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A recent article argued that signals from conventional Raman spectroscopy of organic materials are overwhelmed by edge filter and fluorescence artefacts. The article targeted a subset of Raman spectroscopic investigations of fossil and modern organisms and has implications for the utility of conventional Raman spectroscopy in comparative tissue analytics. The inferences were based on circular reasoning centered around the unconventional analysis of spectra from just two samples, one modern, and one fossil. We validated the disputed signals with in situ Fourier‐Transform Infrared (FT‐IR) Spectroscopy and through replication with different lasers, filters, and operators in independent laboratories. Our Raman system employs a holographic notch filter which is not affected by edge filter or other artefacts. Multiple lines of evidence confirm that conventional Raman spectra of fossils contain biologically and geologically meaningful information. Statistical analyses of large Raman and FT‐IR spectral data sets reveal patterns in fossil composition and yield valuable insights into the history of life. [ABSTRACT FROM AUTHOR]

Soft-bodied fossils of Cambrian age, now known as Burgess Shale-type biotas, were first described from the Parker Slate of the northwest Vermont (USA) slate belt in the late 19th century, 25 years before the discovery of the Burgess Shale in British Columbia, Canada. Here, we report the rediscovery of fossiliferous horizons at Parker's Cobble, the site of the original quarry, which was thought to have been exhausted by excavation. New discoveries include a radiodont, multiple specimens of a new bivalved arthropod, a priapulid, and other undescribed forms. Pervasive soft-sediment deformation suggests accumulation near the toe of a steep unstable slope, similar to the setting of the Burgess Shale. Although fossils are rare, the exceptional preservation of some soft-bodied taxa suggests that recovered diversity was limited by transport into an inhospitable benthic setting rather than by decay, and this implies a potential for future discoveries of new taxa. [ABSTRACT FROM AUTHOR]

The fossil record provides the only direct record of the history of life, but it is an incomplete one. Discriminating between what is absent and what is simply not preserved is critical to macroevolutionary and macroecological inferences. A comparison of diversity data in over 20,000 modern marine assemblages from the Ocean Biogeographic Information System database (OBIS) with fossil occurrence data from the Paleobiology Database (PBDB) yielded a global assessment of assemblage-level fossilization potential. We used two different metrics, taxon fossilization potential and within-environment fossilization potential, to assess the proportion of taxa in a modern community with PBDB occurrences or with PBDB occurrences in the same environment, respectively. Taxon fossilization potential of marine genera varies between environments, from 34% in shallow and deep water to 44% in coral reefs, 51% on seamounts, and 15% in pelagic assemblages. Within-environment fossilization potential, in contrast, does not exceed 32% (in shallow water), a lower value than that obtained in other studies, and it may be zero (on seamounts and pelagic environments). These differences are mainly a product of representation in the rock record and sampling biases rather than taxon duration. [ABSTRACT FROM AUTHOR]

The article discusses a study by N. J. Strausfeld et al which revealed the ancestry of the arthropod segmented brain in an analysis of the lobopodian Cardiodictyon catenulum preserved in 518 million-year-old Cambrian rocks near Kun-ming, China. Topics include the characteristics and features of the arthropods, the difficulty of interpreting the homology of head appendages in living and fossil arthropods and evidence of evolution of the arthropods and other animals during the Cambrian explosion.

The colonization of thewater column is among the most important transformations in the evolution of animal life and global ecosystems. The Devonian nekton revolution has been identified as a major macroevolutionary event signifying the rapid occupation of thewater column by independent radiations of swimming animals. Using new data, an expanded taxonomic coverage, sample standardization and increased ecological resolution, we analysed patterns of nektonization during the Palaeozoic. We find that nekton and eunekton were well established prior to the Devonian and did not diversify dramatically during any Palaeozoic interval. Relative nektic diversity and occurrences decreased rather than increased during the Devonian. Eunektic diversity and occurrences increased throughout the Palaeozoic, but this rise was protracted and cannot be attributed to any single interval. Our new data indicate that the metazoan colonization of the water column was considerably more complex and gradual than previously understood. [ABSTRACT FROM AUTHOR]

The 3.5 Ma Pliocene Bowden shell beds in southeast Jamaica constitute one of the best-known and well-studied paleontological sites in the Greater Antilles. More than 850 species of shelly fossils, dominated by molluscs, have been reported from the unit. Stratigraphic analysis of a newly cleared, continuous section revealed a submarine channel that contains two shelly conglomerates. Elsewhere in the section, newly discovered leaves show variation in modes of transport from mass flow to settling from suspension and are the first such specimens to be reported from Jamaica. The leaves are commonly fragmentary, making taxonomic determination difficult. However, a number of morphotypes are present, including representatives of Lauraceae, Fabaceae, the red mangrove Rhizophora mangle, and, more rarely, Euphorbiaceae, Clethraceae, and Burseraceae. Their occurrence indicates that most of the leaves were sourced from the coastal area, but some were probably derived from further inland. These new observations accentuate the unusual nature of this deposit, which consists of extrabasinal turbidites deposited from hyperpycnal flows. [ABSTRACT FROM AUTHOR]

