Giant cladoxylopsid trees resolve the enigma of the Earth's earliest forest stumps at Gilboa

The evolution of trees of modern size growing together in forests fundamentally changed terrestrial ecosystems. The oldest trees are often thought to be of latest Devonian age (about 380-360 Myr old) as indicated by the widespread occurrence of Archaeopteris (Progymnospermopsida). Late Middle Devonian fossil tree stumps, rooted and still in life position, discovered in the 1870s from Gilboa, New York, and later named Eospermatopteris, are widely cited as evidence of the Earth's 'oldest forest'. However, their affinities and significance have proved to be elusive because the aerial portion of the plant has been unknown until now. Here we report spectacular specimens from Schoharie County, New York, showing an intact crown belonging to the cladoxylopsid Wattieza (Pseudosporochnales) and its attachment to Eospermatopteris trunk and base. This evidence allows the reconstruction of a tall (at least 8 m), tree-fern-like plant with a trunk bearing large branches in longitudinal ranks. The branches were probably abscised as frond-like modules. Lower portions of the trunk show longitudinal carbonaceous strands typical of Eospermatopteris, and a flat bottom with many small anchoring roots. These specimens provide new insight into Earth's earliest trees and forest ecosystems. The tree-fern-like morphology described here is the oldest example so far of an evolutionarily recurrent arborescent body plan within vascular plants. Given their modular construction, these plants probably produced abundant litter, indicating the potential for significant terrestrial carbon accumulation and a detritus-based arthropod fauna by the Middle Devonian period.     

Large Cretaceous sphenodontian from Patagonia provides insight into lepidosaur evolution in Gondwana

Sphenodontian reptiles successfully radiated during Triassic and Jurassic times, but were driven almost to extinction during the Cretaceous period. The sparse Early Cretaceous record of sphenodontians has been interpreted as reflecting the decline of the group in favour of lizards, their suspected ecological successors. However, recent discoveries in Late Cretaceous beds in Patagonia partially modify this interpretation. Numerous skeletons of a new sphenodontian, Priosphenodon avelasi gen. et sp. nov., were collected from a single locality in the Cenomanian-Turonian Candeleros Formation, where it is more abundant than any other tetrapod group recorded in the quarry (for example, Crocodyliformes, Serpentes, Dinosauria and Mammalia). Adult specimens of Priosphenodon reached one metre in length, larger than any previously known terrestrial sphenodontian. Here we propose, using available evidence, that sphenodontians were not a minor component of the Cretaceous terrestrial ecosystems of South America, and that their ecological replacement by squamates was delayed until the early Tertiary. The new discovery helps to bridge the considerable gap in the fossil record (around 120 million years) that separates the Early Cretaceous sphenodontians from their living relatives (Sphenodon).     

古生代植物与昆虫相互作用的化石证据——探秘深时陆地生态系统的窗口

 植物与昆虫是当今陆地生态系统的重要组成部分,两者之间的相互关系为认识陆地生态系统结构和功能提供独一无二的信息。古生代是植物和昆虫起源和早期演化的关键地质时期,然而由于缺乏对该时期化石材料的系统研究,植物和昆虫之间的相互关系及其协同演化过程还存在许多未解之谜。对二叠纪晚期（约2.53亿年前）植物茎干中甲虫蛀孔的详细解剖学研究,证实当时蛀木甲虫利用真菌实现个体发育过程中食性的转变,而且蛀木甲虫可能存在初步的社会分工,并生活在复杂的生态网络中;进一步研究显示晚二叠世蛀木甲虫或对松柏类植物引起严重的虫灾。当前研究表明,渗矿化植物化石标本在探索地质历史时期动植物相互作用方面具有巨大研究潜力,可为深时陆地生态系统的重建和演化提供宝贵信息。     

