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Podocarpium (Fabaceae), characterized by single seeded pods and paripinnate compound leaves, is well known as an extinct legume genus having extensive fossil occurrences from the Miocene of Central Europe and eastern Asia. However, the Palaeogene unambiguous megafossils are quite scarce, especially the Oligocene record from eastern Asia, which heavily impedes our understanding of early dispersal patterns and infrageneric relationships of this enigmatic genus. Here, we described dozens of legume specimens from the Oligocene Ningming Formation of Guangxi in South China, the Early Miocene Guide Group of Qinghai in Northwest China and the Middle–Late Miocene Shengxian Formation of Zhejiang in Southeast China as Podocarpium podocarpum (A. Braun) Herendeen based on extremely similar fruit characters. Meanwhile, we reexamined variation in fruit morphology among the previously reported fruits of Eurasia and present legumes as a basis for interpreting the infrageneric relationship and subfamily affinity of Podocarpium. The high similarities presented by these fossil fruits support the previous recognition of the specimens from the Oligocene–Miocene of Central Europe and the Miocene– Pliocene of eastern Asia as P. podocarpum, but such a low species diversity of Podocarpium appears to indicate a bradytelic morphological evolution for this whole ancient lineage through geologic time. Moreover, judging from seed orientation as well as seed and fruit comparative sizes, the oblong seed is parallel to the long axis of the fruit and its placentation is near the apex of the seed chamber, which favor the previous assignment of Podocarpium to the subfamily Caesalpinioideae. Additionally, we speculated that this extinct genus may prefer a warm and humid (or mildly arid) environment by plotting the megafossil localities on the overall Eocene, Oligocene and Miocene palaeoclimate maps based on continental drift. The Oligocene occurrence from the Ningming Formation in Guangxi, South China sheds new light on the historical biogeographical pattern between Central Europe and eastern Asia, i.e. after the probable origin in low latitude tropic coastal regions of southernmost South China (i.e. Hainan) by the Middle Eocene, Podocarpium may subsequently disperse into Guangxi and then Europe via a probable low-latitude land connection located among the Tethys and Paratethys seas to the southwest of Eurasia in the Early Oligocene, independent of the gradual closure of the Turgai Strait in the middle-high latitudes during the Oligocene.

The fossil records of Burretiodendron Rehder are reviewed based on diagnostic winged fruits from the Oligocene Ningming Formation, Guangxi, South China. Today, this genus is endemic to Southeast Asia with six extant species that are well distributed in limestone mountain forests under a monsoonal climate. The fossil records of this genus were represented only in Yunnan of southwestern China. The fossil fruits are assigned to a new species, Burretiodendron guangxiensis J.L. Dong et B.N. Sun sp. nov., are smaller than those of living species. Burretiodendron is a good indicator of paleoclimate and karstification due to its restricted distribution which is determined by specific temperature, precipitation and the topographic condition. We investigated the climate requirements of Burretiodendron. It is possible to accurately infer that the Ningming paleoflora represented a warm and humid climate with seasonal precipitation during the Oligocene. Edaphic preferences of the nearest living relative identified for the fossil species may point to the existence of a karstic system in the Ningming Region during the Oligocene.

The Oligocene marked the beginning of the present ‘icehouse’ epoch and witnessed the development and evolution of the Asian monsoon system (AMS). In this paper, the early Oligocene Ningming flora of Guangxi, southern China, is analysed to investigate the AMS based on climate proxies derived from Climate Leaf Analysis Multivariate Program (CLAMP). CLAMP results suggest that the prevailing climate experienced by the Ningming flora was humid subtropical with hot summers and warm winters. Although the record of precipitation seasonality is muted, it is about half as strong as that seen today in monsoon climates of South China, indicating a very weak monsoonal signal. Despite suggesting weak rainfall seasonality, the position of the Ningming flora in physiognomic space indicates that leaves exhibit monsoon-adapted morphologies, comparable to today's vegetation exposed to the Indonesia–Australia monsoon (I-AM) and the transitional monsoon area (influenced by the East Asia monsoon, South Asia monsoon and I-AM). Leaf architectural signatures reveal that the Ningming flora grew under a humid subtropical climate with subtle monsoon signatures. Although it is difficult to distinguish the different domains of the Asian monsoon under such a subtle monsoon influence, based on leaf signatures from southern Asia, it can be inferred that the Ningming Basin during the early Oligocene was exposed to a climate regime similar to that today influenced by the I-AM. In addition, the moist enthalpy method was applied to quantitatively reconstruct the paleoelevation of the Ningming Basin. This approach suggests a paleoelevation estimate of ~1.24–1.35 ± 0.52 km for the early Oligocene, suggesting that a drop in paleoelevation of the Ningming Basin took place after the early Oligocene (Rupelian). The CLAMP results suggest that the early Oligocene Ningming area was at a mid-altitude and experienced a humid subtropical climate with subtle monsoon signatures.

