Pathological survey on Temnodontosaurus from the Early Jurassic of southern Germany

Abstract: Paleopathologies document skeletal damage in extinct organisms and can be used to infer the causes of injury, as well as aspects of related biology, ecology and behavior. To date, few studies have been undertaken on Jurassic marine reptiles, while ichthyosaur pathologies in particular have never been systematically evaluated. Here we survey 41 specimens of the apex predator ichthyosaur Temnodontosaurus from the Early Jurassic of southern Germany in order to document the range and absolute frequency of pathologies observed in this taxon as a function of the number of specimens examined. According to our analysis, most observed pathologies in Temnodontosaurus are force-induced traumas with signs of healing, possibly inflicted during aggressive interactions with conspecifics. When the material is preserved, broken ribs are correlated in most of the cases with traumas elsewhere in the skeleton such as cranial injuries. The range of cranial pathologies in Temnodontosaurus is similar to those reported for extinct cetaceans and mosasaurs, which were interpreted as traces of aggressive encounters. Nevertheless, Temnodontosaurus differs from these other marine amniotes in the absence of pathologies in the vertebral column, consistent with the pattern previously documented in ichthyosaurs. We did not detect any instances of avascular necrosis in Temnodontosaurus from southern Germany, which may reflect a shallow diving life style. This study is intended to provide baseline data for the various types of observed pathologies in large ichthyosaurs occupying the ‘apex predator’ niche, and potentially clarifies aspects of species-specific behavior relative to other ichthyosaurs and marine amniotes.

temnodontosaurus
early jurassic
southern germany
ichthyosaur
pathology


Amphibian skull evolution: The developmental and functional context of simplification, bone loss and heterotopy.

Abstract: Despite their divergent morphology, extant and extinct amphibians share numerous features in the timing and spatial patterning of dermal skull elements. Here, I show how the study of these features leads to a deeper understanding of morphological evolution. Batrachians (salamanders and frogs) have simplified skulls, with dermal bones appearing rudimentary compared with fossil tetrapods, and open cheeks resulting from the absence of other bones. The batrachian skull bones may be derived from those of temnospondyls by truncation of the developmental trajectory. The squamosal, quadratojugal, parietal, prefrontal, parasphenoid, palatine, and pterygoid form rudimentary versions of their homologs in temnospondyls. In addition, failure to ossify and early fusion of bone primordia both result in the absence of further bones that were consistently present in Paleozoic tetrapods. Here, I propose a new hypothesis explaining the observed patterns of bone loss and emargination in a functional context. The starting observation is that jaw-closing muscles are arranged in a different way than in ancestors from the earliest ontogenetic stage onwards, with muscles attaching to the dorsal side of the frontal, parietal, and squamosal. The postparietal and supratemporal start to ossify in a similar way as in branchiosaurids, but are fused to neighboring elements to form continuous attachment areas for the internal adductor. The postfrontal, postorbital, and jugal fail to ossify, as their position is inconsistent with the novel arrangement of adductor muscles. Thus, rearrangement of adductors forms the common theme behind cranial simplification, driven by an evolutionary flattening of the skull in the batrachian stem. J. Exp. Zool. (Mol. Dev. Evol.) 9999B: XX-XX, 2014. © 2014 Wiley Periodicals, Inc.

functional context
simplification
bone loss


Pigmented anatomy in Carboniferous cyclostomes and the evolution of the vertebrate eye

Abstract: The success of vertebrates is linked to the evolution of a camera-style eye and sophisticated visual system. In the absence of useful data from fossils, scenarios for evolutionary assembly of the vertebrate eye have been based necessarily on evidence from development, molecular genetics and comparative anatomy in living vertebrates. Unfortunately, steps in the transition from a light-sensitive ‘eye spot’ in invertebrate chordates to an image-forming camera-style eye in jawed vertebrates are constrained only by hagfish and lampreys (cyclostomes), which are interpreted to reflect either an intermediate or degenerate condition. Here, we report—based on evidence of size, shape, preservation mode and localized occurrence—the presence of melanosomes (pigment-bearing organelles) in fossil cyclostome eyes. Time of flight secondary ion mass spectrometry analyses reveal secondary ions with a relative intensity characteristic of melanin as revealed through principal components analyses. Our data support the hypotheses that extant hagfish eyes are degenerate, not rudimentary, that cyclostomes are monophyletic, and that the ancestral vertebrate had a functional visual system. We also demonstrate integument pigmentation in fossil lampreys, opening up the exciting possibility of investigating colour patterning in Palaeozoic vertebrates. The examples we report add to the record of melanosome preservation in Carboniferous fossils and attest to surprising durability of melanosomes and biomolecular melanin.


Animal helminths in human archaeological remains: a review of zoonoses in the past.

Abstract: The authors present a review of records of intestinal parasitic helminths from animals in human archaeological remains, reported since the emergence of paleopathological studies. The objective was to relate paleoparasitological findings to geographic, biotic, and abiotic factors from the environment in which the prehistoric populations lived, and understand some aspects related to the process of human dispersion and biological and cultural evolution. Modification of eating habits and the incorporation of new cultural practices are analyzed from the perspective of zoonoses from prehistory to the present day, especially in Brazilian indigenous populations. Three tables identifying the helminths, their natural hosts, dates, and sites of archaeological findings complete this review. In conclusion, various zoonoses known today have occurred since antiquity, and these data, combined with studies on the emergence and reemergence of diseases, could make possible to compose scenarios for the future.

helminth
human archaeological remain
review
zoonosis


Earliest True Moth Lacewing from the Middle Jurassic of Inner Mongolia, China

Abstract: A new moth lacewing Guithone bethouxi gen. et sp. nov., is described from the Middle Jurassic Jiulongshan Formation (Inner Mongolia, China). This taxon is characterized by robust body, head retracted under pronotum, and remarkable costal space (expanded basad, narrowed distad). Herein, we propose a detailed definition of the lineages of Ithonidae sensu lato (moth lacewings, giant lacewings, and montane lacewings) based on extant groups in order to clarify the systematics of fossil species within the taxon. The comparison shows that Guithone bethouxi gen. et sp. nov. unquestionably represents the earliest true moth lacewing, implying that lineage differentiations within Ithonidae sensu lato must have taken place before the Middle Jurassic. Furthermore the new genus possessing some particular venation characters, such as irrecurrent humeral veinlet and simplified crossveination in radial sector, represents an important intermediate group in the evolution of Ithonidae sensu lato.


Body mass estimation in non‐avian bipeds using a theoretical conversion to quadruped stylopodial proportions

Abstract: Body mass is strongly related to both physiological and ecological properties of living organisms. As a result, generating robust, broadly applicable models for estimating body mass in the fossil record provides the opportunity to reconstruct palaeobiology and investigate evolutionary ecology on a large temporal scale. A recent study provided strong evidence that the minimum circumference of stylopodial elements (humerus and femur) is conservatively associated with body mass in living quadrupeds. Unfortunately, this model is not directly applicable to extinct bipeds, such as non‐avian dinosaurs. This study presents a new equation that mathematically corrects the quadruped equation for use in bipeds. It is derived from the systemic difference in the circumference‐to‐area scaling relationship of two circles (hypothetical quadruped) and one circle (hypothetical biped), which represent the cross‐section of the main weight‐bearing limb bones. When applied to a newly constructed data set of femoral circumferences and body masses in living birds, the new equation reveals errors that are significantly lower than other published equations, but significantly higher than the error inherent in the avian data set. Such errors, however, are expected given the unique overall femoral circumference–body mass scaling relationship found in birds. Body mass estimates for a sample of bipedal dinosaurs using the new model are consistent with recent estimates based on volumetric life reconstructions, but, in contrast, this equation is simpler to use, with the concomitant potential to provide a wider set of body mass estimates for extinct bipeds. Although it is evident that no one estimation model is flawless, the combined use of the corrected quadrupedal equations and the previously published quadrupedal equation offer a consistent approach with which to estimate body masses in both quadrupeds and bipeds. These models have implications for conducting large‐scale macroevolutionary analyses of body size throughout the evolutionary history of terrestrial vertebrates, and, in particular, across major changes in body plan, such as the evolution of bipedality in archosaurs and quadrupedality in dinosaurs.


Fossilization of melanosomes via sulfurization

Abstract: Fossil melanin granules (melanosomes) are an important resource for inferring the evolutionary history of colour and its functions in animals. The taphonomy of melanin and melanosomes, however, is incompletely understood. In particular, the chemical processes responsible for melanosome preservation have not been investigated. As a result, the origins of sulfur‐bearing compounds in fossil melanosomes are difficult to resolve. This has implications for interpretations of original colour in fossils based on potential sulfur‐rich phaeomelanosomes. Here we use pyrolysis gas chromatography mass spectrometry (Py‐GCMS), fourier transform infrared spectroscopy (FTIR) and time of flight secondary ion mass spectrometry (ToF‐SIMS) to assess the mode of preservation of fossil microstructures, confirmed as melanosomes based on the presence of melanin, preserved in frogs from the Late Miocene Libros biota (NE Spain). Our results reveal a high abundance of organosulfur compounds and non‐sulfurized fatty acid methyl esters in both the fossil tissues and host sediment; chemical signatures in the fossil tissues are inconsistent with preservation of phaeomelanin. Our results reflect preservation via the diagenetic incorporation of sulfur, i.e. sulfurization (natural vulcanization), and other polymerization processes. Organosulfur compounds and/or elevated concentrations of sulfur have been reported from melanosomes preserved in various invertebrate and vertebrate fossils and depositional settings, suggesting that preservation through sulfurization is likely to be widespread. Future studies of sulfur‐rich fossil melanosomes require that the geochemistry of the host sediment is tested for evidence of sulfurization in order to constrain interpretations of potential phaeomelanosomes and thus of original integumentary colour in fossils.

melanosomes sulfurization tissue fossilization chemistry


A globally distributed durophagous marine reptile clade supports the rapid recovery of pelagic ecosystems after the Permo-Triassic mass extinction

