Extreme warmth and heat-stressed plankton in the tropics during the Paleocene-Eocene Thermal Maximum

Abstract: During rapid global warming 56 million years ago, tropical sea surface temperatures exceeded 36°C and stressed eukaryotic plankton. Global ocean temperatures rapidly warmed by ~5°C during the Paleocene-Eocene Thermal Maximum (PETM; ~56 million years ago). Extratropical sea surface temperatures (SSTs) met or exceeded modern subtropical values. With these warm extratropical temperatures, climate models predict tropical SSTs >35°C—near upper physiological temperature limits for many organisms. However, few data are available to test these projected extreme tropical temperatures or their potential lethality. We identify the PETM in a shallow marine sedimentary section deposited in Nigeria. On the basis of planktonic foraminiferal Mg/Ca and oxygen isotope ratios and the molecular proxy TEX86H, latest Paleocene equatorial SSTs were ~33°C, and TEX86H indicates that SSTs rose to >36°C during the PETM. This confirms model predictions on the magnitude of polar amplification and refutes the tropical thermostat theory. We attribute a massive drop in dinoflagellate abundance and diversity at peak warmth to thermal stress, showing that the base of tropical food webs is vulnerable to rapid warming.

warmth
plankton
paleocene-eocene thermal maximum


Competition between encrusters on marine hard substrates and its fossil record

Abstract: Many animals and plants that colonize hard surfaces in the sea are sessile and either bore into, or cement themselves permanently to the substrate surface. Because they retain their life positions after fossilization, these sclerobionts offer scope for studying biotic interactions in the fossil record. Encrusting sclerobionts compete actively for living space, with dominant competitors overgrowing the edges of subordinates. In addition to such marginal overgrowths, spatial competition may also occur through fouling in which larvae recruit directly onto the living surfaces of established sclerobionts. Spatial competition has been studied extensively in modern marine communities but there has been little research on competition between encrusters in ancient communities. This reflects poor knowledge of the taxonomy of the sclerobionts involved, as well as problems in distinguishing between overgrowth in vivo and post‐mortem. Nevertheless, if carefully interpreted, the fossil record of sclerobionts can provide an as yet largely unexploited resource for studying the long‐term ecological and evolutionary dynamics of competition.

hard substrate
biotic interaction
fouling
competition
bryozoan


Taphonomic bias and the evolutionary history of the family Cidaridae (Echinodermata: Echinoidea)

Abstract: The class Echinoidea apparently originated during the Ordovician Period and diversified slowly through the Paleozoic Era. The clade then mushroomed in diversity beginning in Late Triassic time and continued expanding into the present. Although this evolutionary history is generally accepted, the taphonomic overprint affecting it has not been explored. To gain a more accurate perception of the evolutionary history of the group, I have compared the diversity history of the family Cidaridae (Echinodermata: Echinoidea) with the preservational style of fossil type species using literature-derived data. The Cidaridae apparently originated in Middle Triassic time and diversified slowly through the Neocomian (Early Cretaceous). Diversity was maintained through the remainder of the Cretaceous and Tertiary Periods, reflecting the diversity history of the subclass. Characterization of the preservational style of type fossil material for the family revealed the following breakdown of preservational states: 60% of species were described on the basis of disarticulated skeletal material, primarily spines; 20% based on intact coronas denuded of spines, apical system, Aristotle's lantern and peristomial plates; 10% based on large coronal fragments; and 10% based on other skeletal elements. This distribution may represent the effect of a disarticulation threshold on the condition of echinoid carcasses before final burial and suggests that preservation of intact specimens may be very unlikely. For cidaroids, previous work has suggested that this threshold is likely to be reached after 7 days of decay. Comparison of the diversity history of the Cidaridae with the preservation data reveals that characteristic patterns of taphonomic overprint have affected the group since its origination in Middle Triassic time, and the nature of that overprint has changed over time: the early diversity history of the group is characterized by occurrences of fragmented fossil material, with spines predominant; further radiation of the group in mid-Jurassic time coincided with an increase in modes of preservation, ranging between exceptionally well-preserved material and disarticulated skeletal elements. Finally, type material is more rarely described from younger stratigraphic intervals (Miocene–Pleistocene) and consists predominantly of disarticulated skeletal elements and coronal fragments larger than an interambulacrum in size. Intact, denuded coronas are noticeably lacking. The number of type species of Cidaridae described in each stratigraphic interval has not been consistent during post-Paleozoic time. Middle Triassic, Malm (Upper Jurassic), Senonian (Upper Cretaceous) and Eocene series yielded significantly (α = .05) higher numbers of type specimens per million years, while the Lias (Lower Jurassic), Dogger (Mid-Jurassic), Lower Cretaceous and Paleocene yielded significantly (α = .05) lower numbers of type specimens per million years. This may be the result of a combination of taxonomic, sampling, and geographical biases.

