Artificial intelligence provides greater accuracy in the classification of modern and ancient bone surface modifications

Abstract: Bone surface modifications are foundational to the correct identification of hominin butchery traces in the archaeological record. Until present, no analytical technique existed that could provide objectivity, high accuracy, and an estimate of probability in the identification of multiple structurally-similar and dissimilar marks. Here, we present a major methodological breakthrough that incorporates these three elements using Artificial Intelligence (AI) through computer vision techniques, based on convolutional neural networks. This method, when applied to controlled experimental marks on bones, yielded the highest rate documented to date of accurate classification (92%) of cut, tooth and trampling marks. After testing this method experimentally, it was applied to published images of some important traces purportedly indicating a very ancient hominin presence in Africa, America and Europe. The preliminary results are supportive of interpretations of ancient butchery in some places, but not in others, and suggest that new analyses of these controversial marks should be done following the protocol described here to confirm or disprove these archaeological interpretations.

classification
bone surface modification
tooth


Fossil skulls reveal that blood flow rate to the brain increased faster than brain volume during human evolution

Abstract: The evolution of human cognition has been inferred from anthropological discoveries and estimates of brain size from fossil skulls. A more direct measure of cognition would be cerebral metabolic rate, which is proportional to cerebral blood flow rate (perfusion). The hominin cerebrum is supplied almost exclusively by the internal carotid arteries. The sizes of the foramina that transmitted these vessels in life can be measured in hominin fossil skulls and used to calculate cerebral perfusion rate. Perfusion in 11 species of hominin ancestors, from Australopithecus to archaic Homo sapiens, increases disproportionately when scaled against brain volume (the allometric exponent is 1.41). The high exponent indicates an increase in the metabolic intensity of cerebral tissue in later Homo species, rather than remaining constant (1.0) as expected by a linear increase in neuron number, or decreasing according to Kleiber's Law (0.75). During 3 Myr of hominin evolution, cerebral tissue perfusion increased 1.7-fold, which, when multiplied by a 3.5-fold increase in brain size, indicates a 6.0-fold increase in total cerebral blood flow rate. This is probably associated with increased interneuron connectivity, synaptic activity and cognitive function, which all ultimately depend on cerebral metabolic rate.

blood flow rate
brain volume
measure
hominin evolution
fossil skull


Analyzing Taphonomic Deformation of Ankylosaur Skulls Using Retrodeformation and Finite Element Analysis

Abstract: Taphonomic deformation can make the interpretation of vertebrate fossil morphology difficult. The effects of taphonomic deformation are investigated in two ankylosaurid dinosaur taxa, Euoplocephalus tutus (to investigate effects on our understanding of intraspecific variation) and Minotaurasaurus ramachandrani (to investigate the validity of this genus). The ratio of orbit maximum rostrocaudal length to perpendicular height is used as a strain ellipse, which can be used to determine if ankylosaur skull fossils have been dorsoventrally compacted during fossilization and diagenesis. The software program Geomagic is used to retrodeform three-dimensional (3D) digital models of the ankylosaur skulls. The effects of sediment compaction are modeled using finite element analysis, and the resulting strain distributions are compared with the retrodeformed models as a test of the retrodeformation method. Taphonomic deformation can account for a large amount of intraspecific variation in Euoplocephalus, but finite element analysis and retrodeformation of Minotaurasaurus shows that many of its diagnostic features are unlikely to result from deformation.

taphonomic deformation
retrodeformation
finite element analysis
amount


Coupled Greenhouse Warming and Deep Sea Acidification in the Middle Eocene

Abstract: [1] The Middle Eocene Climatic Optimum (MECO) is an enigmatic warming event that represents an abrupt reversal in long-term cooling through the Eocene. In order to further assess the timing and nature of this event, we have assembled stable isotope and calcium carbonate concentration records from multiple Deep Sea Drilling Project and Ocean Drilling Program sites for the time interval between ∼43 and 38 Ma. Revised stratigraphy at several sites and compilation of δ18O records place peak warming during the MECO event at 40.0 Ma (Chron C18n.2n). The identification of the δ18O excursion at sites in different geographic regions indicates that the climatic effects of this event were globally extensive. The total duration of the MECO event is estimated at ∼500 ka, with peak warming lasting <100 ka. Assuming minimal glaciation in the late middle Eocene, ∼4°–6°C total warming of both surface and deep waters is estimated during the MECO at the study sites. The interval of peak warming at ∼40.0 Ma also coincided with a worldwide decline in carbonate accumulation at sites below 3000 m depth, reflecting a temporary shoaling of the calcite compensation depth. The synchroneity of deep-water acidification and globally extensive warming makes a persuasive argument that the MECO event was linked to a transient increase in atmospheric pCO2. The results of this study confirm previous reports of significant climatic instability during the middle Eocene. Furthermore, the direct link between warming and changes in the carbonate chemistry of the deep ocean provides strong evidence that changes in greenhouse gas concentrations exerted a primary control on short-term climate variability during this critical period of Eocene climate evolution.


Comparative physiology of suspension-feeding in living brachiopods and bivalves: evolutionary implications

Abstract: This paper presents scaling equations relating suspension-feeding rates to body size for articulate brachiopods and bivalve molluscs, two classes which represent a significant component of the fossil record of marine benthic communities. Clearance (feeding) rates of five species of living articulate brachiopods and three species of epifaunal suspension-feeding bivalve molluscs collected from mid-latitude fjords of Newfoundland and New Zealand were measured in similar experimental conditions. In comparisons within and between the two classes, we found that both plectolophous and spirolophous brachiopods had significantly lower feeding rates than mytilids, which are filibranchs, but that a sympatric primitive eulamellibranch veneroid bivalve had rates comparable to the brachiopods. Articulate brachiopods do not appear to feed effectively at the high algal concentrations which bivalves can exploit. The data on comparative suspension-feeding rates support the hypothesis that past changes in diversity and distribution of bivalves and brachiopods may be related to an overall increase in energy flux and escalation of metabolic rates during the Phanerozoic.


SNAKES OF THE SIWALIK GROUP (MIOCENE OF PAKISTAN): SYSTEMATICS AND RELATIONSHIP TO ENVIRONMENTAL CHANGE

Abstract: The lower and middle Siwalik Group of the Potwar Plateau, Pakistan (Miocene, approximately 18 to 3.5 Ma) is a continuous fluvial sequence that preserves a dense fossil record of snakes. The record consists of approximately 1,500 vertebrae derived from surface-collection and screen-washing of bulk matrix. This record represents 12 identifiable taxa and morphotypes, including Python sp., Acrochordus dehmi, Gansophis potwarensis gen. et sp. nov., Bungarus sp., Chotaophis padhriensis, gen. et sp. nov., and Sivaophis downsi gen. et sp. nov. The record is dominated by Acrochordus dehmi, a fully-aquatic taxon, but diversity increases among terrestrial and semi-aquatic taxa beginning at approximately 10 Ma, roughly coeval with proxy data indicating the inception of the Asian monsoons and increasing seasonality on the Potwar Plateau. Taxonomic differences between the Siwalik Group and coeval European faunas indicate that South Asia was a distinct biogeographic theater from Europe by the middle Miocene. Differences between the Siwalik Group and extant snake faunas indicate significant environmental changes on the Plateau after the last fossil snake occurrences in the Siwalik section.


Identifying the oldest larva of a myrmeleontiformian lacewing – a morphometric approach

Abstract: Neuroptera is one of the smaller ingroups of Holometabola, the ingroup of Insecta characterised by “complete” metamorphosis. Neuroptera comprises about 6000 species in the modern fauna, but appears to have been more diverse in the past. While adults distantly resemble certain moths or damselflies, the larval forms of Neuroptera are mostly fierce predators with prominent venom-injecting stylets. The most well-known of these larvae are probably those of antlions. Antlions and their closer relatives (silky lacewings, split-footed lacewings, ribbon-winged lacewings, spoon-winged lacewings, and owlflies) form a distinct monophyletic ingroup of Neuroptera, Myrmeleontiformia, hence the antlion-like forms. The fossil record of antlion-like larvae dates back far into the Cretaceous; many forms are known by exceptionally wellpreserved specimens entrapped in amber. The oldest fossil record of a neuropteran larva (not an antlion-like form) comes from Lebanese amber. Interestingly, the supposedly oldest record of an antlion-like larva is preserved in rock and comes from the famous Lower Cretaceous Crato Formation. We re-evaluate this fossil based on high-resolution composite photography. Due to the non-availability of many key characters, standard procedures for identifying the specimen to a more narrow ingroup remains challenging. Therefore, we used a morphometric approach. A combination of non-metric multidimensional scaling (NMDS), parallel coordinate plots and discriminant function analysis indicates that the fossil is a representative of the group Ascalaphidae (owlflies) + Myrmeleontidae (antlions). We discuss implications of this result for the fossil record of neuropteran larvae. These include the rather derived morphology of the oldest fossil larva of Myrmeleontiformia in contrast to previous expectations. Furthermore, fossils from soil dwellers can not only be expected to be found in amber, but also as compression fossils.


