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Ecosystem engineers can radically reshape ecosystems by modulating the availability of resources to other organisms through modifying either physical or biological aspects of the environment. The introduction or removal of ecosystem engineers from otherwise stable ecosystems can impact the diversity of co‐occurring species, such as driving local extinctions of native taxa. While these impacts are well established over ecological timescales for a wealth of taxa, the macroevolutionary implications of the onset of ecosystem engineering behaviours are less clear. Despite this uncertainty, ecosystem engineering has been implicated in several major transitions in Earth history including the appearance of extensive bioturbation during the Cambrian substrate revolution and associated Ediacaran–Cambrian turnover, and the Great Oxygenation Event. Whether ecosystem engineers are frequently associated with turnover and extinction in deep time is not known. Here we investigate this with an eco‐evolutionary simulation framework in which we assign lineages the ability to impact the fitness of co‐occurring taxa through phenotype–environment feedback. We explore numerous conditions, including how frequently such feedback occurs, and whether ecosystem engineers modify or create niches. We show that there is no general expected outcome from the introduction of ecosystem engineers. In a minority of runs, ecosystem engineering lineages completely dominate, rendering all others extinct, but in others they persist (but do not dominate), or die out. We suggest that ecosystem engineers have complex impacts, but possess the capacity to profoundly shape diversity, and it is appropriate to consider them alongside other exogenous extinction drivers in deep time. [ABSTRACT FROM AUTHOR]

Mollusks encompass enormous disparity, including familiar clams and snails alongside less familiar aculiferans (chitons and vermiform aplacophorans) with complex multicomponent skeletons. Paleozoic fossils trace crown mollusks to forms exhibiting a combination of biomineralized shells and sclerites (e.g., scales, spines, and spicules). We describe a shell-less, Cambrian stem mollusk, Shishania aculeata gen. et sp. nov., with conical, hollow chitinous sclerites and a smooth girdle, broad foot, and mantle cavity. The sclerites have a microstructure of narrow canals consistent with the impressions of chaetal microvilli found in annelids and brachiopods. Shishania sclerites provide a morphological stepping stone between typical chaetae (chitinous bristles) and the external organic part of aculiferan sclerites that encloses a mineralized body. This discovery reinforces a common origin of lophotrochozoan chaetae and the biomineralized aculiferan sclerites, suggesting that the mollusk ancestor was densely covered with hollow chitinous chaetae. [ABSTRACT FROM AUTHOR]

The documentation of cuticular micro‐ornament is vital for the taxonomic assignment of palaeoscolecids: vermiform lower Palaeozoic ecdysozoans interpreted as stem‐group priapulans or early diverging panarthropods. This is due to the absence of the character‐rich proboscis and tail hooks in palaeoscolecid material not from Burgess Shale‐type Konservat‐Lagerstätten. Here, the cuticular micro‐ornamentation of palaeoscolecids from the upper Silurian (Ludlow) fauna of Leintwardine (Herefordshire, England), is described using scanning electron microscopy and reflectance transformation imaging. This material is taxonomically unstable because it was included in an effective wastebasket genus (Protoscolex) long before these imaging techniques were developed. The Leintwardine material is shown to be most closely comparable to a palaeoscolecid from the Darriwilian (Middle Ordovician) of the Builth–Llandrindod inlier, Powys, Wales, and is transferred accordingly to Radnorscolex Botting et al. as Radnorscolex latus (Bather). The Leintwardine fauna represents the uppermost stratigraphic occurrence of palaeoscolecids, constrained to the Saetograptus leintwardinensis Zone (lower Ludfordian), and the comparatively sparse Silurian palaeoscolecid record is subsequently discussed. It is hypothesized that palaeoscolecids may have become extinct during the mid‐Ludfordian Lau Event, the onset of which is recorded in the biozone immediately above the Leintwardine fauna (Bohemograptus Zone). Finally, the British palaeoscolecid fauna is summarized, including a new record from the Dapingian (Middle Ordovician) of Carmarthenshire, South Wales. [ABSTRACT FROM AUTHOR]

