The ash trees (Fraxinus, Oleaceae) are widely distributed in the Northern Hemisphere and have a rich fossil record, mainly based on samaras and leaves. In contrast, fossil wood attributable to Fraxinus is rare, particularly in East Asia. Here we describe two silicified wood specimens collected from the Early Miocene Xiacaowan Formation in Sihong County, Jiangsu Province, eastern China. The fossil wood is characterized by distinct growth rings, ring-porous wood, solitary earlywood vessels arranged in tangential bands, predominantly alternate intervessel pitting, vasicentric to locally confluent axial parenchyma, and heterocellular multiseriate rays 2-6 cells wide. These anatomical features are consistent with the wood anatomy of extant genus Fraxinus and support assignment to the fossil genus Fraxinoxylon. A new species, Fraxinoxylon sihongense sp. nov., is established based on a unique combination of diagnostic characters. This discovery represents the first record of Fraxinoxylon from Jiangsu Province and the second confirmed fossil wood of Fraxinus affinity reported from China. The occurrence of Fraxinoxylon sihongense in the Xiacaowan Formation confirms the presence of ash trees in eastern China during the Early Miocene. This finding extends the palaeogeographic range of Fraxinus in East Asia and suggests that it was an important component of warm, seasonally humid forests in this region. Our study highlights the significance of fossil wood for reconstructing the evolutionary history and palaeobiogeography of Fraxinus.

BACKGROUND AND AIMS:Royal ferns (Osmundales) are a family of leptosporangiate ferns, which today are limited to six genera in temperate and subtropical climate zones. In the Permian and Triassic, the order was much more diverse and globally distributed. The phylogeographical origins of the crown-group royal ferns have not yet been studied extensively. METHODS:Here, we present a new species of royal fern, Claytosmunda basilica sp. nov., from the Upper Triassic of Antarctica, analysed from thin sections and cellulose acetate peels of fossil rhizomes, and we implement a phylogenetic analysis of the royal ferns based on a morphological character matrix. KEY RESULTS:Claytosmunda basilica sp. nov. has a partly sclerotized pith and a moderately dissected xylem cylinder with prominent leaf gaps. Its two-layered cortex contains several sclerenchyma strands accompanying every leaf trace. Stipe bases show a heterogeneous sclerenchyma cylinder with two lateral masses of thick-walled fibres. Stipular wings contain large masses of sclerenchyma. Especially in its stipe base anatomy, C. basilica is remarkably similar to the extant Claytosmunda claytoniana. It also shares many characteristics with Claytosmunda beardmorensis from the Triassic of Antarctica, although both taxa have a completely different growth form. A close relationship between these three Claytosmunda species is supported by phylogenetic analysis. CONCLUSIONS:Phylogenetic analysis and the comparison of the geographical occurrences of all Permian and Triassic royal fern taxa reveals that crown-group Osmundales originated in the Gondwanan high latitudes, whereas other branches of the royal fern order that originated from tropical to subtropical latitudes went extinct after the Triassic.

In the few available Permian trunk fossils of the Guaireaceae, only the siphonostelic or dictyostelic stem has been preserved, without the petiole base. Thus, the early evolution of the Guaireaceae remains unclear. To better understand the early evolutionary history of this family, additional Palaeozoic trunks with primitive steles are needed. In this study, a new genus and new species of the Guaireaceae, Yangtzepteris songziensis Liu et al. gen. et sp. nov., is erected for a permineralized trunk containing both a protostelic stem and petiole bases from the Permian of Songzi City, Hubei Province, central China. This fossil is the first complete Palaeozoic trunk known from the Guaireaceae. Yangtzepteris is most primitive of the Palaeozoic Guaireaceae genera. This genus is characterized by a large stem, a primitive protostele, and a petiole base without stipular wings; these characters are similar to those of the Rastropteris, which is related to early evolution of the Osmundales. Due to its primitive stele, Yangtzepteris may represent an early stage in the differentiation of the Osmundales. The various osmundalean genera identified from the Permian of South China indicate that the ancient land of Cathaysia was an important region for the early evolution of the family Guaireaceae. Based on the available fossil evidence, we infer that the ancestral group to the Guaireaceae should have a primitive protostele lacking leaf gaps and reniform leaf traces. This putative ancestor may have originated in the Southern Hemisphere in the Early Permian or even the Carboniferous.