Bias and Sensitivity in the Placement of Fossil Taxa Resulting from Interpretations of Missing Data

Abstract: The utility of fossils in evolutionary contexts is dependent on their accurate placement in phylogenetic frameworks, yet intrinsic and widespread missing data make this problematic. The complex taphonomic processes occurring during fossilization can make it difficult to distinguish absence from non-preservation, especially in the case of exceptionally preserved soft-tissue fossils: is a particular morphological character (e.g., appendage, tentacle, or nerve) missing from a fossil because it was never there (phylogenetic absence), or just happened to not be preserved (taphonomic loss)? Missing data have not been tested in the context of interpretation of non-present anatomy nor in the context of directional shifts and biases in affinity. Here, complete taxa, both simulated and empirical, are subjected to data loss through the replacement of present entries (1s) with either missing (?s) or absent (0s) entries. Both cause taxa to drift down trees, from their original position, toward the root. Absolute thresholds at which downshift is significant are extremely low for introduced absences (two entries replaced, 6% of present characters). The opposite threshold in empirical fossil taxa is also found to be low; two absent entries replaced with presences causes fossil taxa to drift up trees. As such, only a few instances of non-preserved characters interpreted as absences will cause fossil organisms to be erroneously interpreted as more primitive than they were in life. This observed sensitivity to coding non-present morphology presents a problem for all evolutionary studies that attempt to use fossils to reconstruct rates of evolution or unlock sequences of morphological change. Stem-ward slippage, whereby fossilization processes cause organisms to appear artificially primitive, appears to be a ubiquitous and problematic phenomenon inherent to missing data, even when no decay biases exist. Absent characters therefore require explicit justification and taphonomic frameworks to support their interpretation.

placement
fossil taxa
taphonomic process
morphological character
misinterpretation


Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land

Abstract: Tetrapod biodiversity today is great; over the past 400 Myr since vertebrates moved onto land, global tetrapod diversity has risen exponentially, punctuated by losses during major extinctions. There are links between the total global diversity of tetrapods and the diversity of their ecological roles, yet no one fully understands the interplay of these two aspects of biodiversity and a numerical analysis of this relationship has not so far been undertaken. Here we show that the global taxonomic and ecological diversity of tetrapods are closely linked. Throughout geological time, patterns of global diversity of tetrapod families show 97 per cent correlation with ecological modes. Global taxonomic and ecological diversity of this group correlates closely with the dominant classes of tetrapods (amphibians in the Palaeozoic, reptiles in the Mesozoic, birds and mammals in the Cenozoic). These groups have driven ecological diversity by expansion and contraction of occupied ecospace, rather than by direct competition within existing ecospace and each group has used ecospace at a greater rate than their predecessors.

ecological diversity
vertebrate
land
diversification


A new stem group echinoid from the Triassic of China leads to a revised macroevolutionary history of echinoids during the end-Permian mass extinction

Abstract: The Permian–Triassic bottleneck has long been thought to have drastically altered the course of echinoid evolution, with the extinction of the entire echinoid stem group having taken place during the end-Permian mass extinction. The Early Triassic fossil record of echinoids is, however, sparse, and new fossils are paving the way for a revised interpretation of the evolutionary history of echinoids during the Permian–Triassic crisis and Early Mesozoic. A new species of echinoid, Yunnanechinus luopingensis n. sp. recovered from the Middle Triassic (Anisian) Luoping Biota fossil Lagerstätte of South China, displays morphologies that are not characteristic of the echinoid crown group. We have used phylogenetic analyses to further demonstrate that Yunnanechinus is not a member of the echinoid crown group. Thus a clade of stem group echinoids survived into the Middle Triassic, enduring the global crisis that characterized the end-Permian and Early Triassic. Therefore, stem group echinoids did not go extinct during the Palaeozoic, as previously thought, and appear to have coexisted with the echinoid crown group for at least 23 million years. Stem group echinoids thus exhibited the Lazarus effect during the latest Permian and Early Triassic, while crown group echinoids did not.

echinoid
end-permian mass extinction
phylogenetic analysis


Ocean chemistry and atmospheric CO2 sensitivity to carbon perturbations throughout the Cenozoic

Abstract: We assess the response of atmospheric CO2 (pCO2) and ocean chemistry to carbon perturbations, placing modern carbon‐cycle sensitivity in the context of the Cenozoic. We use the carbon‐cycle model LOSCAR to study the effect of perturbations over the past 67 Ma. Our results indicate that atmospheric CO2 and surface ocean pH were slightly more sensitive to carbon perturbations during the Miocene (∼15 Ma ago) compared to modern conditions and less sensitive during the earlier part of the Cenozoic. We find that the sensitivity to carbon input at the Paleocene‐Eocene boundary (∼56 Ma ago) was most likely lower compared to modern conditions. Further, we show that the Cenozoic evolution of steady state pCO2 and seawater Mg/Ca ratios is critical for the system's sensitivity to a carbon release.

carbon perturbation
cenozoic
ocean chemistry


A roller-like bird (Coracii) from the Early Eocene of Denmark

Abstract: The fossil record of crown group birds (Neornithes) prior to the Cretaceous-Paleogene boundary is scarce and fragmentary. Early Cenozoic bird fossils are more abundant, but are typically disarticulated and/or flattened. Here we report the oldest roller (Coracii), Septencoracias morsensis gen. et sp. nov. (Primobucconidae), based on a new specimen from the Early Eocene (about 54 million years ago) Fur Formation of Denmark. The new fossil is a nearly complete, three-dimensionally preserved and articulated skeleton. It lies at the lower end of the size range for extant rollers. Salient diagnostic features of Septencoracias relative to other Coracii include the proportionally larger skull and the small, ovoid and dorsally positioned narial openings. Our discovery adds to the evidence that the Coracii had a widespread northern hemisphere distribution in the Eocene. Septencoracias is the oldest substantial record of the Picocoraciae and provides a reliable calibration point for molecular phylogenetic studies.

roller-like bird
early eocene
primobucconidae
geranopterus


Global mean surface temperature and climate sensitivity of the early Eocene Climatic Optimum (EECO), Paleocene–Eocene Thermal Maximum (PETM), and latest Paleocene

Abstract:
Abstract. Accurate estimates of past global mean surface temperature (GMST) help to
contextualise future climate change and are required to estimate the
sensitivity of the climate system to CO2 forcing through Earth's history.
Previous GMST estimates for the latest Paleocene and early Eocene
(∼57 to 48 million years ago) span a wide range
(∼9 to 23 ∘C higher than pre-industrial) and
prevent an accurate assessment of climate sensitivity during this extreme
greenhouse climate interval. Using the most recent data compilations, we
employ a multi-method experimental framework to calculate GMST during the
three DeepMIP target intervals: (1) the latest Paleocene (∼57 Ma), (2) the Paleocene–Eocene Thermal Maximum (PETM; 56 Ma), and (3) the early
Eocene Climatic Optimum (EECO; 53.3 to 49.1 Ma). Using six different
methodologies, we find that the average GMST estimate (66 % confidence)
during the latest Paleocene, PETM, and EECO was 26.3 ∘C (22.3 to
28.3 ∘C), 31.6 ∘C (27.2 to 34.5 ∘C), and
27.0 ∘C (23.2 to 29.7 ∘C), respectively. GMST estimates
from the EECO are ∼10 to 16 ∘C warmer than
pre-industrial, higher than the estimate given by the Intergovernmental Panel on Climate Change (IPCC) 5th
Assessment Report (9 to 14 ∘C higher than pre-industrial).
Leveraging the large “signal” associated with these extreme warm climates,
we combine estimates of GMST and CO2 from the latest Paleocene, PETM,
and EECO to calculate gross estimates of the average climate sensitivity
between the early Paleogene and today. We demonstrate that “bulk”
equilibrium climate sensitivity (ECS; 66 % confidence) during the latest
Paleocene, PETM, and EECO is 4.5 ∘C (2.4 to 6.8 ∘C),
3.6 ∘C (2.3 to 4.7 ∘C), and 3.1 ∘C (1.8 to
4.4 ∘C) per doubling of CO2. These values are generally
similar to those assessed by the IPCC (1.5 to 4.5 ∘C per doubling
CO2) but appear incompatible with low ECS values (<1.5 per
doubling CO2).

surface temperature
climate sensitivity
paleocene


Pampean megamammals in Europe: the fossil collections from Santiago Roth

Abstract: Santiago Roth was a Swiss fossil finder, naturalist, and paleontologist that emigrated to Argentina in 1866. His work largely influenced the discipline in the country at the end of the twentieth century, particularly the stratigraphy of the Pampean region. Some of his collections of Pampean fossils were sold to museums and private collectors in Europe and were accompanied by elaborated catalogues. Fossils in the Roth's catalogues N° 2 and 3 are housed today in the Natural History Museum of Denmark, fossils from catalogues N° 4 to 6, were sold to Swiss museums, with Catalogue N° 5 currently housed at the Department of Paleontology, Universität Zürich. Here, we provide a general framework on the stratigraphy from the Roth's Pampean fossil sites, summarize the history of the Pampean fossils in Europe originally collected by Roth, and provide historical and curatorial details of the Roth's collection at the


A lifetime of the Variscan orogenic plateau from uplift to collapse as recorded by the Prague Basin, Bohemian Massif

Abstract: Abstract The Ordovician to Middle Devonian Prague Basin, Bohemian Massif, represents the shallowest crust of the Variscan orogen corresponding to c. 1–4 km palaeodepth. The basin was inverted and multiply deformed during the Late Devonian to early Carboniferous Variscan orogeny, and its structural inventory provides an intriguing record of complex geodynamic processes that led to growth and collapse of a Tibetan-type orogenic plateau. The northeastern part of the Prague Basin is a simple syncline cross-cut by reverse/thrust faults and represents a doubly vergent compressional fan accommodating c. 10–19 % ~NW–SE shortening, only minor syncline axis-parallel extension and significant crustal thickening. The compressional structures were locally overprinted by vertical shortening, kinematically compatible with ductile normal shear zones that exhumed deep crust in the orogen's interior at c. 346–337 Ma. On a larger scale, the deformation history of the Prague Syncline is consistent with building significant palaeoelevation during Variscan plate convergence. Based on a synthesis of finite deformation parameters observed across the upper crust in the centre of the Bohemian Massif, we argue for a differentiated within-plateau palaeotopography consisting of domains of local thickening alternating with topographic depressions over lateral extrusion zones. The plateau growth, involving such complex three-dimensional internal deformations, was terminated by its collapse driven by multiple interlinked processes including gravity, voluminous magma emplacement and thermal softening in the hinterland, and far-field plate-boundary forces resulting from the relative dextral motion of Gondwana and Laurussia.

orogenic plateau
prague basin
bohemian massif


The global Hangenberg Crisis (Devonian–Carboniferous transition): review of a first-order mass extinction