Time‐scaled phylogenies underpin the interrogation of evolutionary processes across deep timescales, as well as attempts to link these to Earth's history. By inferring the placement of fossils and using their ages as temporal constraints, tip dating under the fossilized birth–death (FBD) process provides a coherent prior on divergence times. At the same time, it also links topological and temporal accuracy, as incorrectly placed fossil terminals should misinform divergence times. This could pose serious issues for obtaining accurate node ages, yet the interaction between topological and temporal error has not been thoroughly explored. We simulate phylogenies and associated morphological datasets using methodologies that incorporate evolution under selection, and are benchmarked against empirical datasets. We find that datasets of 300 characters and realistic levels of missing data generally succeed in inferring the correct placement of fossils on a constrained extant backbone topology, and that true node ages are usually contained within Bayesian posterior distributions. While increased fossil sampling improves the accuracy of inferred ages, topological and temporal errors do not seem to be linked: analyses in which fossils resolve less accurately do not exhibit elevated errors in node age estimates. At the same time, inferred divergence times are biased, probably due to a mismatch between the FBD prior and the shape of our simulated trees. While these results are encouraging, suggesting that even fossils with uncertain affinities can provide useful temporal information, they also emphasize that palaeontological information cannot overturn discrepancies between model priors and the true diversification history. [ABSTRACT FROM AUTHOR]

Fossil material assigned to Nenoxites from the late Ediacaran Khatyspyt Formation of Arctic Siberia (550–544 Ma) has been presented as evidence for bioturbation prior to the basal Cambrian boundary. However, that ichnological interpretation has been challenged, and descriptions of similar material from other global localities support a body fossil origin. Here we combine x‐ray computed tomography, scanning electron microscopy and petrographic methods to evaluate the body or trace fossil nature of Nenoxites from the Khatyspyt Formation. The fossilized structures consist of densely packed chains of three‐dimensionally preserved silicic, bowl‐shaped elements surrounded by distinct sedimentary halos, in a dolomitized matrix. Individual bowl‐shaped elements can exhibit diffuse mineralogical boundaries and bridging connections between elements, both considered here to result from silicification and dolomitization during diagenesis. This new morphological and petrological evidence, in conjunction with recent studies of the late Ediacaran tubular taxa Ordinilunulatus and Shaanxilithes from China, suggest that the Khatyspyt specimens most probably reflect a coquina deposit of Shaanxilithes‐like body fossils. Our data support the possibility of Shaanxilithes‐like organisms representing total group eumetazoans. [ABSTRACT FROM AUTHOR]

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Machaeridians are armoured annelids that were morphologically diverse during the Palaeozoic. The scleritome developed from fleshy protrusions at the base of each parapodium, with alternating segments giving rise to differentiated inner and outer shell plates. The elytra‐like anatomy of the shell‐bearing soft tissues and distinctive jaw apparatus support an affinity of machaeridians with aphroditacean scaleworms. While frequently found as disarticulated remains, whole scleritomes of machaeridians are rare. Only a few species are represented by multiple articulated individuals, rendering many aspects of our knowledge of scleritome construction and growth uncertain. Here we describe a collection of articulated scleritomes of the plumulitid machaeridian Plumulites tafennaensis Chauvel from the Upper Ordovician (Katian) Upper Tiouririne Formation of Morocco that includes individuals representing both adult and juvenile stages. These scleritomes shed light on the morphology of the anterior region in plumulitids and show an increase in the number of shell plates with increasing size, suggesting that unlike some derived lepidocoleids, at least some plumulitids added segments repeatedly during ontogeny. Shell plates with a distinctive umbo have previously been assigned exclusively to the anterior region, but our material shows that they are present along the scleritome, with corresponding sclerites on the opposite side of the skeleton showing normal morphologies. We suggest that these plates are abnormal and best explained as healed injuries, replacing plates that had been previously removed from the body, demonstrating the capacity for machaeridians to regenerate lost body parts, a feature that is widespread in living annelids. [ABSTRACT FROM AUTHOR]