A new tree fern of the family Tempskyaceae, Tempskya hailunensis sp. nov., is described herein based on a silicified trunk from the Cretaceous of Hailun City, Heilongjiang Province, Northeast China. The new species is composed of dichotomizing large stems surrounded by a mesh of adventitious roots, petioles, and leaf-like structures, constituting a solid and compact false trunk. The dorsiventral stems contain solenosteles that have long internodes with mostly two leaf traces. The stem cortex consists of a sclerenchymatous outer zone and a parenchymatous inner zone, and the stem pith is divided into a parenchymatous outer zone and a sclerenchymatous inner zone. Wide multicellular scales are attached to the stem epidermis. Leaf-like structures embedded among adventitious roots in the trunk are isobilateral, thick, and without distinct intercellular spaces. Also present are dispersed annuli of sporangia, which are only few cells long and apparently uniseriate. Though it cannot be fully ruled out that these vegetative and fertile remains belong to epiphytes that colonized the Tempskya trunk, the consistent and exclusive occurrence of these particular types of remains makes it likely that they belonged to the Tempskya plant itself. This new species represents only the second fossil record of Tempskya from China, increasing the known diversity of this genus during the Cretaceous both in Asia and globally. Moreover, it provided evidence for recognizing probable leaf structure and growth habit of Tempskya.

Silicified conifer wood assignable to Xenoxylon meisteri from the Upper Cretaceous of northeastern China provides evidence of the presence of wood-degrading fungi and xylophagous arthropods, and also indicates the existence of a relationship between fungi and arthropods. Evidence of arthropod activities occurs in the form of vertical and horizontal borings that are lined on the inside with small coprolites. The borings are much larger (up to 2.4 mm in diameter) than the coprolites (74e127 mm in diameter), suggesting that two different animals, a larger one that made the borings and a smaller one that produced the coprolites, lived in them, either simultaneously or one after another. The wood in the surroundings of the borings contains different types of fungal remains. Especially abundant are slender, septate, and multi-branched hyphae on which thick-walled chlamydospores and other hyphal inflations are formed. Hyphae traversing from one host cell to another usually produce a swelling close to where they enter the cell wall. Decay holes in the infected wood suggest that this fungus was a wood-degrading saprotroph, probably a member of the Ascomycota. The fungus also occurs inside the arthropod borings, where it forms chains of barrel-shaped cells, likely conidia, suggesting that the arthropods may have served as dispersal vectors for the fungus. Xenoxylon meisteri provides the first indication of a tripartite plant-arthropod-fungal association from the Mesozoic of China, and gives new insights into the complex network of organismal relationships that existed in Cretaceous terrestrial ecosystems. (c) 2024 Elsevier Ltd. All rights reserved.

简要报道黑龙江伊春下白垩统裸子植物木化石组合,包括4科8属:柏科柏型木属Cupressinoxylon、落羽杉型木属Taxodioxylon,罗汉松科?叶枝杉型木属Phiyllocladoxylon,松科雪松型木属Cedroxylon、油杉型木属Keteleerioxylon、云杉型木属Piceoxylon,红豆杉科红豆杉型木属Taxaceoxylon和异木属Xenoxylon.其中,松科木化石多样性最高,占据绝对优势.叶枝杉型木属、红豆杉型木属首次在黑龙江地区发现.当前木化石组合是东亚地区发现的类群最为丰富的白垩纪木化石组合之一,丰富了我国白垩纪裸子植物化石记录.木化石记录表明东北地区是早白垩世裸子植物多样性中心和分布中心之一.伊春木化石中非正常生长轮和创伤树脂道的出现反映了短时气候波动、自然灾害或者森林生态系统中植物与伴生生物间相互作用现象.该化石组合的进一步深入研究将为认识东亚现代裸子植物演化发展历史及其古环境、古气候背景提供重要依据.