Echinoderms are unique in having a water vascular system with tube feet, which perform a variety of functions in living forms. Here, we report the first example of preserved tube feet in an extinct group of echinoderms. The material, from the Silurian Herefordshire Lagerstätte, UK, is assigned to a new genus and species of rhenopyrgid edrioasteroid, Heropyrgus disterminus. The tube feet attach to the inner surface of compound interradial plates and form two sets, an upper and a lower, an arrangement never reported previously in an extant or extinct echinoderm. Cover plates are absent and floor plates are separated creating a large permanent entrance to the interior of the oral area. The tube feet may have captured food particles that entered the oral area and/or enhanced respiration. The pentameral symmetry of the oral surface transitions to eight columns in which the plates are vertically offset resulting in a spiral appearance. This change in symmetry may reflect flexibility in the evolutionary development of the axial and extraxial zones in early echinoderm evolution. [ABSTRACT FROM AUTHOR]

Cascolus ravitis gen. et sp. nov. is a three-dimensionally preserved fossil crustacean with soft parts from the Herefordshire (Silurian) Lagerstätte, UK. It is characterized by a head with a head shield and five limb pairs, and a thorax (pereon) with nine appendage-bearing segments followed byan apodous abdomen (pleon). All the appendages except the first are biramous and have a gnathobase. The post-mandibular appendages are similar one to another, and bear petal-shaped epipods that probably functioned as a part of the respiratory-circulatory system. Cladistic analysis resolves the new taxon as a stem-group leptostracan (Malacostraca). This well-preserved arthropod provides novel insights into the evolution of appendage morphology, tagmosis and the possible respiratory-circulatory physiology of a basal malacostracan. [ABSTRACT FROM AUTHOR]

A single specimen of a new species of the chasmataspidid Diploaspis Størmer, 1972 is described from the upper Silurian (Pridoli) Phelps Member of the Fiddlers Green Formation (Bertie Group) in Herkimer County, New York State, USA. Diploaspis praecursor sp. nov. is distinguished by the shape of the posterolateral margins of the buckler, which are drawn out into angular epimera, and by the lack of elongate tubercles on the postabdomen. This discovery increases the taxonomic diversity of the Bertie Group by extending the geographic extent of Diploaspididae into North America. D. praecursor pre-dates previously known species of Diploaspis by more than 10 million years. [ABSTRACT FROM PUBLISHER]

The ~430-My-old Herefordshire, United Kingdom, Lagerstätte has yielded a diversity of remarkably preserved invertebrates, many of which provide fundamental insights into the evolutionary history and ecology of particular taxa. Here we report a new arthropod with 10 tiny arthropods tethered to its tergites by long individual threads. The head of the host, which is covered by a shield that projects anteriorly, bears a long stout uniramous antenna and a chelate limb followed by two biramous appendages. The trunk comprises 11 segments, all bearing limbs and covered by tergites with long slender lateral spines. A short telson bears long parallel cerci. Our phylogenetic analysis resolves the new arthropod as a stem-group mandibulate. The evidence suggests that the tethered individuals are juveniles and the association represents a complex brooding behavior. Alternative possibilities--that the tethered individuals represent a different epizoic or parasitic arthropod--appear less likely. [ABSTRACT FROM AUTHOR]

In the last 20 years, much taphonomic experimentation has focused on the interpretation of exceptionally preserved fossils. Decay experiments have been used to interpret the features preserved in soft-bodied fossils and to determine the sequence of character loss and its impact on phylogenetic position. Experiments on the impact of microbial communities on decay and mineralization have started to illuminate the processes involved in the fossilization of soft tissues, including embryos. The role of decay in promoting authigenic mineralization has been used to investigate the formation of Ediacaran macrofossils and concretions. Maturation experiments have shown how the constituents of animals and plants are transformed over time to a macromolecular material that converges on a similar stable composition. Other maturation experiments have explained how structural colours in fossils are altered from the original. A major area requiring investigation is the role of specific types of microbes in decay and their impact on sediment and pore water chemistry, as well as the environmental controls that determine their presence and level of activity. Microbial activity has received less attention than other factors in attempts to explain why the occurrence and nature of exceptional preservation varies in time and space through the fossil record. [ABSTRACT FROM AUTHOR]

