Abstract: Poropat, S.F., Nair, J.P., Syme, C.E., Mannion, P.D., Upchurch, P., Hocknull, S.A., Cook, A.G., Tischler, T.R. & Holland, T. XX.XXXX. 2017. Reappraisal of Austrosaurus mckillopi Longman, 1933 from the Allaru Mudstone of Queensland, Australia’s first named Cretaceous sauropod dinosaur. Alcheringa 41, 543–580. ISSN 0311-5518 Austrosaurus mckillopi was the first Cretaceous sauropod reported from Australia, and the first Cretaceous dinosaur reported from Queensland (northeast Australia). This sauropod taxon was established on the basis of several fragmentary presacral vertebrae (QM F2316) derived from the uppermost Lower Cretaceous (upper Albian) Allaru Mudstone, at a locality situated 77 km west-northwest of Richmond, Queensland. Prior to its rediscovery in 2014, the type site was considered lost after failed attempts to relocate it in the 1970s. Excavations at the site in 2014 and 2015 led to the recovery of several partial dorsal ribs and fragments of presacral vertebrae, all of which clearly pertained to a single sauropod dinosaur. The discovery of new material of the type individual of Austrosaurus mckillopi, in tandem with a reassessment of the material collected in the 1930s, has facilitated the rearticulation of the specimen. The resultant vertebral series comprises six presacral vertebrae—the posteriormost cervical and five anteriormost dorsals—in association with five left dorsal ribs and one right one. The fragmentary nature of the type specimen has historically hindered assessments of the phylogenetic affinities of Austrosaurus, as has the fact that these evaluations were often based on a subset of the type material. The reappraisal of the type series of Austrosaurus presented herein, on the basis of both external morphology and internal morphology visualized through CT data, validates it as a diagnostic titanosauriform taxon, tentatively placed in Somphospondyli, and characterized by the possession of an accessory lateral pneumatic foramen on dorsal vertebra I (a feature that appears to be autapomorphic) and by the presence of a robust ventral mid-line ridge on the centra of dorsal vertebrae I and II. The interpretation of the anteriormost preserved vertebra in Austrosaurus as a posterior cervical has also prompted the re-evaluation of an isolated, partial, posterior cervical vertebra (QM F6142, the ‘Hughenden sauropod’) from the upper Albian Toolebuc Formation (which underlies the Allaru Mudstone). Although this vertebra preserves an apparent unique character of its own (a spinopostzygapophyseal lamina fossa), it is not able to be referred unequivocally to Austrosaurus and is retained as Titanosauriformes indet. Austrosaurus mckillopi is one of the oldest known sauropods from the Australian Cretaceous based on skeletal remains and potentially provides phylogenetic and/or palaeobiogeographic context for later taxa such as Wintonotitan wattsi, Diamantinasaurus matildae and Savannasaurus elliottorum. Stephen F. Poropat* [sporopat@swin.edu.au; stephenfporopat@gmail.com] Department of Chemistry and Biotechnology, Swinburne University of Technology, John St, Hawthorn, Victoria 3122, Australia; Jay P. Nair [j.nair@uq.edu.au; jayraptor@gmail.com] School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia; Caitlin E. Syme [caitlin.syme@uqconnect.edu.au] School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia; Philip D. Mannion [philipdmannion@gmail.com] Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK; Paul Upchurch [p.upchurch@ucl.ac.uk] Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK; Scott A. Hocknull [scott.hocknull@qm.qld.gov.au] Geosciences, Queensland Museum, 122 Gerler Rd, Hendra, Queensland 4011, Australia; Alex G. Cook [alex.cook@y7mail.com] School of Earth Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia; Travis R. Tischler [travisr.tischler@outlook.com] Australian Age of Dinosaurs Museum of Natural History, Lot 1 Dinosaur Drive, PO Box 408, Winton, Queensland 4735, Australia; Timothy Holland [drtimothyholland@gmail.com] Kronosaurus Korner, 91 Goldring St, Richmond, Queensland 4822, Australia. *Also affiliated with: Australian Age of Dinosaurs Museum of Natural History, Lot 1 Dinosaur Drive, PO Box 408, Winton, Queensland 4735, Australia.

austrosaurus mckillopi longman
australia
sauropod dinosaur


Precursory siphuncular membranes in the body chamber of Phyllopachyceras and comparisons with other ammonoids

Abstract: Organic membranes preserved in the rear part of the body chamber of the Late Cretaceous phylloceratid ammonite Phyllopachyceras ezoense were examined with scanning electron microscopy (SEM) on the basis of well-preserved specimens from Hokkaido, Japan. SEM observations revealed that the membranes are continuous with the siphuncular tube wall in the phragmocone and consist of two layers, both of which are made of a dark, primarily conchiolin material; namely, a thinner inner homogeneous layer and a thicker outer layer with gently inclined pillar-like units. Hence, they are interpreted as the precursory siphuncular membranes. The precursory siphuncular membranes are not associated with any other organic components such as the siphuncular sheets reported in some Paleozoic and Mesozoic ammonoids. Unlike the tube-like condition in the phragmocone, the precursory siphuncular membranes in the body chamber of the specimens examined do not form a tube shape; on the ventral side the membranes are truncated and directly contact the outer shell wall. These observations suggest that the inner and outer layers of the precursory siphuncular membranes in the body chamber were respectively formed by the siphuncular epithelium from the inner side and by the invaginated septal epithelium from the outer side. It is also postulated that at the initial stage of septal formation, the rear part of the body moved slowly forward, developing a circumsiphonal invagination of the septal epithelium. Because similar conchiolin membranes are occasionally preserved in the body chambers of other phylloceratids, the above morphogenetic process applies to all members of the Phylloceratina. The tube-shaped structure in the rear part of the body chamber of desmoceratid Damesites consists only of nacreous layer. We interpret it as a pathologically overgrown prochoanitic septal neck.

body chamber
ammonoid
precursory siphuncular membrane


87Sr/86Sr and 14C evidence for peccary (Tayassuidae) introduction challenges accepted historical interpretation of the 1657 Ligon map of Barbados

Abstract: Contemporary West Indian biodiversity has been shaped by two millennia of non-native species introductions. Understanding the dynamics of this process and its legacy across extended temporal and spatial scales requires accurate knowledge of introduction timing and the species involved. Richard Ligon’s 17th century account and celebrated map of early colonial Barbados records the translocation of several Old World species to the island in the post-contact era, including pigs (Sus scrofa) believed to have been released by passing sailors the century prior. Here we challenge this long-accepted historical narrative, presenting evidence that Ligon’s “pigs” were in fact peccaries, a New World continental mammal often confused with wild boars. We document the first recorded instance of non-native peccary (Tayassuidae) on Barbados based on a securely identified mandibular specimen from a historic archaeological context. Results of specimen 87Sr/86Sr and AMS radiocarbon assays, along with newly reported data from Sr isotope environmental analyses, indicate a local origin dating to AD 1645–1670/1780–1800. These data support the presence of living peccary on Barbados some time during the first 175 years of English settlement, which, based on review of historical and archaeological data, most likely arises from 16th century peccary introduction from the Guianas/Trinidad by the Spanish or Portuguese. We argue dimorphic representations of “pigs” on Ligon’s map reflect the co-occurrence of peccary and European domestic swine on historic Barbados. Our findings overturn conventional history and provide greater taxonomic and chronological resolution for Caribbean bioinvasion studies, helping to refine our understanding of potential ecological impacts. In addition, the new bioavailable 87Sr/86Sr data for Barbados reported here advance current efforts toward mapping the Caribbean Sr isoscape.


Best Practices for Justifying Fossil Calibrations

Abstract:
Our ability to correlate biological evolution with climate change, geological evolution, and other historical patterns is essential to understanding the processes that shape biodiversity. Combining data from the fossil record with molecular phylogenetics represents an exciting synthetic approach to this challenge. The first molecular divergence dating analysis (Zuckerkandl and Pauling 1962) was based on a measure of the amino acid differences in the hemoglobin molecule, with replacement rates established (calibrated) using paleontological age estimates from textbooks (e.g., Dodson 1960). Since that time, the amount of molecular sequence data has increased dramatically, affording ever-greater opportunities to apply molecular divergence approaches to fundamental problems in evolutionary biology. To capitalize on these opportunities, increasingly sophisticated divergence dating methods have been, and continue to be, developed. In contrast, comparatively, little attention has been devoted to critically assessing the paleontological and associated geological data used in divergence dating analyses. The lack of rigorous protocols for assigning calibrations based on fossils raises serious questions about the credibility of divergence dating results (e.g., Shaul and Graur 2002; Brochu et al. 2004; Graur and Martin 2004; Hedges and Kumar 2004; Reisz and Muller 2004a, 2004b; Theodor 2004; van Tuinen and Hadly 2004a, 2004b; van Tuinen et al. 2004; Benton and Donoghue 2007; Donoghue and Benton 2007; Parham and Irmis 2008; Ksepka 2009; Benton et al. 2009; Heads 2011).

The assertion that incorrect calibrations will negatively influence divergence dating studies is not controversial. Attempts to identify incorrect calibrations through the use of a posteriori methods are available (e.g., Near and Sanderson 2004; Near et al. 2005; Rutschmann et al. 2007; Marshall 2008; Pyron 2010; Dornburg et al. 2011). We do not deny that a posteriori methods are a useful means of evaluating calibrations, but there can be no substitute for a priori assessment of the veracity of paleontological data.

Incorrect calibrations, those based upon fossils that are phylogenetically misplaced or assigned incorrect ages, clearly introduce error into an analysis. Consequently, thorough and explicit justification of both phylogenetic and chronologic age assessments is necessary for all fossils used for calibration. Such explicit justifications will help to ensure that divergence dating studies are based on the best available data. Unfortunately, the majority of previously published calibrations lack explicit explanations and justifications of the age and phylogenetic position of the key fossils. In the absence of explicit justifications, it is difficult to distinguish between correct and incorrect calibrations, and it becomes difficult to reevaluate previous claims in light of new data. Paleontology is a dynamic science, with new data and perspectives constantly emerging as a result of new discoveries (see Kimura 2010 for a recent case where the age of the earliest known record of a clade was more than doubled). Calibrations based upon the best available evidence at a given time can become inappropriate as the discovery of new specimens, new phylogenetic analyses, and ongoing stratigraphic and geochronologic revisions refine our understanding of the fossil record.