Abstract: Abstract The global Hangenberg Crisis near the Devonian–Carboniferous boundary (DCB) represents a mass extinction that is of the same scale as the so-called ‘Big Five’ first-order Phanerozoic events. It played an important role in the evolution of many faunal groups and destroyed complete ecosystems but affected marine and terrestrial environments at slightly different times within a short time span of c. 100–300 kyr. The lower crisis interval in the uppermost Famennian started as a prelude with a minor eustatic sea-level fall, followed rather abruptly by pantropically widespread black shale deposition (Hangenberg Black Shale and equivalents). This transgressive and hypoxic/anoxic phase coincided with a global carbonate crisis and perturbation of the global carbon cycle as evidenced by a distinctive positive carbon isotope excursion, probably as a consequence of climate/salinity-driven oceanic overturns and outer-shelf eutrophication. It is the main extinction level for marine biota, especially for ammonoids, trilobites, conodonts, stromatoporoids, corals, some sharks, and deeper-water ostracodes, but probably also for placoderms, chitinozoans and early tetrapods. Extinction rates were lower for brachiopods, neritic ostracodes, bryozoans and echinoderms. Extinction patterns were similar in widely separate basins of the western and eastern Prototethys, while a contemporaneous marine macrofauna record from high latitudes is missing altogether. The middle crisis interval is characterized by a gradual but major eustatic sea-level fall, probably in the scale of more than 100 m, that caused the progradation of shallow-water siliciclastics (Hangenberg Sandstone and equivalents) and produced widespread unconformities due to reworking and non-deposition. The glacio-eustatic origin of this global regression is proven by miospore correlation with widespread diamictites of South America and South and North Africa, and by the evidence for significant tropical mountain glaciers in eastern North America. This isolated and short-lived plunge from global greenhouse into icehouse conditions may follow the significant drawdown of atmospheric CO2 levels due to the prior massive burial of organic carbon during the global deposition of black shales. Increased carbon recycling by intensified terrestrial erosion in combination with the arrested burial of carbonates may have led to a gradual rise of CO2 levels, re-warming, and a parallel increase in the influx of land-derived nutrients. The upper crisis interval in the uppermost Famennian is characterized by initial post-glacial transgression and a second global carbon isotope spike, as well as by opportunistic faunal blooms and the early re-radiation of several fossil groups. Minor reworking events and unconformities give evidence for continuing smaller-scale oscillations of sea-level and palaeoclimate. These may explain the terrestrial floral change near the Famennian–Tournaisian boundary and contemporaneous, evolutionarily highly significant extinctions of survivors of the main crisis. Still poorly understood small-scale events wiped out the last clymeniid ammonoids, phacopid trilobites, placoderms and some widespread brachiopod and foraminiferan groups. The post-crisis interval in the lower Tournaisian is marked by continuing eustatic rise (e.g. flooding of the Old Red Continent), and significant radiations in a renewed greenhouse time. But the recovery had not yet reached the pre-crisis level when it was suddenly interrupted by the global, second-order Lower Alum Shale Event at the base of the middle Tournaisian.

global hangenberg crisis
review
mass extinction
hangenberg black shale
devonian-carboniferous transition


ONTOGENY AND HETEROCHRONY IN THE EARLY CAMBRIAN ORYCTOCEPHALID TRILOBITES CHANGASPIS, DUYUNASPIS AND BALANGIA FROM CHINA

Abstract: Abstract:  Ontogenies are described for the first time for three species of Early Cambrian oryctocephalid trilobites: the oryctocephaline Changaspis elongata Lee, in Chien and the oryctocarines Duyunaspis duyunensis Chang and Chien, in Zhou et al. and Balangia balangensis Chien from the Balang Formation in eastern Ghuizhou Province, south‐west China. The complete protaspid to holaspid ontogeny for Duyunaspis duyunensis and incomplete meraspid to holaspid ontogenies for Changaspis elongata and Balangia balangensis are described. The relative degree of ontogenetic variation within the lineage Duyunaspis duyunensis–Balangia balangensis is analysed and indicates that Balangia may have evolved from Duyunaspis by paedomorphosis. Decrease in thoracic segment number and concomitant increase in pygidial segment number in the later genus mirrors the pattern seen in the evolution of another oryctocephalid genus, Arthricocephalus. In both cases, selection was probably targeting an increase in cephalic convexity. This resulted in the evolution of a larger pygidium due to increased elevation of the axis above the substrate. The ontogenetic development of Changaspis provides evidence supporting the view that the Oryctocarinae may be considered as paedomorphic descendants of the Oryctocephalinae.

duyunaspis balangia paedomorphosis ontogeny


Current understanding on the Cambrian Explosion: questions and answers

Abstract: The Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

cambrian explosion
animal body
episodic biomineralization


The Oldest Caseid Synapsid from the Late Pennsylvanian of Kansas, and the Evolution of Herbivory in Terrestrial Vertebrates

Abstract: The origin and early evolution of amniotes (fully terrestrial vertebrates) led to major changes in the structure and hierarchy of terrestrial ecosystems. The first appearance of herbivores played a pivotal role in this transformation. After an early bifurcation into Reptilia and Synapsida (including mammals) 315 Ma, synapsids dominated Paleozoic terrestrial vertebrate communities, with the herbivorous caseids representing the largest vertebrates on land. Eocasea martini gen. et sp. nov., a small carnivorous caseid from the Late Carboniferous, extends significantly the fossil record of Caseidae, and permits the first clade-based study of the origin and initial evolution of herbivory in terrestrial tetrapods. Our results demonstrate for the first time that large caseid herbivores evolved from small, non-herbivorous caseids. This pattern is mirrored by three other clades, documenting multiple, independent, but temporally staggered origins of herbivory and increase in body size among early terrestrial tetrapods, leading to patterns consistent with modern terrestrial ecosystem.

late pennsylvanian
herbivory
terrestrial vertebrate
caseidae
body size


Climate constrains the evolutionary history and biodiversity of crocodylians

Abstract: The fossil record of crocodylians and their relatives (pseudosuchians) reveals a rich evolutionary history, prompting questions about causes of long-term decline to their present-day low biodiversity. We analyse climatic drivers of subsampled pseudosuchian biodiversity over their 250 million year history, using a comprehensive new data set. Biodiversity and environmental changes correlate strongly, with long-term decline of terrestrial taxa driven by decreasing temperatures in northern temperate regions, and biodiversity decreases at lower latitudes matching patterns of increasing aridification. However, there is no relationship between temperature and biodiversity for marine pseudosuchians, with sea-level change and post-extinction opportunism demonstrated to be more important drivers. A ‘modern-type' latitudinal biodiversity gradient might have existed throughout pseudosuchian history, and range expansion towards the poles occurred during warm intervals. Although their fossil record suggests that current global warming might promote long-term increases in crocodylian biodiversity and geographic range, the 'balancing forces' of anthropogenic environmental degradation complicate future predictions.

biodiversity crocodylian latitude aridification


The Triassic to Early Jurassic palynological record of the Tarim Basin, China

Abstract: The Tarim Basin, located in northwestern China, is an important oil-bearing region, and the extensive non-marine Mesozoic successions make this a key location for understanding environmental changes through the Triassic and Jurassic. Palynological analyses on samples from Lunnan-1 and Tazhong-1 drill cores from the northern and central part of the Tarim Basin reveal wellpreserved spore-pollen assemblages. Five palynological assemblages, i.e. Tarim Triassic 1 (TT1)-Tarim Triassic 4 (TT4) and Tarim Jurassic 1 (TJ1), spanning the Early Triassic to Early Jurassic were identified based on compositional changes, which are supported by ordination of samples using non-metric multidimensional scaling (NMDS). The Early Triassic assemblages possess abundant bryophytes and Densoisporites spp.-producers, which potentially represent a recovery succession follow-ing the end-Permian event. The Late Triassic spore-pollen assemblages are more similar to those of the North China Palynofloral Province compared to the South China Province. Based on our phytogeographic analysis, we propose that the western section of the boundary between the North and South China palynofloras should be placed at the southern margin of the Tarim Basin.


A new era in palaeomicrobiology: prospects for ancient dental calculus as a long-term record of the human oral microbiome

Abstract: The field of palaeomicrobiology is dramatically expanding thanks to recent advances in high-throughput biomolecular sequencing, which allows unprecedented access to the evolutionary history and ecology of human-associated and environmental microbes. Recently, human dental calculus has been shown to be an abundant, nearly ubiquitous, and long-term reservoir of the ancient oral microbiome, preserving not only microbial and host biomolecules but also dietary and environmental debris. Modern investigations of native human microbiota have demonstrated that the human microbiome plays a central role in health and chronic disease, raising questions about changes in microbial ecology, diversity and function through time. This paper explores the current state of ancient oral microbiome research and discusses successful applications, methodological challenges and future possibilities in elucidating the intimate evolutionary relationship between humans and their microbes.

palaeomicrobiology
dental calculus
oral microbiome


Large palaeophiid and nigerophiid snakes from Paleogene Trans-Saharan Seaway deposits of Mali

Abstract: The Paleogene was a time of high diversity for snakes, and was characterized by some of the largest species known to have existed. Among these snakes were pan-Tethyan marine species of Nigerophiidae and Palaeophiidae. The latter family included the largest sea snake, Palaeophis colossaeus, known from the Trans-Saharan Seaway of Mali during the Eocene. This paper describes new material collected from Malian Trans-Saharan Seaway deposits, including additional material of Palaeophis colossaeus, a new, large species of nigerophiid, Amananulam sanogoi gen. et sp. nov., and a medium-sized snake of indeterminate affinities. The material provides new information on the intracolumnar variation of the vertebral column in Palaeophis colossaeus. We estimate the total length of each species by regression of vertebral measurements on body size. Both Palaeophis colossaeus and Amananulam sanogoi gen. et sp. nov. are the largest or among the largest members of their respective clades. The large size of Tethyan snakes may be indicative of higher temperatures in the tropics than are present today.

snake
paleogene
trans-saharan seaway deposit


The evolution and extinction of the ichthyosaurs from the perspective of quantitative ecospace modelling