In the present study, we analyzed seven wooden bows and 13 arrows excavated from the cemeteries of Subeixi Culture (13th century BCE-AD second century) in the Turpan Basin, northwest China. A total of six taxa, viz. Morus sp., Salix sp., Picea sp., Lonicera sp., Betula sp., and Tamarix sp. were identified. Some of these taxa have been generally accepted to be suitable for bow-and-arrow production. All these taxa were local in origin but distributed in different ecotonal zones, including oases, saline-alkali lands, and mountain areas. Previous archaeological studies have confirmed that the Subeixi populations lived an agro-pastoral life. By analyzing the possible provenance of these wood samples, it can be hypothesized that these ancient agro-pastoralists moved between the Turpan Basin and the Tianshan Mountains on a seasonal basis.

Well-preserved Cretaceous trunk fragments of Cycadeoidea(Cycadeoidaceae)were recently found in Keshan County,Heilongjiang Province,Northeast China.These fossils represent important evidence of the distribution of this group of plants in East Asia.In these trunk fragments,the stem cortices and leaf bases with cones are preserved.The leaf bases are rhombic with cones infrequently distributed among leaf bases.The cortex is broad and consists of fundamental parenchyma cells,numerous secretory ducts and C-shaped leaf traces with adaxial secondary xylem and abaxial secondary phloem.The genus Cycadeoidea,which is widely distributed in the Cretaceous deposits of East Asia,North America and Western Europe,was an important component of Cretaceous floras.Bennettitalean trunk fossils with well-preserved anatomical structures are rarely known from China.These fossils are important for studies of the evolution of genus Cycadeoidea and for stratigraphic correlation.

A new species of the Osmundaceae, Plenasium xiei sp. nov., is herein described from the Cretaceous of Northeast China. The specimens examined here represent the earliest unequivocal record of the extant genus Plenasium in Eurasia based on fossil rhizomes. The rhizome consists of a central stem with a mantle of petiole bases and adventitious roots. The stem contains an ectophloic-dictyoxylic siphonostele and a two-layered cortex. The C-shaped leaf trace bears two protoxylem bundles at the point of separation from the stele. The pith is heterogeneous. The parenchymatous inner cortex is thinner than the sclerenchymatous outer cortex. Lobed sclerenchyma bands occur at the adaxial sides of the stem xylem strands, in the concavity of the leaf trace, and along the adaxial side of the vascular bundles of the petiole base. In distal petiole portions, the sclerenchyma band splits into several groups in the transverse view. Sclerenchyma rings are heterogeneous with an abaxial sclerenchymatous arc of thick-walled fibers. Numerous sclerenchyma strands of thick-walled fibers appear in the petiolar inner cortex and the stipular wing. These fossils provide unambiguous evidence for the existence of subgenus Plenasium of modern Plenasium by at least the Late Cretaceous, demonstrating the longevity of this extant subgenus. Altogether the leaf and rhizome fossil records of Plenasium indicate that this genus was widely distributed across North America and Eurasia from the Early Cretaceous to the Early Cenozoic, followed by a range restriction to Eurasia in the Late Cenozoic. Extant Plenasium species are only known from East and Southeast Asia.

The earliest and most primitive fossil trunk or rhizome taxa of the family Osmundaceae, as important evidence for understanding its early evolutionary history, have so far all come from the Permian of the Ural Mountains region of European Russia. In this study, a thamnopteroid rhizome fossil, one of the most primitive members of the Osmundaceae, is reported from the Permian of Heilongjiang Province, Northeast China, based on a permineralized rhizome fragment consisting of the cortex and petiole bases with coprolites. This is the first report of a thamnopteroid rhizome found outside the Ural Mountains region since the previous thamnopteroid rhizome was described more than 90 years ago. Still, all known thamnopteroid trunks and rhizomes, i.e., from the Ural Mountains region and Heilongjiang Province, occurred within the realm of the Angara flora during the Permian. The fossil records suggest that the Angaraland is perhaps the cradle for the early diversification of the Osmundaceae (first family of Osmundales), while the Cathaysia is an important region for the early diversification of the Guaireaceae (another family of Osmundales). The fossil studied herein is the most primitive and earliest record of the Osmundaceae in Asia. For the Mesozoic of Asia, four genera of trunks and rhizomes of Osmundaceae have been found in the Jurassic and Cretaceous of Northeast China and the Cretaceous of the Rajmahal Hills of India. The new fossil serves as crucial evidence for the diversification of the Osmundaceae in Asia from the Paleozoic. The occurrence of coprolites in the parenchyma of the petiole base indicates that Osmundaceae rhizomes were favorable hosts for arthropods and provided a suitable environment for their parasitism