Our primary goals in this paper are to establish the best practices for justifying fossils used for the temporal calibration of molecular phylogenies. Our examples derive mainly, but not exclusively, from the vertebrate fossil record. We hope that our recommendations will lead to more credible calibrations and, as a result, more reliable divergence dates throughout the tree of life. A secondary goal is to help the community (researchers, editors, and reviewers) who might be unfamiliar with fossils to understand and overcome the challenges associated with using paleontological data. In order to accomplish these goals, we present a specimen-based protocol for selecting and documenting relevant fossils and discuss future directions for evaluating and utilizing phylogenetic and temporal data from the fossil record. We likewise encourage biologists relying on nonfossil calibrations for molecular divergence estimates (e.g., ages of island or mountain range formations, continental drift, and biomarkers) to develop their own set of rigorous guidelines so that their calibrations may also be evaluated in a systematic way.

fossil calibration
age estimate
error
good practice
node


Past extent of sea ice in the northern North Atlantic inferred from foraminiferal paleotemperature estimates

Abstract: [1] Using 150 core top samples, we developed a conservative but fairly robust new measure to reconstruct past changes in (maximum) seasonal sea ice distribution in the northern North Atlantic, hitherto a major unknown. The proxy is based on Similarity Maximum Modern-Analog Technique (SIMMAX) estimates of threshold temperatures near the sea surface (SST). Today, almost 100% of all sites with SST >2.5°C during summer, >0.4° for winters 1978–1987, and >0.75°C for Little Ice Age winters lie seaward of the sea ice margin. When applied to >60 sediment records of the Last Glacial Maximum, this proxy shows that peak glacial sea ice was far more restricted than in the “classic” CLIMAP Project Members [1981] reconstruction. During glacial summer, sea ice only covered the Arctic Ocean and western Fram Strait. The northern North Atlantic and Nordic Seas were largely ice-free and thus formed a high-latitude moisture source for the continued buildup of continental ice sheets. In contrast, sea ice spread far south across the Iceland Faeroe Ridge during glacial winter, with an inferred patch of sea ice also in the central east Atlantic, near the center of the Azores High. A broad ice-free channel extended from 50° to 60°N, forming an ideal site for large-scale convection of glacial upper North Atlantic Deep Water. The extreme seasonality in glacial sea ice formation and melt in the Nordic Seas implies a major consumption of the regional energy income.


U-Pb constraints on pulsed eruption of the Deccan Traps across the end-Cretaceous mass extinction

Abstract: Two timelines for extinction The Cretaceous-Paleogene extinction that wiped out the nonavian dinosaurs 66 million years ago was correlated with two extreme events: The Chicxulub impact occurred at roughly the same time that massive amounts of lava were erupting from the Deccan Traps (see the Perspective by Burgess). Sprain et al. used argon-argon dating of the volcanic ash from the Deccan Traps to argue that a steady eruption of the flood basalts mostly occurred after the Chicxulub impact. Schoene et al. used uranium-lead dating of zircons from ash beds and concluded that four large magmatic pulses occurred during the flood basalt eruption, the first of which preceded the Chicxulub impact. Whatever the correct ordering of events, better constraints on the timing and rates of the eruption will help elucidate how volcanic gas influenced climate. Science, this issue p. 866, p. 862; see also p. 815 Large amounts of volcanism may have preceded the large impact associated with the demise of nonavian dinosaurs. Temporal correlation between some continental flood basalt eruptions and mass extinctions has been proposed to indicate causality, with eruptive volatile release driving environmental degradation and extinction. We tested this model for the Deccan Traps flood basalt province, which, along with the Chicxulub bolide impact, is implicated in the Cretaceous-Paleogene (K-Pg) extinction approximately 66 million years ago. We estimated Deccan eruption rates with uranium-lead (U-Pb) zircon geochronology and resolved four high-volume eruptive periods. According to this model, maximum eruption rates occurred before and after the K-Pg extinction, with one such pulse initiating tens of thousands of years prior to both the bolide impact and extinction. These findings support extinction models that incorporate both catastrophic events as drivers of environmental deterioration associated with the K-Pg extinction and its aftermath.

eruption
deccan traps
mass extinction
volcanism


New footprints from Laetoli (Tanzania) provide evidence for marked body size variation in early hominins

Abstract: Laetoli is a well-known palaeontological locality in northern Tanzania whose outstanding record includes the earliest hominin footprints in the world (3.66 million years old), discovered in 1978 at Site G and attributed to Australopithecus afarensis. Here, we report hominin tracks unearthed in the new Site S at Laetoli and referred to two bipedal individuals (S1 and S2) moving on the same palaeosurface and in the same direction as the three hominins documented at Site G. The stature estimates for S1 greatly exceed those previously reconstructed for Au. afarensis from both skeletal material and footprint data. In combination with a comparative reappraisal of the Site G footprints, the evidence collected here embodies very important additions to the Pliocene record of hominin behaviour and morphology. Our results are consistent with considerable body size variation and, probably, degree of sexual dimorphism within a single species of bipedal hominins as early as 3.66 million years ago. DOI: http://dx.doi.org/10.7554/eLife.19568.001


Experimental taphonomy of fish - role of elevated pressure, salinity and pH

Abstract: Experiments are reported to reconstruct the taphonomic pathways of fish toward fossilisation. Acrylic glass autoclaves were designed that allow experiments to be carried out at elevated pressure up to 11 bar, corresponding to water depths of 110 m. Parameters controlled or monitored during decay reactions are pressure, salinity, proton activities (pH), electrochemical potentials (Eh), and bacterial populations. The most effective environmental parameters to delay or prevent putrefaction before a fish carcass is embedded in sediment are (1) a hydrostatic pressure in the water column high enough that a fish carcass may sink to the bottom sediment, (2) hypersaline conditions well above seawater salinity, and (3) a high pH to suppress the reproduction rate of bacteria. Anoxia, commonly assumed to be the key parameter for excellent preservation, is important in keeping the bottom sediment clear of scavengers but it does not seem to slow down or prevent putrefaction. We apply our results to the world-famous Konservat-Lagerstätten Eichstätt-Solnhofen, Green River, and Messel where fish are prominent fossils, and reconstruct from the sedimentary records the environmental conditions that may have promoted preservation. For Eichstätt-Solnhofen an essential factor may have been hypersaline conditions. Waters of the Green River lakes were at times highly alkaline and hypersaline because the lake stratigraphy includes horizons rich in sodium carbonate and halite. In the Messel lake sediments some fossiliferous horizons are rich in FeCO3 siderite, a mineral indicating highly reduced conditions and a high pH.


The radiation of cynodonts and the ground plan of mammalian morphological diversity

Abstract: Cynodont therapsids diversified extensively after the Permo-Triassic mass extinction event, and gave rise to mammals in the Jurassic. We use an enlarged and revised dataset of discrete skeletal characters to build a new phylogeny for all main cynodont clades from the Late Permian to the Early Jurassic, and we analyse models of morphological diversification in the group. Basal taxa and epicynodonts are paraphyletic relative to eucynodonts, and the latter are divided into cynognathians and probainognathians, with tritylodonts and mammals forming sister groups. Disparity analyses reveal a heterogeneous distribution of cynodonts in a morphospace derived from cladistic characters. Pairwise morphological distances are weakly correlated with phylogenetic distances. Comparisons of disparity by groups and through time are non-significant, especially after the data are rarefied. A disparity peak occurs in the Early/Middle Triassic, after which period the mean disparity fluctuates little. Cynognathians were characterized by high evolutionary rates and high diversity early in their history, whereas probainognathian rates were low. Community structure may have been instrumental in imposing different rates on the two clades.


Non-integumentary melanosomes can bias reconstructions of the colours of fossil vertebrates

Abstract: The soft tissues of many fossil vertebrates preserve evidence of melanosomes—micron-scale organelles that inform on integumentary coloration and communication strategies. In extant vertebrates, however, melanosomes also occur in internal tissues. Hence, fossil melanosomes may not derive solely from the integument and its appendages. Here, by analyzing extant and fossil frogs, we show that non-integumentary melanosomes have high fossilization potential, vastly outnumber those from the skin, and potentially dominate the melanosome films preserved in some fossil vertebrates. Our decay experiments show that non-integumentary melanosomes usually remain in situ provided that carcasses are undisturbed. Micron-scale study of fossils, however, demonstrates that non-integumentary melanosomes can redistribute through parts of the body if carcasses are disturbed by currents. Collectively, these data indicate that fossil melanosomes do not always relate to integumentary coloration. Integumentary and non-integumentary melanosomes can be discriminated using melanosome geometry and distribution. This is essential to accurate reconstructions of the integumentary colours of fossil vertebrates.

colour
fossil vertebrate
tissue
non-integumentary melanosome


Reconstruction of the geographic extent of drought anomalies in northwestern China over the last 539 years and its teleconnection with the Pacific Ocean

Abstract: Recent paleo-climatic/environmental studies have resulted in several high-resolution paleo-precipitation/moisture reconstructions in Northwestern (NW) China over extended periods. Nevertheless, those reconstructions are mostly about the climatic history of individual sites, while fine-grained portrayal and analysis of the geographic extent of drought anomalies across the entire NW China are still missing. We based our study on the dryness/wetness grade series of 19 sites in NW China, which are primarily derived from historical documents, to reconstruct the annual geographic extent of drought anomalies in NW China in AD 1470–2008. Our reconstruction reveals the following periods of drought in NW China: the AD 1470s–1490s, 1620s–1640s, 1700s–1720s, 1770s–1790s, 1860s–1870s, and 1910s–1930s. The most extremely dry years were AD 1928 and 1929. In addition, we found that the influence of El Niño Southern Oscillation (ENSO) on the geographic extent of drought anomalies in NW China was non-stationary at the inter-annual to multi-decadal timescale and that the correlation switched from positive to negative since the late ‘Little Ice Age’. We propose that this non-stationary relationship is attributable to the variance of ENSO and the strength of Asian Summer Monsoon. To conclude, we discuss the implications of the above findings within the context of global warming.

geographic extent
drought anomaly
historical document


Arthropods in modern resins reveal if amber accurately recorded forest arthropod communities