Abstract: The role of niche specialization and narrowing in the evolution and extinction of the ichthyosaurs has been widely discussed in the literature. However, previous studies have concentrated on a qualitative discussion of these variables only. Here, we use the recently developed approach of quantitative ecospace modelling to provide a high-resolution quantitative examination of the changes in dietary and ecological niche experienced by the ichthyosaurs throughout their evolution in the Mesozoic. In particular, we demonstrate that despite recent discoveries increasing our understanding of taxonomic diversity among the ichthyosaurs in the Cretaceous, when viewed from the perspective of ecospace modelling, a clear trend of ecological contraction is visible as early as the Middle Jurassic. We suggest that this ecospace redundancy, if carried through to the Late Cretaceous, could have contributed to the extinction of the ichthyosaurs. Additionally, our results suggest a novel model to explain ecospace change, termed the ‘migration model’.

ichthyosaur
perspective
quantitative ecospace


Magnetic detection and characterization of biogenic magnetic minerals: A comparison of ferromagnetic resonance and first‐order reversal curve diagrams

Abstract: Biogenic magnetic minerals produced by magnetotactic bacteria occur ubiquitously in natural aquatic environments. Their identification and characterization are important for interpretation of paleomagnetic and environmental magnetic records. We compare two magnetic methods for their identification and characterization in a diverse set of sedimentary environments: ferromagnetic resonance (FMR) spectroscopy and first‐order reversal curve (FORC) diagrams, constrained by transmission electron microscope observations. The advantages and limitations of each method are evaluated. FMR analysis provides a strong diagnostic indicator because of its ability to detect the strong shape anisotropy that arises from the biogenic chain architecture, but it can be obscured in mixed magnetic mineral assemblages. We develop a new FMR fitting approach that enables separation and characterization of biogenic components in natural samples. FMR spectral fitting on magnetofossil‐bearing samples does not always reveal a strong signature of biogenic magnetite with <111>‐aligned chains, in contrast to whole magnetotactic bacteria cells. This indicates that strictly <111>‐aligned chains are not as common in magnetofossil assemblages, due to either chain collapse or different crystallographic axis orientations. FORC analysis provides an excellent tool for isolating the biogenic component as a “central ridge” signature with peak switching field distribution between ~20 and 60 mT. We also analyzed tuff samples with similar FMR characteristics to biogenic magnetite chains, which can cause ambiguity. We propose a magnetic protocol to improve the robustness and efficiency of biogenic magnetite identification and past microbial activity in a wide range of environments.

characterization
magnetic mineral
resonance


Trilobite compound eyes with crystalline cones and rhabdoms show mandibulate affinities

Abstract: Most knowledge about the structure, function, and evolution of early compound eyes is based on investigations in trilobites. However, these studies dealt mainly with the cuticular lenses and little was known about internal anatomy. Only recently some data on crystalline cones and retinula cells were reported for a Cambrian trilobite species. Here, we describe internal eye structures of two other trilobite genera. The Ordovician Asaphus sp. reveals preserved crystalline cones situated underneath the cuticular lenses. The same is true for the Devonian species Archegonus (Waribole) warsteinensis, which in addition shows the fine structure of the rhabdom in the retinula cells. These results suggest that an apposition eye with a crystalline cone is ancestral for Trilobita. The overall similarity of trilobite eyes to those of myriapods, crustaceans, and hexapods corroborates views of a phylogenetic position of trilobites in the stem lineage of Mandibulata.

compound eye
crystalline cone
rhabdom
trilobite
existence


The walking dead: Blender as a tool for paleontologists with a case study on extinct arachnids

Abstract: Abstract This paper serves two roles. First, it acts as an introduction to Blender, an open-source computer graphics program, which can be of utility to paleontologists. To lessen the software's otherwise steep learning curve, a step-by-step guide to create an idealized reconstruction of a fossil in the form of a three-dimensional model in Blender, or to use the software to render results from ‘virtual paleontology' techniques, is provided as an online supplemental data file. Second, here we demonstrate the use of Blender with a case study on the extinct trigonotarbid arachnids. We report the limb articulations of members of the Devonian genus Palaeocharinus on the basis of exceptionally preserved fossils from the Rhynie Cherts of Scotland. We use these newly reported articulations to create a Blender model, and draw comparisons with the gait of extant arachnids to produce as accurate a representation of the trigonotarbid flexing its limbs and walking as possible, presented in additional online supplemental data files. Knowledge of the limb articulations of trigonotarbid arachnids also allows us to discuss their functional morphology: trigonotarbids' limbs and gait were likely comparable to extant cursorial spiders, but lacked some innovations seen in more derived arachnids.


Hennig's semaphoront concept and the use of ontogenetic stages in phylogenetic reconstruction

Abstract: A new practice in systematics, “semaphoront” coding, treats developmental stages as terminals, and it derives from Hennig's concept of the same name. Semaphoront coding has been implemented recently by Lamsdell and Selden (BMC Evol. Biol., 2013, 13:98) and Wolfe and Hegna (Cladistics, 2014, 30:366) in an effort to understand the relationships of fossil taxa of unknown developmental stage. We submit that this approach is antithetical to cladistic practice and constitutes a gross misunderstanding of Hennig's original idea. Here we review the concept of the semaphoront and clarify the role of the semaphoront in phylogenetic systematics. We contend that treating ontogenetic stages as terminals both violates tenets of phylogenetic systematics and oversimplifies the complexity of developmental processes. We advocate Hennig's alternative of including data from as many semaphoronts as possible, but implemented using the superior total evidence framework. Finally, we contend that the application of semaphoront coding to any palaeontological question requires invoking multiple, unjustified assumptions, and ultimately will not yield a possible phylogenetic solution. A total evidence approach can grapple with the placement of fossil developmental stages, if only imperfectly.


New Protocetid Whale from the Middle Eocene of Pakistan: Birth on Land, Precocial Development, and Sexual Dimorphism

Abstract: Background Protocetidae are middle Eocene (49–37 Ma) archaeocete predators ancestral to later whales. They are found in marine sedimentary rocks, but retain four legs and were not yet fully aquatic. Protocetids have been interpreted as amphibious, feeding in the sea but returning to land to rest. Methodology/Principal Findings Two adult skeletons of a new 2.6 meter long protocetid, Maiacetus inuus, are described from the early middle Eocene Habib Rahi Formation of Pakistan. M. inuus differs from contemporary archaic whales in having a fused mandibular symphysis, distinctive astragalus bones in the ankle, and a less hind-limb dominated postcranial skeleton. One adult skeleton is female and bears the skull and partial skeleton of a single large near-term fetus. The fetal skeleton is positioned for head-first delivery, which typifies land mammals but not extant whales, evidence that birth took place on land. The fetal skeleton has permanent first molars well mineralized, which indicates precocial development at birth. Precocial development, with attendant size and mobility, were as critical for survival of a neonate at the land-sea interface in the Eocene as they are today. The second adult skeleton is the most complete known for a protocetid. The vertebral column, preserved in articulation, has 7 cervicals, 13 thoracics, 6 lumbars, 4 sacrals, and 21 caudals. All four limbs are preserved with hands and feet. This adult is 12% larger in linear dimensions than the female skeleton, on average, has canine teeth that are 20% larger, and is interpreted as male. Moderate sexual dimorphism indicates limited male-male competition during breeding, which in turn suggests little aggregation of food or shelter in the environment inhabited by protocetids. Conclusions/Significance Discovery of a near-term fetus positioned for head-first delivery provides important evidence that early protocetid whales gave birth on land. This is consistent with skeletal morphology enabling Maiacetus to support its weight on land and corroborates previous ideas that protocetids were amphibious. Specimens this complete are virtual ‘Rosetta stones’ providing insight into functional capabilities and life history of extinct animals that cannot be gained any other way.

middle eocene
pakistan
birth
maiacetus
fetus


New Fossil Penguins (Aves, Sphenisciformes) from the Oligocene of New Zealand Reveal the Skeletal Plan of Stem Penguins

Abstract:
ABSTRACT
 Three skeletons collected from the late Oligocene Kokoamu Greensand of New Zealand are among the most complete Paleogene penguins known. These specimens, described here as Kairuku waitaki, gen. et sp. nov., and Kairuku grebneffi, sp. nov., reveal new details of key elements of the stem penguin skeleton associated with underwater flight, including the sternum, flipper, and pygostyle. Relative proportions of the trunk, flippers, and hind limbs can now be determined from a single individual for the first time, offering insight into the body plan of stem penguins and improved constraints on size estimates for ‘giant’ taxa. Kairuku is characterized by an elongate, narrow sternum, a short and flared coracoid, an elongate narrow flipper, and a robust hind limb. The pygostyle of Kairuku lacks the derived triangular cross-section seen in extant penguins, suggesting that the rectrices attached in a more typical avian pattern and the tail may have lacked the propping function utilized by living penguins. New materials described here, along with re-study of previously described specimens, resolve several long-standing phylogenetic, biogeographic, and taxonomic issues stemming from the inadequate comparative material of several of the first-named fossil penguin species. An array of partial associated skeletons from the Eocene—Oligocene of New Zealand historically referred to Palaeeudyptes antarcticus or Palaeeudyptes sp. are recognized as at least five distinct species: Palaeeudyptes antarcticus, Palaeeudyptes marplesi, Kairuku waitaki, Kairuku grebneffi, and an unnamed Burnside Formation species.