Abstract: Marine ecosystem recovery after the Permo-Triassic mass extinction (PTME) has been extensively studied in the shallow sea, but little is known about the nature of this process in pelagic ecosystems. Omphalosauridae, an enigmatic clade of open-water durophagous marine reptiles, potentially played an important role in the recovery, but their fragmentary fossils and uncertain phylogenetic position have hindered our understanding of their role in the process. Here we report the large basal ichthyosauriform Sclerocormus from the Early Triassic of China that clearly demonstrates an omphalosaurid affinity, allowing for the synonymy of the recently erected Nasorostra with Omphalosauridae. The skull also reveals the anatomy of the unique feeding apparatus of omphalosaurids, likely an adaptation for feeding on hard-shelled pelagic invertebrates, especially ammonoids. Morphofunctional analysis of jaws shows that omphalosaurids occupy the morphospace of marine turtles. Our discovery adds another piece of evidence for an explosive radiation of marine reptiles into the ocean in the Early Triassic and the rapid recovery of pelagic ecosystems after the PTME.

rapid recovery
pelagic ecosystem
permo-triassic mass extinction
early triassic


Multivariate and Cladistic Analyses of Isolated Teeth Reveal Sympatry of Theropod Dinosaurs in the Late Jurassic of Northern Germany

Abstract: Remains of theropod dinosaurs are very rare in Northern Germany because the area was repeatedly submerged by a shallow epicontinental sea during the Mesozoic. Here, 80 Late Jurassic theropod teeth are described of which the majority were collected over decades from marine carbonates in nowadays abandoned and backfilled quarries of the 19th century. Eighteen different morphotypes (A—R) could be distinguished and 3D models based on micro-CT scans of the best examples of all morphotypes are included as supplements. The teeth were identified with the assistance of discriminant function analysis and cladistic analysis based on updated datamatrices. The results show that a large variety of theropod groups were present in the Late Jurassic of northern Germany. Identified specimens comprise basal Tyrannosauroidea, as well as Allosauroidea, Megalosauroidea cf. Marshosaurus, Megalosauridae cf. Torvosaurus and probably Ceratosauria. The formerly reported presence of Dromaeosauridae in the Late Jurassic of northern Germany could not be confirmed. Some teeth of this study resemble specimens described as pertaining to Carcharodontosauria (morphotype A) and Abelisauridae (morphotype K). This interpretation is however, not supported by discriminant function analysis and cladistic analysis. Two smaller morphotypes (N and Q) differ only in some probably size-related characteristics from larger morphotypes (B and C) and could well represent juveniles of adult specimens. The similarity of the northern German theropods with groups from contemporaneous localities suggests faunal exchange via land-connections in the Late Jurassic between Germany, Portugal and North America.

late jurassic
northern germany
theropod tooth


Opening the carbon isotope "vital effect" black box, 2, Quantitative model for interpreting foramini

Abstract: Interpretation of carbon isotope records from late Quaternary planktonic foraminifers are confounded due to the presence of a significant physiological component in the carbon isotopic signal. A quantitative carbon isotope (QC) model is presented which relates the carbon isotopic composition of a foraminiferal shell to the physiological processes of respiration and symbiont photosynthesis and to the δ13C value of seawater ΣCO2. The QC model is calibrated with physiological and stable isotopic data from laboratory experiments with living planktonic foraminifers. Model simulations of chamber and shell δ13C values with the symbiont-bearing foraminifers, Orbulina universa and Globigerinoides sacculifer, suggest (1) variations in symbiont density and photosynthetic rate (light level or habitat depth) are the primary physiological parameters controlling intraspecific carbon isotopic variability in these species, (2) respiration has little effect on the δ13C of O. universa, and (3) each chamber in a multichambered foraminiferal test will have a distinct δ13C value depending on its position in the test whorl. Size:δ13C value relationships reported for G. sacculifer from fossil assemblages can be explained as a function of increasing symbiont density during ontogenetic development.

carbon isotope
vital effect
foraminiferal shell


The sauropodomorph biostratigraphy of the Elliot Formation of southern Africa: Tracking the evolution of Sauropodomorpha across the Triassic–Jurassic boundary

Abstract: The latest Triassic is notable for coinciding with the dramatic decline of many previously dominant groups, followed by the rapid radiation of Dinosauria in the Early Jurassic. Among the most common terrestrial vertebrates from this time, sauropodomorph dinosaurs provide an important insight into the changing dynamics of the biota across the Triassic–Jurassic boundary. The Elliot Formation of South Africa and Lesotho preserves the richest assemblage of sauropodomorphs known from this age, and is a key index assemblage for biostratigraphic correlations with other similarly-aged global terrestrial deposits. Past assessments of Elliot Formation biostratigraphy were hampered by an overly simplistic biozonation scheme which divided it into a lower “ Euskelosaurus ” Range Zone and an upper Massospondylus Range Zone. Here we revise the zonation of the Elliot Formation by: (i) synthesizing the last three decades’ worth of fossil discoveries, taxonomic revision, and lithostratigraphic investigation; and (ii) systematically reappraising the stratigraphic provenance of important fossil locations. We then use our revised stratigraphic information in conjunction with phylogenetic character data to assess morphological disparity between Late Triassic and Early Jurassic sauropodomorph taxa. Our results demonstrate that the Early Jurassic upper Elliot Formation is considerably more taxonomically and morphologically diverse than previously thought. In contrast, the sauropodomorph fauna of the Late Triassic lower Elliot Formation remains relatively poorly understood due to the pervasive incompleteness of many key specimens, as well as the relative homogeneity of their diagnostic character suites. Our metrics indicate that both Elliot Formation and global sauropodomorph assemblages had greater morphological disparity within the Early Jurassic than the Late Triassic. This result is discussed in the context of changing palaeoclimatic conditions, as well as macroevolutionary events associated with the end-Triassic extinction.

elliot formation
sauropodomorpha
triassic–jurassic boundary
early jurassic


Surface-circulation change in the southwest Pacific Ocean across the Middle Eocene Climatic Optimum: inferences from dinoflagellate cysts and biomarker paleothermometry

Abstract:
Abstract. Global climate cooled from the early Eocene hothouse (∼52–50 Ma) to the latest
Eocene (∼34 Ma). At the same time, the tectonic evolution of the Southern Ocean was
characterized by the opening and deepening of circum-Antarctic gateways, which affected both
surface- and deep-ocean circulation. The Tasmanian Gateway played a key role in regulating ocean
throughflow between Australia and Antarctica. Southern Ocean surface currents through and around
the Tasmanian Gateway have left recognizable tracers in the spatiotemporal distribution of
plankton fossils, including organic-walled dinoflagellate cysts. This spatiotemporal distribution
depends on both the physicochemical properties of the water masses and the path of surface-ocean
currents. The extent to which climate and tectonics have influenced the distribution and
composition of surface currents and thus fossil assemblages has, however, remained unclear. In
particular, the contribution of climate change to oceanographic changes, superimposed on long-term
and gradual changes induced by tectonics, is still poorly understood. To disentangle the effects of tectonism and climate in the southwest Pacific Ocean, we target
a climatic deviation from the long-term Eocene cooling trend: the Middle Eocene Climatic Optimum
(MECO; ∼40 Ma). This 500 kyr phase of global warming was unrelated
to regional tectonism, and thus provides a test case to investigate the ocean's physicochemical
response to climate change alone. We reconstruct changes in surface-water circulation and
temperature in and around the Tasmanian Gateway during the MECO through new palynological and
organic geochemical records from the central Tasmanian Gateway (Ocean Drilling Program Site 1170),
the Otway Basin (southeastern Australia), and the Hampden Beach section (New Zealand). Our results
confirm that dinocyst communities track specific surface-ocean currents, yet the variability
within the communities can be driven by superimposed temperature change. Together with published
results from the east of the Tasmanian Gateway, our new results suggest a shift in surface-ocean
circulation during the peak of MECO warmth. Simultaneous with high sea-surface temperatures in
the Tasmanian Gateway area, pollen assemblages indicate warm temperate rainforests with
paratropical elements along the southeastern margin of Australia. Finally, based on new age
constraints, we suggest that a regional southeast Australian transgression might have been
coincident with the MECO.

southwest pacific ocean
dinoflagellate cyst
current


Fossil Fishes from China Provide First Evidence of Dermal Pelvic Girdles in Osteichthyans

Abstract: Background The pectoral and pelvic girdles support paired fins and limbs, and have transformed significantly in the diversification of gnathostomes or jawed vertebrates (including osteichthyans, chondrichthyans, acanthodians and placoderms). For instance, changes in the pectoral and pelvic girdles accompanied the transition of fins to limbs as some osteichthyans (a clade that contains the vast majority of vertebrates – bony fishes and tetrapods) ventured from aquatic to terrestrial environments. The fossil record shows that the pectoral girdles of early osteichthyans (e.g., Lophosteus, Andreolepis, Psarolepis and Guiyu) retained part of the primitive gnathostome pectoral girdle condition with spines and/or other dermal components. However, very little is known about the condition of the pelvic girdle in the earliest osteichthyans. Living osteichthyans, like chondrichthyans (cartilaginous fishes), have exclusively endoskeletal pelvic girdles, while dermal pelvic girdle components (plates and/or spines) have so far been found only in some extinct placoderms and acanthodians. Consequently, whether the pectoral and pelvic girdles are primitively similar in osteichthyans cannot be adequately evaluated, and phylogeny-based inferences regarding the primitive pelvic girdle condition in osteichthyans cannot be tested against available fossil evidence. Methodology/Principal Findings Here we report the first discovery of spine-bearing dermal pelvic girdles in early osteichthyans, based on a new articulated specimen of Guiyu oneiros from the Late Ludlow (Silurian) Kuanti Formation, Yunnan, as well as a re-examination of the previously described holotype. We also describe disarticulated pelvic girdles of Psarolepis romeri from the Lochkovian (Early Devonian) Xitun Formation, Yunnan, which resemble the previously reported pectoral girdles in having integrated dermal and endoskeletal components with polybasal fin articulation. Conclusions/Significance The new findings reveal hitherto unknown similarity in pectoral and pelvic girdles among early osteichthyans, and provide critical information for studying the evolution of pelvic girdles in osteichthyans and other gnathostomes.

dermal pelvic girdle
osteichthyan
acanthodian
placoderm
holotype


No (Cambrian) explosion and no (Ordovician) event: A single long-term radiation in the early Palaeozoic