Abstract: Significance It is not known whether the fossil content of amber accurately represents the arthropod biodiversity of past forests, and if and how those fossils can be compared with recent fauna for studies and predictions of biodiversity change through time. Our study of arthropods (mainly insects and spiders) living around the resinous angiosperm tree Hymenaea verrucosa Gaertner, 1791 in the lowland coastal forest of Madagascar, and arthropods trapped by the resin produced by this tree species, demonstrates that amber does not record the true past biodiversity of the entire forest. However, our results reveal how taphonomic processes, arthropod behaviors, and ecological relationships can influence arthropod death assemblages in resins and play a crucial role in controlling their taxonomic compositions. Amber is an organic multicompound derivative from the polymerization of resin of diverse higher plants. Compared with other modes of fossil preservation, amber records the anatomy of and ecological interactions between ancient soft-bodied organisms with exceptional fidelity. However, it is currently suggested that ambers do not accurately record the composition of arthropod forest paleocommunities, due to crucial taphonomic biases. We evaluated the effects of taphonomic processes on arthropod entrapment by resin from the plant Hymenaea, one of the most important resin-producing trees and a producer of tropical Cenozoic ambers and Anthropocene (or subfossil) resins. We statistically compared natural entrapment by Hymenaea verrucosa tree resin with the ensemble of arthropods trapped by standardized entomological traps around the same tree species. Our results demonstrate that assemblages in resin are more similar to those from sticky traps than from malaise traps, providing an accurate representation of the arthropod fauna living in or near the resiniferous tree, but not of entire arthropod forest communities. Particularly, arthropod groups such as Lepidoptera, Collembola, and some Diptera are underrepresented in resins. However, resin assemblages differed slightly from sticky traps, perhaps because chemical compounds in the resins attract or repel specific insect groups. Ground-dwelling or flying arthropods that use the tree-trunk habitat for feeding or reproduction are also well represented in the resin assemblages, implying that fossil inclusions in amber can reveal fundamental information about biology of the past. These biases have implications for the paleoecological interpretation of the fossil record, principally of Cenozoic amber with angiosperm origin.


Diverse Cretaceous larvae reveal the evolutionary and behavioural history of antlions and lacewings

Abstract: Myrmeleontiformia are an ancient group of lacewing insects characterized by predatory larvae with unusual morphologies and behaviours. Mostly soil dwellers with a soft cuticle, their larvae fossilize only as amber inclusions, and thus their fossil record is remarkably sparse. Here, we document a disparate assemblage of myrmeleontiform larvae from the mid-Cretaceous amber (99 Ma) of Myanmar, evidence of a considerable diversification. Our cladistic analysis integrating extant and extinct taxa resolves the fossils as both stem- and crown-groups. Similarities between extinct and extant species permit inferences of larval ethology of the fossil species through statistical correlation analyses with high support, implying that morphological disparity matched behavioural diversity. An improved understanding of the evolutionary history of antlions and relatives supports the conclusion that hunting strategies, such as camouflage and fossoriality, were acquired early within the lineage.


The Impact of Global Warming and Anoxia on Marine Benthic Community Dynamics: an Example from the Toarcian (Early Jurassic)

Abstract: The Pliensbachian-Toarcian (Early Jurassic) fossil record is an archive of natural data of benthic community response to global warming and marine long-term hypoxia and anoxia. In the early Toarcian mean temperatures increased by the same order of magnitude as that predicted for the near future; laminated, organic-rich, black shales were deposited in many shallow water epicontinental basins; and a biotic crisis occurred in the marine realm, with the extinction of approximately 5% of families and 26% of genera. High-resolution quantitative abundance data of benthic invertebrates were collected from the Cleveland Basin (North Yorkshire, UK), and analysed with multivariate statistical methods to detect how the fauna responded to environmental changes during the early Toarcian. Twelve biofacies were identified. Their changes through time closely resemble the pattern of faunal degradation and recovery observed in modern habitats affected by anoxia. All four successional stages of community structure recorded in modern studies are recognised in the fossil data (i.e. Stage III: climax; II: transitional; I: pioneer; 0: highly disturbed). Two main faunal turnover events occurred: (i) at the onset of anoxia, with the extinction of most benthic species and the survival of a few adapted to thrive in low-oxygen conditions (Stages I to 0) and (ii) in the recovery, when newly evolved species colonized the re-oxygenated soft sediments and the path of recovery did not retrace of pattern of ecological degradation (Stages I to II). The ordination of samples coupled with sedimentological and palaeotemperature proxy data indicate that the onset of anoxia and the extinction horizon coincide with both a rise in temperature and sea level. Our study of how faunal associations co-vary with long and short term sea level and temperature changes has implications for predicting the long-term effects of “dead zones” in modern oceans.


Fossil flowers from the early Palaeocene of Patagonia, Argentina, with affinity to Schizomerieae (Cunoniaceae)

Abstract: Abstract Background and Aims Early Palaeocene (Danian) plant fossils from Patagonia provide information on the recovery from the end-Cretaceous extinction and Cenozoic floristic change in South America. Actinomorphic flowers with eight to ten perianth parts are described and evaluated in a phylogenetic framework. The goal of this study is to determine the identity of these fossil flowers and to discuss their evolutionary, palaeoecological and biogeographical significance Methods More than 100 fossilized flowers were collected from three localities in the Danian Salamanca and Peñas Coloradas Formations in southern Chubut. They were prepared, photographed and compared with similar extant and fossil flowers using published literature and herbarium specimens. Phylogenetic analysis was performed using morphological and molecular data. Key results The fossil flowers share some but not all the synapomorphies that characterize the Schizomerieae, a tribe within Cunoniaceae. These features include the shallow floral cup, variable number of perianth parts arranged in two whorls, laciniate petals, anthers with a connective extension, and a superior ovary with free styles. The number of perianth parts is doubled and the in situ pollen is tricolporate, with a surface more like that of other Cunoniaceae outside Schizomerieae, such as Davidsonia or Weinmannia. Conclusions An extinct genus of crown-group Cunoniaceae is recognized and placed along the stem lineage leading to Schizomerieae. Extant relatives are typical of tropical to southern-temperate rainforests, and these fossils likely indicate a similarly warm and wet temperate palaeoclimate. The oldest reliable occurrences of the family are fossil pollen and wood from the Upper Cretaceous of the Antarctica and Argentina, whereas in Australia the family first occurs in upper Palaeocene deposits. This discovery demonstrates that the family survived the Cretaceous–Palaeogene boundary event in Patagonia and that diversification of extant lineages in the family was under way by the earliest Cenozoic.


Deciphering the early evolution of echinoderms with Cambrian fossils

Abstract: Echinoderms are a major group of invertebrate deuterostomes that have been an important component of marine ecosystems throughout the Phanerozoic. Their fossil record extends back to the Cambrian, when several disparate groups appear in different palaeocontinents at about the same time. Many of these early forms exhibit character combinations that differ radically from extant taxa, and thus their anatomy and phylogeny have long been controversial. Deciphering the earliest evolution of echinoderms therefore requires a detailed understanding of the morphology of Cambrian fossils, as well as the selection of an appropriate root and the identification of homologies for use in phylogenetic analysis. Based on the sister‐group relationships and ontogeny of modern species and new fossil discoveries, we now know that the first echinoderms were bilaterally symmetrical, represented in the fossil record by Ctenoimbricata and some early ctenocystoids. The next branch in echinoderm phylogeny is represented by the asymmetrical cinctans and solutes, with an echinoderm‐type ambulacral system originating in the more crownward of these groups (solutes). The first radial echinoderms are the helicoplacoids, which possess a triradial body plan with three ambulacra radiating from a lateral mouth. Helicocystoids represent the first pentaradial echinoderms and have the mouth facing upwards with five radiating recumbent ambulacra. Pentaradial echinoderms diversified rapidly from the beginning of their history, and the most significant differences between groups are recorded in the construction of the oral area and ambulacra, as well as the nature of their feeding appendages. Taken together, this provides a clear narrative of the early evolution of the echinoderm body plan.

early evolution
echinoderm
cambrian fossil


The Mesozoic marine revolution: evidence from snails, predators and grazers

Abstract: Tertiary and Recent marine gastropods include in their ranks a complement of mechanically sturdy forms unknown in earlier epochs. Open coiling, planispiral coiling, and umbilici detract from shell sturdiness, and were commoner among Paleozoic and Early Mesozoic gastropods than among younger forms. Strong external sculpture, narrow elongate apertures, and apertural dentition promote resistance to crushing predation and are primarily associated with post-Jurassic mesogastropods, neogastropods, and neritaceans. The ability to remodel the interior of the shell, developed primarily in gastropods with a non-nacreous shell structure, has contributed greatly to the acquisition of these antipredatory features. The substantial increase of snail-shell sturdiness beginning in the Early Cretaceous has accompanied, and was perhaps in response to, the evolution of powerful, relatively small, shell-destroying predators such as teleosts, stomatopods, and decapod crustaceans. A simultaneous intensification of grazing, also involving skeletal destruction, brought with it other fundamental changes in benthic community structure in the Late Mesozoic, including a trend toward infaunalization and the disappearance or environmental restriction of sessile animals which cannot reattach once they are dislodged. The rise and diversification of angiosperms and the animals dependent on them for food coincides with these and other Mesozoic events in the marine benthos and plankton. The new predators and prey which evolved in conjunction with the Mesozoic reorganization persisted through episodes of extinction and biological crisis. Possibly, continental breakup and the wide extent of climatic belts during the Late Mesozoic contributed to the conditions favorable to the evolution of skeleton-destroying consumers. This tendency may have been exaggerated by an increase in shelled food supply resulting from the occupation of new adaptive zones by infaunal bivalves and by shell-inhabiting hermit crabs. Marine communities have not remained in equilibrium over their entire geological history. Biotic revolutions made certain modes of life obsolete and resulted in other adaptive zones becoming newly occupied.

mesozoic marine revolution
predator
phanerozoic
mmr


Are hyoliths Palaeozoic lophophorates?