Cretaceous dinosaur bone contains recent organic material and provides an environment conducive to microbial communities

Abstract: Fossils were thought to lack original organic molecules, but chemical analyses show that some can survive. Dinosaur bone has been proposed to preserve collagen, osteocytes, and blood vessels. However, proteins and labile lipids are diagenetically unstable, and bone is a porous open system, allowing microbial/molecular flux. These ‘soft tissues’ have been reinterpreted as biofilms. Organic preservation versus contamination of dinosaur bone was examined by freshly excavating, with aseptic protocols, fossils and sedimentary matrix, and chemically/biologically analyzing them. Fossil ‘soft tissues’ differed from collagen chemically and structurally; while degradation would be expected, the patterns observed did not support this. 16S rRNA amplicon sequencing revealed that dinosaur bone hosted an abundant microbial community different from lesser abundant communities of surrounding sediment. Subsurface dinosaur bone is a relatively fertile habitat, attracting microbes that likely utilize inorganic nutrients and complicate identification of original organic material. There exists potential post-burial taphonomic roles for subsurface microorganisms.

dinosaur bone
organic material
microbial community


Approximate evolutionary stasis for bivalve morphology over millions of years: a multivariate, multilineage study

Abstract: We have calculated rates of evolution for 19 lineages of Neogene bivalves over time intervals ranging from 1 ma to 17 ma. Our morphometric comparisons are based on 24 variables, for which we have made more than 43,000 individual measurements normalized for shell size. We initially assessed evolutionary changes in shape for 19 early Pliocene (4 ma old) species of bivalves by comparing these forms to their closest living relatives, which in 12 cases have traditonally been assigned to the same species. To make our study unbiased and comprehensive, we included all species that met certain predetermined guidelines and that offered suitable fossil material for measurement. We compared early Pliocene and Recent populations using (1) all 24 variables treated separately, (2) multivariate distance (Mahalanobis' D), based on the full set of variables, and (3) eigenshapes for shell outlines. For these comparisons, we used as a yardstick the same measures of morphologic distance applied to pairs of geographically separated Recent populations that belong to eight of the living species to which the fossil populations were compared. As it turns out, with minor exceptions, the distribution of morphologic distances between 4 ma old and Recent populations resembled the distribution of distances between conspecific Recent populations. We calculated net rates of evolution separating pairs of populations that belong to single lineages. For all intervals of time, the distribution of differences between population means for individual variables is remarkably similar to a comparable distribution representing the comparison of pairs of conspecific Recent populations from separate geographic regions. Because morphologic differences between populations do not vary greatly with evolutionary time, measured “rates” of evolution, on the average, decrease with interval of measurement. Because these differences resemble intraspecific variability, however, the rates do not represent significant evolution. Evolution has followed a weak zigzag course, yielding only trivial net trends. The weak and reversible “trends” that we measured yield net rates averaging less than 10 millidarwins, which is much lower than most rates previously reported for marine invertebrates (average ~200 millidarwins for a 1 ma interval and ~60 millidarwins for a 10 ma interval). We attribute this disparity (1) to the fact that most previously published rates have been calculated when a significant amount of evolution was recognized in advance (often for a poorly documented lineage) and (2) to the fact that most measured variables have represented nothing more than some measure of body size. We conclude that shape, as opposed to size, has been highly stable in bivalve evolution over millions of years and 106–107 generations. We conclude that to characterize rates or evolution for any group of organisms, one must employ a large, unbiased sample of measurements for numerous well-documented lineages, and one must segregate data depicting shape from data depicting size.


The modified gap excess ratio (GER*) and the stratigraphic congruence of dinosaur phylogenies.

Abstract: Palaeontologists routinely map their cladograms onto what is known of the fossil record. Where sister taxa first appear as fossils at different times, a ghost range is inferred to bridge the gap between these dates. Some measure of the total extent of ghost ranges across the tree underlies several indices of cladistic/stratigraphic congruence. We investigate this congruence for 19 independent, published cladograms of major dinosaur groups and report exceptional agreement between the phylogenetic and stratigraphic patterns, evidenced by sums of ghost ranges near the theoretical minima. This implies that both phylogenetic and stratigraphic data reflect faithfully the evolutionary history of dinosaurs, at least for the taxa included in this study. We formally propose modifications to an existing index of congruence (the gap excess ratio; GER), designed to remove a bias in the range of values possible with trees of different shapes. We also propose a more informative index of congruence--GER*--that takes account of the underlying distribution of sums of ghost ranges possible when permuting stratigraphic range data across the tree. Finally, we incorporate data on the range of possible first occurrence dates into our estimates of congruence, extending a procedure originally implemented with the modified Manhattan stratigraphic measure and GER to our new indices. Most dinosaur data sets maintain extremely high congruence despite such modifications.

gap
excess ratio
stratigraphic congruence


Unique near isometric ontogeny in the pterosaur
 Rhamphorhynchus
 suggests hatchlings could fly

Abstract: Rhamphorhynchus muensteri is one of the best-known flying reptiles, represented by >130 well-preserved fossil specimens, from hatchlings to full adults. The life history of this pterosaur remains controversial as to when in ontogeny they took flight. Here, we assess the growth of these animals based on the lengths of numerous key elements. We show that changes in the skeletal anatomy of this reptile across its post-hatch size range reveal that R. muensteri exhibited overall near isometric growth in the wings, with slightly negative allometry in the humerus, radius and stronger negative allometry in the fourth metacarpal compared to body length, and slightly positive allometry in the second and third phalanges compared to body length. This pattern is near unique among flying vertebrates and suggests R. muensteri flew soon after hatching. In bats and birds, offspring do not typically fly until nearly adult sized. Conversely, near isometric growth in Rhamphorhynchus suggests it was a precocial flier and that individuals may have inhabited several sequential foraging niches over their lifespan, as some terrestrial and aquatic vertebrates do today. □ Bats, birds, ontogeny, precocial flight, pterosaurs.

ontogeny pterosaur hatchling adult flight


The role of experiments in investigating the taphonomy of exceptional preservation

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

experiment
exceptional preservation
fossilization
mineralization


Body mass estimation in Early Miocene native South American ungulates: a predictive equation based on 3D landmarks

Abstract: South American native ungulates include extinct taxa that evolved within the geographical context given by the isolation of South America during most of the Cenozoic. The ungulates (orders Notoungulata, Litopterna and Astrapotheria) of the Santa Cruz Formation (late Early Miocene) are particularly interesting for paleobiological studies due to their diversity, richness and quality of preservation of the specimens. The body mass estimation of extinct species is one of the basic biological attributes for paleobiological reconstructions. The most common way to estimate body mass from fossils is using linear regression. Here, we used geometric morphometric techniques in order to estimate their body mass. We used regressions based on centroid size of 3D craniomandibular landmark configurations, including extant ungulates (their size and ecological relatives). Cases were weighted to maximize the taxonomic evenness. A broad body size range was recorded. The highest predictive power is obtained with those functions derived from the highest taxonomic and ecological diversity. The highest taxonomic richness corresponds to masses below 100 kg. Among Notoungulata, typotheres (Hegetotheriidae + Interatheriidae) vary from 1 to less than 10 kg, while the smaller toxodontid reached 100 kg and the larger 500 kg. Litoptern proterotheriid body masses vary from 10 to 50 kg, and macraucheniids surpass 100 kg. The astrapotheres (Astrapotheria) reached (or even surpassed) 1000 kg, being the only megamammal in the Santacrucian ungulate assemblage.

early miocene
ungulate
body mass estimation


Hyena paleogenomes reveal a complex evolutionary history of cross-continental gene flow between spotted and cave hyena

Abstract: Westbury et al. reveal the genome-level evolutionary relationships between extinct cave and extant spotted hyena. The genus Crocuta (African spotted and Eurasian cave hyenas) includes several closely related extinct and extant lineages. The relationships among these lineages, however, are contentious. Through the generation of population-level paleogenomes from late Pleistocene Eurasian cave hyena and genomes from modern African spotted hyena, we reveal the cross-continental evolutionary relationships between these enigmatic hyena lineages. We find a deep divergence (~2.5 Ma) between African and Eurasian Crocuta populations, suggesting that ancestral Crocuta left Africa around the same time as early Homo. Moreover, we find discordance between nuclear and mitochondrial phylogenies and evidence for bidirectional gene flow between African and Eurasian Crocuta after the lineages split, which may have complicated prior taxonomic classifications. Last, we find a number of introgressed loci that attained high frequencies within the recipient lineage, suggesting some level of adaptive advantage from admixture.

gene flow
cave hyena
genus crocuta
late pleistocene
hyena


Tests and confidence intervals for a common upper endpoint in fossil taxa

Abstract: Statistical inference about the upper and lower endpoints of the stratigraphic ranges of fossil taxa can be based on the pattern of finds. Strauss and Sadler (1989) described a test and confidence interval for a common upper or lower endpoint in two or more taxa. This approach is conservative, in the sense that it provides only an upper bound on the significance level. This paper describes and illustrates a test and confidence interval for which the significance level is known.

confidence interval
endpoint
fossil taxa


Recharacterization of ancient DNA miscoding lesions: insights in the era of sequencing-by-synthesis

Abstract: Although ancient DNA (aDNA) miscoding lesions have been studied since the earliest days of the field, their nature remains a source of debate. A variety of conflicting hypotheses exist about which miscoding lesions constitute true aDNA damage as opposed to PCR polymerase amplification error. Furthermore, considerable disagreement and speculation exists on which specific damage events underlie observed miscoding lesions. The root of the problem is that it has previously been difficult to assemble sufficient data to test the hypotheses, and near-impossible to accurately determine the specific strand of origin of observed damage events. With the advent of emulsion-based clonal amplification (emPCR) and the sequencing-by-synthesis technology this has changed. In this paper we demonstrate how data produced on the Roche GS20 genome sequencer can determine miscoding lesion strands of origin, and subsequently be interpreted to enable characterization of the aDNA damage behind the observed phenotypes. Through comparative analyses on 390 965 bp of modern chloroplast and 131 474 bp of ancient woolly mammoth GS20 sequence data we conclusively demonstrate that in this sample at least, a permafrost preserved specimen, Type 2 (cytosine→thymine/guanine→adenine) miscoding lesions represent the overwhelming majority of damage-derived miscoding lesions. Additionally, we show that an as yet unidentified guanine→adenine analogue modification, not the conventionally argued cytosine→uracil deamination, underpins a significant proportion of Type 2 damage. How widespread these implications are for aDNA will become apparent as future studies analyse data recovered from a wider range of substrates.