Abstract: The Cambrian 'Explosion', located by many authors between 540 and 520 million years ago (Ma), is considered to be an abrupt appearance in the fossil record of most animal phyla, with a sudden increase of complex morphologies across metazoan groups. In a few recent papers, the Great Ordovician Biodiversification 'Event' (GOBE) has similarly been restricted to a single dramatic biodiversification 'event' in the Darriwilian Stage of the Middle Ordovician Series, between 470 and 455 Ma, although historically the biodiversification is considered as an aggregation of radiation 'events' capturing a large and complex increase of taxonomic diversity of marine invertebrates covering the entire Ordovician. A review of biodiversity curves of marine organisms during the early Palaeozoic, including some based on data in the Paleobiology Database (PBDB) and the Geobiodiversity Database (GBDB), points towards a single, large-scale, long-term early Palaeozoic radiation of life that already started in the late Precambrian. An abrupt 'explosion' of diversity in the Cambrian or a significant 'event' in the Ordovician are not visible in our biodiversity studies, because they are either regional, or only reflect a single group of organisms. It is evident that the datasets remain incomplete, in particular those for many geographical areas and for several fossil groups, that are not covered by the PBDB and GBDB; also, such areas remain so far poorly or entirely unstudied. Some recently published biodiversity curves have to be considered with care, as the truly global diversity estimates of marine organisms during the early Palaeozoic remain elusive. Here, we argue that published curves of taxonomic richness, which show distinct periods of diversification, cannot sufficiently be disentangled from biases. We therefore question the existence of a distinct Cambrian 'Explosion' and global Ordovician 'Event' in the global datasets. Both terms, Cambrian 'Explosion' and Great Ordovician Biodiversification 'Event should be used as conceptional terms only. The first represents the appearance of almost all animal phyla during the late Precambrian and early Cambrian, whereas the second term embraces the numerous and complex radiations that occurred during the entire Ordovician.


New discoveries of glirids and eomyids (Mammalia, Rodentia) in the Early Miocene of the Junggar basin (Northern Xinjiang province, China)

Abstract: We report herein new discoveries of Gliridae and Eomyidae (Mammalia, Rodentia) from the new Early Miocene locality XJ 200604, located northwest to the Burqin city, northern Xinjiang province, China. These specimens represent three taxa of Gliridae, including a new species (Miodyromys asiamediae nov. sp., Microdyromys aff. orientalis and Eliomys? sp.), and four taxa of Eomyidae (Asianeomys aff. engesseri, Asianeomys sp., Keramidomys sp. and Eomyidae indet). The identification of two forms that are closely related to Microdyromys orientalis and Asianeomys engesseri suggests an Early Miocene age of the locality but does not allow a more precise age determination. The new discoveries of Gliridae and Eomyidae again reveal the relative scarcity of the two families in the Early Miocene of Central Asia, in contrast to the coeval rich European record. Such a discrepancy in taxonomic diversity and abundance is hypothesized as resulting from different environmental evolutions during the Early Miocene, most notably the onset of a mid-latitude dry climate in Central Asia linked to combine effects of the Tibetan Plateau uplift and the retreat of the Paratethys Sea.


Late Middle Eocene primate from Myanmar and the initial anthropoid colonization of Africa

Abstract: Reconstructing the origin and early evolutionary history of anthropoid primates (monkeys, apes, and humans) is a current focus of paleoprimatology. Although earlier hypotheses frequently supported an African origin for anthropoids, recent discoveries of older and phylogenetically more basal fossils in China and Myanmar indicate that the group originated in Asia. Given the Oligocene-Recent history of African anthropoids, the colonization of Africa by early anthropoids hailing from Asia was a decisive event in primate evolution. However, the fossil record has so far failed to constrain the nature and timing of this pivotal event. Here we describe a fossil primate from the late middle Eocene Pondaung Formation of Myanmar, Afrasia djijidae gen. et sp. nov., that is remarkably similar to, yet dentally more primitive than, the roughly contemporaneous North African anthropoid Afrotarsius. Phylogenetic analysis suggests that Afrasia and Afrotarsius are sister taxa within a basal anthropoid clade designated as the infraorder Eosimiiformes. Current knowledge of eosimiiform relationships and their distribution through space and time suggests that members of this clade dispersed from Asia to Africa sometime during the middle Eocene, shortly before their first appearance in the African fossil record. Crown anthropoids and their nearest fossil relatives do not appear to be specially related to Afrotarsius, suggesting one or more additional episodes of dispersal from Asia to Africa. Hystricognathous rodents, anthracotheres, and possibly other Asian mammal groups seem to have colonized Africa at roughly the same time or shortly after anthropoids gained their first toehold there.

middle eocene
myanmar
colonization
anthropoid primate
african origin


Eutherian morphological disparity across the end‐Cretaceous mass extinction

Abstract: © 2015 The Linnean Society of London. In the aftermaths of mass extinction events, during radiations of clades, and in several other evolutionary scenarios, there is often a decoupling of taxonomic diversity and morphological disparity. The placental mammal radiation after the end-Cretaceous mass extinction is one of the archetypal adaptive radiations, but the change in morphological disparity of the entire skeleton has never been quantified across this important boundary. We reconstruct ancestral morphologies of 680 discrete morphological characters onto dated phylogenies of 177 mostly Cretaceous and Palaeogene eutherians (placental mammals and their stem relatives). Using a new approach to incorporate morphologies representing ghost lineages, we assess three measures of morphological disparity (sum of ranges, sum of variances and mean pairwise dissimilarity) across stage-level time bins within the Cretaceous and Palaeogene. We find that the range-based metric suggests that eutherian disparity increased immediately after the end-Cretaceous mass extinction, while both variance-based metrics declined from the Campanian to the Maastrichtian, but showed no change in disparity from the Maastrichtian to the Puercan - the first North American Land Mammal Age of the Paleocene. Increases in variance-based metrics lag behind the range-based metric and per-lineage accumulation rate, suggesting that the response of mammals to the Cretaceous-Palaeogene event was characterized by an early radiation that increased overall morphospace occupation, followed later by specialization that resulted in increased dissimilarity.

morphological disparity
mass extinction
entire skeleton


Non-dinosaurian Dinosauromorpha

Abstract: Abstract Ichnological evidence suggests that dinosauromorphs originated by the Early Triassic, and skeletal remains of non-dinosaur representatives of the clade occur from the Anisian to the end of the Triassic. These taxa are small- to medium-sized, vary in feeding and locomotor features, and occurred over most of western Pangaea. They include the small lagerpetids from the Mid–Late Triassic of Argentina and the United States, and the larger, quadrupedal Silesauridae, with records in the Middle Triassic of Africa and Argentina, and in the Late Triassic of Europe, the Americas and northern Africa. The former group represents the earliest diverging dinosauromorphs, whereas silesaurids are more closely related to Dinosauria. Other dinosauromorphs include the archetypal early dinosauriform Marasuchus lilloensis (Middle Triassic of Argentina) and poorly known/controversial taxa such as Lewisuchus admixtus and Saltopus elginensis. The earliest diverging dinosauromorphs may have preyed on small animals (including insects), but cranio-dental remains are rare; by contrast, most silesaurids probably included plant material in their diet, as indicated by their modified jaw apparatus and teeth. Our knowledge of the anatomy and thus relationships of non-dinosaurian Dinosauromorpha is still deficient, and we suspect that future discoveries will continue to reveal novel patterns and hypotheses of palaeobiology and biogeography.

triassic
silesauridae
non-dinosaurian dinosauromorpha


Revisiting the origin and diversification of vascular plants through a comprehensive Bayesian analysis of the fossil record

Abstract: Summary Plants have a long evolutionary history, during which mass extinction events dramatically affected Earth's ecosystems and its biodiversity. The fossil record can shed light on the diversification dynamics of plant life and reveal how changes in the origination–extinction balance have contributed to shaping the current flora. We use a novel Bayesian approach to estimate origination and extinction rates in plants throughout their history. We focus on the effect of the ‘Big Five’ mass extinctions and on estimating the timing of origin of vascular plants, seed plants and angiosperms. Our analyses show that plant diversification is characterized by several shifts in origination and extinction rates, often matching the most important geological boundaries. The estimated origin of major plant clades predates the oldest macrofossils when considering the uncertainties associated with the fossil record and the preservation process. Our findings show that the commonly recognized mass extinctions have affected each plant group differently and that phases of high extinction often coincided with major floral turnovers. For instance, after the Cretaceous–Paleogene boundary we infer negligible shifts in diversification of nonflowering seed plants, but find significantly decreased extinction in spore‐bearing plants and increased origination rates in angiosperms, contributing to their current ecological and evolutionary dominance.

diversification
vascular plant
mass extinction event


Late Quaternary paleoceanography of the tropical Atlantic, 2: The seasonal cycle of sea surface temperatures, 0–20,000 years B.P.

Abstract: Foraminiferal species abundances are used to estimate seasonal variability of late Quaternary sea surface temperatures in the tropical Atlantic Ocean. Empirical orthogonal functions analysis of 28 time series isolates two patterns (modes) of variation. The dominant mode 1 reflects seasonal temperature contrast of the South Equatorial Current region 5°–6°C higher at the glacial maximum than at present, probably indicating larger seasonal variations of the southern trade winds. Forcing for this pattern may have come from equatorward compression of glacial climate zones due to high-latitude cooling in both hemispheres and/or suppression of meridional monsoonal circulation via feedback from northern hemisphere ice cover. When compared with CLIMAP estimates of lower seasonal variations of glacial age sea ice fronts in Antarctica, mode 1 suggests decoupling of low- and high- latitude seasonal cycles in the southern hemisphere on a glacial-interglacial scale. Mode 2 variations reflect seasonal contrast in sea surface temperature of 2°–3°C less 9000 to 14,000 years B.P. than at present along the equator and in the eastern subtropical Atlantic, perhaps related to an equatorial position of the Intertropical Convergence Zone, weakened trade winds, and/or strengthened monsoonal circulation during deglaciation. Our findings emphasize the need to isolate spatially coherent (and thus dynamically linked) patterns of climate change from a complex record of multiple climatic effects. Only then can effective tests of hypotheses be made with a coupled strategy of data acquisition and climate modeling.

seasonal cycle
sea surface temperature
year b.p.
cooling


Evaluation of a New Method of Fossil Retrodeformation by Algorithmic Symmetrization: Crania of Papionins (Primates, Cercopithecidae) as a Test Case