Background: Eurypterids are a diverse group of chelicerates known from ~250 species with a sparse Ordovician record currently comprising 11 species; the oldest fully documented example is from the Sandbian of Avalonia. The Middle Ordovician (Darriwilian) fauna of the Winneshiek Lagerstätte includes a new eurypterid species represented by more than 150 specimens, including some juveniles, preserved as carbonaceous cuticular remains. This taxon represents the oldest described eurypterid, extending the documented range of the group back some 9 million years. Results: The new eurypterid species is described as Pentecopterus decorahensis gen. et sp. nov.. Phylogenetic analysis places Pentecopterus at the base of the Megalograptidae, united with the two genera previously assigned to this family by the shared possession of two or more pairs of spines per podomere on prosomal appendage IV, a reduction of all spines except the pair on the penultimate podomere of appendage V, and an ornamentation of guttalate scales, including angular scales along the posterior margin of the dorsal tergites and in longitudinal rows along the tergites. The morphology of Pentecopterus reveals that the Megalograptidae are representatives of the derived carcinosomatoid clade and not basal eurypterids as previously interpreted. Conclusions: The relatively derived position of megalograptids within the eurypterids indicates that most eurypterid clades were present by the Middle Ordovician. Eurypterids either underwent an explosive radiation soon after their origination, or earlier representatives, perhaps Cambrian in age, remain to be discovered. The available instars of Pentecopterus decorahensis suggest that eurypterids underwent extreme appendage differentiation during development, a potentially unique condition among chelicerates. The high degree of appendage specialization in eurypterids is only matched by arachnids within chelicerates, supporting a sister taxon relationship between them. [ABSTRACT FROM AUTHOR]

Background: Eurypterids are a diverse group of chelicerates known from ~250 species with a sparse Ordovician record currently comprising 11 species; the oldest fully documented example is from the Sandbian of Avalonia. The Middle Ordovician (Darriwilian) fauna of the Winneshiek Lagerstätte includes a new eurypterid species represented by more than 150 specimens, including some juveniles, preserved as carbonaceous cuticular remains. This taxon represents the oldest described eurypterid, extending the documented range of the group back some 9 million years. Results: The new eurypterid species is described as Pentecopterus decorahensis gen. et sp. nov.. Phylogenetic analysis places Pentecopterus at the base of the Megalograptidae, united with the two genera previously assigned to this family by the shared possession of two or more pairs of spines per podomere on prosomal appendage IV, a reduction of all spines except the pair on the penultimate podomere of appendage V, and an ornamentation of guttalate scales, including angular scales along the posterior margin of the dorsal tergites and in longitudinal rows along the tergites. The morphology of Pentecopterus reveals that the Megalograptidae are representatives of the derived carcinosomatoid clade and not basal eurypterids as previously interpreted. Conclusions: The relatively derived position of megalograptids within the eurypterids indicates that most eurypterid clades were present by the Middle Ordovician. Eurypterids either underwent an explosive radiation soon after their origination, or earlier representatives, perhaps Cambrian in age, remain to be discovered. The available instars of Pentecopterus decorahensis suggest that eurypterids underwent extreme appendage differentiation during development, a potentially unique condition among chelicerates. The high degree of appendage specialization in eurypterids is only matched by arachnids within chelicerates, supporting a sister taxon relationship between them. [ABSTRACT FROM AUTHOR]

The article discusses a study on role of amber, fossilized resin from trees, in preserving soft-bodied organisms that otherwise fail to appear in the fossil record. It states majority of creatures in amber are insects, and that they are often preserve the finest 3D details, and mentions that rate of transformation, which involve polymerization, varies with resin chemistry and environmental conditions. It notes that oldest amber known to contain arthropod inclusions is Triassic in age.

Harry Whittington's 1975 monograph on Opabinia was the first to highlight how some of the Burgess Shale animals differ markedly from those that populate today's oceans. Categorized by Stephen J. Gould as a 'weird wonder' (Wonderful life,1 9 8 9 ) Opabinia, together with other unusual Burgess Shale fossils, stimulated ongoing debates about the early evolution of the major animal groups and the nature of the Cambrian explosion. The subsequent discovery of a number of other exceptionally preserved fossil faunas of Cambrian and early Ordovician age has significantly augmented the information available on this critical interval in the history of life. Although Opabinia initially defied assignment to any group of modern animals, it is now interpreted as lying below anomalocaridids on the stem leading to the living arthropods. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society. [ABSTRACT FROM AUTHOR]