Concerted political attention has focused on reducing deforestation (1-3), and this remains the cornerstone of most biodiversity conservation strategies (4-6). However, maintaining forest cover may not reduce anthropogenic forest disturbances, which are rarely considered in conservation programmes (6). These disturbances occur both within forests, including selective logging and wildfires (7,8), and at the landscape level, through edge, area and isolation effects (9). Until now, the combined effect of anthropogenic disturbance on the conservation value of remnant primary forests has remained unknown, making it impossible to assess the relative importance of forest disturbance and forest loss. Here we address these knowledge gaps using a large data set of plants, birds and dung beetles (1,538, 460 and 156 species, respectively) sampled in 36 catchments in the Brazilian state of Para. Catchments retaining more than 69-80% forest cover lost more conservation value from disturbance than from forest loss. For example, a 20% loss of primary forest, the maximum level of deforestation allowed on Amazonian properties under Brazil's Forest Code (5), resulted in a 39-54% loss of conservation value: 96-171% more than expected without considering disturbance effects. We extrapolated the disturbance-mediated loss of conservation value throughout Para, which covers 25% of the Brazilian Amazon. Although disturbed forests retained considerable conservation value compared with deforested areas, the toll of disturbance outside Para's strictly protected areas is equivalent to the loss of 92,000-139,000 [km.sup.2] of primary forest. Even this lowest estimate is greater than the area deforested across the entire Brazilian Amazon between 2006 and 2015 (ref. 10). Species distribution models showed that both landscape and within-forest disturbances contributed to biodiversity loss, with the greatest negative effects on species of high conservation and functional value. These results demonstrate an urgent need for policy interventions that go beyond the maintenance of forest cover to safeguard the hyper-diversity of tropical forest ecosystems., Protecting tropical forests is a fundamental pillar of many national and international strategies for conserving biodiversity (4-6). Although improved regulatory and incentive measures have reduced deforestation rates in some tropical [...]

Cnidarians form a disparate phylum of animals and their diploblastic body plan represents a key step in animal evolution. Cnidarians are split into two main classes; anthozoans (sea anemones, corals) are benthic polyps, while medusozoans (hydroids, jellyfishes) generally have alternating life cycle stages of polyps and medusae. A sessile polyp is present in both groups and is widely regarded as the ancestral form of their last common ancestor. However, the nature and anatomy of the ancestral polyp, particularly of medusozoans, is controversial, owing to the divergent body plans of the extant lineages and the scarcity of medusozoan soft tissues in the fossil record. Here, we redescribe Conicula striata Luo & Hu from the early Cambrian Chengjiang biota, south China, which has previously been interpreted as a polyp, lophophorate or deuterostome. Through re-examination of the holotype and 51 exceptionally preserved specimens, we show that C. striata possessed features of both anthozoans and medusozoan polyps. A conical, annulated organic skeleton (periderm) fully encasing a polyp is found in fossil and living medusozoans, while a tubular pharynx extending from the mouth into a gut partitioned by c. 28 mesenteries, resembling the actinopharynx of anthozoans. Our phylogenetic analyses recover C. striata as a stem-group medusozoan, implying that the wealth of medusozoan diversity derived, ultimately, from an anemone-like ancestor. [ABSTRACT FROM AUTHOR]

Governments continue to narrowly equate improved well-being with economic growth, contrary to decades of development scholarship. The capabilities approach, instead, emphasizes freedom and what individuals are able to do and to be within society. However, it underplays structural determinants of social inequities and says little about violence, a dominant problem in metropolitan areas of Latin America. Framing our analysis around capabilities and theorizing on disadvantage, we examine experiences of inequity and violence in Manaus, a metropolis in the Brazilian Amazon. We show how the threat of physical violence is highly corrosive because it underpins a cluster of disadvantage that profoundly impacts central capabilities, including emotions, bodily integrity, and affiliation. Social isolation is commonplace because interactions are perceived as risks rather than pathways to mutual recognition. Violence begets violence in low-income neighborhoods and this constrains capabilities, causes shame and indignity, and limits potential for self-realization. Policy makers should address how disadvantaged people feel about themselves, relate to others, and are able to decide how to conduct their daily lives. [ABSTRACT FROM AUTHOR]