A new record of Cretaceous platanaceous wood, Platanoxylon sp., is described from Keshan, Heilongjiang Province, Northeast China. The features indicating it belongs to Platanoxylon include: growth rings distinct, wood diffuse-porous, vessels numerous, solitary and in short radial or tangential multiples, perforation plates exclusively scalariform, intervessel pits opposite, elliptical, horizontally elongated, vessel-ray pits similar to intervessel pits, some fibers with distinctly bordered pits, axial parenchyma diffuse, rays mostly large homocellular multiseriate, rarely uniseriate, and crystals often in ray cells. Fossil platanaceous woods are common in the Northern Hemisphere. Yet, Plalanoxylon sp. is China's first report of fossil Platanaceae wood. It is also China's first record of Cretaceous angiosperm wood. This wood and compression floras indicate that the Platanaceae were in northern China from the Late Cretaceous to the Eocene.

The fossil trunks and rhizomes of Osmundaceae provide important information about its evolutionary history. Due to limited records of the Mesozoic trunks and rhizomes in the Eurasia of the Northern Hemisphere, our understanding on the fossil diversity of the Osmundaceae is hindered. Two new species of the Osmundaceae trunks, Osmundacaulis asiatica sp. nov. and Osmundacaulis sinica sp. nov. representing the first discovery of the Mesozoic tree fern genus Osmundacaulis in Eurasia, are described from Wudalianchi and Qiqihar, Heilongjiang Province, Northeast China, which enriches the plant diversity of the Osmundaceae in the Eurasia, and provides vital evidence for studying the distribution, radiation and evolution of the genus during the Cretaceous. The fossil records suggest that Osmundacaulis species may have evolved from a common ancestor, which first appeared in the Australian portion of Pangaea, and then spread to ancient northern North America and ancient East Asia. Since then, they developed into different species through their own evolutionary lines. The Chinese species have a special local feature that the outer cortex is thicker than the inner cortex, in contrast with reported Osmundacaulis species having thinner outer cortex and thicker inner cortex. Long-term geographic isolation may have led to the radiation of diverse Osmundacaulis species and the appearance of region-specific features, such as the thick outer cortex and the thin inner cortex of the Chinese species. Among all reported Osmundacaulis species, the two new species found in China, O. nerii from the Jurassic of Australia and the O. lemonii from the Jurassic of the USA, have special groups of mucilage-sacs inside sclerenchyma ring of petiole base. Mucilage sacs probably originated independently among taxonomic groups, representing convergent adaptations to similar habitats, rather than indicating genetic inheritance from a common ancestor.

我国东北地区是北半球少有的中生代紫萁科茎干化石产地之一.该地区出产的茎干化石为研究中生代紫萁科的演化历史提供了重要证据.我国过去报道的紫萁科茎干化石来自东北地区的侏罗系.近期在东北松辽盆地北部白垩系发现了紫萁科茎干化石,为认识紫萁科在中生代晚期的演化发展过程提供了不可或缺的证据.本研究报道了在黑龙江省五大连池市和平镇发现的白垩纪紫萁科叶柄基化石.横切面上看叶柄基以茎缺失的位置为中心螺旋状排列,较为紧密.维管束木质部呈深凹的C形,末端向内弯曲.维管束凹陷处有薄的C形、边缘呈波纹状的厚壁组织带.C形维管束与厚壁组织带之间分布着薄壁细胞组成的粘液囊.内皮层中分布着不规则排列的若干厚壁组织束.近轴端叶柄基托叶翼中分布有2个较大和若干小的厚壁组织束;大的厚壁组织束呈水滴形.随着叶柄基由近轴端向远轴端的延伸,维管束近轴面凹陷处的厚壁组织带长度增长,粘液囊数量增加;托叶翼中厚壁组织束数量相应增加,除了两个大的厚壁组织束外,它们附近增加了若干大小不等的厚壁组织束和单个厚壁纤维细胞.当前化石是我国第一个白垩纪保存解剖结构的紫萁科化石记录.其结构特征与灭绝的Osmundacaulis和现存的Plenasium的叶柄基比较相似,可能代表了白垩纪以上两属的成员之一.由于目前欧亚大陆白垩纪还未见Osmundacaulis和Plenasium的茎干化石记录,当前化石的发现丰富了欧亚大陆白垩纪紫萁科植物的多样性.