Abstract: Abstract The phylogenetic position of hyoliths has long been unsettled, with recent discoveries of a tentaculate feeding apparatus (‘lophophore’) and fleshy apical extensions from the shell (‘pedicle’) suggesting a lophophorate affinity. Here, we describe the first soft parts associated with the feeding apparatus of an orthothecid hyolith, Triplicatella opimus from the Chengjiang biota of South China. The tuft-like arrangement of the tentacles of T. opimus differs from that of hyolithids, suggesting they collected food directly from the substrate. A reassessment of the feeding organ in hyolithids indicates that it does not represent a lophophore and our analysis of the apical structures associated with some orthothecids show that these represent crushed portions of the shell and are not comparable to the brachiopod pedicle. The new information suggests that hyoliths are more likely to be basal members of the lophotrochozoans rather than lophophorates closely linked with the Phylum Brachiopoda.

hyolith
lophophorate
phylogenetic position


In quest for a phylogeny of Mesozoic mammals

Abstract: We propose a phylogeny of all major groups of Mesozoic mammals based on phylogenetic analyses of 46 taxa and 275 osteological and dental characters, using parsimony methods (Swofford 2000) . Mammalia sensu lato (Mammaliaformes of some authors) are monophyletic. Within mammals, Sinoconodon is the most primitive taxon. Sinoconodon, morganucodontids, docodonts, and Hadrocodium lie outside the mammalian crown group (crown therians + Monotremata) and are, successively, more closely related to the crown group. Within the mammalian crown group, we recognize a fundamental division into australosphenidan (Gondwana) and boreosphenidan (Laurasia) clades, possibly with vicariant geographic distributions during the Jurassic and Early Cretaceous. We provide additional derived characters supporting these two ancient clades, and we present two evolutionary hypotheses as to how the molars of early monotremes could have evolved. We consider two alternative placements of allotherians (haramiyids + multituberculates). The first, supported by strict consensus of most parsimonious trees, suggests that multituberculates (but not other alllotherians) are closely related to a clade including spalacotheriids + crown therians (Trechnotheria as redefined herein). Alternatively, allotherians can be placed outside the mammalian crown group by a constrained search that reflects the traditional emphasis on the uniqueness of the multituberculate dentition. Given our dataset, these alternative topologies differ in tree-length by only ~0.6% of the total tree length; statistical tests show that these positions do not differ significantly from one another. Similarly, there exist two alternative positions of eutriconodonts among Mesozoic mammals, contingent on the placement of other major mammalian clades. Of these, we tentatively favor recognition of a monophyletic Eutriconodonta, nested within the mammalian crown group. We suggest that the "obtuse-angle symmetrodonts" are paraphyletic, and that they lack reliable and unambiguous synapomorphies.

phylogeny
mesozoic mammal
dental character
crown therian
australosphenida


Age, Correlation, and Lithostratigraphic Revision of the Upper Cretaceous (Campanian) Judith River Formation in Its Type Area (North-Central Montana), with a Comparison of Low- and High-Accommodation Alluvial Records

Abstract: Despite long-standing significance in the annals of North American stratigraphy and paleontology, key aspects of the Upper Cretaceous Judith River Formation remain poorly understood. We re-evaluate Judith River stratigraphy and propose new reference sections that both document the range of lithologies present in the type area in north-central Montana and reveal dramatic changes in facies architecture, fossil content, and rock accumulation rates that can be mapped throughout the type area and into the plains of southern Alberta and Saskatchewan. One section spans the basal contact of the Judith River Formation with marine shales of the underlying Claggett Formation. This contact, which lies along the base of the Parkman Sandstone Member of the Judith River Formation, is erosional and consistent with an episode of forced regression, contrary to previous descriptions. A second reference section spans the entire Judith River Formation. This complete section hosts a lithologic discontinuity, herein referred to as the mid-Judith discontinuity, that reflects a regional reorganization of terrestrial and marine depositional systems associated with a turnaround from regressive to transgressive deposition. The mid-Judith discontinuity correlates with the base of three backstepping marine sequences in the eastern sector of the type area and is thus interpreted as the terrestrial expression of a maximum regressive surface. This mid-Judith discontinuity defines the boundary between the new McClelland Ferry and overlying Coal Ridge Members of the Judith River Formation. The shallow marine sandstones that form the backstepping sequences represent the leading edge of the Bearpaw transgression in this region and are formalized as the new Woodhawk Member of the Judith River Formation in a third reference section. New 40Ar/39Ar ages indicate (1) that the mid-Judith discontinuity formed ∼76.2 Ma, coincident with the onset of the Bearpaw transgression in central Montana; and (2) that the Bearpaw Sea had advanced westward beyond the Judith River type area by ∼75.2 Ma, on the basis of the dating of a bentonite bed at the base of the Bearpaw Formation. These new ages also provide more confident age control for important vertebrate fossil occurrences in the Judith River Formation. Facies analysis across the mid-Judith discontinuity reveals how alluvial systems respond to regional base-level rise, which is implicit with the increase in rock accumulation rates and marine transgression. With the increase in accommodation signaled by the mid-Judith discontinuity, the alluvial system shifted in dominance from fluvial channel to overbank deposits, with greater tidal influence in channel sands, more hydromorphic and carbonaceous overbank deposits, and a higher frequency of bentonites and skeletal concentrations, suggesting higher preservation rates. These features, along with the appearance of extraformational pebbles above the discontinuity, are consistent with an upstream tectonic explanation for the addition of accommodation.

judith river formation
montana
mid-judith discontinuity
western interior seaway


A Paleogenomic Perspective on Evolution and Gene Function: New Insights from Ancient DNA

Abstract: Background After three decades of research aimed at recovering DNA from preserved remains, the field of ancient DNA is moving rapidly toward the sequencing and analysis of complete paleogenomes. These data provide a means to better understand evolutionary processes through time, including inference of ancient demography and admixture between lineages, as well as adaptive evolution within populations. The increasing scope of paleogenomics. The proportion of sequence reads that are mappable to a reference genome decreases rapidly with evolutionary distance (blue bars). Recent divergence from a living species is therefore key to successful paleogenomic assembly. Fortunately, most species are diverged from a living relative by <50 million years, so it should in principle be possible to generate paleogenomes for a wide taxonomic variety of organisms. Ma, millions of years ago. Advances Key advances enabling a paleogenomic perspective include improvements in DNA extraction and library preparation, as well as methods to enrich ancient libraries for targeted loci. These methods have made it possible to isolate ancient DNA from a far wider range of preservation environments than has been assumed to be attainable, including extending the temporal reach of ancient DNA back to nearly 1 million years. Outlook Although relatively few paleogenomes have been published to date, their number is rising rapidly, and it is increasingly clear that the range of specimens from which paleogenomes could be produced is much larger than has been assumed previously. As more data become available, including genomic data from living organisms, the capacity to use paleogenomic data to infer evolutionary change through time will continue to expand, particularly with respect to the evolution of populations and the link between genotype and phenotype. The Present of the Past A major goal of evolutionary biology is to understand the process of speciation and the changes that have accompanied and shaped the current distribution of species. Paleogenomics directly addresses these questions through the use of ancient DNA. Shapiro and Hofreiter (10.1126/science.1236573) review the origins and growth of this field and explain how challenges owing to the limited amount of DNA available for analysis and the possibility of contamination by modern material have been overcome. The publication of partial and complete paleogenomes within the last few years has reinvigorated research in ancient DNA. No longer limited to short fragments of mitochondrial DNA, inference of evolutionary processes through time can now be investigated from genome-wide data sampled as far back as 700,000 years. Tremendous insights have been made, in particular regarding the hominin lineage. With rare exception, however, a paleogenomic perspective has been mired by the quality and quantity of recoverable DNA. Though conceptually simple, extracting ancient DNA remains challenging, and sequencing ancient genomes to high coverage remains prohibitively expensive for most laboratories. Still, with improvements in DNA isolation and declining sequencing costs, the taxonomic and geographic purview of paleogenomics is expanding at a rapid pace. With improved capacity to screen large numbers of samples for those with high proportions of endogenous ancient DNA, paleogenomics is poised to become a key technology to better understand recent evolutionary events.

paleogenomic perspective
ancient dna
evolutionary process


At the feet of the dinosaurs: the early history and radiation of lizards

Abstract: Lizards, snakes and amphisbaenians together constitute the Squamata, the largest and most diverse group of living reptiles. Despite their current success, the early squamate fossil record is extremely patchy. The last major survey of squamate palaeontology and evolution was published 20 years ago. Since then, there have been changes in systematic theory and methodology, as well as a steady trickle of new fossil finds. This review examines our current understanding of the first 150 million years of squamate evolution in the light of the new data and changing ideas. Contrary to previous reports, no squamate fossils are currently documented before the Jurasis. Nonetheless, indirect evidence predicts that squamates had evolved by at least the middle Triassic, and diversified into existing major lineages before the end of this period. There is thus a major gap in the squamate record at a time when key morphological features were evolving. With the exception of fragmentary remains from Africa and India, Jurassic squamates are known only from localities in northern continents (Laurasia). The situation improves in the Early Cretaceous, but the southern (Gondwanan) record remains extremely poor. This constrains palaeobiogeographic discussion and makes it difficult to predict centres of origin for major squamate clades on the basis of fossil evidence alone. Preliminary mapping of morphological characters onto a consensus tree demonstrates stages in the sequence of acquisition for some characters of the skull and postcranial skeleton, but many crucial stages – most notably those relating to the acquisition of squamate skull kinesis – remain unclear.

lizard amphisbaenian squamate lepidosauria


The ear region of earliest known elephant relatives: new light on the ancestral morphotype of proboscideans and afrotherians

Abstract: One of the last major clades of placental mammals recognized was the Afrotheria, which comprises all main endemic African mammals. This group includes the ungulate‐like paenungulates, and among them the elephant order Proboscidea. Among afrotherians, the petrosal anatomy remains especially poorly known in Proboscidea. We provide here the first comparative CT scan study of the ear region of the two earliest known proboscideans (and paenungulates), Eritherium and Phosphatherium, from the mid Palaeocene and early Eocene of Morocco. It is helpful to characterize the ancestral morphotype of Proboscidea to understand petrosal evolution within proboscideans and afrotherians. The petrosal structure of these two taxa shows several differences. Eritherium is more primitive than Phosphatherium and closer to the basal paenungulate Ocepeia in several traits (inflated tegmen tympani, very deep fossa subarcuata and ossified canal for ramus superior of stapedial artery). Phosphatherium, however, retains plesiomorphies such as a true crus commune secundaria. A cladistic analysis of petrosal traits of Eritherium and Phosphatherium among Proboscidea results in a single tree with a low level of homoplasy in which Eritherium, Phosphatherium and Numidotherium are basal. This contrasts with previous phylogenetic studies showing homoplasy in petrosal evolution among Tethytheria. It suggests that evolutionary modalities of petrosal characters differ with the taxonomic level among Afrotheria: noticeable convergences occurred among the paenungulate orders, whereas little homoplasy seems to have occurred at intra‐ordinal level in orders such as Proboscidea. Most petrosal features of both Eritherium and Phosphatherium are primitive. The ancestral petrosal morphotype of Proboscidea was not specialized but was close to the generalized condition of paenungulates, afrotherians, and even eutherians. This is consistent with cranial and dental characters of Eritherium, suggesting that the ancestral morphotypes of the different paenungulate orders were close to each other. Specializations occurred rapidly after the ordinal radiation of Paenungulata.