Abstract: Diagenetic distortion can be a major obstacle to collecting quantitative shape data on paleontological specimens, especially for three-dimensional geometric morphometric analysis. Here we utilize the recently -published algorithmic symmetrization method of fossil reconstruction and compare it to the more traditional reflection & averaging approach. In order to have an objective test of this method, five casts of a female cranium of Papio hamadryas kindae were manually deformed while the plaster hardened. These were subsequently “retrodeformed” using both algorithmic symmetrization and reflection & averaging and then compared to the original, undeformed specimen. We found that in all cases, algorithmic retrodeformation improved the shape of the deformed cranium and in four out of five cases, the algorithmically symmetrized crania were more similar in shape to the original crania than the reflected & averaged reconstructions. In three out of five cases, the difference between the algorithmically symmetrized crania and the original cranium could be contained within the magnitude of variation among individuals in a single subspecies of Papio. Instances of asymmetric distortion, such as breakage on one side, or bending in the axis of symmetry, were well handled, whereas symmetrical distortion remained uncorrected. This technique was further tested on a naturally deformed and fossilized cranium of Paradolichopithecus arvernensis. Results, based on a principal components analysis and Procrustes distances, showed that the algorithmically symmetrized Paradolichopithecus cranium was more similar to other, less-deformed crania from the same species than was the original. These results illustrate the efficacy of this method of retrodeformation by algorithmic symmetrization for the correction of asymmetrical distortion in fossils. Symmetrical distortion remains a problem for all currently developed methods of retrodeformation.

retrodeformation
algorithmic symmetrization
crania


Subfamily Limoniinae Speiser, 1909 (Diptera, Limoniidae) from Baltic Amber (Eocene): The Genus Elephantomyia Osten Sacken, 1860

Abstract: A revision of the genus Elephantomyia Osten Sacken (Diptera: Limoniidae) from Baltic amber (Eocene) is presented. Four species--E. baltica Alexander, E. brevipalpa Loew, E. longirostris Loew, and E. pulchella Loew--are redescribed and documented with photographs and drawings. In addition, two new species of the genus are described: Elephantomyia bozenae sp. nov., and Elephantomyia irinae sp. nov. All these fossil species are placed within the subgenus Elephantomyia. A key to the extinct species of Elephantomyia is provided, and the genus' ecological pattern and evolutionary aspects are discussed.


Dietary resilience among hunter-gatherers of Tierra del Fuego: Isotopic evidence in a diachronic perspective

Abstract: The native groups of Patagonia have relied on a hunter-gatherer economy well after the first Europeans and North Americans reached this part of the world. The large exploitation of marine mammals (i.e., seals) by such allochthonous groups has had a strong impact on the local ecology in a way that might have forced the natives to adjust their subsistence strategies. Similarly, the introduction of new foods might have changed local diet. These are the premises of our isotopic-based analysis. There is a large set of paleonutritional investigations through isotopic analysis on Fuegians groups, however a systematic exploration of food practices across time in relation to possible pre- and post-contact changes is still lacking. In this paper we investigate dietary variation in hunter-gatherer groups of Tierra del Fuego in a diachronic perspective, through measuring the isotopic ratio of carbon (∂13C) and nitrogen (∂15N) in the bone collagen of human and a selection of terrestrial and marine animal samples. The data obtained reveal an unexpected isotopic uniformity across prehistoric and recent groups, with little variation in both carbon and nitrogen mean values, which we interpret as the possible evidence of resilience among these groups and persistence of subsistence strategies, allowing inferences on the dramatic contraction (and extinction) of Fuegian populations.

resilience
tierra del fuego
diachronic perspective


The skull of Ekaltadeta ima (Marsupialia, Hypsiprymnodontidae?): An analysis of some marsupial cranial features and a re-investigation of propleopine phylogeny, with notes on the inference of carnivory in mammals

Abstract: The near-complete skull of the Giant Rat-kangaroo Ekaltadeta ima is described from a middle Miocene deposit at Riversleigh, north western Queensland. Surprisingly, the results of phylogenetic analysis indicate no special relationship with the only other hypsiprymnodontids for which substantial cranial material is known (Hypsiprymnodon moschatus, H. bartholomaii), but within Macropodoidea, a number of derived features present in E. ima are found only in another extinct taxon, the Balbarinae. Recent studies have suggested that Balbarinae may not represent a basal macropodid clade as thought by most previous authors and furthermore that the subfamily is perhaps distinct from all other kangaroos. In light of these findings an interesting possibility is noted, i.e., that Propleopinae and Balbarinae may represent a monophyletic clade to the exclusion of all other taxa. Preliminary results of investigation into dietary habitus indicate that Propleopinae represents a radiation of medium- to large-sized omnivorous kangaroos. Within this clade it is reiterated that a tendency toward carnivory might be inferred from the relative importance of high amplitude vertical shearing versus horizontal shearing and/or crushing elements in the dentition.


Ecomorphological selectivity among marine teleost fishes during the end-Cretaceous extinction

Abstract: Despite the attention focused on mass extinction events in the fossil record, patterns of extinction in the dominant group of marine vertebrates—fishes—remain largely unexplored. Here, I demonstrate ecomorphological selectivity among marine teleost fishes during the end-Cretaceous extinction, based on a genus-level dataset that accounts for lineages predicted on the basis of phylogeny but not yet sampled in the fossil record. Two ecologically relevant anatomical features are considered: body size and jaw-closing lever ratio. Extinction intensity is higher for taxa with large body sizes and jaws consistent with speed (rather than force) transmission; resampling tests indicate that victims represent a nonrandom subset of taxa present in the final stage of the Cretaceous. Logistic regressions of the raw data reveal that this nonrandom distribution stems primarily from the larger body sizes of victims relative to survivors. Jaw mechanics are also a significant factor for most dataset partitions but are always less important than body size. When data are corrected for phylogenetic nonindependence, jaw mechanics show a significant correlation with extinction risk, but body size does not. Many modern large-bodied, predatory taxa currently suffering from overexploitation, such billfishes and tunas, first occur in the Paleocene, when they appear to have filled the functional space vacated by some extinction victims.

marine teleost fish
end-cretaceous extinction
body size
extinction risk
ecomorphological selectivity


Dinosaur origin of egg color: oviraptors laid blue-green eggs

Abstract: Protoporphyrin (PP) and biliverdin (BV) give rise to the enormous diversity in avian egg coloration. Egg color serves several ecological purposes, including post-mating signaling and camouflage. Egg camouflage represents a major character of open-nesting birds which accomplish protection of their unhatched offspring against visually oriented predators by cryptic egg coloration. Cryptic coloration evolved to match the predominant shades of color found in the nesting environment. Such a selection pressure for the evolution of colored or cryptic eggs should be present in all open nesting birds and relatives. Many birds are open-nesting, but protect their eggs by continuous brooding, and thus exhibit no or minimal eggshell pigmentation. Their closest extant relatives, crocodiles, protect their eggs by burial and have unpigmented eggs. This phylogenetic pattern led to the assumption that colored eggs evolved within crown birds. The mosaic evolution of supposedly avian traits in non-avian theropod dinosaurs, however, such as the supposed evolution of partially open nesting behavior in oviraptorids, argues against this long-established theory. Using a double-checking liquid chromatography ESI-Q-TOF mass spectrometry routine, we traced the origin of colored eggs to their non-avian dinosaur ancestors by providing the first record of the avian eggshell pigments protoporphyrin and biliverdin in the eggshells of Late Cretaceous oviraptorid dinosaurs. The eggshell parataxon Macroolithus yaotunensis can be assigned to the oviraptor Heyuannia huangi based on exceptionally preserved, late developmental stage embryo remains. The analyzed eggshells are from three Late Cretaceous fluvial deposits ranging from eastern to southernmost China. Reevaluation of these taphonomic settings, and a consideration of patterns in the porosity of completely preserved eggs support an at least partially open nesting behavior for oviraptorosaurs. Such a nest arrangement corresponds with our reconstruction of blue-green eggs for oviraptors. According to the sexual signaling hypothesis, the reconstructed blue-green eggs support the origin of previously hypothesized avian paternal care in oviraptorid dinosaurs. Preserved dinosaur egg color not only pushes the current limits of the vertebrate molecular and associated soft tissue fossil record, but also provides a perspective on the potential application of this unexplored paleontological resource.


CALIBRATED DIVERSITY, TREE TOPOLOGY AND THE MOTHER OF MASS EXTINCTIONS: THE LESSON OF TEMNOSPONDYLS

Abstract: Abstract:  Three family‐level cladistic analyses of temnospondyl amphibians are used to evaluate the impact of taxonomic rank, tree topology, and sample size on diversity profiles, origination and extinction rates, and faunal turnover. Temnospondyls are used as a case study for investigating replacement of families across the Permo‐Triassic boundary and modality of recovery in the aftermath of the end‐Permian mass extinction. Both observed and inferred (i.e. tree topology‐dependent) values of family diversity have a negligible effect on the shape of the diversity curve. However, inferred values produce both a flattening of the curve throughout the Cisuralian and a less pronounced increase in family diversity from Tatarian through to Induan than do observed values. Diversity curves based upon counts of genera and species display a clearer distinction between peaks and troughs. We use rarefaction techniques (specifically, rarefaction of the number of genera and species within families) to evaluate the effect of sampling size on the curve of estimated family‐level diversity during five time bins (Carboniferous; Cisuralian; Guadalupian–Lopingian; Early Triassic; Middle Triassic–Cretaceous). After applying rarefaction, we note that Cisuralian and Early Triassic diversity values are closer to one another than they are when the observed number of families is used; both values are also slightly higher than the Carboniferous estimated diversity. The Guadalupian–Lopingian value is lower than raw data indicate, reflecting in part the depauperate land vertebrate diversity from the late Cisuralian to the middle Guadalupian (Olson’s gap). The time‐calibrated origination and extinction rate trajectories plot out close to one another and show a peak in the Induan, regardless of the tree used to construct them. Origination and extinction trajectories are disjunct in at least some Palaeozoic intervals, and background extinctions exert a significant role in shaping temnospondyl diversity in the lowermost Triassic. Finally, species‐, genus‐, and family trajectories consistently reveal a rapid increase in temnospondyl diversity from latest Permian to earliest Triassic as well as a decline near the end of the Cisuralian. However, during the rest of the Cisuralian family diversity increases slightly and there is no evidence for a steady decline, contrary to previous reports.

