like and dimorphic. The leaves are amphistomatic, and the stomata are elliptical or oblong, haplocheilic, and monocyclic type. Based on a detailed comparison with the extant genera of Cupressaceae sensu lato, our fossils are classified into the genus Platycladus. The occurrence of P. yunnanensis sp. nov. indicates that this genus had a more southernly natural distribution in the late Miocene than at present. Molecular phylogeny and fossil records support a pre-Oligocene common ancestor for the genera Platycladus, Microbiota and Calocedrus. The separation of the three taxa was most likely caused by the arid belt across Central China during the Oligocene. In addition, the cooling down of the global temperature and the strengthening of Asian monsoon since the Miocene will further promote the migration of these genera.

Variation in Ginkgo biloba L. leaf characters across a climatic gradient in China.

Fossil leaves assigned to the genus Ginkgo are increasingly being used to reconstruct Mesozoic and Tertiary environments based on their stomatal and carbon isotopic characteristics. We sought to provide a more secure basis for understanding variations seen in the plant fossil record by determining the natural variability of these properties of sun and shade leaf morphotypes of Ginkgo biloba trees under the present atmospheric CO2 concentration and a range of contemporary climates in three Chinese locations (Lanzhou, Beijing, and Nanjing). Climate had no major effects on leaf stomatal index (proportion of leaf surface cells that are stomata) but did result in more variable stomatal densities. The effects of climate and leaf morphotype on stomatal index were rather conserved (<1%) and much less than the response of trees to recent CO2 increases. Leaf carbon isotope discrimination (delta) was highest for trees in Nanjing, which experience a warm, moist climate, whereas trees in the most arid site (Lanzhou) had the lowest delta values. Interestingly, the variation in delta shown by leaf populations of trees from China and the United Kingdom was very similar to that of fossil Ginkgo cuticles dating to the Mesozoic and Tertiary, which suggests to us that the physiology of leaf carbon uptake and regulation of water loss in Ginkgo has remained highly conserved despite the potential for evolutionary change over millions of years.