ear region
ancestral morphotype
proboscidean


Finite Element Analysis and Understanding the Biomechanics and Evolution of Living and Fossil Organisms

Abstract: AbstractFinite element analysis (FEA) is a technique that reconstructs stress, strain, and deformation in a digital structure. Although commonplace in engineering and orthopedic science for more than 30 years, only recently has it begun to be adopted in the zoological and paleontological sciences to address questions of organismal morphology, function, and evolution. Current research tends to focus on either deductive studies that assume a close relationship between form and function or inductive studies that aim to test this relationship, although explicit hypothesis-testing bridges these two standpoints. Validation studies have shown congruence between in vivo or in vitro strain and FE-inferred strain. Future validation work on a broad range of taxa will assist in phylogenetically bracketing our extinct animal FE-models to increase confidence in our input parameters, although currently, FEA has much potential in addressing questions of form-function relationships, providing appropriate questions are ask...

fea
strain
deformation
finite element analysis
load


Human Remains from the Pleistocene-Holocene Transition of Southwest China Suggest a Complex Evolutionary History for East Asians

Abstract: Background Later Pleistocene human evolution in East Asia remains poorly understood owing to a scarcity of well described, reliably classified and accurately dated fossils. Southwest China has been identified from genetic research as a hotspot of human diversity, containing ancient mtDNA and Y-DNA lineages, and has yielded a number of human remains thought to derive from Pleistocene deposits. We have prepared, reconstructed, described and dated a new partial skull from a consolidated sediment block collected in 1979 from the site of Longlin Cave (Guangxi Province). We also undertook new excavations at Maludong (Yunnan Province) to clarify the stratigraphy and dating of a large sample of mostly undescribed human remains from the site. Methodology/Principal Findings We undertook a detailed comparison of cranial, including a virtual endocast for the Maludong calotte, mandibular and dental remains from these two localities. Both samples probably derive from the same population, exhibiting an unusual mixture of modern human traits, characters probably plesiomorphic for later Homo, and some unusual features. We dated charcoal with AMS radiocarbon dating and speleothem with the Uranium-series technique and the results show both samples to be from the Pleistocene-Holocene transition: ∼14.3-11.5 ka. Conclusions/Significance Our analysis suggests two plausible explanations for the morphology sampled at Longlin Cave and Maludong. First, it may represent a late-surviving archaic population, perhaps paralleling the situation seen in North Africa as indicated by remains from Dar-es-Soltane and Temara, and maybe also in southern China at Zhirendong. Alternatively, East Asia may have been colonised during multiple waves during the Pleistocene, with the Longlin-Maludong morphology possibly reflecting deep population substructure in Africa prior to modern humans dispersing into Eurasia.

pleistocene-holocene transition
southwest china
human remain
hominin


Hunting the Extinct Steppe Bison (Bison priscus) Mitochondrial Genome in the Trois-Frères Paleolithic Painted Cave

Abstract: Despite the abundance of fossil remains for the extinct steppe bison (Bison priscus), an animal that was painted and engraved in numerous European Paleolithic caves, a complete mitochondrial genome sequence has never been obtained for this species. In the present study we collected bone samples from a sector of the Trois-Frères Paleolithic cave (Ariège, France) that formerly functioned as a pitfall and was sealed before the end of the Pleistocene. Screening the DNA content of the samples collected from the ground surface revealed their contamination by Bos DNA. However, a 19,000-year-old rib collected on a rock apart the pathway delineated for modern visitors was devoid of such contaminants and reproducibly yielded Bison priscus DNA. High-throughput shotgun sequencing combined with conventional PCR analysis of the rib DNA extract enabled to reconstruct a complete mitochondrial genome sequence of 16,318 bp for the extinct steppe bison with a 10.4-fold coverage. Phylogenetic analyses robustly established the position of the Bison priscus mitochondrial genome as basal to the clade delineated by the genomes of the modern American Bison bison. The extinct steppe bison sequence, which exhibits 93 specific polymorphisms as compared to the published Bison bison mitochondrial genomes, provides an additional resource for the study of Bovinae specimens. Moreover this study of ancient DNA delineates a new research pathway for the analysis of the Magdalenian Trois-Frères cave.

bison priscus
mitochondrial genome
present study


Simulation of Eocene extreme warmth and high climate sensitivity through cloud feedbacks

Abstract: A state-of-the-art climate model successfully simulates Early Eocene extreme warmth and high climate sensitivity during the PETM. The Early Eocene, a period of elevated atmospheric CO2 (>1000 ppmv), is considered an analog for future climate. Previous modeling attempts have been unable to reproduce major features of Eocene climate indicated by proxy data without substantial modification to the model physics. Here, we present simulations using a state-of-the-art climate model forced by proxy-estimated CO2 levels that capture the extreme surface warmth and reduced latitudinal temperature gradient of the Early Eocene and the warming of the Paleocene-Eocene Thermal Maximum. Our simulations exhibit increasing equilibrium climate sensitivity with warming and suggest an Eocene sensitivity of more than 6.6°C, much greater than the present-day value (4.2°C). This higher climate sensitivity is mainly attributable to the shortwave cloud feedback, which is linked primarily to cloud microphysical processes. Our findings highlight the role of small-scale cloud processes in determining large-scale climate changes and suggest a potential increase in climate sensitivity with future warming.

extreme warmth
high climate sensitivity
simulation


Fossilization causes organisms to appear erroneously primitive by distorting evolutionary trees

Abstract: Fossils are vital for calibrating rates of molecular and morphological change through geological time, and are the only direct source of data documenting macroevolutionary transitions. Many evolutionary studies therefore require the robust phylogenetic placement of extinct organisms. Here, we demonstrate that the inevitable bias of the fossil record to preserve just hard, skeletal morphology systemically distorts phylogeny. Removal of soft part characters from 78 modern vertebrate and invertebrate morphological datasets resulted in significant changes to phylogenetic signal; it caused individual taxa to drift from their original position, predominately downward toward the root of their respective trees. This last bias could systematically inflate evolutionary rates inferred from molecular data because first fossil occurrences will not be recognised as such. Stem-ward slippage, whereby fundamental taphonomic biases cause fossils to be interpreted as erroneously primitive, is therefore a ubiquitous problem for all biologists attempting to infer macroevolutionary rates or sequences.


Definition, diagnosis, and origin of Mammalia

Abstract: ABSTRACT Mammalia is defined by its ancestry as the taxon originating with the most recent common ancestor of extant Monotremata and Theria. To diagnose Mammalia as so defined, 176 character transformations in the skull and postcranial skeleton, distributed among Placentalia, Marsupialia, Multituberculata, Monotremata, Morganucodontidae, Tritylodontidae, and Exaeretodon, were polarized, scored, and subjected to PAUP. Only one most parsimonious tree was identified (BL = 190, CI = 0.926): (Exaeretodon (Tritylodontidae (Morganucodontidae (Monotremata (Multituberculata (Marsupialia, Placentalia)))))). Thirty-seven osteological synapomorphies diagnose Mammalia. Triassic and Early Jurassic taxa commonly referred to as mammals, including Morganucodontidae, Kuehneotheriidae, and Haramiyidae, were found to lie outside of Mammalia. These fossils document that the mammalian lineage had diverged from other known synapsid lineages by the Norian (Late Triassic). However, the earliest evidence that Monotremata and Theri...

mammalia tritylodontidae definition cynodont


Late Cretaceous mega-, meso-, and microfloras from Lower Silesia

Abstract: Late Cretaceous plants from the North Sudetic Basin (Lower Silesia, south-western Poland) are reviewed on the basis of megaflora from 17 localities (270 identifiable specimens), mesoflora from two localities, and microflora from four localities. Major sites are Rakowice Małe and Bolesławiec. Eight megafloral assemblages are distinguished (Assemblage 1, Turonian; Assemblages 2, 3, lower–middle Coniacian; Assemblages 4, 5, upper Coniacian?–lower Santonian?; Assemblages 6–8, lower–middle Santonian); the bulk of the palaeoflora is from Assemblages 4–6 and 8. Megaflora consists of 29 taxa (6 ferns, 4 conifers, and 19 angiosperms). Geinitzia reichenbachii the most common species. westerhausianum (Richter, Halamski and Kvaček comb. nov. is a trifoliolate leaf re-interpreted as a representative of Fagales. Three species of Dewalquea are distinguished: Dewalquea haldemiana , Dewalquea insignis , and Dewalquea aff. gelindenensis . Platanites willigeri Halamski and Kvaček sp. nov. is characterised by trifoliolate leaves, the median leaflet of which is ovate, unlobed, with a serrate margin, and cuneate base. Palaeocommunities inferred from the megafossil record include: a back swamp forest dominated by Geinitzia , with abundant ferns; a Dryophyllum -dominated riparian forest; a forest with Dewalquea and Platanites willigeri possibly located in the marginal part of the alluvial plain; dunes with D. haldemiana and Konijnenburgia ; a fern savanna with patches of Pinus woodlands. Palynoassemblage A from the Nowogrodziec Member, studied mostly at Rakowice Małe and Żeliszów, consists of 126 taxa, including 105 terrestrial palynomorphs (54 bryophyte, lycophyte, and pteridophyte spores, 16 gymnosperms, 35 angiosperms). The mega- and mesofossil records are dominated by angiosperms; the palynoassemblages are dominated by ferns. Palaeocommunities represented solely by the microfossil record are halophytic (with Frenelopsis and unconfirmed presence of Nypa ) and pioneer vegetation. Palaeocommunities are intermediate in general character between those pre-dating the Cretaceous Terrestrial Revolution and modern, angiosperm- dominated vegetation. In comparison to older plant assemblages from contiguous areas laurophylls are much rarer; this might correspond to a real phenomenon of exclusion of lauroids from Santonian riparian forests. The studied assemblage is more similar to younger palaeofloras than to older ones; this might be interpreted as stabilisation of communities after a period of pronounced change related to the rise to dominance of the angiosperms. In contrast to widespread endemism among vertebrates of the European Archipelago, the plant cover consists mostly of species that are widely distributed.