tree
mass extinction
amphibian
triassic
olson


The use of MSR (Minimum Sample Richness) for sample assemblage comparisons

Abstract: Abstract Minimum Sample Richness (MSR) is defined as the smallest number of taxa that must be recorded in a sample to achieve a given level of inter-assemblage classification accuracy. MSR is calculated from known or estimated richness and taxonomic similarity. Here we test MSR for strengths and weaknesses by using 167 published mammalian local faunas from the Paleogene and early Neogene of the Quercy and Limagne area (Massif Central, southwestern France), and then apply MSR to 84 Oligo-Miocene faunas from Riversleigh, northwestern Queensland, Australia. In many cases, MSR is able to detect the assemblages in the data set that are potentially too incomplete to be used in a similarity-based comparative taxonomic analysis. The results show that the use of MSR significantly improves the quality of the clustering of fossil assemblages. We conclude that this method can screen sample assemblages that are not representative of their underlying original living communities. Ultimately, it can be used to identify which assemblages require further sampling before being included in a comparative analysis.

msr
minimum sample richness
local faunas
riversleigh


Bottom water anoxia, inoceramid colonization, and benthopelagic coupling during black shale deposition on Demerara Rise (Late Cretaceous western tropical North Atlantic)

Abstract: [1] The bulk rock geochemistry and inoceramid isotopic composition from Cenomanian to Santonian, finely laminated, organic-rich black shales, recovered during Ocean Drilling Program Leg 207 on Demerara Rise (western tropical North Atlantic), suggest persistent anoxic (free H2S) conditions within the sediments and short-term variations within a narrow range of anoxic to episodically dysoxic bottom waters over a ∼15 Ma time interval. In addition to being organic-rich, the 50–90 m thick sections examined exhibit substantial bulk rock enrichments of Si, P, Ba, Cu, Mo, Ni, and Zn relative to World Average Shale. These observations point to high organic burial fluxes, likely driven by high primary production rates, which led to the establishment of intensely sulfidic pore waters and possibly bottom waters, as well as to the enrichments of Cr, Mo, U, and V in the sediments. At the same time, the irregular presence of benthic inoceramids and foraminifera in this facies demonstrates that the benthic environment could not have been continuously anoxic. The δ13C and δ15N values of the inoceramid shell organics provide no evidence of chemosymbiosis and are consistent with pelagic rain as being a significant food source. Demerara Rise inoceramids also exhibit well-defined, regularly spaced growth lines that are tracked by δ13C and δ18O variations in shell carbonate that cannot be simply explained by diagenesis. Instead, productivity variations in surface waters may have paced the growth of the shells during brief oxygenation events suitable for benthic inoceramid settlement. These inferences imply tight benthopelagic coupling and more dynamic benthic conditions than generally portrayed during black shale deposition. By invoking different temporal scales for geochemical and paleontological data, this study resolves recent contradictory conclusions (e.g., sulfidic sedimentary conditions versus dysoxic to suboxic benthic waters) drawn from studies of either sediment geochemistry or fossil distributions alone on Demerara Rise. This variability may be relevant for discussions of black shales in general.

benthopelagic coupling
black shale deposition
tropical north atlantic


The variations in the East Asian summer monsoon over the past 3 kyrs and the controlling factors

Abstract:
the mechanisms driving the variations in the centennial-scale east Asian summer monsoon (eAsM) remain unclear. Here, we use the δ 18 o records from adult ostracode shells to reconstruct the eAsM variations over the last 3 kyrs in southwestern Japan. A common variation with a 200 yr periodicity among the Asian monsoonal regions was recognized between BC 800 and BC 100. Since then, neither a correlation between the eAsM variation and solar activity or a common eAsM variation through eAsM regions has been identified. The evidence reveals that solar activity dominantly affected the centennialscale EASM variations throughout Asian monsoonal regions until BC 100. Furthermore, factors other than solar activity that varied and differed in specific regions controlled the EASM intensity due to decreasing summer solar insolation in the Northern Hemisphere after BC 100. These relations indicate that the dominant factor that affects the EASM variations shifts according to the solar insolation intensity.
Climates in Asia are strongly controlled by monsoons that are linked to the global climate 1,2 . The East Asian monsoon, which is one of the largest monsoon systems, covers the regions including China, the Korean Peninsula and Japan 3 . The East Asian monsoon is composed of southeastern winds in summer and northwestern winds in winter. The summer monsoon transports a large volume of water vapour to the continents, providing important water resources. High-resolution speleothem records from caves have clarified the variations in the East Asian summer monsoon (EASM) and their relations to other climate and sun patterns. In particular, new records from various regions over the last two decades have improved the understanding of monsoon mechanisms and the driving forces during the Quaternary 4,5 . Numerous EASM records, particularly those from stalagmites in Chinese caves, have indicated that both the orbital-scale and millennial-scale EASM variations are mainly due to solar insolation [4] [5] [6] [7] [8] [9] . In addition to sun activity, CO 2 concentrations 10 , the El Niño-Southern Oscillation (ENSO) 11 , and climate in the high latitudes of the Northern Hemisphere 4,12 have been proposed to be strongly linked to the intensity of the Asian summer monsoon. However, due to the small number of centennial-scale EASM records compared to the number of orbital-and millennial-scale records, coherent centennial-scale EASM variations and the relationships between the centennial-scale EASM variations and solar activity remain vague.
Regardless of the significance and usefulness of the δ 18 O records in stalagmites, their inconsistencies between nearby caves have been recognized 7, 13 . Furthermore, there are controversies that the δ 18 O records in stalagmites from southern China reflect the isotopic compositions of water vapour from the upstream source region and not the EASM intensity in southern China 12,14-17 . Thus, the EASM records derived from other materials are required.
Ostracoda is a microcrustacea that inhabits aquatic environments throughout the world. The calcareous shells of Ostracoda are well preserved in the bottom sediments of freshwater lakes, brackish lakes and marine environments 18 . The δ 18 O of the adult shell of a brackish species Bicornucythere bisanensis has been used as a tool to reconstruct the past summer precipitation induced by the EASM in Lake Nakaumi, southwest Japan 19 (Fig. 1 ). According to the EASM records based on this method, centennial-scale EASM variations with periodicities of 300-500 yrs and no relationship with solar activity during the last 1.8 kyrs were defined. This result disagreed with the previous observations that the EASM was strongly linked to solar activities, as found in orbital-and millennial-scale EASM variations. In the present study, we reconstructed the centennial-scale EASM intensity over the last 3 kyrs to reveal the common EASM intensity and its relation to solar activity.


Primates in the Eocene

Abstract: The mammalian order Primates made its first appearance in the fossil record during the Paleocene-Eocene thermal maximum (PETM), the global greenhouse warming event that marks the beginning of the Eocene. Two primate superfamilies, Tarsioidea and Adapoidea, dominate early and middle Eocene primate faunas. Warm climates enabled primates to thrive, and warming events within the Eocene facilitated cosmopolitan dispersal. Declining diversity at the end of the Eocene reflects environmental cooling. Fossils of earliest Tarsioidea and Adapoidea are similar dentally, often confused, and appear closely related as stem or crown Haplorhini. The superfamily Tarsioidea is represented by a single genus, Tarsius, living today, while Adapoidea appear to be ancestral to living Anthropoidea. Little is known of the Eocene history of strepsirrhine Lemuroidea and Lorisoidea. Temporal scaling of molecular clock ages suggests that Strepsirrhini appeared before Haplorhini in the Paleocene or possibly with Haplorhini at the beginning of the Eocene. Substantial skeletons of Eocene primates like those of adapoid Darwinius and Europolemur from Messel in Germany and Notharctus and Smilodectes from western North America constrain phylogenetic interpretation of primate relationships much more than dental remains ever can. A specialised grasping foot distinguishes early primates from other mammals. Traits associated in a functional complex include replacement of claws by nails on all digits; movement of the pedal fulcrum from the metatarsals to the tarsals; elongation of digit IV relative to digit III, with reduction of digit II and sometimes III; and then secondary development of a grooming claw or claws on digits II and sometimes III. The specialised grasping foot of early primates was later moderated in the emergence of anthropoid primates.


A new otter of giant size, Siamogale melilutra sp. nov. (Lutrinae: Mustelidae: Carnivora), from the latest Miocene Shuitangba site in north-eastern Yunnan, south-western China, and a total-evidence phylogeny of lutrines

Abstract: Otters (subfamily Lutrinae) are semi-aquatic predators in the family Mustelidae. Modern otters have a worldwide distribution but their fossil record is poor, often consisting of fragmentary jaws and teeth. Multiple lineages have developed bunodont dentitions with enlargements of molars, usually for cracking molluscs or other hard foods. Some lineages have evolved badger-like teeth and, as a result, were often confused with melines (Old World badger clade). Siamogale thailandica Ginsburg, Invagat, & Tassy, 1983 from the middle Miocene basin of Mae Moh in northern Thailand is one such species, whose fragmentary dental remains have thus far impeded our understanding. A new species of fossil otter, Siamogale melilutra sp. nov., represented by a nearly complete cranium, mandible and partial skeletons of at least three individuals, was recovered from the latest Miocene (∼6.2 Ma) lignite beds of the Shuitangba Site in north-eastern Yunnan Province, south-western China. Computed tomography (CT) restoration of the crushed skull reveals a combination of otter-like and badger-like cranial and dental characteristics. The new species belongs to the Lutrinae because of its possession of a large infraorbital canal and ventral expansion of the mastoid process, among other traits. A distally expanded M1, however, gives a badger-like appearance. In overall morphology the Shuitangba otter is closest to Siamogale thailandica. A previously described jaw (‘Lutra’ aonychoides) from the early Pliocene of the Yushe Basin in north China is also here referred to S. melilutra. No previous attempt has been made to provide a global phylogenetic framework for otters. We present the first combined morphological and molecular (nuclear and mitochondrial DNAs) character matrices of five extant (Pteronura, Lontra, Enhydra, Aonyx, Lutra) and eight extinct genera (Tyrrhenolutra, Paralutra, Paludolutra, Enhydritherium, Siamogale, Vishnuonyx, Sivaonyx, Enhydriodon) to better understand the evolution of bunodont otters. Parsimony and Bayesian analyses consistently recover an eastern Asian clade that includes forms from Shuitangba, Yushe and Mae Moh, all of which are referred to Siamogale. http://zoobank.org/urn:lsid:zoobank.org:pub:5C637018-0772-4C78-AA4B-783B71085D9D