Background: Thylacocephala is a group of enigmatic extinct arthropods. Here we provide a full description of the oldest unequivocal thylacocephalan, a new genus and species Thylacares brandonensis, which is present in the Silurian Waukesha fauna from Wisconsin, USA. We also present details of younger, Jurassic specimens, from the Solnhofen lithographic limestones, which are crucial to our interpretation of the systematic position of Thylacocephala. In the past, Thylacocephala has been interpreted as a crustacean ingroup and as closely related to various groups such as cirripeds, decapods or remipeds. Results: The Waukesha thylacocephalan, Thylacares brandonensis n. gen. n. sp., bears compound eyes and raptorial appendages that are relatively small compared to those of other representatives of the group. As in other thylacocephalans the large bivalved shield encloses much of the entire body. The shield lacks a marked optical notch. The eyes, which project just beyond the shield margin, appear to be stalked. Head appendages, which may represent antennulae, antennae and mandibles, appear to be present. The trunk is comprised of up to 22 segments. New details observed on thylacocephalans from the Jurassic Solnhofen lithographic limestones include antennulae and antennae of Mayrocaris bucculata, and endites on the raptorial appendages and an elongate last trunk appendage in Clausocaris lithographica. Preserved features of the internal morphology in C. lithographica include the muscles of the raptorial appendage and trunk. Conclusions: Our results indicate that some ‘typical’ thylacocephalan characters are unique to the group; these autapomorphies contribute to the difficulty of determining thylacocephalan affinities. While the new features reported here are consistent with a eucrustacean affinity, most previous hypotheses for the position of Thylacocephala within Eucrustacea (as Stomatopoda, Thecostraca or Decapoda) are shown to be unlikely. A sister group relationship to Remipedia appears compatible with the observed features of Thylacocephala but more fossil evidence is required to test this assertion. The raptorial appendages of Thylacocephala most likely projected 45 degrees abaxially instead of directly forward as previously reconstructed. The overall morphology of thylacocephalans supports a predatory mode of life. [ABSTRACT FROM AUTHOR]

The discovery of traces of a blood meal in the abdomen of a 50-million-year-old mosquito reminds us of the insights that the chemistry of fossils can provide. Ancient DNA is the best known fossil molecule. It is less well known that new fossil targets and a growing database of ancient gene sequences are paralleled by discoveries on other classes of organic molecules. New analytical tools, such as the synchrotron, reveal traces of the original composition of arthropod cuticles that are more than 400 my old. Pigments such as melanin are readily fossilized, surviving virtually unaltered for ∼200 my. Other biomarkers provide evidence of microbial processes in ancient sediments, and have been used to reveal the presence of demosponges, for example, more than 635 mya, long before their spicules appear in the fossil record. Ancient biomolecules are a powerful complement to fossil remains in revealing the history of life. [ABSTRACT FROM AUTHOR]

Multiple beds in the Frankfort Shale (Upper Ordovician, New York State), including the original "Beecher's Trilobite Bed," yield fossils with pyritized soft-tissues. A bed-by-bed geochemical and sedimentological analysis was carried out to test previous models of soft-tissue pyritization by investigating environmental, deposi-tional and diagenetic conditions in beds with and without soft-tissue preservation. Highly-reactive iron (FeHR), total iron (FeT),δ34S, organic carbon and redox-sensitive trace elements were measured. In particular, the partitioning of highly-reactive iron between iron-carbonates (Fe-carb), iron-oxides (Fe-ox), magnetite (Fe-mag), and pyrite (FeP) was examined. Overall, the multi-proxy sedimentary geochemical data suggest that the succession containing pyritized trilobite beds was deposited under a dysoxic water-column, in agreement with the paleontological data. The data do not exclude brief episodes of water-column anoxia characterized by a ferruginous rather than an euxinic state. However, the highest FeHR/FeT values and redox-sensitive trace element enrichments occur in siltstone portions of turbidite beds and in concretions, suggesting that subsequent diagenesis had a significant effect on the distribution of redox-sensitive elements in this succession. Moderately high FeHR/FeT and FeP/FeHR, low organic carbon, enriched δ34S, and the frequent presence of iron-rich carbonate concretions in beds with soft tissue preservation confirm that pyritization was favored where pore-waters were iron-dominated in sediments relatively poor in organic carbon. [ABSTRACT FROM AUTHOR]

Structural coloration underpins communication strategies in many extant insects but its evolution is poorly understood. This stems, in part, from limited data on how color alters during fossilization. We resolve this by using elevated pressures and temperatures to simulate the effects of burial on structurally colored cuticles of modern beetles. Our experiments show that the color generated by multilayer reflectors changes due to alteration of the refractive index and periodicity of the cuticle layers. Three-dimensional photonic crystals are equally resistant to degradation and thus their absence in fossil insects is not a function of limited preservation potential but implies that these color-producing nanostructures evolved recently. Structural colors alter directly to black above a threshold temperature in experiments, identifying burial temperature as the primary control on their preservation in fossils. Color-producing nanostructures can, however, survive in experimentally treated and fossil cuticles that now are black. An extensive cryptic record is thus available in fossil insects to illuminate the evolution of structural color. [ABSTRACT FROM AUTHOR]