evolutionary history
echinodermata
echinoidea
fragment


New specimens of the earliest European passeriform bird

Abstract: We describe new specimens of the oldest European passeriform bird from the early Oligocene of Germany. This bird has hitherto been known only from a poorly preserved skeleton and we report here a second slab of the same specimen and an additional fragmentary skull. The new specimens allow the description of a new species, Wieslochia weissi gen. et. sp. nov., which lacks apomorphies of crown group Oscines, the taxon including most extant and all European passeriform species. In overall osteology, Wieslochia most closely resembles extant Suboscines but these similarities may be plesiomorphic for Passeriformes. W. weissi differs from the stem species pattern hypothesized for Eupasseres in the morphology of the distal carpometacarpus, the absence of a hooked processus acrocoracoideus (coracoid), and the presence of furrows instead of certain canals on the hypotarsus, and may even be outside crown group Eupasseres, the clade including Oscines and Suboscines. Because the earliest European fossil record of oscine passerines is from the late Oligocene, passerines outside crown group Oscines may have colonized Europe before the arrival of Oscines from the Australian continental plate.

european passeriform bird
passeriformes
new specimen


Exceptionally preserved Leptolepidae (Actinopterygii, Teleostei) from the late Early Jurassic Fossil-Lagerstätten of Grimmen and Dobbertin (Mecklenburg-Western Pomerania, Germany).

Abstract: Exceptionally well-preserved fishes of the family Leptolepidae (Actinopterygii, Teleostei) from the late Early Jurassic Fossil-Lagerstätten of Grimmen and Dobbertin (Mecklenburg-Western Pomerania, NE Germany) are reported and detailed anatomical descriptions are given. The described material specifically derives from the "Green Series", which represents a specific facies that falls within the lower part of the early Toarcian Harpoceras falciferum ammonite Zone. Complete skeletons are rare, and most specimens are represented by isolated skulls. Most of the skulls are fully articulated and show only a low degree of compaction, while some specimens are almost three-dimensionally preserved. The leptolepid fauna comprises Leptolepis coryphaenoides, L. normandica, L. jaegeri, a possible Proleptolepis, and two other taxa, which are described in open nomenclature. Several anatomical characters, such as the shape of premaxilla, maxilla, dentary, preopercle, the cephalic sensory canals, and the dentition of the jaws, are discussed and compared to former studies. The new material provides novel insights into morphology, diversity and palaeobiogeography of leptolepid fishes. The records of Leptolepis coryphaenoides, L. normandica and L. jaegeri from Grimmen and Dobbertin represent the northeastern-most occurrences of these species from Europe, suggesting that they inhabited the whole central European epicontinental sea during the early Toarcian. The possible occurrence of Proleptolepis in the lower Toarcian of Grimmen suggests that this genus might have had a much wider palaeobiogeographical and temporal distribution, since specimens attributed to Proleptolepis have previously been reported only from the Sinemurian of western Europe.

actinopterygii
teleostei
mecklenburg-western pomerania


COMPUTED TOMOGRAPHY OF AN ANOLIS LIZARD IN DOMINICAN AMBER: SYSTEMATIC, TAPHONOMIC, BIOGEOGRAPHIC, AND EVOLUTIONARY IMPLICATIONS

Abstract: The cranial morphology of an Anolis lizard preserved in Dominican amber, observed using pseudo-three-dimensional reconstructed images derived from highresolution X-ray computed tomography (CT) data, demonstrates the lack of a splenial in the lower jaw. The specimen is referred to T-clade anoles, the clade that includes the A. chlorocyanus species group, to which two other Dominican anoles in amber have been referred. The pattern of bone breakage and loss suggests trauma followed by decomposition prior to entombment. The trunk-crown ecomorph of A. chlorocyanus species group anoles was established on what was to become Hispaniola between approximately 33 and 20 million years ago.

tomography
anolis lizard
dominican amber


Endemicity and palaeobiogeography of the Osteostraci and Galeaspida: a test of scenarios of gnathostome evolution

Abstract: Abstract:  Armoured stem‐gnathostomes (jawless vertebrates previously termed ‘ostracoderms’) have long been assumed to exhibit strong endemicity. This assumption has underpinned their utility in many palaeobiogeographic studies as well as scenarios regarding the evolution and dominance of jawed vertebrates over their jawless relatives. The hypothesis of endemicity in stem‐gnathostomes is investigated for the first time in the light of the phylogeny of the closest relatives of jawed vertebrates – Osteostraci and Galeaspida. Palaeobiogeography of each is reconstructed using Fitch optimization and modified Brooks Parsimony Analysis. Palaeobiogeographic distributions corroborate phylogeny. Results, along with consideration of the Heterostraci, enable identification of similar patterns across groups (broad ancestral range, Early Devonian expansion, endemic and pandemic clades within each, and Middle Devonian radiation events) and inferences to the palaeogeographic relationship between major terranes (i.e. Laurentia, Baltica, Avalonia, Kara, Altaids, South China, Tarim). Comparison of basin and terrane level analyses identifies the different palaeogeographic processes responsible for the distributions of each group: sea‐level changes in the case of the Osteostraci and rifting in the case of the Galeaspida. The general endemic nature of the Osteostraci and Galeaspida is confirmed, and thus the hypothesis that the demise and extinction of stem‐gnathostomes was because of their limited dispersal capacity is supported.