Automatic taxonomic identification based on the Fossil Image Dataset (>415,000 images) and deep convolutional neural networks

Abstract: Abstract. The rapid and accurate taxonomic identification of fossils is of great significance in paleontology, biostratigraphy, and other fields. However, taxonomic identification is often labor-intensive and tedious, and the requisition of extensive prior knowledge about a taxonomic group also requires long-term training. Moreover, identification results are often inconsistent across researchers and communities. Accordingly, in this study, we used deep learning to support taxonomic identification. We used web crawlers to collect the Fossil Image Dataset (FID) via the Internet, obtaining 415,339 images belonging to 50 fossil clades. Then we trained three powerful convolutional neural networks on a high-performance workstation. The Inception-ResNet-v2 architecture achieved an average accuracy of 0.90 in the test dataset when transfer learning was applied. The clades of microfossils and vertebrate fossils exhibited the highest identification accuracies of 0.95 and 0.90, respectively. In contrast, clades of sponges, bryozoans, and trace fossils with various morphologies or with few samples in the dataset exhibited a performance below 0.80. Visual explanation methods further highlighted the discrepancies among different fossil clades and suggested similarities between the identifications made by machine classifiers and taxonomists. Collecting large paleontological datasets from various sources, such as the literature, digitization of dark data, citizen-science data, and public data from the Internet may further enhance deep learning methods and their adoption. Such developments will also possibly lead to image-based systematic taxonomy to be replaced by machine-aided classification in the future. Pioneering studies can include microfossils and some invertebrate fossils. To contribute to this development, we deployed our model on a server for public access at www.ai-fossil.com.

taxonomic identification
fossil image dataset
convolutional neural network
training
web crawler


A micromorphological analysis of stratigraphic integrity and site formation at Cactus Hill, an Early Paleoindian and hypothesized pre‐Clovis occupation in south‐central Virginia, USA

Abstract: Twenty thin sections were studied from Cactus Hill, a ca. 20 ka stratified sand dune site in Virginia, USA, with a Clovis and hypothesized pre‐Clovis component. The high‐resolution soil micromorphology investigation focused on testing the integrity of Clovis and pre‐Clovis stratigraphy from one location where there is a high density of artifacts. Site formation processes were dominated by eolian (dune) sand formation. There was also ephemeral topsoil development and associated occupation, along with their penecontemporaneous disturbance and dispersal by scavenging animals (assumed) and localized down‐working by small invertebrate mesofauna (as evidenced by aggregates of fine phytolith‐rich humic soil and fine soil‐coated charcoal fragments). Partial erosion of these occupation soils (deflation?) was followed by successive sand burial. Post‐depositional processes affecting these sand‐buried occupations involved only small‐scale bioturbation and overprinting of clay lamellae, suggesting site stratigraphy has been stable for a long time. Soil micromorphological analysis has defined a difference between occupational units (pre‐Clovis and Clovis) and sterile units found between these units as well as above and below. In summary, according to this analysis, the site appears intact with only minor disturbances affecting the long‐term integrity of the stratigraphy. © 2008 Wiley Periodicals, Inc.

micromorphological analysis
integrity
cactus hill


A well-preserved respiratory system in a Silurian ostracod

Abstract: Ostracod crustaceans are diverse and ubiquitous in aqueous environments today but relatively few known species have gills. Ostracods are the most abundant fossil arthropods but examples of soft-part preservation, especially of gills, are exceptionally rare. A new ostracod, Spiricopia aurita (Myodocopa), from the marine Silurian Herefordshire Lagerstätte (430 Mya), UK, preserves appendages, lateral eyes and gills. The respiratory system includes five pairs of gill lamellae with hypobranchial and epibranchial canals that conveyed haemolymph. A heart and associated vessels had likely evolved in ostracods by the Mid-Silurian.

respiratory system
ostracod
silurian herefordshire lagerstätte


Aspects of the adaptive morphology and evolution of the Trigoniidae

Abstract: During the Jurassic and Early Cretaceous, the Trigoniidae were the dominant family of shallow-burrowing bivalves of warm, shallow seas. Neotrigonia is the only genus that survives today. Judging from the biology of Neotrigonia and the functional morphology and occurrence of extinct genera, the Trigoniidae represent an advanced family of burrowing Bivalvia. The family has been characterized by efficient locomotion, owing in large part to the presence of an unusually muscular foot, resembling that of the living Cardiidae. Other unusual features of the Trigoniidae relate to the presence of the foot. Complex hinge teeth with secondary dentition evolved to maintain valve alignment at the wide angles of gape required for extrusion of the foot. Myophorous buttresses evolved to support the large anterior hinge teeth. These anterior features seem to have obstructed the evolution of a prosogyrous shape of the kind that facilitates burrowing within many other bivalve taxa. Alternatively, there evolved in the Trigoniidae various kinds of external shell ornamentation that aided in burrowing. Thus, the many unusual morphological features of the Trigoniidae have been strongly coadaptive. The Mesozoic Trigoniidae seem to have been more advanced animals than any shallow-burrowing, suspension-feeding bivalves of the Palaeozoic and also than certain successful living groups with similar modes of life. Though slightly less advanced than the Cardiidae, they can be regarded as the cockles of the Mesozoic. Had the group not suddenly been decimated by environmental deterioration at the end of the Mesozoic, it would undoubtedly flourish today. Neotrigonia has, in fact, speciated at a high rate in comparison with other living genera of bivalves. A relatively recent origin and lack of primitive features disqualify Neotrigonia from status as a living fossil genus. It is the sole survivor of its family, but an advanced and modern animal nonetheless.


Skull and postcranium of the bystrowianid Bystrowiella schumanni from the Middle Triassic of Germany, and the position of chroniosuchians within Tetrapoda

Abstract: Chroniosuchians form a mainly terrestrial or semi-terrestrial clade of Permian and Triassic crocodile- or varanid-like tetrapods, usually considered stem amniotes, but with disputed affinities within that grade. Two groups can be distinguished, the chroniosuchids and bystrowianids. Whereas the chroniosuchid skull and postcranium are well known, our knowledge of bystrowianids is restricted mainly to isolated vertebrae and osteoderms. The Middle Triassic bystrowianid Bystrowiella schumanni from south-western Germany was identified as the first taxon of this clade outside Russia and China, based on the morphology of its vertebrae and osteoderms. Here we expand on a full description of cranial and postcranial remains from this taxon, based on a partially articulated specimen and further isolated material. The material comprises large parts of the dermal skull roof, the pectoral girdle, ribs and limbs, and sheds light on many anatomical regions formerly unknown in bystrowianids. Among the autapomorphic features of Bystrowiella are the premaxilla with an edentulous crest lateral to the choana, the premaxillary teeth with conspicuous size differences, the jugal with an extremely long, narrow anterior process, and the enlarged postparietals and tabulars forming facets for articulation with the anteriormost osteoderm. As in chroniosuchids, the pre- and postfrontal are not in contact, but unlike in chroniosuchids, the internarial fontanelle and the antorbital fenestra are absent. In the amniote-like postcranium, the interclavicle is slender and has a conspicuous parasternal process, the humerus is waisted and bears a short supinator process, and the long, curved trunk ribs have widely separated rib heads and a slender shaft without blades or processes. Phylogenetic analysis, particularly based on numerous new postcranial features, supports the monophyly of chroniosuchians, even when the constituent synapomorphies (osteoderm and vertebral characters) are excluded from the matrix. Chroniosuchians nest at the base of the amniote stem, forming an unresolved polytomy with Silvanerpeton, embolomeres and more advanced stem amniotes.


Adaptation, Niche Conservatism, and Convergence: Comparative Studies of Leaf Evolution in the California Chaparral

Abstract: Small leaves and low specific leaf area (SLA) have long been viewed as adaptations to Mediterranean‐type climates in many species of evergreen woody plants. However, paleobotanical and floristic evidence suggests that in many cases these traits originated prior to the advent of the summer‐drought climate regime. In this study, molecular phylogenies and ancestral state reconstructions were used to test the hypothesis of adaptive leaf evolution in 12 lineages of evergreen shrubs in the California chaparral. Across all lineages there was a small but significant shift toward lower SLA, but there were no trends in leaf size evolution. For individual lineages, adaptive changes were detected in only three cases for SLA and in one case for leaf size. Three of these cases of evolutionary change were observed in taxa derived from cool temperate ancestors (e.g., Heteromeles). In contrast, most lineages originating from subtropical ancestors exhibited relative stasis in leaf trait evolution (e.g., Ceanothus). The absence of change suggests that ancestors of chaparral taxa had already acquired appropriate traits that contributed to their success under Mediterranean‐type climates. These results illustrate how biogeographic history may influence patterns of trait evolution and adaptation and highlight the contribution of ecological sorting processes to the assembly and functional ecology of regional biotas.

leaf evolution
california chaparral
ancestral state reconstruction


Locomotor diversity within past and present guilds of large predatory mammals

Abstract: The impact of environment, interspecific competition, and, to a lesser extent history, on the structure of the guild of large predatory mammals is explored in one fossil and four Recent communities. Two aspects are emphasized: (1) the number of species within each guild and (2) the extent of locomotor convergence as inferred from morphology among the constituent species. Locomotor behavior reflects habitat choice, hunting mode, and escape strategy, all of which appear to be important avenues of adaptive divergence among coexisting predators. Locomotor behavior in extinct and extant predators is determined from body weight and five measured characteristics of the postcranial skeleton, including ungual shape, elbow shape, and limb proportions. Results indicate that levels of morphologic and inferred ecologic similarity between large predators are higher in the tropical grassland guild of East Africa than in the equivalent guilds of either tropical or temperate forest. This may be due to the great density and diversity of terrestrial herbivores in the productive grasslands. The fossil guild, from the Late Chadron–Orellan (Oligocene) of North America, appears most similar to the tropical forest guilds, but the predators seem to have been slower and more robust than their modern counterparts. Since the Orellan represents an early stage in the evolution of large, fissiped carnivores, both ancestry and time could have influenced Orellan guild structure.

