Sponge grade body fossil with cellular resolution dating 60 Myr before the Cambrian

An extraordinarily well preserved, 600-million-year (Myr)-old, three-dimensionally phosphatized fossil displaying multiple independent characters of modern adult sponges has been analyzed by SEM and synchrotron X-ray tomography. The fossilized animal (Eocyathispongia qiania gen. et sp. nov.) is slightly more than 1.2 mm wide and 1.1 mm tall, is composed of hundreds of thousands of cells, and has a gross structure consisting of three adjacent hollow tubes sharing a common base. The main tube is crowned with a large open funnel, and the others end in osculum-like openings to the exterior. The external surface is densely covered with flat tile-like cells closely resembling sponge pinacocytes, and this layer is punctuated with smaller pores. A dense patch of external structures that display the form of a lawn of sponge papillae has also survived. Within the main funnel, an area where features of the inner surface are preserved displays a regular pattern of uniform pits. Many of them are surrounded individually by distinct collars, mounted in a supporting reticulum. The possibility cannot be excluded that these pits are the remains of a field of choanocytes. The character set evinced by this specimen, ranging from general anatomy to cell type, uniquely indicates that this specimen is a fossil of probable poriferan affinity. So far, we have only this single specimen, and although its organized and complex cellular structure precludes any reasonable interpretation that its origin is abiogenic, confirmation that it is indeed a fossilized sponge will clearly require discovery of additional specimens

Decimetre-scale multicellular eukaryotes from the 1.56-billion-year-old Gaoyuzhuang Formation in North China

Fossils of macroscopic eukaryotes are rarely older than the Ediacaran Period (635–541 million years (Myr)), and their interpretation remains controversial. Here, we report the discovery of macroscopic fossils from the 1,560-Myr-old Gaoyuzhuang Formation, Yanshan area, North China, that exhibit both large size and regular morphology. Preserved as carbonaceous compressions, the Gaoyuzhuang fossils have statistically regular linear to lanceolate shapes up to 30 cm long and nearly 8 cm wide, suggesting that the Gaoyuzhuang fossils record benthic multicellular eukaryotes of unprecedentedly large size. Syngenetic fragments showing closely packed ∼10 μm cells arranged in a thick sheet further reinforce the interpretation. Comparisons with living thalloid organisms suggest that these organisms were photosynthetic, although their phylogenetic placement within the Eukarya remains uncertain. The new fossils provide the strongest evidence yet that multicellular eukaryotes with decimetric dimensions and a regular developmental program populated the marine biosphere at least a billion years before the Cambrian Explosion

Open X-Embodiment:Robotic learning datasets and RT-X models

Large, high-capacity models trained on diverse datasets have shown remarkable successes on efficiently tackling downstream applications. In domains from NLP to Computer Vision, this has led to a consolidation of pretrained models, with general pretrained backbones serving as a starting point for many applications. Can such a consolidation happen in robotics? Conventionally, robotic learning methods train a separate model for every application, every robot, and even every environment. Can we instead train "generalist" X-robot policy that can be adapted efficiently to new robots, tasks, and environments? In this paper, we provide datasets in standardized data formats and models to make it possible to explore this possibility in the context of robotic manipulation, alongside experimental results that provide an example of effective X-robot policies. We assemble a dataset from 22 different robots collected through a collaboration between 21 institutions, demonstrating 527 skills (160266 tasks). We show that a high-capacity model trained on this data, which we call RT-X, exhibits positive transfer and improves the capabilities of multiple robots by leveraging experience from other platforms. The project website is robotics-transformer-x.github.io

Effect of Machining Trajectory on Grinding Force of Complex-Shaped Stone by Robotic Manipulator

Complex-shaped stone products (CSSPs) have become stone products with high added economic value due to their complex overall shape, outline structure, and various curved surfaces. Recently, robotic manipulators—pieces of intelligent machining equipment—equipped with grinding end-effectors have significantly replaced handheld equipment and have also shown significant advantages in grinding efficiency and modeling flexibility. However, natural stone generally has the characteristics of poor craftsmanship and low rigidity. Improper control of the grinding force while grinding can easily cause the stone blank to break and scrap the workpiece. Therefore, in this study, we consider CSSPs and examine their surface curvature characteristics. The matching relationship between surface characteristics and machining trajectory is studied through simulation. Furthermore, the grinding force fluctuation in the finishing is optimized, and the optimal machining trajectory of the finishing process is determined to improve the surface profile error. Then, the simulation reliability is verified through experiments. The results show a 52.8% reduction in the grinding force fluctuation and a 36.9% reduction in the surface profile error after machining

Morphology of diverse radiodontan head sclerites from the early Cambrian Chengjiang Lagerstätte, south-west China