A new Cretaceous tree fern species from the family Tempskyaceae, Tempskya zhangii sp. nov., from Keshan County, Heilongjiang Province, Northeast China, is described based on silicified fragments. The species is characterized by dichotomizing stems embedded in a matrix of adventitious roots, together forming a solid and compact false trunk. The dorsiventral stems are composed of solenosteles, and their internodes are short with 2-3 (rarely 4) leaf traces. A three-layered cortex includes a sclerenchymatous outer zone, parenchymatous middle zone, and an inner zone composed of sclerenchyma band and parenchyma cells. The pith consists of a parenchymatous outer zone and sclerenchymatous inner zone. The petiole has a single C- or U-shaped vascular strand. The adventitious root has diarch xylem surrounded by an inner sclerenchymatous and an outer parenchymatous cortex. In possessing these characters, T. zhangii is more similar to T. wyomingensis from the Cretaceous of North America than to other species of Tempskya. However, the Chinese species distinctly differs from T. wyomingensis in having a sclerenchymatous outer cortex, parenchymatous middle cortex, and sparse parenchyma in the xylem. It is the first record of Ternpskya from China and the fourth from Asia. This species, together with Cyatheaceae, Osmundaceae, Cycadeoidaceae, and conifers found in the same region constituted the plant community at the time. (C) 2017 Elsevier Ltd. All rights reserved.

We describe a new species, Gleditsioxylon jiangsuensis (Leguminosae), a new record of Robinia zirkelii (Platen) Matten, Gastaldo & Lee (Leguminosae), and a new record of Moroxylon xinhuaensis Yin, Liu & Cheng (Moraceae) from the early Miocene strata of Sihong County in Jiangsu Province, eastern China. Gleditsioxylon jiangsuensis sp. nov. is the first report of Gleditsioxylon fossil wood from China. These fossil woods, combined with paleontological records, may indicate that the boundary between the subtropical and the temperate zones in eastern China during the early Miocene was located north of its modern location.

ABSTRACT The Pliocene fluvio-lacustrine sediments of the Yuanmou Basin, Yunnan, near the southeastern part of Qinghai-Tibet Plateau, China, have yielded diverse and abundant assemblages of fossilized mammals and woods. The Yuanmou fossil woods reveal a wood flora with the highest diversity in the Cenozoic wood in China. The woods can play an important role in understanding palaeofloristics and in reconstructing palaeoclimate of southeastern China. In this study, we describe ten angiosperm taxa and three gymnosperm taxa namely: Castanopsis makinoi (Ogura) Suzuki & Terada (Fagaceae), Cedreloxylon cristalliferum Selmeier (Meliaceae), Dalbergioxylon biseriatensis sp. nov. (Fabaceae), Lagerstroemioxylon yuanmouensis Cheng, Li, Jiang & Wang (Lythraceae), Lithocarpoxylon microporosum sp. nov., Lithocarpoxylon sp. (Fagaceae), Paraalbizioxylon sinica sp. nov., P. yunnanensis sp. nov. (Fabaceae), Pterocaryoxylon huxii sp. nov. (Juglandaceae), Zelkova wakimizui (Watari) Watari (Ulmaceae), Abies sp. (Pinaceae), Cephalotaxus sp. (Cephalotaxaceae), and Picea sp. (Pinaceae). Nearest living relative (NLR) comparisons of these taxa, coupled with previously identified taxa, suggest that altitudinal vegetation zones were present in the Yuanmou region during the Pliocene: (i) subtropical evergreen and deciduous mixed broad-leaved forest dominated by Pterocarya/Juglans, Albizia/Acacia, Bischofia and allied taxa at lower elevations, (ii) subtropical evergreen broad-leaved forest dominated by Quercus/Lithocarpus and Castanopsis at middle altitudes of mountains around the basin, and (iii) evergreen coniferous forest of Abies, Picea and other genera at the higher elevations of the mountains. Based on the habits of the NLRs, the prevailing climate was probably humid subtropical and thus differed from the present-day hot and dry climate supporting savanna. It is suggested that subtropical forest was predominant in Yunnan, while tropical rainforest occurred in southwest Asia and India during the same period. The uplift of the mountains near the Qinghai-Tibet plateau in western Yunnan presumably acted as a barrier to block warm and humid air from the Indian Ocean, which influenced the dispersal and distribution of plants.