guild
large predatory mammal
postcranial skeleton


An unusual new genus of istiodactylid pterosaurfrom China based on a near complete specimen

Abstract: A new genus and species of istiodactylid pterosaur, Luchibang xingzhe gen. et sp. nov., from the Lower Cretaceous Yixian Formation of China is erected based on a near complete specimen lacking only the posterior of the skull and the tail. The holotype individual is skeletally immature and already bigger than most istiodactylids suggesting a large wingspan at adult. This is the most complete istiodactylid specimen known to date and provides new information on the anatomy of this group and their putative ecology. The animal is unusual in having postcranial robust and elongate hindlimbs, which marks it as different to other istiodactylids and other pteranodontoids.

new genus
istiodactylid
near complete speciman


Tetrapod distribution and temperature rise during the Permian–Triassic mass extinction

Abstract: The Permian–Triassic mass extinction (PTME) had an enormous impact on life in three ways: by substantially reducing diversity, by reshuffling the composition of ecosystems and by expelling life from the tropics following episodes of intense global warming. But was there really an ‘equatorial tetrapod gap', and how long did it last? Here, we consider both skeletal and footprint data, and find a more complex pattern: (i) tetrapods were distributed both at high and low latitudes during this time; (ii) there was a clear geographic disjunction through the PTME, with tetrapod distribution shifting 10–15° poleward; and (iii) there was a rapid expansion phase across the whole of Pangea following the PTME. These changes are consistent with a model of generalized migration of tetrapods to higher latitudinal, cooler regions, to escape from the superhot equatorial climate in the earliest Triassic, but the effect was shorter in time scale, and not as pronounced as had been proposed. In the recovery phase following the PTME, this episode of forced range expansion also appears to have promoted the emergence and radiation of entirely new groups, such as the archosaurs, including the dinosaurs.

low latitude
migration
tetrapod distribution
early triassic


The Early Pliocene extinction of the mega-toothed shark Otodus megalodon: a view from the eastern North Pacific

Abstract: The extinct giant shark Otodus megalodon is the last member of the predatory megatoothed lineage and is reported from Neogene sediments from nearly all continents. The timing of the extinction of Otodus megalodon is thought to be Pliocene, although reports of Pleistocene teeth fuel speculation that Otodus megalodon may still be extant. The longevity of the Otodus lineage (Paleocene to Pliocene) and its conspicuous absence in the modern fauna begs the question: when and why did this giant shark become extinct? Addressing this question requires a densely sampled marine vertebrate fossil record in concert with a robust geochronologic framework. Many historically important basins with stacked Otodus-bearing Neogene marine vertebrate fossil assemblages lack well-sampled and well-dated lower and upper Pliocene strata (e.g., Atlantic Coastal Plain). The fossil record of California, USA, and Baja California, Mexico, provides such an ideal sequence of assemblages preserved within well-dated lithostratigraphic sequences. This study reviews all records of Otodus megalodon from post-Messinian marine strata from western North America and evaluates their reliability. All post-Zanclean Otodus megalodon occurrences from the eastern North Pacific exhibit clear evidence of reworking or lack reliable provenance; the youngest reliable records of Otodus megalodon are early Pliocene, suggesting an extinction at the early-late Pliocene boundary (∼3.6 Ma), corresponding with youngest occurrences of Otodus megalodon in Japan, the North Atlantic, and Mediterranean. This study also reevaluates a published dataset, thoroughly vetting each occurrence and justifying the geochronologic age of each, as well as excluding several dubious records. Reanalysis of the dataset using optimal linear estimation resulted in a median extinction date of 3.51 Ma, somewhat older than a previously proposed Pliocene-Pleistocene extinction date (2.6 Ma). Post-middle Miocene oceanographic changes and cooling sea surface temperature may have resulted in range fragmentation, while alongside competition with the newly evolved great white shark (Carcharodon carcharias) during the Pliocene may have led to the demise of the megatoothed shark. Alternatively, these findings may also suggest a globally asynchronous extinction of Otodus megalodon.

pliocene
shark otodus megalodon
eastern north pacific


SPECIES DISCRIMINATION AND EVOLUTIONARY MODE OF BUCHIA (BIVALVIA: BUCHIIDAE) FROM UPPER JURASSIC–LOWER CRETACEOUS STRATA OF GRASSY ISLAND, BRITISH COLUMBIA, CANADA

Abstract: Abstract:  Buchiid bivalves are geographically widespread in Upper Jurassic and Lower Cretaceous strata of the Northern Hemisphere. They are often abundant and their short stratigraphic ranges make them ideal biostratigraphic index fossils; these characteristics also render them useful for study of evolutionary patterns. We used multivariate methods to determine if we could discriminate between species of Buchia and examine how morphological characters change through time within the genus. Using ten morphological characters to describe shell shape and size, we tested for taxonomic differences and morphologic change in populations of buchiids collected from a single stratigraphic section on Grassy Island, located along the west coast of Vancouver Island, British Columbia. Morphometric analysis utilized traditional morphological metrics and techniques, including linear and angular measurements as well as Fourier (outline shape) analyses. Phenetic discrimination revealed considerable overlap among the recognized species in the morphospace, as well as a fairly low discriminatory power between species when compared as a group using a step‐wise canonical variate analysis. Step‐wise discriminant analyses between species pairs gave rise to much higher classification rates, suggesting that different characters are important for distinguishing between different species pairs. Our results also indicate that single individuals and small sample sizes of Buchia specimens are insufficient for biostratigraphic discrimination (unless other rarely preserved features such as the hinge and bysuss ear are available) and that a number of previously described species variants may not be taxonomically valid. A biolog using the multivariate axis that best discriminates between species (CV1) and a random walk‐based test using a Hurst estimate analysis indicate a gradualistic evolutionary mode for the Buchia species of Grassy Island. Shell shape and size of buchiids do not appear to be closely tied to lithofacies changes over the c. 10 myr time interval, suggesting that ecophenotypic variation (as it relates to substrate changes) probably had minimal influence on morphology.


A review of climate reconstructions from terrestrial climate archives covering the first millennium AD in northwestern Europe

Abstract: Abstract Large changes in landscape, vegetation, and culture in northwestern (NW) Europe during the first millennium AD seem concurrent with climatic shifts. Understanding of this relation requires high-resolution palaeoclimate reconstructions. Therefore, we compiled available climate reconstructions from sites across NW Europe (extent research area: 10°W–20°E, 45°–60°N) through review of literature and the underlying data, to identify supraregional climatic changes in this region. All reconstructions cover the period from AD 1 to 1000 and have a temporal resolution of ≤50 yr. This resulted in 22 climate reconstructions/proxy records based on different palaeoclimate archives: chironomids (1), pollen (6), Sphagnum mosses (1), stalagmites (8), testate amoebae (4), and tree rings (2). Comparing all temperature reconstructions, we conclude that summer temperatures between AD 1 and 250 were relatively high, and the period between AD 250 and 700 was characterised by colder summer conditions. The period from AD 700 to 1000 was again characterised by warmer summers. These temperature shifts occurred in the whole of NW Europe. In contrast, the compilation of precipitation reconstructions does not show a common pattern across NW Europe either as a result of a heterogeneous precipitation pattern or the lack of suitable and consistent precipitation proxies.

climate reconstruction
europe
proxy record


Diversity of tissues in acanthodians with Nostolepis-type histological structure

Abstract: Acanthodian scales with Nostolepis-type histological structure are separated into five groups based on the presence/absence and extent of stranggewebe, odontocytic and syncitial mesodentine networks, cellular unipolar mesodentine, bone-like mesodentine and durodentine in scale crowns. Two new families of acanthodians are erected, based primarily on histological structure of scales: the Vesperaliidae (stranggewebe extending throughout the scale crown) and the Acritolepidae (bone-like mesodentine in the scale crown). The latter family includes species erected for articulated fish. The families Tchunacanthidae and Lenacanthidae are united in the single family Tchunacanthidae, characterized by having scale crowns with mesodentine formed mainly by unipolar cells. A sixth group, which we exclude from the Nostolepis-type, has scale crowns composed of dentine without lacunae, plus durodentine, and bases with only rare osteocyte cavities. The new groups promote the revision and reassignment of many "nostolepid" taxa, in particular removing many species from the genus Nostolepis. Four new genera are erected: Pechoralepis (including part of Nostolepis), assigned to Acritolepidae nov.; and three genera assigned to an indeterminate family, which scales are composed of only odontocytic mesodentine without stranggewebe: Nostovicina (including part of Nostolepis), Nobilesquama (including part of Nostolepis), and Peregrinosquama (including part of Watsonacanthus). Histological structures are considered the primary characters of taxonomical value when based on isolated scales. Unfortunately, scale histology is unknown for most articulated acanthodians.

tissue
acanthodians
nostolepis-type histological structure
mesodentine


Males Resemble Females: Re-Evaluating Sexual Dimorphism in Protoceratops andrewsi (Neoceratopsia, Protoceratopsidae)

Abstract: Background Protoceratops andrewsi (Neoceratopsia, Protoceratopsidae) is a well-known dinosaur from the Upper Cretaceous of Mongolia. Some previous workers hypothesized sexual dimorphism in the cranial shape of this taxon, using qualitative and quantitative observations. In particular, width and height of the frill as well as the development of a nasal horn have been hypothesized as potentially sexually dimorphic. Methodology/Principal Findings Here, we reassess potential sexual dimorphism in skulls of Protoceratops andrewsi by applying two-dimensional geometric morphometrics to 29 skulls in lateral and dorsal views. Principal Component Analyses and nonparametric MANOVAs recover no clear separation between hypothetical “males” and “females” within the overall morphospace. Males and females thus possess similar overall cranial morphologies. No differences in size between “males” and “females” are recovered using nonparametric ANOVAs. Conclusions/Significance Sexual dimorphism within Protoceratops andrewsi is not strongly supported by our results, as previously proposed by several authors. Anatomical traits such as height and width of the frill, and skull size thus may not be sexually dimorphic. Based on PCA for a data set focusing on the rostrum and associated ANOVA results, nasal horn height is the only feature with potential dimorphism. As a whole, most purported dimorphic variation is probably primarily the result of ontogenetic cranial shape changes as well as intraspecific cranial variation independent of sex.