Abstract: Thulborn, R.A., 2013. Lark Quarry revisited: a critique of methods used to identify a large dinosaurian track-maker in the Winton Formation (Albian–Cenomanian), western Queensland, Australia. Alcheringa, http://dx.doi.org/10.1080/03115518.2013.748482 A remarkable assemblage of dinosaur tracks in the Winton Formation (Albian–Cenomanian) at Lark Quarry, a site in western Queensland, Australia, has long been regarded as evidence of a dinosaurian stampede. However, one recently published study has claimed that existing interpretation of Lark Quarry is incorrect because the largest track-maker at the site was misidentified and could not have played a pivotal role in precipitating a stampede. That recent study has identified the largest track-maker as an ornithopod (bipedal plant-eating dinosaur) similar or identical to Muttaburrasaurus and not, as formerly supposed, a theropod (predaceous dinosaur) resembling Allosaurus. Those iconoclastic claims are examined here and are shown to be groundless: they are based partly on misconceptions and partly on fabricated data that have been assessed uncritically using quantitative measures of questionable significance. Such ill-founded claims do not reveal any substantial flaw in the existing interpretation of the Lark Quarry dinosaur tracks.

large dinosaurian track-maker
winton formation
western queensland


A phylogeny of Cenozoic macroperforate planktonic foraminifera from fossil data

Abstract: We present a complete phylogeny of macroperforate planktonic foraminifer species of the Cenozoic Era (∼65 million years ago to present). The phylogeny is developed from a large body of palaeontological work that details the evolutionary relationships and stratigraphic (time) distributions of species‐level taxa identified from morphology (‘morphospecies’). Morphospecies are assigned to morphogroups and ecogroups depending on test morphology and inferred habitat, respectively. Because gradual evolution is well documented in this clade, we have identified many instances of morphospecies intergrading over time, allowing us to eliminate ‘pseudospeciation’ and ‘pseudoextinction’ from the record and thereby permit the construction of a more natural phylogeny based on inferred biological lineages. Each cladogenetic event is determined as either budding or bifurcating depending on the pattern of morphological change at the time of branching. This lineage phylogeny provides palaeontologically calibrated ages for each divergence that are entirely independent of molecular data. The tree provides a model system for macroevolutionary studies in the fossil record addressing questions of speciation, extinction, and rates and patterns of evolution.

phylogeny
cenozoic
planktonic foraminifera
morphospecie


Body size, sampling completeness, and extinction risk in the marine fossil record

Abstract: Abstract. Larger body size has long been assumed to correlate with greater risk of extinction, helping to shape body-size distributions across the tree of life, but a lack of comprehensive size data for fossil taxa has left this hypothesis untested for most higher taxa across the vast majority of evolutionary time. Here we assess the relationship between body size and extinction using a data set comprising the body sizes, stratigraphic ranges, and occurrence patterns of 9408 genera of fossil marine animals spanning eight Linnaean classes across the past 485 Myr. We find that preferential extinction of smaller-bodied genera within classes is substantially more common than expected due to chance and that there is little evidence for preferential extinction of larger-bodied genera. Using a capture–mark–recapture analysis, we find that this size bias of extinction persists even after accounting for a pervasive bias against the sampling of smaller-bodied genera within classes. The size bias in extinction also persists after including geographic range as an additional predictor of extinction, indicating that correlation between body size and geographic range does not provide a simple explanation for the association between size and extinction. Regardless of the underlying causes, the preferential extinction of smaller-bodied genera across many higher taxa and most of geologic time indicates that the selective loss of large-bodied animals is the exception, rather than the rule, in the evolution of marine animals.

extinction risk
marine animal
class
body size


Brachiopods hitching a ride: an early case of commensalism in the middle Cambrian Burgess Shale

Abstract:
Ecological interactions, including symbiotic associations such as mutualism, parasitism and commensalism are crucial factors in generating evolutionary novelties and strategies. Direct examples of species interactions in the fossil record generally involve organisms attached to sessile organisms in an epibiont or macroboring relationship. Here we provide support for an intimate ecological association between a calcareous brachiopod (Nisusia) and the stem group mollusc Wiwaxia from the Burgess Shale. Brachiopod specimens are fixed to Wiwaxia scleritomes, the latter showing no signs of decay and disarticulation, suggesting a live association. We interpret this association as the oldest unambiguous example of a facultative ectosymbiosis between a sessile organism and a mobile benthic animal in the fossil record. The potential evolutionary advantage of this association is discussed, brachiopods benefiting from ease of attachment, increased food supply, avoidance of turbid benthic conditions, biofoul and possible protection from predators, suggesting commensalism (benefiting the symbiont with no impact for the host). While Cambrian brachiopods are relatively common epibionts, in particular on sponges, the association of Nisusia with the motile Wiwaxia is rare for a brachiopod species, fossil or living, and suggests that symbiotic associations were already well established and diversified by the ''middle'' (Series 3, Stage 5) Cambrian.
ymbiosis in a broad sense refers to the intimate physical association between two organisms, commonly one species (symbiont) living with a host species 1 , associations that are notoriously difficult to detect in the fossil record. Seen as a crucial factor in the evolution of organisms 2 , symbiotic relationships are displayed by millions of modern day organisms canvasing the terrestrial and marine realms. Associations can take a number of forms, generally categorized based on the impact incurred by the host 3 , including parasitism (negative impact on the host), mutualism (positive impacts for both host and symbiont) and commensalism (no direct impact for host but positive for the symbiont). Symbiosis is a poorly studied aspect of the fossil record, owing largely to taphonomic biases that inconveniently inhibit preservation of direct interaction between two or more organisms in life. Despite the difficulties, various forms of symbiosis have been identified in the fossil record, principally from Ordovician and younger strata and predominantly dealing with epibiont and macroboring organisms 4 .
Brachiopods, one of the dominant filter feeders of the Palaeozoic, frequently play both roles, acting as symbionts and as hosts. Attaching themselves to various sessile organisms for support 5 and having a range of organisms living on 6,7 and to some extent inside their shell 8, 9 . Brachiopods generally attach to hard substrates by means of a pedicle, this includes substrates such as, sponges 10 , algae 5 , other brachiopods 11 , disarticulated skeletal elements 12 , an attachment strategy that has not significantly changed since the phylum arose in the Cambrian 13 . Brachiopods have, in rare instances, been documented attached to the spines of live echinoids from the Carboniferous (Pennsylvanian) echinoderm Lagersta ¨tte in the Winchell Formation of Texas 14 . Exceptionally preserved in situ records of Cambrian brachiopods attached to other organisms have been reported from Burgess Shale-type deposits 5, 10 , and such associations generally involve other sessile organisms such as sponges and algae. Enigmatic shells (possibly brachiopods) attached to the disk of the eldoniid Rotadiscus 15 , have also been reported, but it is not clear whether eldoniids had a semi-vagrant lifestyle 16 or were entirely sessile 15 . A couple of occurrences of brachiopods possibly attached to unambiguous vagile organisms have also been noted from the Burgess Shale, including on the arthropod Sidneyia inexpectans 17 and on an isolated sclerite of the stem group mollusk Wiwaxia corrugata 18 . However, in both cases the possible attachments occurred on disarticulated body elements suggesting the hosts represented molts or carcasses and not live animals. One other example involved a complete and

commensalism
burgess shale
ecological interaction
brachiopod
cambrian lagerstätten


Subsequent biotic crises delayed marine recovery following the late Permian mass extinction event in northern Italy

Abstract: The late Permian mass extinction event was the largest biotic crisis of the Phanerozoic and has the longest recovery interval of any extinction event. It has been hypothesised that subsequent carbon isotope perturbations during the Early Triassic are associated with biotic crises that impeded benthic recovery. We test this hypothesis by undertaking the highest-resolution study yet made of the rock and fossil records of the entire Werfen Formation, Italy. Here, we show that elevated extinction rates were recorded not only in the Dienerian, as previously recognised, but also around the Smithian/Spathian boundary. Functional richness increases across the Smithian/Spathian boundary associated with elevated origination rates in the lower Spathian. The taxonomic and functional composition of benthic faunas only recorded two significant changes: (1) reduced heterogeneity in the Dienerian, and (2) and a faunal turnover across the Smithian/Spathian boundary. The elevated extinctions and compositional shifts in the Dienerian and across the Smithian/Spathian boundary are associated with a negative and positive isotope excursion, respectively, which supports the hypothesis that subsequent biotic crises are associated with carbon isotope shifts. The Spathian fauna represents a more advanced ecological state, not recognised in the previous members of the Werfen Formation, with increased habitat differentiation, a shift in the dominant modes of life, appearance of stenohaline taxa and the occupation of the erect and infaunal tiers. In addition to subsequent biotic crises delaying the recovery, therefore, persistent environmental stress limited the ecological complexity of benthic recovery prior to the Spathian.

recovery
mass extinction event
biotic crisis
early triassic


Otoliths in situ from Sarmatian (Middle Miocene) fishes of the Paratethys. Part III: tales from the cradle of the Ponto-Caspian gobies

Abstract: Articulated fossil fish skeletons with otoliths in situ provide a unique opportunity to link these two, otherwise independent data sets of skeletons and otoliths. They provide calibration points for otoliths also adding important information for the evolutionary interpretation of fishes. Here, we review nine articulated skeletons of gobies from the early Sarmatian of Dolje, Croatia, and Belgrade, Serbia, which were previously regarded as members of a single gobiid and a callionymid species. We found them to represent five different gobiid species belonging to five different genera, four of which are related to extant endemic Ponto-Caspian gobiid lineages. The species are: Aphia macrophthalma n.sp., Proneogobius n.gen. pullus (the only previously recognized species), Protobenthophilus n.gen. squamatus n.sp., Economidichthys triangularis (a species first described based on otoliths) and Hesperichthys n.gen. reductus n.sp. Five specimens contained otoliths in situ and a sixth shows imprints of otoliths which unfortunately must have been lost in the past, probably during preparation of the fossil. Together, they represent all five species recognized by skeletons, and three are linked to otolith-based species. Isolated otoliths have been reviewed from a variety of collections from Sarmatian strata in Austria, Bulgaria, Czechia, Romania and Slovakia resulting in the description of five new otolith-based species: Benthophilus? ovisulcus n.sp., Benthophilus styriacus n.sp., Protobenthophilus strashimirovi n.sp., Economidichthys altidorsalis n.sp. and Knipowitschia bulgarica n.sp. Our review demonstrates that all major endemic Ponto-Caspian gobiid lineages were already present during Sarmatian times, thereby pushing back their origin by approximately 5-10 myr in comparison to previously published dates for dichotomies. In our assessment, the origination of these lineages is linked to the early stage of separation of the Paratethys from the world oceans and the ecological changes that occurred during that time. These geological events parallel a dramatic increase in gobiid radiation and speciation, giving rise to many lineages, not all of which have persisted until today.