Human population dynamics in Europe over the Last Glacial Maximum

Abstract: Significance Despite its importance for understanding genetic, cultural, and linguistic evolution, prehistoric human population history has remained difficult to reconstruct. We show that the dynamics of the human population in Europe from 30,000 to 13,000 y ago can be simulated using ethnographic and paleoclimate data within the climate envelope modeling approach. Correspondence between the population simulation and archaeological data suggests that population dynamics were indeed driven by major climate fluctuations, with population size varying between 130,000 and 410,000 people. Although climate has been an important determinant of human population dynamics, the climatic conditions during the last glacial were not as harsh as is often presented, because even during the coldest phases, the climatically suitable area for humans covered 36% of Europe. The severe cooling and the expansion of the ice sheets during the Last Glacial Maximum (LGM), 27,000–19,000 y ago (27–19 ky ago) had a major impact on plant and animal populations, including humans. Changes in human population size and range have affected our genetic evolution, and recent modeling efforts have reaffirmed the importance of population dynamics in cultural and linguistic evolution, as well. However, in the absence of historical records, estimating past population levels has remained difficult. Here we show that it is possible to model spatially explicit human population dynamics from the pre-LGM at 30 ky ago through the LGM to the Late Glacial in Europe by using climate envelope modeling tools and modern ethnographic datasets to construct a population calibration model. The simulated range and size of the human population correspond significantly with spatiotemporal patterns in the archaeological data, suggesting that climate was a major driver of population dynamics 30–13 ky ago. The simulated population size declined from about 330,000 people at 30 ky ago to a minimum of 130,000 people at 23 ky ago. The Late Glacial population growth was fastest during Greenland interstadial 1, and by 13 ky ago, there were almost 410,000 people in Europe. Even during the coldest part of the LGM, the climatically suitable area for human habitation remained unfragmented and covered 36% of Europe.

europe
last glacial maximum
human population dynamic


Possible role of oceanic heat transport in early Eocene climate.

Abstract: Increased oceanic heat transport has often been cited as a means of maintaining warm high-latitude surface temperatures in many intervals of the geologic past, including the early Eocene. Although the excess amount of oceanic heat transport required by warm high latitude sea surface temperatures can be calculated empirically, determining how additional oceanic heat transport would take place has yet to be accomplished. That the mechanisms of enhanced poleward oceanic heat transport remain undefined in paleoclimate reconstructions is an important point that is often overlooked. Using early Eocene climate as an example, we consider various ways to produce enhanced poleward heat transport and latitudinal energy redistribution of the sign and magnitude required by interpreted early Eocene conditions. Our interpolation of early Eocene paleotemperature data indicate that an approximately 30% increase in poleward heat transport would be required to maintain Eocene high-latitude temperatures. This increased heat transport appears difficult to accomplish by any means of ocean circulation if we use present ocean circulation characteristics to evaluate early Eocene rates. Either oceanic processes were very different from those of the present to produce the early Eocene climate conditions or oceanic heat transport was not the primary cause of that climate. We believe that atmospheric processes, with contributions from other factors, such as clouds, were the most likely primary cause of early Eocene climate.

oceanic heat transport
heat transport
eocene climate


Small-Bodied Humans from Palau, Micronesia

Abstract: Newly discovered fossil assemblages of small bodied Homo sapiens from Palau, Micronesia possess characters thought to be taxonomically primitive for the genus Homo. Background Recent surface collection and test excavation in limestone caves in the rock islands of Palau, Micronesia, has produced a sizeable sample of human skeletal remains dating roughly between 940-2890 cal ybp. Principle Findings Preliminary analysis indicates that this material is important for two reasons. First, individuals from the older time horizons are small in body size even relative to “pygmoid” populations from Southeast Asia and Indonesia, and thus may represent a marked case of human insular dwarfism. Second, while possessing a number of derived features that align them with Homo sapiens, the human remains from Palau also exhibit several skeletal traits that are considered to be primitive for the genus Homo. Significance These features may be previously unrecognized developmental correlates of small body size and, if so, they may have important implications for interpreting the taxonomic affinities of fossil specimens of Homo.


Abstract: Tineo, D.E., Bona, P., Pérez, L.M., Vergani, G.D., González, G., Poiré, D.G., Gasparini, Z.N. & Legarreta, P., 1.10.2014. Palaeoenvironmental implications of the giant crocodylian Mourasuchus (Alligatoridae, Caimaninae) in the Yecua Formation (late Miocene) of Bolivia. Alcheringa 39, xxx–xxx. ISSN 0311-5518 Outcrops of the Yecua Formation (late Miocene) are exposed for approximately 230 m along the La Angostura section of the Piraí River (50 km southwest of Santa Cruz de la Sierra). These reveal massive (argillic palaeosols) and laminated (quiet-water lacustrine and marsh settings) mudstones interbedded with thin sandstones containing microfossils, molluscs and vertebrate remains. Significantly, the succession hosts a giant crocodylian, Mourasuchus (Alligatoridae, Caimaninae), which is represented by both skull and postcranial fragments found in association with freshwater turtles and fishes. Mourasuchus was distributed widely from the middle Miocene of Colombia to upper Miocene of Venezuela, Brazil and Argentina, suggesting connections between major fluvial systems and an active mechanism for dispersal of South American freshwater vertebrates during the Miocene. David Eric Tineo [tineo.d.e@gmail.com] and Daniel Gustavo Poiré [dgpoire@yahoo.com.ar], CONICET—Centro de Investigaciones Geológicas, Universidad Nacional de La Plata. Calle 1 (644), B1900FWA, La Plata, Argentina; Paula Bona [paulabona26@gmail.com] and Zulma Gasparini [zgaspari@fcnym.unlp.edu.ar], CONICET—División Paleontología Vertebrados, Museo de La Plata. Paseo del Bosque s/n, B1900FWA, La Plata, Argentina; Leandro Martín Pérez [pilosaperez@gmail.com] CONICET—División Paleozoología Invertebrados, Museo de La Plata. Paseo del Bosque s/n, B1900FWA, La Plata, Argentina; Gustavo Dardo Vergani [gvergani@pluspetrol.net]—Pluspetrol S.A. Lima (339), C1073AAG, Ciudad Autónoma de Buenos Aires, Argentina; Gloria González Rigas [ggonzalez@pluspetrol.net]—Pluspetrol Bolivia Corporation SA, Av. Grigotá esq. Las Palmas, Santa Cruz de la Sierra, Bolivia; Pablo Legarreta [plegarreta@pluspetrol.net]—Pluspetrol S.A. Lima (339), C1073AAG, Ciudad Autónoma de Buenos Aires, Argentina.

alligatoridae
late miocene
palaeoenvironmental implication


Functional integration for enrolment constrains evolutionary variation of phacopid trilobites despite developmental modularity

Abstract: Modularity and integration are variational properties expressed at various levels of the biological hierarchy. Mismatches among these levels, for example developmental modules that are integrated in a functional unit, could be informative of how evolutionary processes and trade‐offs have shaped organismal morphologies as well as clade diversification. In the present study, we explored the full, integrated and modular spaces of two developmental modules in phacopid trilobites, the cephalon and the pygidium, and highlight some differences among them. Such contrasts reveal firstly that evolutionary processes operating in the modular spaces are stronger in the cephalon, probably due to a complex regime of selection related to the numerous functions ensured by this module. Secondly, we demonstrate that the same pattern of covariation is shared among species, which also differentiate along this common functional integration. This common pattern might be the result of stabilizing selection acting on the enrolment and implying a coordinate variation between the cephalon and the pygidium in a certain direction of the morphospace. Finally, we noticed that Austerops legrandi differs slightly from other species in that its integration is partly restructured in the way the two modules interact. Such a divergence can result from the involvement of the cephalon in several vital functions that may have constrained the response of the features involved in enrolment and reorganized the covariation of the pygidium with the cephalon. Therefore, it is possible that important evolutionary trade‐offs between enrolment and other functions on the cephalon might have partly shaped the diversification of trilobites.

phacopid trilobite
trilobite
functional integration


Abstract: Commercial mining northeast of Sarasota, SW Florida (USA), since the 1960s has exposed Plio-Pleistocene marine shell beds of the Tamiami Formation, a complex sequence of mixed carbonate and siliciclastic beds containing a malacofauna that is a mixture of subtropical and temperate species. Material used for the current study consists of shells of the bivalve Anomia simplex d’Orbigny, 1853 encrusted by bryozoans. The shells were collected from Units 10/11 of the lower Tamiami Formation, estimated as being late Pliocene (Piacenzian). This paper describes the bryozoan fauna associated with these ‘jingle shells’, which is of relatively low diversity, totaling 29 species, and comprises one cyclostome and 28 cheilostomes. Six cheilostome species are new: Micropora stellata sp. nov., Microporella sarasotaensis sp. nov., Microporella tamiamiensis sp. nov., Pourtalesella chiarae sp. nov., Spiniflabellum laurae sp. nov., and Trypostega composita sp. nov. Of the previously described species, six are extant and have western Atlantic distributions, while 12 species are known only from the fossil record. The bulk of the assemblage comprises a limited number of species represented by hundreds of colonies, while the remaining species are rare and represented by a single or a few colonies. Colonization of the shells is likely to have happened postmortem, considering the high percentage of valves encrusted on both surfaces. A large number of overgrowth interactions have been observed among the bryozoan colonies, thus this taxonomic revision is the necessary baseline for ecological analyses aiming to establish a ranking of species in a competitive hierarchy. Emanuela Di Martino. Department of Earth Sciences, Natural History Museum, Cromwell Road, SW7 5BD, London, United Kingdom. e.di-martino@nhm.ac.uk Paul D. Taylor. Department of Earth Sciences, Natural History Museum, Cromwell Road, SW7 5BD, London, United Kingdom. p.taylor@nhm.ac.uk Roger W. Portell. Division of Invertebrate Paleontology, Florida Museum of Natural History, University of Florida, Gainesville, FL 32611–7800, USA. portell@flmnh.ufl.edu http://zoobank.org/236D37F3-8616-4CF3-ADE7-54F84499D6EF Di Martino, Emanuela, Taylor, Paul D., and Portell, Roger W. 2019. Anomia-associated bryozoans from the upper Pliocene (Piacenzian) lower Tamiami Formation of Florida, USA. Palaeontologia Electronica 22.1.11A 1-65. https://doi.org/10.26879/920 palaeo-electronica.org/content/2019/2404-tamiami-formation-bryozoans Copyright: March 2019 Palaeontological Association. This is an open access article distributed under the terms of Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0), which permits users to copy and redistribute the material in any medium or format, provided it is not used for commercial purposes and the original author and source are credited, with indications if any changes are made. creativecommons.org/licenses/by-nc-sa/4.0/ DI MARTINO, TAYLOR, & PORTELL: TAMIAMI FORMATION BRYOZOANS