A new genus and species of Cretaceous Cyatheacean tree fern, Heilongjiangcaulis keshanensis gen. et sp. nov., is erected for several permineralized stems collected at the Keshan County in Songliao Basin, Heilongjiang Province, Northeast China. The new taxon is characterized by a dictyostelic, erect stem with dense multicellular scales and surrounded by persistent petiole bases and adventitious roots. The stem contains a central pith lacking medullary bundles, which is surrounded by a dictyostele, and the cortex externally. Each meristele of the dictyostelic ring is enclosed by a sclerenchyma sheath. The pith and cortex are parenchymatous. The proximal petiole bases present a frond trace composed of numerous meristeles, arranged in 1 abaxial and 2 adaxial arcs, with internally projecting bundles on the upper and lateral sides. The feature combination of the new genus is nearly identical to the anatomical structures of modern scaly genera of the Cyatheaceae apart from the absence of medullary bundles. It is interpreted as a primitive representative of early Cyatheaceae, that closely resembles the modern scaly genera, which suggests that in the Cretaceous, the tree ferns in this family were already in possession of most of the anatomical characteristics observed in extant taxa. The fossil records of the stems, petioles, and spores indicate that during the Jurassic and Cretaceous, the Northeastern region of Asia may have been one of the distribution centers of early Cyatheaceae.

Songliao Basin is one of the largest,thickest and best preserved Cretaceous continental sedimentary basins in China.Palynological studies show that Cyathidites spores are common in the Cretaceous strata in the basin.As Cyatheaceae and Dicksoniaceae are spread in common by means of Cyathidites spores,the discovery of the Cyathidites spores is still considered to be an ambiguous evidence for the existence of Cyatheaceae plants,which hinders further precise analysis of paleoenvironment and paleoclimate in the basin.A series of Cretaceous Cyatheaceae stem fossils,found from Keshan County,Qiqihar City,Heilongjiang Province,provide solid evidence for the presence of Cyatheaceae tree fern in the Songliao Basin.The studied fossils are permineralized stem fragments of Cyatheaceae tree fern,and each piece consists of pith,dictyostele and cortex.Each meristele is S-,U-or W-shaped in transverse section,enclosed by a sclerenchyma sheath.Margins of the meristeles of the main dictyostelic ring curve deeply toward cortex or pith at the distal end of each leaf gap.Pith and cortex are parenchymatous,in which medullary bundles and roots are abundant.Wound tissues often occur in pith.This specimen is the first fossil record of Cyatheaceae trunk found in China,which suggests that ancestor taxa of the extant Cyatheaceae tree fern now living in tropical or subtropical region used to grow near Keshan County in northern Songliao Basin in Cretaceous.The present fossils and their associated petrified fossils of Tempskya and Bennettitales,may indicate that the paleoclimate there might have been tropical or subtropical.

A well preserved big Cycadeoidea (Cycadeoidaceae, Bennettitales) fossil trunk has recently been found from the Cretaceous strata in Darhan Muminggan Joint Banner, Baotou City, Inner Mongolia. The trunk in columnar shape measures 56cm in height and 48cm in maximum diameter. It consists of central pith, peripheral xylem cylinder, petiole bases and cones from the central part to the outside. The dense rhombic bases of the petiole are helically arranged on the surface of the trunk. The petiole bases decrease in size from the base to the apex of the trunk, with cones unevenly scattered in between. This specimen is the first complete fossil trunk of Cycadeoidea found in China. The fossil wood of Xenoxylon latiporosum (Cramer) Gothan (Gymnosperm) is recognized near the fossil trunk. The trunk and other fossil woods are important materials for studying the evolution of Cycadeoidea and the composition of Cretaceous flora in northern China.