Intrinsic versus extrinsic biases in the fossil record: contrasting the fossil record of echinoids in the Triassic and early Jurassic using sampling data, phylogenetic analysis, and molecular clocks

Abstract: Abstract Four independent lines of evidence, (1) the quality of specimen preservation, (2) taxonomic collection curves, (3) molecular divergence estimates, and (4) ghost lineage analysis of a genus-level cladogram, point to echinoids having a much poorer fossil record in the Triassic than in the Lower Jurassic. Furthermore, preservational differences between Triassic and Lower Jurassic echinoids have remained a consistent feature over 160 years of discovery. Differences exist in how effectively paleontologists have collected the fauna from available outcrops in the Triassic and Lower Jurassic. Collection curves suggest that rocks have been more efficiently searched for their fossils in Europe than elsewhere in the world, and that Lower Jurassic faunas are better sampled from available outcrop than Triassic faunas. The discovery of Triassic taxa has quickened in pace over the past 4 decades (though largely driven by a single Lagerstätte—the St. Cassian beds) while discoveries of new taxa from the Lower Jurassic have slowed. Molecular analysis of extant families and ghost lineage analysis of Triassic and Lower Jurassic genera both point to poorer sampling of Triassic faunas. This difference in the quality of the fossil record may be partially explained by differences in rock outcrop area, as marine sedimentary rocks are much less common in the Triassic than in the Lower Jurassic. However, improving biomechanical design of the echinoid test over this critical time interval was probably as important, and better explains observed preservational trends. Changes in the quality of the echinoid fossil record were thus driven as much by intrinsic biological factors as by sampling patterns.


A new scyphozoan from the Cambrian Fortunian Stage of South China

Abstract: Animals with radial symmetry are abundant in the Cambrian Fortunian Stage of South China, but with relatively low diversity: representatives include Olivooides, Quadrapyrgites, carinachitiids, hexangulaconulariids and Pseudooides. Here, we report a new radial animal, Qinscyphus necopinus gen. et sp. nov., from the Fortunian small shelly fauna of southern Shaanxi Province, South China. Qinscyphus necopinus has a cup‐shaped profile, with slightly raised annuli and five groups of triangular thickenings in pentaradial symmetry. This organism has a comparable morphology to, and thus a close affinity with, Olivooides and Quadrapyrgites, and is interpreted as a coronate scyphozoan. This discovery adds a new crown‐group cnidarian to the Cambrian Explosion.

scyphozoan
cambrian fortunian stage
south china


Ecomorphological diversifications of Mesozoic marine reptiles: the roles of ecological opportunity and extinction

Abstract: Mesozoic marine ecosystems were dominated by several clades of reptiles, including sauropterygians, ichthyosaurs, crocodylomorphs, turtles, and mosasaurs, that repeatedly invaded ocean ecosystems. Previous research has shown that marine reptiles achieved great taxonomic diversity in the Middle Triassic, as they broadly diversified into many feeding modes in the aftermath of the Permo-Triassic mass extinction, but it is not known whether this initial phase of evolution was exceptional in the context of the entire Mesozoic. Here, we use a broad array of disparity, morphospace, and comparative phylogenetic analyses to test this. Metrics of ecomorphology, including functional disparity in the jaws and dentition and skull-size diversity, show that the Middle to early Late Triassic represented a time of pronounced phenotypic diversification in marine reptile evolution. Following the Late Triassic extinctions, diversity recovered, but disparity did not, and it took over 100 Myr for comparable variation to recover in the Campanian and Maastrichtian. Jurassic marine reptiles generally failed to radiate into vacated functional roles. The signatures of adaptive radiation are not seen in all marine reptile groups. Clades that diversified during the Triassic biotic recovery, the sauropterygians and ichthyosauromorphs, do show early diversifications, early high disparity, and early burst, while less support for these models is found in thalattosuchian crocodylomorphs and mosasaurs. Overall, the Triassic represented a special interval in marine reptile evolution, as a number of groups radiated into new adaptive zones.

diversification
marine reptile
reptile
ecological opportunity
ecomorphological diversification


An elasmobranch assemblage from the terrestrial-marine transitional Lethbridge Coal Zone (Dinosaur Park Formation: Upper Campanian), Alberta, Canada

Abstract: The change in depositional environments observed in the Cretaceous (Upper Campanian) strata in the region of Dinosaur Provincial Park, Alberta, from the proximal coastal plain deposits of the Oldman Formation to the lowland coastal plain deposits of the Dinosaur Park Formation, reveals an associated change in faunal composition. An assemblage collected from a microvertebrate site in the paralic deposits of the Lethbridge Coal Zone (uppermost Dinosaur Park Formation) reflects an increasing marine influence. Elasmobranch (sharks and rays) remains are the most abundant, both in terms of number of overall taxa and number of elements, and they are the best-preserved specimens. However, several brackish-water-tolerant osteichthyan taxa, and four reptile taxa (two marine and two terrestrial), were also recovered, although they exhibited evidence of extensive taphonomic reworking. The elasmobranch fauna collected from the Dinosaur Park locality is uncommon for vertebrate microfossil assemblages in the Dinosaur Park Formation of Alberta and in equivalent beds in Montana. Seven of the 10 taxa collected from this site [Cretorectolobus olsoni Case, 1978; Eucrossorhinus microcuspidatus Case, 1978; Odontaspis aculeatus (Cappetta and Case, 1975); Archaeolamna kopingensis judithensis Siverson, 1992; Protoplatyrhina renae Case, 1978; Ischyrhiza mira Leidy, 1856; and Ptychotrygon blainensis Case, 1978] are recorded for the first time from the uppermost section of the Judith River Group in Alberta; Carcharias steineri (Case, 1987), represents the first occurrence within the upper Judith River Group from either Alberta or Montana.

lethbridge coal zone
dinosaur park formation
upper campanian


Estimating dispersal and evolutionary dynamics in diploporan blastozoans (Echinodermata) across the great Ordovician biodiversification event

Abstract: Echinoderms make up a substantial component of Ordovician marine invertebrates, yet their speciation and dispersal history as inferred within a rigorous phylogenetic and statistical framework is lacking. We use biogeographic stochastic mapping (BSM; implemented in the R package BioGeoBEARS) to infer ancestral area relationships and the number and type of dispersal events through the Ordovician for diploporan blastozoans and related species. The BSM analysis was divided into three time slices to analyze how dispersal paths changed before and during the great Ordovician biodiversification event (GOBE) and within the Late Ordovician mass extinction intervals. The best-fit biogeographic model incorporated jump dispersal, indicating this was an important speciation strategy. Reconstructed areas within the phylogeny indicate the first diploporan blastozoans likely originated within Baltica or Gondwana. Dispersal, jump dispersal, and sympatry dominated the BSM inference through the Ordovician, while dispersal paths varied in time. Long-distance dispersal events in the Early Ordovician indicate distance was not a significant predictor of dispersal, whereas increased dispersal events between Baltica and Laurentia are apparent during the GOBE, indicating these areas were important to blastozoan speciation. During the Late Ordovician, there is an increase in dispersal events among all paleocontinents. The drivers of dispersal are attributed to oceanic and epicontinental currents. Speciation events plotted against geochemical data indicate that blastozoans may not have responded to climate cooling events and other geochemical perturbations, but additional data will continue to shed light on the drivers of early Paleozoic blastozoan speciation and dispersal patterns.

dispersal
ordovician biodiversification event
phylogeny


Dinosaur tracks from the Langenberg Quarry (Late Jurassic, Germany) reconstructed with historical photogrammetry: Evidence for large theropods soon after insular dwarfism

Abstract: Here we describe dinosaur tracks from the Langenberg Quarry near Goslar (Lower Saxony) that represent the first footprints from the Late Jurassic of Germany discovered outside the Wiehen Mountains. The footprints are preserved in Kimmeridgian marginal marine carbonates. They vary in length from 36 to 47 cm and were made by theropod dinosaurs. The original tracksite with 20 footprints was destroyed by quarrying soon after its discovery in 2003. Only the five best defined footprints were excavated. Based on scanned-in analog photographs which were taken during the excavation, a three-dimensional (3-D) model of the original tracksite was generated by applying historical photogrammetry. The resulting model is accurate enough to allow a detailed description of the original tracksite. Different preservation types result from changing substrate properties and include both well-defined footprints and deeply impressed footprints with elongated heel and variably defined digit impressions. The tracksite was discovered stratigraphically close to the bone accumulation of the dwarfed sauropod dinosaur Europasaurus holgeri and probably records a sea level fall along with a faunal interchange, which would likely have eliminated the resident dwarf island fauna. The two largest and best preserved footprints differ from most other Late Jurassic theropod footprints in their great width. Two different trackmaker species might have been present at the site. Several hypotheses presented in a recent paper on Late Jurassic dinosaur tracks from the Wiehen Mountains by Diedrich (2011b) are commented upon herein.

late jurassic
historical photogrammetry
faunal interchange
dinosaur track


Spatial point pattern analysis of traces (SPPAT): An approach for visualizing and quantifying site-selectivity patterns of drilling predators

Abstract: Site-selectivity analysis of drilling predation traces may provide useful behavioral information concerning a predator interacting with its prey. However, traditional approaches exclude some spatial information (i.e., oversimplified trace position) and are dependent on the scale of analysis (e.g., arbitrary grid system used to divide the prey skeleton into sectors). Here we introduce the spatial point pattern analysis of traces (SPPAT), an approach for visualizing and quantifying the distribution of traces on shelled invertebrate prey, which includes improved collection of spatial information inherent to drillhole location (morphometric-based estimation), improved visualization of spatial trends (kernel density and hotspot mapping), and distance-based statistics for hypothesis testing (K-, L-, and pair correlation functions). We illustrate the SPPAT approach through case studies of fossil samples, modern beach-collected samples, and laboratory feeding trials of naticid gastropod predation on bivalve prey. Overall results show that kernel density and hotspot maps enable visualization of subtle variations in regions of the shell with higher density of predation traces, which can be combined with the maximum clustering distance metric to generate hypotheses on predatory behavior and anti-predatory responses of prey across time and geographic space. Distance-based statistics also capture the major features in the distribution of traces across the prey skeleton, including aggregated and segregated clusters, likely associated with different combinations of two modes of drilling predation, edge and wall drilling. The SPPAT approach is transferable to other paleoecologic and taphonomic data such as encrustation and bioerosion, allowing for standardized investigation of a wide range of biotic interactions.

point pattern analysis
trace
sppat
predation
hotspot map


A review of trabecular bone functional adaptation: what have we learned from trabecular analyses in extant hominoids and what can we apply to fossils?