Abstract: Deccan volcanism, one of Earth’s largest fl ood basalt provinces, erupted ~80% of its total volume (phase 2) during a relatively short time in the uppermost Maastrichtian paleomagnetic chron C29r and ended with the Cretaceous-Tertiary boundary mass extinction. Full biotic recovery in the marine realm was delayed at least 500 k.y. or until after the last Deccan eruptions in C29n (phase 3, 14% of the total Deccan volume). For over 30 yr, the mass extinction has been commonly attributed to the Chicxulub impact, and the delayed recovery remained an enigma. Here, we demonstrate that the two phases of Deccan volcanism can account for both the mass extinction and delayed marine recovery. In India, a direct correlation between Deccan eruptions (phase 2) and the mass extinction reveals that ~50% of the planktic foraminifer species gradually disappeared during volcanic eruptions prior to the fi rst of four lava megafl ows, reaching ~1500 km across India, and out to the Bay of Bengal. Another 50% disappeared after the fi rst megafl ow, and the mass extinction was complete with the last megafl ow. Throughout this interval, blooms of the disaster opportunist Guembelitria cretacea dominate shallow-marine assemblages in coeval intervals from India to the Tethys and the Atlantic Oceans to Texas. Similar high-stress environments dominated by blooms of Guembelitria and/or Globoconusa are observed correlative with Deccan volcanism phase 3 in the early Danian C29n, followed by full biotic recovery after volcanism ended. The mass extinction and high-stress conditions may be explained by the intense Deccan volcanism leading to rapid global warming and cooling in C29r and C29n, enhanced weathering, continental runoff, and ocean acidifi cation, resulting in a carbonate crisis in the marine environment. *jpunekar@princeton.edu Punekar, J., Mateo, P., and Keller, G., 2014, Effects of Deccan volcanism on paleoenvironment and planktic foraminifera: A global survey, in Keller, G., and Kerr, A.C., eds., Volcanism, Impacts, and Mass Extinctions: Causes and Effects: Geological Society of America Special Paper 505, p. 91–116, doi:10.1130/2014.2505(04). For permission to copy, contact editing@geosociety.org. © 2014 The Geological Society of America. All rights reserved. on August 25, 2014 specialpapers.gsapubs.org Downloaded from

volcanism
paleoenvironment
planktic foraminifera


An Early Triassic gladius associated with soft tissue remains from Idaho, USA—a squid-like coleoid cephalopod at the onset of Mesozoic Era

Abstract:
We describe an Olenekian (Early Triassic) “fossil squid” belonging to the oldest complex Mesozoic marine biota collected
in the Lower Shale unit of the Lower Triassic Thaynes Group in Idaho, USA. The studied specimen shows a
tapered structure embedded in a cylindrical soft body. Morphological, ultrastructural and geochemical features of the
specimen suggest that it corresponds to an internally-shelled cephalopod exhibiting a tapered micro-laminated gladius
with rachis, narrow median and lateral fields and a large conus; a pair of posterior large fin-supported cartilages and
fins; ventral and dorsal mantle band-shape structures, the dorsal one being cartilaginous; mantle patches; a stomach
containing undigested arm-hooks and sheet-like pieces of potential flooded ink. Coupled SEM/EDS analyses show
that (i) arm-hooks and ink were pseudomorphed by nanoparticles (less than 0.6 mm in diameter) of carbon, (ii) gladius
and soft tissues were substituted by granules of calcium phosphate, (iii) cartilage canalicula’s were partially filled with
calcium phosphate grains and crystals of Zn- and S-containing minerals. The specimen was hence probably fossilized
due to metabolism of P- and C-accumulating bacteria. Based on this specimen, Idahoteuthis parisiana Doguzhaeva and
Brayard gen. et sp. nov. and Idahoteuthidae Doguzhaeva and Brayard fam. nov. are erected. This family is characterized
by an elongated, cylindrical, dorsally cartilaginous muscular mantle; well-developed, about 0.2 mantle length, rounded
anteriorly and acute posteriorly, fin-supported cartilages and similarly shaped two fins at conical mantle termination,
and thin slender gladius with narrow median and lateral fields, rachis and breviconic conus. This family assumedly falls
in Myopsida (Decabrachia). A streamlined body, large fin-supported cartilages and eroded arm-hooks in the stomach of
Idahoteuthis Doguzhaeva and Brayard gen. nov. suggest that this was a maneuverable cannibal predator that dwelled in
the subequatorial shallow sea of the west coast of Pangaea.


Brain and eyes of Kerygmachela reveal protocerebral ancestry of the panarthropod head

Abstract: Recent discoveries of fossil nervous tissue in Cambrian fossils have allowed researchers to trace the origin and evolution of the complex arthropod head and brain based on stem groups close to the origin of the clade, rather than on extant, highly derived members. Here we show that Kerygmachela from Sirius Passet, North Greenland, a primitive stem-group euarthropod, exhibits a diminutive (protocerebral) brain that innervates both the eyes and frontal appendages. It has been surmised, based on developmental evidence, that the ancestor of vertebrates and arthropods had a tripartite brain, which is refuted by the fossil evidence presented here. Furthermore, based on the discovery of eyes in Kerygmachela, we suggest that the complex compound eyes in arthropods evolved from simple ocelli, present in onychophorans and tardigrades, rather than through the incorporation of a set of modified limbs.


Confidence intervals on stratigraphic ranges: partial relaxation of the assumption of randomly distributed fossil horizons

Abstract: The equations for calculating classical confidence intervals on the end points of stratigraphic ranges are based on the restrictive assumption of randomly distributed fossil finds. Herein, a method is presented for calculating confidence intervals on the end-points of stratigraphic ranges that partially relaxes this assumption: the method will work for any continuous distribution of gap sizes, not just those generated by random processes. The price paid for the generality of the new approach is twofold: (1) there are uncertainties associated with the sizes of the confidence intervals, and (2) for large confidence values (e.g., 95%) a rich fossil record is required to place upper bounds on the corresponding confidence intervals. This new method is not universal; like the method for calculating classical confidence intervals it is based on the assumption that there is no correlation between gap size and stratigraphic position. The fossil record of the Neogene Caribbean bryozoan Metrarabdotos is analyzed with the new approach. The equations developed here, like those for classical confidence intervals, should not be applied to stratigraphic ranges based on discrete sampling regimes, such as those typically established from deep-sea drilling cores, though there are exceptions to this rule.

stratigraphic range
assumption
confidence interval


Diverse and complex developmental mechanisms of early Ediacaran embryo-like fossils from the Weng'an Biota, southwest China

Abstract: The origin and early evolution of animal development remain among the many deep, unresolved problems in evolutionary biology. As a compelling case for the existence of pre-Cambrian animals, the Ediacaran embryo-like fossils (EELFs) from the Weng'an Biota (approx. 609 Myr old, Doushantuo Formation, South China) have great potential to cast light on the origin and early evolution of animal development. However, their biological implications can be fully realized only when their phylogenetic positions are correctly established, and unfortunately, this is the key problem under debate. As a significant feature of developmental biology, the cell division pattern (CDP) characterized by the dynamic spatial arrangement of cells and associated developmental mechanisms is critical to reassess these hypotheses and evaluate the diversity of the EELFs; however, their phylogenetic implications have not been fully realized. Additionally, the scarcity of fossil specimens representing late developmental stages with cell differentiation accounts for much of this debate too. Here, we reconstructed a large number of EELFs using submicron resolution X-ray tomographic microscopy and focused on the CDPs and associated developmental mechanisms as well as features of cell differentiation. Four types of CDPs and specimens with cell differentiation were identified. Contrary to the prevailing view, our results together with recent studies suggest that the diversity and complexity of developmental mechanisms documented by the EELFs are much higher than is often claimed. The diverse CDPs and associated development features including palintomic cleavage, maternal nutrition, asymmetric cell divisions, symmetry breaking, establishment of polarity or axis, spatial cell migration and differentiation constrain some, if not all, EELFs as total-group metazoans. This article is part of the theme issue ‘The impact of Chinese palaeontology on evolutionary research’.

developmental mechanism
embryo-like fossil
weng'an biota


New insights into the enigmatic Cretaceous family Spathiopterygidae (Hymenoptera: Diaprioidea)

Abstract: The Cretaceous family Spathiopterygidae (Hymenoptera: Diaprioidea), containing five species in four genera, showed a wide distribution from the upper Barremian to the Turonian. We describe two new representatives of the family from the upper Albian San Just outcrop in the eastern Iberian Peninsula that correspond to Diameneura marveni gen. et sp. nov. Santer and Alvarez-Parra and to a female member of Mymaropsis turolensis Engel and Ortega-Blanco, 2013. The forewing venation of Diameneura marveni gen. et sp. nov. is interpreted, allowing an appropriate comparison for future descriptions. Furthermore, we provide a diagnosis for Mymaropsis baabdaensis since no diagnosis was proposed in the initial paper. We indicate the taphonomic characteristics of the newly described specimens, discuss the interrelationships of the family, and provide new insights about the sexual dimorphism and palaeobiology of spathiopterygids.

family spathiopterygidae
hymenoptera
diaprioidea


Computational fluid dynamics as a tool for testing functional and ecological hypotheses in fossil taxa

Abstract: Computational fluid dynamics is a method for simulating fluid flows that has been widely used in engineering for decades, and which also has applications for studying function and ecology in fossil taxa. However, despite the possible benefits of this approach, computational fluid dynamics has been used only rarely in palaeontology to date. The theoretical basis underlying the technique is outlined and the main steps involved in carrying out computer simulations of fluid flows are detailed. I also describe previous studies that have applied the method to fossils and discuss their potential for informing future research directions in palaeontology. Computational fluid dynamics can enable large‐scale comparative analyses, as well as exacting tests of hypotheses related to the function and ecology of ancient organisms. In this way, it could transform our understanding of many extinct fossil groups.