New legume fossils can provide a historical perspective of their early evolution and biogeographic history. Three legume species, Albizia ningmingensis sp. nov., Leguminocarpum sp. 1 and Leguminocarpum sp. 2, from the Oligocene Ningming Formation of Guangxi, South China, are described on the basis of morphological and/or anatomical characteristics. Albizia ningmingensis sp. nov. bears a close resemblance to the extant species Albizia kalkora in morphology and anatomy and represents a reliable occurrence of Albizia in the Oligocene deposits of China. An incomplete fruit fossil is described as Leguminocarpum sp. 1, predominantly on the basis of anatomical characteristics. Fruits of Leguminocarpum sp. 2 are straight and strongly asymmetrical, with one straight suture and the other strongly constricted. The occurrence of Albizia fruits indicate that Albizia elements existed in the South China during the Oligocene. Our legume fossils, together with earlier records of three Bauhinia species, indicate that a flora with the unusual abundance of legumes was present in South China in the Oligocene. The legumes from the Ningming Formation, having a relatively high diversity, can contribute to the palaeoclimatic interpretation and indicate that the Oligocene Ningming flora most likely lived in a tropical-to-warm subtropical climate.

Recently, several leaf fossils with good cuticles were discovered from the Oligocene deposits in Guangxi, China. The high fossilization potential of these leaves and easily identifiable stomata and epidermal cells make them an excellent source for CO2 reconstruction. In this study, atmospheric CO2 of the Oligocene is reconstructed using the mechanistic-theoretical model based on stomatal data, photosynthesis and gas exchange control and using an alternative method based only on stomatal ratio. Fossil leaves of Buxus ningmingensis, Chuniophoenix slenderifolius and Cephalotaxus ningmingensis, two angiosperms and one gymnosperm, were considered. It was found that some differences were present between the results obtained by the two methods. The SR-based method yields a somewhat narrower CO2 range (from 355 to 578 ppmv) than the model approach (from 255 to 972 ppmv) which encloses the former range. The CO2 results derived from the three species using the two approaches are overlapped to a high degree with CO2 data from other terrestrial plants and phytoplankton material. More data provided by different proxies are desirable to unravel the interactions between atmospheric CO2 and climate change for the Oligocene.

A new fossiliferous horizon from the Middle Triassic Dingjiayao Formation, Pingchuan District, Gansu Province, China is described. The plant assemblage preserves a diverse community of horsetails, ferns and seeds of unknown systematic affinity. Ferns are the most diverse elements of the assemblage and are also ecologically dominant, while horsetails contribute a smaller component to floristic diversity and have a lower abundance. Here, five fern taxa are assigned to Marantoidea, Symopteris, Neuropteridium, Cladophlebis and Sphenopteris. Also, six species belonging to three horsetail taxa are described from this assemblage, which are assigned to Equisetites, Echinostachys and Neocalamites. Additionally, remains of doubtful botanical attribution comprise Carpolithus seeds. Some of these groups are recorded from the Middle Triassic of China for the first time. The preservation of these fossils suggests that the assemblage was buried autochthonously or para-autochthonously by volcanic ash fall. Fossilization of these specimens occurred rapidly after the specimens embedded in the volcaniclastic sediments. Also the plant assemblage indicates a local riparian environment in a warm, humid climate.