The Mollusca is one of the most diverse, important and well-studied invertebrate phyla; however, relationships among major molluscan taxa have long been a subject of controversy. In particular, the position of the shell-less vermiform Aplacophora and its relationship to the better-known Polyplacophora (chitons) have been problematic: Aplacophora has been treated as a paraphyletic or monophyletic group at the base of the Mollusca, proximate to other derived clades such as Cephalopoda, or as sister group to the Polyplacophora, forming the clade Aculifera. Resolution of this debate is required to allow the evolutionary origins of Mollusca to be reconstructed with confidence. Recent fossil finds support the Aculifera hypothesis, demonstrating that the Palaeozoic-era palaeoloricate 'chitons' included taxa combining certain polyplacophoran and aplacophoran characteristics. However, fossils combining an unambiguously aplacophoran-like body with chiton-like valves have remained elusive. Here we describe such a fossil, Kulindroplax perissokomos gen. et sp. nov., from the Herefordshire Lagerstätte (about 425 million years bp), a Silurian deposit preserving a marine biota in unusual three-dimensional detail. The specimen is reconstructed three-dimensionally through physical-optical tomography. Phylogenetic analysis indicates that this and many other palaeoloricate chitons are crown-group aplacophorans. [ABSTRACT FROM AUTHOR]

The basic arrangement of limbs in euarthropods consists of a uni-ramous head appendage followed by a series of biramous appen-dages. The body is divided into functional units or tagmata which are usually distinguished by further differentiation of the limbs. The living horseshoe crabs are remnants of a much larger diversity of aquatic chelicerates. The limbs of the anterior and posterior divisions of the body of living horseshoe crabs differ in the loss of the outer and inner ramus, respectively, of an ancestral biramous limb. Here we report a new fossil horseshoe crab from the mid-Silurian Lagerstätte in Herefordshire, United Kingdom (approxi-mately 425 Myr B.P.), a site that has yielded a remarkably preserved assemblage of soft-bodied fossils. The limbs of the new form can be homologized with those of living Limulus, but retain an ances-tral biramous morphology. Remarkably, however, the two limb branches originate separately, providing fossil evidence to suggest that repression or loss of gene expression might have given rise to the appendage morphology of Limulus. Both branches of the pro-somal limbs of this new fossil are robust and segmented in contrast to their morphology in Cambrian arthropods, revealing that a true biramous limb was once present in chelicerates as well as in the mandibulates [ABSTRACT FROM AUTHOR]

Structural colors are generated by scattering of light by variations in tissue nanostructure. They are widespread among animals and have been studied most extensively in butterflies and moths (Lepidoptera), which exhibit the widest diversity of photonic nanostructures, resultant colors, and visual effects of any extant organism. The evolution of structural coloration in lepidopterans, however, is poorly understood. Existing hypotheses based on phylogenetic and/or structural data are controversial and do not incorporate data from fossils. Here we report the first example of structurally colored scales in fossil lepidopterans; specimens are from the 47-million-year-old Messel oil shale (Germany). The preserved colors are generated by a multilayer reflector comprised of a stack of perforated laminae in the scale lumen; differently colored scales differ in their ultrastructure. The original colors were altered during fossilization but are reconstructed based upon preserved ultrastructural detail. The dorsal surface of the forewings was a yellow-green color that probably served as a dual-purpose defensive signal, i.e. aposematic during feeding and cryptic at rest. This visual signal was enhanced by suppression of iridescence (change in hue with viewing angle) achieved via two separate optical mechanisms: extensive perforation, and concave distortion, of the multilayer reflector. The fossils provide the first evidence, to our knowledge, for the function of structural color in fossils and demonstrate the feasibility of reconstructing color in non-metallic lepidopteran fossils. Plastic scale developmental processes and complex optical mechanisms for interspecific signaling had clearly evolved in lepidopterans by the mid-Eocene. [ABSTRACT FROM AUTHOR]

Anomalocaridids, giant lightly sclerotized invertebrate predators, occur in a number of exceptionally preserved early and middle Cambrian (542-501 million years ago) biotas and have come to symbolize the unfamiliar morphologies displayed by stem organisms in faunas of the Burgess Shale type. They are characterized by a pair of anterior, segmented appendages, a circlet of plates around the mouth, and an elongate segmented trunk lacking true tergites with a pair of flexible lateral lobes per segment. Disarticulated body parts, such as the anterior appendages and oral circlet, had been assigned to a range of taxonomic groups-but the discovery of complete specimens from the middle Cambrian Burgess Shale showed that these disparate elements all belong to a single kind of animal. Phylogenetic analyses support a position of anomalocaridids in the arthropod stem, as a sister group to the euarthropods. The anomalocaridids were the largest animals in Cambrian communities. The youngest unequivocal examples occur in the middle Cambrian Marjum Formation of Utah but an arthropod retaining some anomalocaridid characteristics is present in the Devonian of Germany. Here we report the post-Cambrian occurrence of anomalocaridids, from the Early Ordovician (488-472 million years ago) Fezouata Biota in southeastern Morocco, including specimens larger than any in Cambrian biotas. These giant animals were an important element of some marine communities for about 30 million years longer than previously realized. The Moroccan specimens confirm the presence of a dorsal array of flexible blades attached to a transverse rachis on the trunk segments; these blades probably functioned as gills. [ABSTRACT FROM AUTHOR]