Ferns diversified in the shadow of angiosperms

The rise of angiosperms during the Cretaceous period is often portrayed as coincident with a dramatic drop in the diversity and abundance of many seed-free vascular plant lineages, including ferns. This has led to the widespread belief that ferns, once a principal component of terrestrial ecosystems, succumbed to the ecological predominance of angiosperms and are mostly evolutionary holdovers from the late Palaeozoic/early Mesozoic era. The first appearance of many modern fern genera in the early Tertiary fossil record implies another evolutionary scenario; that is, that the majority of living ferns resulted from a more recent diversification. But a full understanding of trends in fern diversification and evolution using only palaeobotanical evidence is hindered by the poor taxonomic resolution of the fern fossil record in the Cretaceous. Here we report divergence time estimates for ferns and angiosperms based on molecular data, with constraints from a reassessment of the fossil record. We show that polypod ferns (> 80% of living fern species) diversified in the Cretaceous, after angiosperms, suggesting perhaps an ecological opportunistic response to the diversification of angiosperms, as angiosperms came to dominate terrestrial ecosystems.     

CO2 and the end-Triassic mass extinction.

The end of the Triassic period was marked by one of the largest and most enigmatic mass-extinction events in Earth's history and, with few reliable marine geochemical records, terrestrial sediments offer an important means of deciphering environmental changes at this time. Tanner et al. describe an isotopic study of Mesozoic fossil soils which suggests that the atmospheric concentration of carbon dioxide (pCO2) across the Triassic-Jurassic boundary was relatively constant (within 250 p.p.m.v.), but this is inconsistent with high-resolution evidence from the stomatal characters of fossil leaves. Here I show that the temporal resolution of the fossil-soil samples may have been inadequate for detecting a transient rise in pCO2. I also show that the fossil-soil data are consistent with a large increase in pCO2 across the Triassic-Jurassic boundary when variations in the stable carbon isotope (denoted as delta13C) in terrestrial plant leaves are taken into account. These factors suggest that the linkage between pCO2, global warming and the end-Triassic mass extinction remains intact.     

A Silurian sea spider

Pycnogonids (sea spiders) are marine arthropods numbering some 1,160 extant species. They are globally distributed in depths of up to 6,000 metres, and locally abundant; however, their typically delicate form and non-biomineralized cuticle has resulted in an extremely sparse fossil record that is not accepted universally. There are two opposing views of their phylogenetic position: either within Chelicerata as sister group to the euchelicerates, or as a sister taxon to all other euarthropods. The Silurian Herefordshire Konservat-Lagerstatte in England (approximately 425 million years (Myr) bp) yields exceptionally preserved three-dimensional fossils that provide unrivalled insights into the palaeobiology of a variety of invertebrates. The fossils are preserved as calcitic void in-fills in carbonate concretions within a volcaniclastic horizon, and are reconstructed digitally. Here we describe a new pycnogonid from this deposit, which is the oldest adult sea spider by approximately 35 Myr and the most completely known fossil species. The large chelate first appendage is consistent with a chelicerate affinity for the pycnogonids. Cladistic analyses place the new species near the base of the pycnogonid crown group, implying that the latter had arisen by the Silurian period.     

Silurian brachiopods with soft-tissue preservation

'Articulated' rhynchonelliformean brachiopods are abundant shelly fossils, but the direct fossil record of their soft parts was hitherto confined to a single pyritized trace possibly representing a lophophore. Anatomical knowledge of extinct rhynchonelliformeans relies heavily on analogies to extant species; these analogies are untested for stem-group clades. The Silurian Herefordshire (UK) Konservat-Lagerst?tte (about 425 Myr bp) yields exceptionally preserved three-dimensional fossils that provide unrivalled insights into the palaeobiology of a variety of invertebrates. The fossils are preserved as calcitic void in-fills in carbonate concretions within a volcaniclastic horizon, and are reconstructed digitally. Here we describe a stem-group rhynchonelliformean specimen from this deposit; it most probably belongs in the order Orthida. A robust ridged pedicle with distal rootlets is preserved, together with a lophophore and other soft-tissue structures. The pedicle morphology is novel, urging caution in inferring stem-group rhynchonelliformean anatomy from that of crown-group species. Smaller brachiopods are attached to the specimen; these include a probable atrypide, with pedicle and marginal setae preserved.     

A microworld in Triassic amber

Amber provides an effective medium for conservation of soft-bodied microorganisms, but finds older than 135 million years are very rare and have not so far contained any microbial inclusions. Here we describe 220-million-year-old droplets of amber containing bacteria, fungi, algae and protozoans that are assignable to extant genera. These inclusions provide insight into the evolution and palaeoecology of Lower Mesozoic microorganisms: it seems that the basal levels of food webs of terrestrial communities (biocoenoses) have undergone little or no morphological change from the Triassic to the Recent.     