Three species of Palaeocarya were found from the Oligocene Ningming Formation of Guangxi, South China. Two species have been identified, Palaeocarya guangxiensis and Palaeocarya ningmingensis, and a new species is described, Palaeocarya longipedicelata J.L. Dong et B.N. Sun sp. nov. The new species is diagnosed primarily by a distinct long pedicel of 8.0–10.0 mm in length, lobe base tri-veined, upper pinnate venation with retuse apex, small prophyllum, and nutlet without hair. The epidermal cells show obscure polygons with undulated cell walls from the tri-lobed bract and show clear polygons with straight cell walls from the pedicel. The peltate scales and circular peltate trichomes are also observed. The occurrence of these winged fruit fossils from the Oligocene suggests that Palaeocarya began to diversify no later than the Oligocene in Guangxi, South China. From the correlation between present fossils with previously published fossils from the Oligocene Jilin, Northeast China, it can be inferred that Palaeocarya had a wide distribution during the Oligocene in China, ranging from the south to the northeast. Based on the analysis of the ecological requirements of the extant relative species, Engelhardia, Alfaropsis and accompanying plant and fungi fossils, we can infer that the palaeoclimate of the Ningming region should be considered a warm and humid tropical–subtropical climate. Finally, we speculate that the Ningming Basin during the Oligocene was close to the low-latitude mountains. Drei Arten von Palaeocarya wurden in der oligozanen Ningming-Formation in Guangxi (S-China) gefunden. Zwei Arten wurden identifiziert, Palaeocarya guangxiensis und Palaeocarya ningmingensis, wie auch eine neue Art (Palaeocarya longipedicelata J.L. Dong et B.N. Sun sp. nov.) beschrieben wird. Die neue Art wurde primar anhand des langen, ausgepragten Pedicellus mit einer Lange von 8.0–10.0 mm, der dreiaderigen Basis der Loben, der oben gefiederten Aderung mit gestutztem Apex, dem kleinem Vorblatt und der kleinen, haarfreien Nuss festgelegt. Die Epidermalzellen weisen ein undeutliches Polygon mit undulierenden Zellwanden des dreiaderigen Deckblatts und deutliche Polygone mit geraden Zellwanden des Pedicellus auf. Peltate Schuppen und runde, peltate Trichome wurden ebenfalls festgestellt. Dieses Fossilvorkommen geflugelter Fruchte aus dem Oligozan belegt den Beginn der Diversifizierung von Palaeocarya spatestens im Oligozan des sudchinesischen Guangxi. Ein Vergleich zwischen den vorliegenden Fossilien mit fruher publizierten Funden aus dem Oligozan von Jilin (NE-China) ermoglicht den Ruckschluss, dass Palaeocarya eine weite Verbreitung wahrend des Oligozans in China aufwies, vom Suden bis zum Nordosten. Aus der okologischen Analyse heutiger verwandter Arten wie Engelhardia und Alfaropsis nebst begleitenden Pflanzen- und Pilzfossilien konnen wir schliesen, dass das Palaoklima der Ningming-Region ein warmes, humides, tropisch–subtropisches Klima war. Wir vermuten, dass das Ningming-Becken wahrend des Oligozans an aquatornahe Berge grenzte.

The study of plant–insect interactions can provide valuable information about terrestrial ecosystems. A plant assemblage from the Toupi Formation of Jiangxi, China, provides indirect evidence of the plant–insect interactions that occurred in a Miocene forest community. A total of 123 dicot leaf specimens were examined and 25 of them showed traces of insect herbivory. Twenty-four damage types were identified and categorized into eight functional feeding groups. These traces indicate that insects interacted with these plants for various purposes, including feeding, sheltering and egg laying. To survey the responses of plant–insect interactions to climate conditions, the data on insect damage frequency and temperature variables from the Toupi assemblage and four other assemblages (from the middle Miocene to the early Pleistocene) from China were analyzed based on a linear stepwise regression analysis. The analysis suggests that there is a significant positive correlation between the damage frequency and the coldest month (mean) temperature (CMT) (R2 = 0.709 and P = .047). The present result provides additional support for the hypothesis that the CMT, rather than the mean annual temperature, could be one of the factors influencing the frequency of damage in paleoflora communities. When compared to the four other assemblages, the Toupi assemblage has the lowest damage frequency which could be due to the lowest CMT. It is possible that a low CMT could result in a low insect metabolic rate per unit area and unit time, leading to a low frequency of insect attack and a low herbivory rate.

Several three-dimensionally preserved Pious female cones from the upper Miocene Shengxian Formation of Zhejiang Province, eastern China, were identified as two fossil species, Pinus preyunnanensis X.H. Xu and B.N. Sun sp. nov. and Pinus prekesiya Xing, Liu and Zhou. Morphologically, comparisons of P. preyunnanensis sp. nov. with previously published Cenozoic cones and related extant pine cones reveal that the present specimens differ from all of them. The new species has the closest affinity with the extant Pious yunnanensis. The occurrence of P. preyunnanensis sp. nov. and P. prekesiya from the upper Miocene in Zhejiang, eastern China, indicates that 1) P. yunnanensis and Pinus kesiya (or their ancestral taxa) had a wider distribution during the late Miocene compared to the present; 2) P. yunnanensis and P. kesiya (or their ancestral taxa) disappeared from eastern China probably because of the prominent declining cold month mean temperature from the Miocene to the present; and 3) the differentiation of P. yunnanensis and P. kesiya can be traced back in eastern China to at least the late Miocene. (C) 2015 Elsevier B.V. All rights reserved.

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.