A new genus and species of synziphosurine (Chelicerata) is described from the Silurian (Wenlock) Scotch Grove Formation Konservat-Lagerstätte in Clinton County, Iowa. Camanchia grovensis n. gen. n. sp. is characterized by a sub-triangular carapace, ten opisthosomal segments divided into a preabdomen of seven and a postabdomen of three, and a tuberculate ornament on the carapace and pleural margins. A single new specimen from the same location is assigned to Venustulus waukeshaensis, originally described from the Late Llandovery Waukesha Konservat-Lagerstätte of Wisconsin. A comparison of the musculature of C. grovensis with that of living Limulus polyphemus and the Jurassic Mesolimulus walchi from Nusplingen, Germany shows that it is much simpler, consistent with the status of synziphosurines as stem xiphosurids. [ABSTRACT FROM AUTHOR]

Four new genera and species of annelid, Hunsrueckochaeta hohensteini, Ewaldips feyi, Crocancistrius lutzi and Scopyrites magnus, are described from the Hunsrück Slate (Lower Emsian) of Germany, as well as new material of Bundenbachochaeta eschenbachensis  Bartels and Blind, 1995 . The specimens preserve details of the appendages and other aspects of the morphology as a result of pyritization. A phylogenetic analysis using the morphological data matrix of Rouse and Fauchald places four of the five genera basal to the Aciculata; the fifth Ewaldips falls within the Scolecida. The diversity of annelids represented in the Hunsrück Slate is similar to that in the other major Palaeozoic Konservat-Lagerstätten that yield them, including the Cambrian Burgess Shale and the Late Carboniferous Mazon Creek biota. [ABSTRACT FROM AUTHOR]

The Silurian and Lower Devonian pterygotid eurypterids were the largest of all arthropods, but their origin and early evolution are poorly understood. Pterygotus? ventricosus from Kokomo, Indiana, is shown to be the most basal of the pterygotids and constitutes the sister taxon to the rest of the clade. P.?  ventricosus has walking appendages similar to those of Slimonia, which is the sister taxon of pterygotids. There is no evidence in P.?  ventricosus of the dorsal median pretelson carina characteristic of other pterygotids, but the taxon does have the typical pterygotid undivided genital appendage. The status of the iconic pterygotid character (and presumed synapomorphy), the enlargement of the chelicerae, is uncertain in the Kokomo pterygotid. All the diagnostic characters of pterygotids did not develop simultaneously. A new genus Ciurcopterus is erected to accommodate the Kokomo pterygotid and Pterygotus? sarlei Ciurca and Tetlie. [ABSTRACT FROM AUTHOR]

The discovery that machaeridians (class Machaeridia Withers, 1926) are annelids allows their mode of locomotion to be interpreted in the context of the body plan of this phylum. The Plumulitidae were errant epibenthic forms, moving with parapodia. The body of Turrilepadidae and Lepidocoleidae, however, was enclosed largely within the mineralized plates that make up the skeleton. Articulated specimens indicate that these machaeridians were able to burrow like other annelids using peristaltic locomotion. A lepidocoleid specimen indicates that multiple waves of shortened and contracted regions moved over the body. This is in contrast to the mode of locomotion in earthworms and most polychaetes, but similar to peristaltic progression in Polyphysia (Scalibregmidae). Either the rugose sculpture (turrilepadids) and/or the margins of the overlapping shell plates functioned as a burrowing sculpture, allowing forward movement but preventing backwards slipping. A trace from the Devonian Hunsrück Slate associated with a lepidocoleid indicates that considerable flexing of the skeleton was possible, but this is an escape trace and does not represent normal locomotion. Features of the skeleton of machaeridians are convergent on those of molluscs where the shells likewise function in protection and burrowing. [ABSTRACT FROM AUTHOR]

Although Cambrian Burgess Shale-type (BST) biotas are fundamental to understanding the radiation of metazoans, the nature of their extraordinary preservation remains controversial. There remains disagreement about the importance of the role of early mineral replication of soft tissues versus the conservation of primary organic remains. Most prior work focused on soft-bodied fossils from the two most important BST biotas, those of the Burgess Shale (Canada) and Maotianshan Shale (Chengjiang, China). Fossils from these two deposits do not provide ideal candidates for specimen-level taphonomic study because they have been altered: the Burgess Shale by greenschist facies metamorphism and the Maotianshan Shale by intensive subsurface weathering. Elemental mapping of soft-bodied fossils from 11 other BST deposits worldwide demonstrates that BST preservation represents a single major taphonomic pathway that may share a common cause wherever it occurs. The conservation of organic tissues, and not early authigenic mineralization, is the primary mechanism responsible for the preservation of BST assemblages. Early authigenic mineral replacement preserves certain anatomical features of some specimens, but the preservation of non-biomineralized BST fossils requires suppression of the processes that normally lead to the degradation of organic remains in marine environments. [ABSTRACT FROM AUTHOR]