<p>Recorded in exceptionally preserved Lagerstätten, the radiodontans (including anomalocaridids) are cosmopolitan, soft-bodied, stem-group euarthropods that inhabited Palaeozoic seas. They are notable for their unique morphology, peculiar ecology and basal position in euarthropod evolution. The early Cambrian Chengjiang Lagerstätte has yielded some of the oldest radiodontans, including three unquestionable taxa – <i>Anomalocaris saron</i> Hou <i>et al</i>., 1995, <i>Amplectobelua symbrachiata</i> Hou <i>et al</i>., 1995 and <i>Lyrarapax unguispinus</i> Cong <i>et al</i>., 2014 – based on articulated specimens. However, recent discoveries of the Burgess Shale <i>Hurdia</i> Walcott, 1912 and the Fezouata <i>Aegirocassis benmoulae</i> Van Roy <i>et al</i>., 2015 highlight the presence of another radiodontan group (Hurdiidae) characterized by a tripartite head sclerite complex consisting of one central element and a pair of lateral elements. Here, we describe six morphotypes of possible hurdiid head sclerite elements from the Chengjiang Lagerstätte, some of which are closely associated with other typical radiodontan body parts. These, recognized as central elements, include two new species of the same new genus, <i>Tauricornicaris latizonae</i> gen. et sp. nov. and <i>T</i>. <i>oxygonae</i> gen. et sp. nov., and a former bivalved euarthropod, <i>Zhenghecaris shankouensis</i> Vannier <i>et al</i>., 2006. Another three unnamed sclerite elements are identified as lateral elements. These sclerite elements from Chengjiang provide detailed anatomy, such as mammillary tubercles and soft-tissue reticulate structure, to help understand the morphology and biology of all hurdiid head sclerites. A common single dorsal plate in <i>Anomalocaris saron</i> and <i>Amplectobelua symbrachiata</i> is confirmed. Although the morphologically diverse central and lateral elements of the Hurdiidae and the conserved dorsal plate of the Anomalocarididae + Amplectobeluidae reflect a major distinction in radiodontan body plans, they share a fundamental structure of double layers of cuticle. The Chengjiang specimens not only clarify the morphology and biology of the radiodontan head sclerites in general, but also illuminate the diversity and disparity of radiodontans in their early evolutionary history.</p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:urn:lsid:zoobank.org:pub:D0590390-A85A-493A-8529-B2DF64D91169" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:D0590390-A85A-493A-8529-B2DF64D91169</a></p

Orthrozanclus elongata n. sp. and the significance of sclerite-covered taxa for early trochozoan evolution

Orthrozanclus is a shell-bearing, sclerite covered Cambrian organism of uncertain taxonomic affinity, seemingly representing an intermediate between its fellow problematica Wiwaxia and Halkieria. Attempts to group these slug-like taxa into a single ‘halwaxiid’ clade nevertheless present structural and evolutionary difficulties. Here we report a new species of Orthrozanclus from the early Cambrian Chengjiang Lagerstätte. The scleritome arrangement and constitution in this material corroborates the link between Orthrozanclus and Halkieria, but not with Wiwaxia — and calls into question its purported relationship with molluscs. Instead, the tripartite construction of the halkieriid scleritome finds a more compelling parallel in the camenellan tommotiids, relatives of the brachiopods and phoronids. Such a phylogenetic position would indicate the presence of a scleritome in the common ancestor of the three major trochozoan lineages, Mollusca, Annelida and Brachiozoa. On this view, the absence of fossil Ediacaran sclerites is evidence against any ‘Precambrian prelude’ to the explosive diversification of these phyla in the Cambrian, c. 540–530 million years ago

Successional Trajectory Over 10Years of Vegetation Restoration of Abandoned Slope Croplands in the Hill-Gully Region of the Loess Plateau

Revegetation has been the primary management approach for solving the problems caused by severe soil erosion in the Loess Plateau. The&nbsp;objectives of this work were to explore the successional trajectory of the different types of restoration and discuss their potential effectiveness&nbsp;for the control of soil erosion. The presence and coverage of plants in 40 permanent plots were investigated during two periods (2003&ndash;2006&nbsp;and 2013). The naturally and artificially revegetated communities studied in the two surveys were classified using two-way indicator species&nbsp;analysis, and their relationships were analyzed using detrended correspondence analysis. Under natural revegetation, the communities succeed in the following order: annual plants &rarr; perennial plants &rarr; short rhizome tufts and subshrubs. Under artificial revegetation, succession&nbsp;was interrupted by artificial planting, and a Gramineae herb layer persisted through the years with few changes in species composition. Additionally, species richness, diversity, and evenness increased, while ecological dominance decreased during succession in both revegetation&nbsp;types. Succession rate was rapid at the initial stage and then slowed down gradually. Succession followed different trajectories under natural and artificial revegetation, and based on the potential effects of the two approaches on soil erosion and soil desiccation, we suggest that natural revegetation is preferable over artificial revegetation.<br style="orphans: 2; text-align: -webkit-auto; widows: 2;" /