Abstract: Many of the unresolved debates in palaeoanthropology regarding evolution of particular locomotor or manipulative behaviours are founded in differing opinions about the functional significance of the preserved external fossil morphology. However, the plasticity of internal bone morphology, and particularly trabecular bone, allowing it to respond to mechanical loading during life means that it can reveal greater insight into how a bone or joint was used during an individual's lifetime. Analyses of trabecular bone have been commonplace for several decades in a human clinical context. In contrast, the study of trabecular bone as a method for reconstructing joint position, joint loading and ultimately behaviour in extant and fossil non‐human primates is comparatively new. Since the initial 2D studies in the late 1970s and 3D analyses in the 1990s, the utility of trabecular bone to reconstruct behaviour in primates has grown to incorporate experimental studies, expanded taxonomic samples and skeletal elements, and improved methodologies. However, this work, in conjunction with research on humans and non‐primate mammals, has also revealed the substantial complexity inherent in making functional inferences from variation in trabecular architecture. This review addresses the current understanding of trabecular bone functional adaptation, how it has been applied to hominoids, as well as other primates and, ultimately, how this can be used to better interpret fossil hominoid and hominin morphology. Because the fossil record constrains us to interpreting function largely from bony morphology alone, and typically from isolated bones, analyses of trabecular structure, ideally in conjunction with that of cortical structure and external morphology, can offer the best resource for reconstructing behaviour in the past.

review
trabecular bone
functional adaptation
behaviour


Are brachiopods better than bivalves? Mechanisms of turbidity tolerance and their interaction with feeding in articulates

Abstract: The dominance of Paleozoic articulate brachiopods in once-muddy environments may be explained by an array of mechanisms and structures that reject nonfood particles, in some cases without interruption of feeding: (1) behavioral flexibility of the lophophore and its individual filaments; (2) persistent, variable-speed rejection currents on the mantle, which sometimes concentrate pseudofeces in topographically controlled vortices; (3) costae and alae (which have many other probable functions); (4) inhalant currents elevated above substrate; (5) marginal setae. Some mantle currents parallel (and presumably augment) lophophore feeding currents; others diverge up to 90° to provide rejection while feeding continues. Contrary to previous reports, the lateral cilia seem to be involved in rejection and may reverse. Repeated claims for the superiority of the gill of suspension-feeding bivalves over the “weak” individual filaments of the lophophore are probably false. In suspension-feeding bivalves, simultaneous feeding and rejection are likely to be hindered by fused gill elements and mucus-trapping of food. The energetically efficient articulates are predicted to have a competitive advantage over suspension-feeding bivalves when oxygen or food is limiting, as, for example, after a bolide impact.


Phylogeny and diversification of bryozoans

Abstract: Although only a small fraction of the estimated 6000 extant bryozoan species has been analysed in a molecular phylogenetic context, the resultant trees have increased our understanding of the interrelationships between major bryozoan groups, as well as between bryozoans and other metazoan phyla. Molecular systematic analyses have failed to recover the Lophophorata as a monophyletic clade until recently, when phylogenomic data placed the Brachiopoda as sister to a clade formed by Phoronida + Bryozoa. Among bryozoans, class Phylactolaemata has been shown to be the sister group of Gymnolaemata + Stenolaemata, corroborating earlier anatomical inferences. Despite persistent claims, there are no unequivocal bryozoans of Cambrian age: the oldest bryozoans are stenolaemates from the Tremadocian of China. Stenolaemates underwent a major radiation during the Ordovician, but the relationships between the six orders involved are poorly understood, mostly because the simple and plastic skeletons of stenolaemates make phylogenetic analyses difficult. Bryozoans were hard‐hit by the mass extinction/s in the late Permian and it was not until the Middle Jurassic that they began to rediversify, initially through the cyclostome stenolaemates. The most successful post‐Palaeozoic order (Cheilostomata) evolved a calcareous skeleton de novo from a soft‐bodied ancestor in the Late Jurassic, maintained a low diversity until the mid‐Cretaceous and then began to radiate explosively. A remarkable range of morphological structures in the form of highly modified zooidal polymorphs, or non‐zooidal or intrazooidal modular elements, is postulated to have evolved repeatedly in this group. Crucially, many of these structures have been linked to micropredator protection and can be interpreted as key traits linked to the diversification of cheilostomes.

diversification
bryozoan
phylogenetic analysis
zooid arrangement
ctenostome-grade ancestor


Evidence on relation of brain to endocranial cavity in oviraptorid dinosaurs

Abstract: Brains in living tetrapods other than birds and mammals do not entirely fill the brain cavities. Examination of dinosaur braincases does not usually allow determination relating to how close walls of endocranial cavity lay to the surface of brain. The here described fragment of a skull roof of an oviraptorid dinosaur, Ingenia yanshini, shows perfectly preserved, numerous vascular imprints that cover the internal surfaces of frontals and parietals in the region roofing the cerebral hemispheres and cerebellum. This specimen shows that in oviraptorids the brain closely fitted the brain cavity, to the extent found in birds and mammals. Among dinosaurs, only one similar case has been previously reported in an ornithomimid, Dromiceiomimus brevitertius, but the preserved vascular imprints are less numerous and regular in this dinosaur than in Ingenia yanshini.

brain
endocranial cavity
oviraptorid dinosaur
skull roof
theropod


Flies and flowers: taxonomic diversity of anthophiles and pollinators

Abstract: Abstract The Diptera are the second most important order among flower-visiting (anthophilous) and flower-pollinating insects worldwide. Their taxonomic diversity ranges from Nematocera to Brachycera, including most families within the suborders. Especially important are Syrphidae, Bombyliidae, and Muscoidea. Other families, especially of small flies, are less appreciated and often overlooked for their associations with flowers. We have compiled records of their flower visitations to show that they may be more prevalent than usually thought. Our knowledge of anthophilous Diptera needs to be enhanced by future research concerning (i) the significance of nocturnal Nematocera and acalypterate muscoids as pollinators, (ii) the extent to which the relatively ineffective pollen-carrying ability of some taxa can be compensated by the abundance of individuals, and (iii) the role of Diptera as pollinators of the first flowering plants (Angiospermae) by using phylogenetic and palaeontological evidence. Specializations in floral relationships involve the morphology of Diptera, especially of their mouthparts, nutritional requirements, and behaviour, as well as concomitant floral attributes. The South African flora has the most highly specialized relations with dipterous pollinators, but in arctic and alpine generalist fly–flower relations are important in pollination and fly nutrition. Résumé Les diptères occupent le second rang au monde parmi les ordres d’insectes qui visitent les fleurs (anthophiles) et qui assurent la pollinisation. Leur diversité taxonomique va des nématocères aux brachycères et inclut presque toutes les familles de ces sous-ordres, en particulier les Syrphidae, les Bombyliidae et les Muscoidea qui occupent une place prépondérante. Les associations des autres familles avec les fleurs, particulièrement les familles de mouches de petite taille, passent souvent inaperçues. Nous avons compilé des données sur leurs visites aux fleurs dans le but de démontrer qu’elles sont probablement plus importantes qu’on ne le croit. Nos connaissances des diptères anthophiles doivent être complétées par d’autres recherches (i) pour déterminer l’importance des nématocères nocturnes et des muscoïdes acalyptères comme pollinisateurs, (ii) pour évaluer jusqu’à quel point l’inefficacité relative de certains taxons comme transporteurs de pollen peut être compensée par l’abondance des individus et (iii) pour juger du rôle des diptères comme pollinisateurs des premières plantes à fleurs (Angiospermae) en utilisant des données phylogénétiques et paléontologiques. Les spécialisations de relations fleurs–insectes sont basées sur des particularités morphologiques des diptères, surtout de leurs pièces buccales, sur leurs besoins nutritifs et sur leur comportement, en même temps que sur les attributs correspondants des fleurs. La flore de l’Afrique du Sud est celle qui a les relations les plus spécialisées avec les diptères pollinisateurs. Cependant, dans les régions arctiques et alpines, des relations apparemment non spécialisées entre les mouches et les fleurs sont importantes pour la pollinisation des fleurs et l’alimentation des mouches. [Traduit par la Rédaction]


The “evolution” of Anomalocaris and its classification in the arthropod class Dinocarida (nov.) and order Radiodonta (nov.)

Abstract: The remarkable “evolution” of the reconstructions of Anomalocaris, the extraordinary predator from the 515 million year old Middle Cambrian Burgess Shale of British Columbia, reflects the dramatic changes in our interpretation of early animal life on Earth over the past 100 years. Beginning in 1892 with a claw identified as the abdomen and tail of a phyllocarid crustacean, parts of Anomalocaris have been described variously as a jellyfish, a sea-cucumber, a polychaete worm, a composite of a jellyfish and sponge, or have been attached to other arthropods as appendages. Charles D. Walcott collected complete specimens of Anomalocaris nathorsti between 1911 and 1917, and a Geological Survey of Canada party collected an almost complete specimen of Anomalocaris canadensis in 1966 or 1967, but neither species was adequately described until 1985. At that time they were interpreted by Whittington and Briggs to be representatives of “a hitherto unknown phylum.” Here, using recently collected specimens, the two species are newly reconstructed and described in the genera Anomalocaris and Laggania, and interpreted to be members of an extinct arthropod class, Dinocarida, and order Radiodonta, new to science. The long history of inaccurate reconstruction and mistaken identification of Anomalocaris and Laggania exemplifies our great difficulty in visualizing and classifying, from fossil remains, the many Cambrian animals with no apparent living descendants.