The Upper Carboniferous insect Gerarus from Mazon Creek was reinvestigated to assess the affinities of the Geraridae. Specimens were examined using an environmental scanning electron microscope. The evidence, including an inflated clypeus and characters of the wing venation, for placing the family in Paraneoptera (hemipteroids) is equivocal; Gerarus is assigned to the Archaeorthoptera in the stem-group Orthoptera. The presence of leg exites in Gerarus and other Mazon Creek specimens could not be confirmed. Definitive evidence for the origin of insect wings remains to be discovered. [ABSTRACT FROM AUTHOR]

The Middle Cambrian Spence Shale Member (Langston Formation) and Wheeler and Marjum Formations of Utah are known to contain a diverse soft-bodied fauna, but important new paleontological material continues to be uncovered from these strata. New specimens of anomalocaridids include the largest and smallest near complete examples yet reported from Utah. New material of stem group arthropods includes two new genera and species of arachnomorphs: Nettapezoura basilika and Dicranocaris guntherorum. Other new arachnomorph material includes a new species of Leanchoilia comparable to L. protogonia Simonetta, 1970; Leanchoilia superlata? Walcott, 1912; Sidneyia Walcott, 1911a; and Mollisonia symmetrica Walcott, 1912. L. protogonia from the Burgess Shale is confirmed as a separate species and is not a composite fossil. The first example of the trilobite Elrathia kingii preserving traces of the appendages is described. In addition, new material of the bivalved arthropods Canadaspis Novozhilov in Orlov, 1960; Branchiocaris Briggs, 1976; Waptia Walcott, 1912; and Isoxys Walcott, 1890 is described. [ABSTRACT FROM AUTHOR]

Opabinia regalis has long been regarded as a curious animal, with its five eyes, its long flexible anterior process, and gill lamellae carried on the outside of overlapping lateral lobes. More recently, Opabinia has been reconstructed with lobopod limbs lying adaxial but separate from the lateral lobes. This version of Opabinia represented a lobopod–arthropod transition and prompted a hypothesis for the origin of the biramous limb that involved uniting the lobopod limb with a lateral lobe. New evidence of elemental maps is consistent with previous interpretations of the triangular structures in Opabinia as lateral extensions of the gut; there is no convincing evidence for the presence of lobopod limbs. Re-examination of critical specimens reveals that the gill lamellae are not on the outside of the lateral lobes. The limbs of Opabinia resemble the phyllopodous exopod of arthropods; the posterior margin is fringed with blades. Opabinia remains on the stem of euarthropods but not as a part of a paraphyletic Lobopodia. The Lobopodia is a clade of Cambrian armoured lobopods and onychophorans. A new hypothesis for the origin of the arthropod biramous limb from an exopod like that in Opabinia is presented, which involves an endite-bearing phyllopodous limb as an intermediate stage. [ABSTRACT FROM AUTHOR]

A new metazoan, Skeemella clavula gen. et sp. nov., is described from the Middle Cambrian Pierson Cove Formation of the Drum Mountains, Utah, USA. Skeemella is similar to vetulicolians, but differs from other examples of this group in the relative proportions of the anterior and posterior sections, the large number of divisions, and the elongate bifid termination. The posterior section is arthropodan in character. The similarity of this fossil to vetulicolians throws hypotheses of their deuterostome affinity into question and highlights their problematic status. [ABSTRACT FROM AUTHOR]

A new synziphosurine (Chelicerata:Xiphosura) is described from the Late Llandovery (Silurian) Konservat-Lagerstätte of Waukesha, Wisconsin, USA. Venustulus waukeshaensis n.gen. and sp. is characterized by a semicircular carapace with a slightly procurved posterior margin lacking genal spines and an opisthosoma composed of 10 freely articulating segments, divided into a preabdomen of seven segments with blunt pleurae and a postabdomen of three segments lacking pleurae. The tail spine is short and styliform. This is the earliest known unequivocal synziphosurine, extending their fossil record from the Wenlock to the Llandovery, and only the second species to be described with prosomal appendages; the presence of six pairs (a pair of chelicerae and five pairs of walking legs) contrasts with the seven in the synziphosurine Weinbergina opitzi, but is comparable to the number in modem horseshoe crabs. V. waukeshaensis n. gen. and sp. is not assigned to a family here pending a wider revision, but it bears most resemblance to the Weinberginidae. [ABSTRACT FROM AUTHOR]