AMF对间套作体系中植物-土壤-微生物相互作用的影响及机制

丛枝菌根真菌（AMF）能与自然环境中的多数陆生植物互利共生。间套作种植作为增加农田生态系统生物多样性的重要措施，能显著提高植物对农田环境中多种资源的利用率。在间套作体系中，AMF通过对农作物和土壤环境的影响，提高农田生态系统的经济产量并促进其可持续发展。本文从AMF对宿主植物根系特征的影响、AMF对宿主植物根际微生物群落结构功能的影响、AMF在改善土壤结构提高土壤肥力方面的作用、菌根植物间共生菌丝网络的养分资源传递分配等方面，阐述AMF对间套作体系中植物-土壤-微生物相互作用的影响及其机制，为AMF在农业方面的进一步应用提供理论基础。     

Endangered plants persist under phosphorus limitation

Nitrogen enrichment is widely thought to be responsible for the loss of plant species from temperate terrestrial ecosystems. This view is based on field surveys and controlled experiments showing that species richness correlates negatively with high productivity and nitrogen enrichment. However, as the type of nutrient limitation has never been examined on a large geographical scale the causality of these relationships is uncertain. We investigated species richness in herbaceous terrestrial ecosystems, sampled along a transect through temperate Eurasia that represented a gradient of declining levels of atmospheric nitrogen deposition--from approximately 50 kg ha(-1) yr(-1) in western Europe to natural background values of less than 5 kg ha(-1) yr(-1) in Siberia. Here we show that many more endangered plant species persist under phosphorus-limited than under nitrogen-limited conditions, and we conclude that enhanced phosphorus is more likely to be the cause of species loss than nitrogen enrichment. Our results highlight the need for a better understanding of the mechanisms of phosphorus enrichment, and for a stronger focus on conservation management to reduce phosphorus availability.     

New light shed on the oldest insect

Insects are the most diverse lineage of all life in numbers of species, and ecologically they dominate terrestrial ecosystems. However, how and when this immense radiation of animals originated is unclear. Only a few fossils provide insight into the earliest stages of insect evolution, and among them are specimens in chert from Rhynie, Scotland's Old Red Sandstone (Pragian; about 396-407 million years ago), which is only slightly younger than formations harbouring the earliest terrestrial faunas. The most well-known animal from Rhynie is the springtail Rhyniella praecursor (Entognatha; Collembola), long considered to be the oldest hexapod. For true insects (Ectognatha), the oldest records are two apparent wingless insects from later in the Devonian period of North America. Here we show, however, that a fragmentary fossil from Rhynie, Rhyniognatha hirsti, is not only the earliest true insect but may be relatively derived within basal Ectognatha. In fact, Rhyniognatha has derived characters shared with winged insects, suggesting that the origin of wings may have been earlier than previously believed. Regardless, Rhyniognatha indicates that insects originated in the Silurian period and were members of some of the earliest terrestrial faunas.     

The discovery of Jurassic plants in Shenzhen of Guangdong,southern China and related significance

Investigations of major marine and non-marine geologic and biotic events across the Triassic-Jurassic transition rely predominantly on detailed stratigraphic frameworks and biodiversity analyses. The alternating sequences of marine and terrestrial Triassic-Jurassic for- mations in Guangdong Province represent one of the most remarkable coal-bearing series in southern China. The Lower Jurassic Jinji Formation is widely distributed in Guangdong, with continuously outcropped sections and rich marine and non-marine fossil fauna. However, as little research has been conducted on fossil plant remains in the Jinji Formation, it is difficult to understand the systematics, diversity, and floral aspects of the Jurassic. Here we report on the recent collection of rich fossil plants from the Jinji Formation in the Dapeng area of Shenzhen, southern Guangdong Province. Our studies demonstrate taxonomical affiliations, preservation status, and diversity features of these plant fossils, which are marked by the close associ- ation of densely preserved, pinnae and rachis connected leaves, and the bennettitalean reproductive organs of Wil- liamsoniella, which may represent an Early Jurassic plant community dominated by Otozamites of the bennettitales. This work not only represents the first discovery of fossil plants in the Shenzhen area, but is also the first docu- mentation of Jurassic plants in Guangdong and the Pearl River Delta regions. Research related to these plant fossils will be helpful in the correlation of the Early Mesozoiccoal-bearing strata in Guangdong, and will provide a dee- per understanding of variations in plant diversity of the Triassic and Jurassic transition in southern China. Addi- tionally, it will provide terrestrial plant evidence for explorations in Jurassic palaeoecology, palaeoclimatology, and palaeogeography of southern China.     