sexual dimorphism
neoceratopsia
protoceratopsidae


Habitat suitability and the genetic structure of human populations during the Last Glacial Maximum (LGM) in Western Europe

Abstract: Human populations in Western Europe during the Last Glacial Maximum were geographically constrained to glacial refugia by the severity of the climate and ecological risk factors. In this research we use an agent-based model of human mobility and interaction, based on ethnographic and archaeological data, to explore the impact of ecological risk on human population structure via a reconstructed landscape of habitat suitability. The agent-based model allows us to evaluate the size and location of glacial refugia, the size of the populations occupying them and the degree of genetic relatedness between people occupying these areas. To do this, we model the probability of an agent foraging groups’ survival as a function of habitat suitability. The model’s simulated “genomes” (composed of regionally specific genetic markers) allow us to track long-term trends of inter-regional interaction and mobility. The results agree with previous archaeological studies situating a large glacial refugium spanning southern France and northeastern Spain, but we expand on those studies by demonstrating that higher rates of population growth in this central refugium led to continuous out-migration and therefore genetic homogeneity across Western Europe, with the possible exception of the Italian peninsula. These results concur with material culture data from known archaeological sites dating to the Last Glacial Maximum and make predictions for future ancient DNA studies.

human population
glacial maximum
refugia
survival
habitat suitability


The trilobite upper limb branch is a well-developed gill

Abstract: The trilobite upper limb branch served as a gill, resolving a long-standing debate about its function. Whether the upper limb branch of Paleozoic “biramous” arthropods, including trilobites, served a respiratory function has been much debated. Here, new imaging of the trilobite Triarthrus eatoni shows that dumbbell-shaped filaments in the upper limb branch are morphologically comparable with gill structures in crustaceans that aerate the hemolymph. In Olenoides serratus, the upper limb’s partial articulation to the body via an extended arthrodial membrane is morphologically comparable to the junction of the respiratory book gill of Limulus and differentiates it from the typically robust exopod junction in Chelicerata or Crustacea. Apparently limited mechanical rotation of the upper branch may have protected the respiratory structures. Partial attachment of the upper branch to the body wall may represent an intermediate state in the evolution of limb branch fusion between dorsal attachment to the body wall, as in Radiodonta, and ventral fusion to the limb base, as in extant Euarthropoda.


Life History of Rhamphorhynchus Inferred from Bone Histology and the Diversity of Pterosaurian Growth Strategies

Abstract: Background Rhamphorhynchus from the Solnhofen Limestones is the most prevalent long tailed pterosaur with a debated life history. Whereas morphological studies suggested a slow crocodile-like growth strategy and superprecocial volant hatchlings, the only histological study hitherto conducted on Rhamphorhynchus concluded a relatively high growth rate for the genus. These controversial conclusions can be tested by a bone histological survey of an ontogenetic series of Rhamphorhynchus. Methodology/Principal Findings Our results suggest that Bennett's second size category does not reflect real ontogenetic stage. Significant body size differences of histologically as well as morphologically adult specimens suggest developmental plasticity. Contrasting the ‘superprecocial hatchling’ hypothesis, the dominance of fibrolamellar bone in early juveniles implies that hatchlings sustained high growth rate, however only up to the attainment of 30–50% and 7–20% of adult wingspan and body mass, respectively. The early fast growth phase was followed by a prolonged, slow-growth phase indicated by parallel-fibred bone deposition and lines of arrested growth in the cortex, a transition which has also been observed in Pterodaustro. An external fundamental system is absent in all investigated specimens, but due to the restricted sample size, neither determinate nor indeterminate growth could be confirmed in Rhamphorhynchus. Conclusions/Significance The initial rapid growth phase early in Rhamphorhynchus ontogeny supports the non-volant nature of its hatchlings, and refutes the widely accepted ‘superprecocial hatchling’ hypothesis. We suggest the onset of powered flight, and not of reproduction as the cause of the transition from the fast growth phase to a prolonged slower growth phase. Rapidly growing early juveniles may have been attended by their parents, or could have been independent precocial, but non-volant arboreal creatures until attaining a certain somatic maturity to get airborne. This study adds to the understanding on the diversity of pterosaurian growth strategies.

rhamphorhynchus
pterosaurian growth strategy
hatchling
life history


Evidence from "Köppen signatures" of fossil plant assemblages for effective heat transport of Gulf Stream to subarctic North Atlantic during Miocene cooling

Abstract: Shallowing of the Panama Sill and the closure of the Central American Seaway initiated the modern Loop Current–Gulf Stream circulation pattern during the Miocene, but no direct evidence has yet been provided for effective heat transport to the northern North Atlantic during that time. Climatic signals from 11 precisely dated plant-bearing sedimentary rock formations in Iceland, spanning 15–0.8 million years (Myr), resolve the impacts of the developing Miocene global thermohaline circulation on terrestrial vegetation in the subarctic North Atlantic region. "Koppen signatures" were implemented to express climatic properties of fossil plant taxa and their potential modern analogues using the principal concept of the generic Koppen–Geiger climate system, which is based on plant distribution patterns. Using Koppen signatures and the correlation between Koppen climate zones and major global vegetation zones, fossil assemblages were used to trace major vegetation shifts. This evidence was combined with evidence from tectonics and palaeoceanography. In contrast to the global climatic trend, the vegetation record reveals no cooling between ~ 15 and 12 Myr, whereas periods of climatic deterioration between 12 and 10 Myr, 8 and 4 Myr, and in the Pleistocene are in phase with increased pulses of ice-rafted debris in the Northern Hemisphere. The observed sequence of climate change in the northern North Atlantic can most likely be explained by an effective Gulf Stream-mediated heat transport from the middle Miocene onwards.

effective heat transport
north atlantic
miocene


The Miocene mammal Necrolestes demonstrates the survival of a Mesozoic nontherian lineage into the late Cenozoic of South America

Abstract: The early Miocene mammal Necrolestes patagonensis from Patagonia, Argentina, was described in 1891 as the only known extinct placental “insectivore” from South America (SA). Since then, and despite the discovery of additional well-preserved material, the systematic status of Necrolestes has remained in flux, with earlier studies leaning toward placental affinities and more recent ones endorsing either therian or specifically metatherian relationships. We have further prepared the best-preserved specimens of Necrolestes and compared them with newly discovered nontribosphenic Mesozoic mammals from Argentina; based on this, we conclude that Necrolestes is related neither to marsupials nor placentals but is a late-surviving member of the recently recognized nontherian clade Meridiolestida, which is currently known only from SA. This conclusion is supported by a morphological phylogenetic analysis that includes a broad sampling of therian and nontherian taxa and that places Necrolestes within Meridiolestida. Thus, Necrolestes is a remnant of the highly endemic Mesozoic fauna of nontribosphenic mammals in SA and extends the known record of meridiolestidans by almost 45 million years. Together with other likely relictual mammals from earlier in the Cenozoic of SA and Antarctica, Necrolestes demonstrates the ecological diversity of mammals and the mosaic pattern of fauna replacement in SA during the Cenozoic. In contrast to northern continents, the Cenozoic faunal history of SA was characterized by a long period of interaction between endemic mammalian lineages of Mesozoic origin and metatherian and eutherian lineages that probably dispersed to SA during the latest Cretaceous or earliest Paleocene.


Earliest known European mammals: a review of the Morganucodonta from Saint-Nicolas-de-Port (Upper Triassic, France)

Abstract: The Rhaetian locality of Saint-Nicolas-de-Port (France) has yielded the most abundant and diverse mammalian assemblage known from the Late Triassic. Most of the material remains undescribed. We review here the morganucodonts from Saint-Nicolas-de-Port. We identify the upper and lower molariforms of the genus Brachyzostrodon. We also identify in the site Morganucodon peyeri, previously known from the Late Triassic of Hallau (Switzerland), as well as the genera Paceyodon and Paikasigudodon. The description of the new species Megazostrodon chenali sp. nov. extends the stratigraphical and geographical range of the genus, previously known from the Early Jurassic of southern Africa. Finally, another new morganucodont, Rosierodon anceps gen. et sp. nov., is described. The Morganucodonta is recognized as the most diverse order of Late Triassic mammals. Current fossil data suggest that Europe was the centre of initial diversification of morganucodonts at the end of the Triassic, and that morganucodonts were not much affected by the extinction event at the Triassic/Jurassic transition. http://zoobank.org/urn:lsid:zoobank.org:pub:0D30F723-7D65-49B7-8375-BF916BFA0BBA


Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds

Abstract: Turning large dinosaurs into small birds Most paleontologists agree that birds are descended from dinosaurs. How did such large terrestrial or aquatic animals evolve into small feathered fliers? Lee et al. used two large databases of theropod morphology to explore possible evolutionary patterns that may have driven this dramatic transformation (see the Perspective by Benton). They found no clear pattern of miniaturization across the entire clade of Theropoda. However, several lines of evidence suggested that the lineage leading to birds underwent sustained miniaturization. Within that lineage, body sizes decreased and species evolved faster. They also developed ecological and morphological innovations linked to smaller body sizes. Science, this issue p. 562; see also p. 508 Birds evolved from their dinosaurian ancestors through a period characterized by sustained and repeated decreases in size. [Also see Perspective by Benton] Recent discoveries have highlighted the dramatic evolutionary transformation of massive, ground-dwelling theropod dinosaurs into light, volant birds. Here, we apply Bayesian approaches (originally developed for inferring geographic spread and rates of molecular evolution in viruses) in a different context: to infer size changes and rates of anatomical innovation (across up to 1549 skeletal characters) in fossils. These approaches identify two drivers underlying the dinosaur-bird transition. The theropod lineage directly ancestral to birds undergoes sustained miniaturization across 50 million years and at least 12 consecutive branches (internodes) and evolves skeletal adaptations four times faster than other dinosaurs. The distinct, prolonged phase of miniaturization along the bird stem would have facilitated the evolution of many novelties associated with small body size, such as reorientation of body mass, increased aerial ability, and paedomorphic skulls with reduced snouts but enlarged eyes and brains.

miniaturization
anatomical innovation
dinosaurian ancestor
small body size
skull