Acaenoplax hayae is a spinose worm-like animal from the Silurian Herefordshire Lagerstätte of England, a deposit that preserves high-fidelity soft-part morphology of invertebrates in three dimensions. Specimens have been serially ground and reconstructed by computer to their three-dimensional form. Acaenoplax bears serially repeated transverse ridges dorsally, each with an array of probably aragonitic spines inclined posteriorly. Oblique ventral lobe-rows correspond in position to the dorsal ridges. Aragonitic dorsal valves overlie every third ridge; the penultimate valve is absent leaving a total of seven. The anterior termination is disk-like, surrounding an antero-medial mouth. At the posterior termination there is a cavity between the posteriormost dorsal and a posteroventral valve, from which soft-part projections extend. Acaenoplax is interpreted as a creeping epibenthic animal that fed on sessile prey. It is an ‘aculiferan’ mollusc, combining unique autapomorphic structures with characters typical of the Polyplacophora and Aplacophora. Its morphology can be accommodated within both of the competing schemes of molluscan phylogeny, and its closest living relatives in both cases are aplacophorans. The highly serialized morphology of Acaenoplax is unique within the Mollusca, but the pattern it highlights is an attractive candidate for the primitive state of serial repetition within the phylum. [ABSTRACT FROM AUTHOR]

Abstract. Four new genera and species of arthropod, Cambronatus brasseli, Wingertshellicus backesi, Eschenbachiellus wuttkensis and Magnoculus blindi, are described from the Hunsruck Slate (Lower Emsian) of Germany. All four occur in the Wingertshell Member in the vicinity of Bundenbach. They preserve remarkable details of the ventral morphology, including the appendages, as a result of pyritization. In each case the body consists of just two tagmata, a cephalon and a large number of similar trunk somites. Both Cambronatus and Wingertshellicus have fluke-like appendages making up a tail fan. The affinities of these arthropods lie with the Crustacea, apart from Magnoculus, which is an arachnomorph, but they do not fall within those clades with modern representatives. They show that morphologies other than those represented by trilobites and modern arthropod groups persisted long after the Cambrian, at least in muddy bottom marine settings. [ABSTRACT FROM AUTHOR]

More than 300 specimens of the previously rare arthropodAlalcomenaeus cambricusSimonetta have been collected from a new Burgess Shale locality in theGlossopleuraZone on Mount Stephen, British Columbia. This new material provides much more complete information on its morphology. The cephalon was covered by a shield. A pair of pedunculate eyes and three median eyes were followed by a large anterior appendage, the 'great appendage', bearing three long flagella. The two posterior head appendages, like those of the trunk, were biramous. They consisted of a segmented, inner branch, and a flap-like outer branch, fringed with long filaments. The trunk consisted of 11 somites, each protected by a tergite and bearing a pair of biramous limbs. The telson was paddle-like and fringed posteriorly with wide flat spines.Alalcomenaeuswas probably a predator, moving mainly by swimming. It is now known to be one of the more abundant, widely distributed and longest ranging of Burgess Shale arthropod genera. Its affinities lie with the Arachnomorpha. [ABSTRACT FROM AUTHOR]

Presents information on a study which investigated fossil arthropods to establish the extent to which the major structural biopolymeric components of the cuticle survive. Component of arthropod fossils; Methods used in the study; Discussion on the results; Diagenesis of fossil cuticles.

The crustaceans, like the other major living groups of arthropods, have a long evolutionary history. The earliest examples occur in the Cambrian, and fossils of this age are a critical source of evidence of relationships both within the Crustacea, and between the Crustacea and other major arthropod groups. Canadaspis perfecta, from the Middle Cambrian Burgess Shale, is important as one of the oldest well-documented crustaceans. The evidence for reconstructing its remarkable combination of primitive and derived characters is reviewed, and its possible phylogenetic significance re-assessed. [ABSTRACT FROM AUTHOR]

The article discusses research which showed that the trace fossils in the Ordovician Borrowdale Volcanic Group (BVG) were hosted within very fine dacitic tuffs. Topics discussed include the presence of volcanic ash, negative evidence for a freshwater lacustrine depositional setting, BVG as sedimentological evidence of fresh-water lake-dwelling arthropods and reasons why the global singularity of a trace fossil-bearing Ordovician lacustrine succession is not possible.

The article offers information on the result of the study involving the decay of two living forms similar to the earliest chordates in China. The two living forms include the lancelet Branchiostoma, a fish-like invertebrate having a stiffened structure called the notochord and the larva of the lamprey. Based on the research, the decomposition of the two living organism always occur in more or less the same sequence. It also mentions that the appearance of the carcass in being transformed by decay until it appears like the simpler morphology of an ancestral chordate.

Great-appendage arthropods, characterized by a highly modified anterior limb, were previously unknown after the Middle Cambrian. One fossil from the Lower Devonian Hunsrück Slate, Germany, extends the stratigraphic range of these arthropods by ∼100 million years. Schinderhannes bartelsi shows an unusual combination of anomalocaridid and euarthropod characters, including a highly specialized swimming appendage. A cladistic analysis indicates that the new taxon is basal to crown-group euarthropods and that the great-appendage arthrapods are paraphyletic. This new fossil shows that features of the anomalocaridids, including the multisegmanted raptorial appendage and circular plated mouth, persisted long after the initial radiation of the euarthropod [ABSTRACT FROM AUTHOR]