基于并行电法的重阳木根系空间分布探测试验研究

探测树木根系的空间分布,对了解树木的生长及移栽等具有重要的作用。利用并行电法技术进行树木根系三维空间分布特征探测试验,通过在重阳木周边7.5 m×9.5 m范围内布置观测系统进行数据采集,对采集到的数据进行多测线联合反演得到三维电阻率图像。结果表明:探测范围内的根系分布呈现出南测密集,北侧稀少的特征;探测区域根系根径范围主要分布在200~300 mm;深度为0.46 m位置处根系量最大且根系生物量最多;重阳木根系下方土壤中含水充足,结果图呈现了根系与地下环境间的相互关系。该成果在研究树木根系空间分布范围及特征方面具有良好的应用前景。     

Use-wear analysis confirms the use of Palaeolithic bone tools by the Lingjing Xuchang early human

During 2007–2008 excavations at the Lingjing site near Xuchang, Henan Province, dated back to around 100–80 ka ago, a large quantity of mammalian fossil remains were recovered along with a remarkable cluster of Early Modern Human (EMH) skull fragments in situ. Observably some of those animal bones were probably modified into tools. A use-wear analysis was carried out to examine the functions of modified bone tools. The results suggest that Lingjing bone tools were used for drilling, penetrating, and scraping animal substances, and that some might have been hafted during the use. This study confirms that early existence of intentionally-modified bone tools at human occupations of the early Late Pleistocene in northern China. This discovery suggests making and use of bone tools were inevitably a part of early human behaviors and cultural development, as such of stone tools.     

Two new carnivores from an unusual late Tertiary forest biota in eastern North America

Late Cenozoic terrestrial fossil records of North America are biased by a predominance of mid-latitude deposits, mostly in the western half of the continent. Consequently, the biological history of eastern North America, including the eastern deciduous forest, remains largely hidden. Unfortunately, vertebrate fossil sites from this vast region are rare, and few pertain to the critically important late Tertiary period, during which intensified global climatic changes took place. Moreover, strong phylogenetic affinities between the flora of eastern North America and eastern Asia clearly demonstrate formerly contiguous connections, but disparity among shared genera (eastern Asia-eastern North America disjunction) implies significant periods of separation since at least the Miocene epoch. Lacustrine sediments deposited within a former sinkhole in the southern Appalachian Mountains provide a rare example of a late Miocene to early Pliocene terrestrial biota from a forested ecosystem. Here we show that the vertebrate remains contained within this deposit represent a unique combination of North American and Eurasian taxa. A new genus and species of the red (lesser) panda (Pristinailurus bristoli), the earliest and most primitive so far known, was recovered. Also among the fauna are a new species of Eurasian badger (Arctomeles dimolodontus) and the largest concentration of fossil tapirs ever recorded. Cladistical analyses of the two new carnivores strongly suggest immigration events that were earlier than and distinct from previous records, and that the close faunal affinities between eastern North America and eastern Asia in the late Tertiary period are consistent with the contemporaneous botanical record.     

Doubling the estimate of invertebrate biomass in a rainforest canopy

Forest canopies represent the functional interface between 90% of the Earth's terrestrial biomass and the atmosphere and include some of the most threatened of all terrestrial ecosystems. However, we lack even a basic understanding of how the biomass of plants and animals is distributed throughout forest canopies, even though this information is vital for estimating energy flow, carbon cycling, resource use and the transfer of materials within this ecosystem. Here we measure the biomass of invertebrates living in a common rainforest epiphyte, describe a striking relationship between fern size and the biomass of animals within the ferns, and reveal that one large epiphyte may contain an invertebrate biomass similar to that found in the whole of the rest of the tree crown on which it is growing. Using these data, we show that including the fauna of these epiphytes--a neglected component in rainforest ecosystems--can more than double our estimate of the total invertebrate biomass in an entire rainforest canopy.     