fossil taxa
flow
computational fluid dynamic
cfd


Greenhouse to icehouse: a biostratigraphic review of latest Devonian–Mississippian glaciations and their global effects

Abstract: Abstract The latest Devonian–Mississippian interval records the long-term transition from Devonian greenhouse conditions into the Late Palaeozoic Ice Age (LPIA). This transition was punctuated by three short glaciation events in the latest Famennian, mid-Tournaisian and Visean stages, respectively. Primary evidence for glaciation is based on diamictite deposits and striated pavements in South America, Appalachia and Africa. The aim of this review is to assess the primary biostratigraphic and sedimentological data constraining diamictite deposits through this transition. These data are then compared to the wider record of eustasy, mass extinction and isotope stratigraphy in the lower palaeolatitudes. Precise age determinations are vital to integrate high- and low-palaeolatitude datasets, and to understand the glacial control on wider global changes. Palynological techniques currently provide the best biostratigraphic tool to date these glacial deposits and to correlate the effects of glaciation globally. This review highlights a high degree of uncertainty in the known history of early LPIA glaciation as much of the primary stratigraphic data are limited and/or unpublished. Future high-resolution stratigraphic studies are needed to constrain the history of glaciation both spatially and temporally through the latest Devonian and Mississippian.

review
glaciation
mass extinction
sea level fall
gondwana


The PMIP4 contribution to CMIP6 – Part 2: Two interglacials, scientific objective and experimental design for Holocene and Last Interglacial simulations

Abstract: Two interglacial epochs are included in the suite of Paleoclimate Modeling Intercomparison Project (PMIP4) simulations in the Coupled Model Intercomparison Project (CMIP6). The experimental protocols for simulations of the mid-Holocene (midHolocene, 6000 years before present) and the Last Interglacial (lig127k, 127 000 years before present) are described here. These equilibrium simulations are designed to examine the impact of changes in orbital forcing at times when atmospheric greenhouse gas levels were similar to those of the preindustrial period and the continental configurations were almost identical to modern ones. These simulations test our understanding of the interplay between radiative forcing and atmospheric circulation, and the connections among large-scale and regional climate changes giving rise to phenomena such as land-sea contrast and high-latitude amplification in temperature changes, and responses of the monsoons, as compared to today. They also provide an opportunity, through carefully designed additional sensitivity experiments, to quantify the strength of atmosphere, ocean, cryosphere, and land-surface feedbacks. Sensitivity experiments are proposed to investigate the role of freshwater forcing in triggering abrupt climate changes within interglacial epochs. These feedback experiments naturally lead to a focus on climate evolution during interglacial periods, which will be examined through transient experiments. Analyses of the sensitivity simulations will also focus on interactions between extratropical and tropical circulation, and the relationship between changes in mean climate state and climate variability on annual to multi-decadal timescales. The comparative abundance of paleoenvironmental data and of quantitative climate reconstructions for the Holocene and Last In-terglacial make these two epochs ideal candidates for systematic evaluation of model performance, and such comparisons will shed new light on the importance of external feedbacks (e.g., vegetation, dust) and the ability of state-of-the-art models to simulate climate changes realistically.


Intense Hurricane Activity Over the Past 1500 Years at South Andros Island, The Bahamas

Abstract: Hurricanes cause substantial loss of life and resources in coastal areas. Unfortunately, historical hurricane records are too short and incomplete to capture hurricane‐climate interactions on multi‐decadal and longer timescales. Coarse‐grained, hurricane‐induced deposits preserved in blue holes in the Caribbean can provide records of past hurricane activity extending back thousands of years. Here we present a high resolution record of intense hurricane events over the past 1500 years from a blue hole on South Andros Island on the Great Bahama Bank. This record is corroborated by shorter reconstructions from cores collected at two nearby blue holes. The record contains coarse‐grained event deposits attributable to known historical hurricane strikes within age uncertainties. Over the past 1500 years, South Andros shows evidence of four active periods of hurricane activity. None of these active intervals occurred in the past 163 years. We suggest that Intertropical Convergence Zone position modulates hurricane activity on the island based on a correlation with Cariaco Basin titanium concentrations. An anomalous gap in activity on South Andros Island in the early 13th century corresponds to a period of increased volcanism. The patterns of hurricane activity reconstructed from South Andros Island closely match those from the northeastern Gulf of Mexico but are anti‐phased with records from New England. We suggest that either changes in local environmental conditions (e.g., SSTs) or a northeastward shift in storm tracks can account for the increased activity in the western North Atlantic when the Gulf of Mexico and southeastern Caribbean are less active.

hurricane activity
south andros island
event deposit
local environmental condition


Hyolitha: status of the phylum

Abstract: Hyoliths are operculate calcareous shells found in Palaeozoic rocks. Runnegar et al. (1975) suggested that they be referred to a new phylum (Hyolitha) but Marek & Yochelson (1976) and Dzik (1978) preferred to regard them as an extinct class of the Mollusca. Since the hyolith cone is not easily homologized with the monoplacophoran shell, the exoskeletons of the shelled Mollusca and the Hyolitha appear to have developed independently. Reconstructions of the anatomy of hyoliths indicate that it is unlikely that both groups shared a common molluscan ancestor. Therefore, hyoliths are probably not molluscs. Previous reconstructions of articulated hyolithids have suggested that left and right appendages (helens) curved dorsally. Crushed articulated specimens from the Burgess Shale indicate that this conclusion is incorrect; hyoltthid helens seem to have curved ventrally when the animals were alive.


A new high-resolution chronology for the late Maastrichtian warming event: Establishing robust temporal links with the onset of Deccan volcanism

Abstract: The late Maastrichtian warming event was defined by a global temperature increase of ∼2.5–5 °C that occurred ∼150–300 k.y. before the Cretaceous-Paleogene (K-Pg) mass extinction. This transient warming event has traditionally been associated with a major pulse of Deccan Traps (west-central India) volcanism; however, large uncertainties associated with radiogenic dating methods have long hampered a definitive correlation. Here we present a new high-resolution, single species, benthic stable isotope record from the South Atlantic, calibrated to an updated orbitally tuned age model, to provide a revised chronology of the event, which we then correlate to the latest radiogenic dates of the main Deccan Traps eruption phases. Our data reveal that the initiation of deep-sea warming coincides, within uncertainty, with the onset of the main phase of Deccan volcanism, strongly suggesting a causal link. The onset of deep-sea warming is synchronous with a 405 k.y. eccentricity minimum, excluding a control by orbital forcing alone, although amplified carbon cycle sensitivity to orbital precession is evident during the greenhouse warming. A more precise understanding of Deccan-induced climate change paves the way for future work focusing on the fundamental role of these precursor climate shifts in the K-Pg mass extinction.

maastrichtian warming event
onset
deccan volcanism


A Retrospective Examination of Paleoparasitology and Its Establishment in the Journal of Parasitology

Abstract: Abstract:  Volume 95 (2009) of the Journal of Parasitology represented a significant benchmark in the history of paleoparasitology when it received on the cover formal recognition as a topical area for publication. This retrospective examination chronicles the emergence of paleoparasitology, from its origins as an adjunct contribution to the study of prehistoric human populations to its modern expression as a sub-disciplinary interest. The aim of paleoparasitology is to elucidate the temporal and spatial dimensions of parasitism from the fossil record of human and non-human host populations.


Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary

Abstract: Pterosaurs were the first vertebrates to evolve powered flight and the largest animals to ever take wing. The pterosaurs persisted for over 150 million years before disappearing at the end of the Cretaceous, but the patterns of and processes driving their extinction remain unclear. Only a single family, Azhdarchidae, is definitively known from the late Maastrichtian, suggesting a gradual decline in diversity in the Late Cretaceous, with the Cretaceous–Paleogene (K-Pg) extinction eliminating a few late-surviving species. However, this apparent pattern may simply reflect poor sampling of fossils. Here, we describe a diverse pterosaur assemblage from the late Maastrichtian of Morocco that includes not only Azhdarchidae but the youngest known Pteranodontidae and Nyctosauridae. With 3 families and at least 7 species present, the assemblage represents the most diverse known Late Cretaceous pterosaur assemblage and dramatically increases the diversity of Maastrichtian pterosaurs. At least 3 families—Pteranodontidae, Nyctosauridae, and Azhdarchidae—persisted into the late Maastrichtian. Late Maastrichtian pterosaurs show increased niche occupation relative to earlier, Santonian-Campanian faunas and successfully outcompeted birds at large sizes. These patterns suggest an abrupt mass extinction of pterosaurs at the K-Pg boundary.

pterosaur
mass extinction
first vertebrate
late maastrichtian pterosaur


The impact of shifts in marine biodiversity hotspots on patterns of range evolution: Evidence from the Holocentridae (squirrelfishes and soldierfishes)

Abstract: One of the most striking biodiversity patterns is the uneven distribution of marine species richness, with species diversity in the Indo‐Australian Archipelago (IAA) exceeding all other areas. However, the IAA formed fairly recently, and marine biodiversity hotspots have shifted across nearly half the globe since the Paleogene. Understanding how lineages have responded to shifting biodiversity hotspots represents a necessary historic perspective on the formation and maintenance of global marine biodiversity. Such evolutionary inferences are often challenged by a lack of fossil evidence that provide insights into historic patterns of abundance and diversity. The greatest diversity of squirrelfishes and soldierfishes (Holocentridae) is in the IAA, yet these fishes also represent some of the most numerous fossil taxa in deposits of the former West Tethyan biodiversity hotspot. We reconstruct the pattern of holocentrid range evolution using time‐calibrated phylogenies that include most living species and several fossil lineages, demonstrating the importance of including fossil species as terminal taxa in ancestral area reconstructions. Holocentrids exhibit increased range fragmentation following the West Tethyan hotspot collapse. However, rather than originating within the emerging IAA hotspot, the IAA has acted as a reservoir for holocentrid diversity that originated in adjacent regions over deep evolutionary time scales.

marine biodiversity
range evolution
holocentridae