An early tetrapod from 'Romer's Gap'

The fossil record of early tetrapods has been increased recently by new finds from the Devonian period and mid-late Early Carboniferous period. Despite this, understanding of tetrapod evolution has been hampered by a 20-million-year gap ('Romer's Gap') that covers the crucial, early period when many key features of terrestrial tetrapods were acquired. Here I describe the only articulated skeleton of a tetrapod, Pederpes, yet found from the Tournaisian epoch (354-344 million years ago (Myr)). The new taxon includes a pes with five robust digits, but a very small, possibly supernumerary digit preserved on the manus suggests the presence of polydactyly. Polydactylous early tetrapods may have survived beyond the end of the Devonian and pentadactyly cannot be assumed for the pes. However, the pes has characteristics that distinguish it from the paddle-like feet of the Devonian forms and resembles the feet of later, more terrestrially adapted Carboniferous forms. Pederpes is the earliest-known tetrapod to show the beginnings of terrestrial locomotion and was at least functionally pentadactyl. With its later American sister-genus, Whatcheeria, it represents the next most primitive tetrapod clade after those of the Late Devonian, bridging the temporal, morphological and phylogenetic gaps that have hitherto separated Late Devonian and mid-Carboniferous tetrapod faunas.     

Effect of climate change relative to ozone depletion on UV exposure in subarctic lakes

The effect of stratospheric ozone depletion on increases in ambient levels of solar ultraviolet (UV) radiation in high-latitude regions' has raised concerns about the response of northern ecosystems to environmental change. The concentration of coloured dissolved organic material, which is derived from terrestrial vegetation and acts as a screen for ultraviolet radiation, is low in high-latitude lakes. The underwater light environment in these lakes is therefore likely to be sensitive to small variations in the supply of this material, in addition to the effects of ozone depletion. Here we use fossil diatom assemblages in combination with bio-optical models to estimate the magnitude of past variations in the underwater light regime of a lake at the boreal tree line. We find large shifts in underwater UV-B, UV-A and photosynthetically available radiation associated with changes in the input of coloured dissolved organic material into subarctic lakes during the Holocene. The inferred changes in biological exposure to UV radiation were at least two orders of magnitude greater than those associated with moderate (30%) ozone depletion. Our findings indicate that freshwater ecosystems at present located across vegetation gradients will experience significant shifts in underwater spectral irradiance through the effects of climate change on catchment vegetation and the export of coloured dissolved organic material.     

Anthropology: the earliest toothless hominin skull

The site of Dmanisi in the Eurasian republic of Georgia has yielded striking hominin, faunal and archaeological material as evidence for the presence of early Homo outside Africa 1.77 million years ago, documenting an important episode in human evolution. Here we describe a beautifully preserved skull and jawbone from a Dmanisi hominin of this period who had lost all but one tooth several years before death. This specimen not only represents the earliest case of severe masticatory impairment in the hominin fossil record to be discovered so far, but also raises questions about alternative subsistence strategies in early Homo.     

Earliest evidence for efficient oral processing in a terrestrial herbivore

Herbivores can increase their digestion rate by mechanically reducing particle size through oral trituration. Groups of terrestrial vertebrates with the greatest capacity to reduce tough plant foods orally are also the most abundant and diverse, as exemplified by ornithopod dinosaurs during the Mesozoic and extant artiodactyl and perissodactyl mammals. Thus, the effective oral processing of high-fibre plant material seems to represent an evolutionary innovation of both functional and macroevolutionary significance. However, evidence for oral processing is poorly documented in the fossil record, especially during the initial stages of terrestrial vertebrate diversification. Here we report on the basal anomodont Suminia getmanovi, the only known Palaeozoic vertebrate in which unequivocal specializations in its cranium and teeth for high-fibre herbivory are well preserved. We propose that the capacity to comminute tough plant foods was critical to the diversification of anomodonts, the most diverse, widely dispersed and abundant group of Palaeozoic terrestrial vertebrates, and to the onset of modern terrestrial ecosystems.