palaeobiogeography galeaspida baltica endemicity


New early Barstovian (middle Miocene) vertebrates from the upper Torreya Formation, eastern Florida panhandle

Abstract: ABSTRACT A new vertebrate fauna has been recovered from the Dogtown Member of the Torreya Formation, Hawthorn Group (early to middle Miocene), northern Gadsden County, Florida. Fossils were recovered from four fuller's earth clay mines. This new fauna, called the Willacoochee Creek Fauna (WCF), contains at least 68 vertebrate taxa, including 29 mammals, from marine, freshwater, and terrestrial environments. The WCF is restricted to the early Barstovian land-mammal age based on the presence of Copemys, Perognathus, Rakomeryx, and Ticholeptus, and the overlapping chronologic ranges of 8 other mammals. Lanthanotherium, Perognathus, and a squalodont whale are reported from the southeastern U.S. for the first time. Biochronological range extensions into the early Barstovian are proposed for Lanthanotherium, Anchitherium clarencei and “Merychippus” primus. The WCF is the first well documented early Barstovian fauna in the southeastern U.S., thus filling a large gap in the temporal distribution of vertebrate fau...

early barstovian
middle miocene
torreya formation


Shell microstructure of the early bivalve Pojetaia and the independent origin of nacre within the mollusca

Abstract: Abstract:  Pojetaia and Fordilla are the oldest bivalve molluscs, occurring in roughly co‐eval rocks from the Tommotian, and are the only undisputed, well‐known bivalves from the Cambrian. New specimens reveal that Pojetaia had a laminar inner shell microstructure reminiscent of the foliated aragonite of modern monoplacophorans, and the same is true for Fordilla. A similar shell microstructure is seen in Anabarella and Watsonella, providing support for the hypothesis that they are the ancestors of bivalves. Foliated aragonite shares many similarities with nacre, and it may have been the precursor to nacre in bivalves. No cases of undisputed nacre occur in the Cambrian, in spite of much shell microstructure data from molluscs of this time period. Thus, although considered by many to be homologous among molluscs, we conclude that nacre convergently evolved in monoplacophorans, gastropods, bivalves, and cephalopods. This independent origin of nacre appears to have taken place during, or just prior to, the Great Ordovician Biodiversification Event and represents a significant step in the arms race between predators and molluscan prey.

independent origin
nacre
shell microstructure


The endemic radiodonts of the Cambrian Stage 4 Guanshan biota of South China

Abstract: The Guanshan Biota (South China, Cambrian, Stage 4) contains a diverse assemblage of biomineralizing and non-biomineralizing animals. Sitting temporally between the Stage 3 Chengjiang and Wuliuan Kaili Biotas, the Guanshan Biota contains numerous fossil organisms that are exclusive to this exceptional deposit. The Guanshan Konservat-Lagerstätte is also unusual amongst Cambrian strata that preserve non-biomineralized material, as it was deposited in a relatively shallow water setting. In this contribution we double the diversity of radiodonts known from the Guanshan Biota from two to four, and describe the second species of Paranomalocaris . In addition, we report the first tamisiocaridid from South China, and confirm the presence of a tetraradial oral cone bearing small and large plates in “Anomalocaris” kunmingensis , the most abundant radiodont from the deposit. All four radiodont species, and three genera, are apparently endemic to the Guanshan Biota. When considered in the wider context of geographically and temporally comparable radiodont faunas, endemism in Guanshan radiodonts is most likely a consequence of the shallower and more proximal environment in which they lived. The strong coupling of free-swimming radiodonts and benthic communities underlines the complex relationship between the palaeobiogeographic and environmental distributions of prey and predators. This local adaptation of radiodonts to their prey is highlighted by the frontal appendage morphology of the two species of Paranomalocaris , apparently specialised to different feeding modes, while the recognition of the limited geographic range of some radiodont faunas highlights the importance of exploring as many deposits as possible to fully understand this group.

cambrian stage
guanshan biota
south china


A Remarkable New Family of Jurassic Insects (Neuroptera) with Primitive Wing Venation and Its Phylogenetic Position in Neuropterida

Abstract: Background Lacewings (insect order Neuroptera), known in the fossil record since the Early Permian, were most diverse in the Mesozoic. A dramatic variety of forms ranged in that time from large butterfly-like Kalligrammatidae to minute two-winged Dipteromantispidae. Principal Findings We describe the intriguing new neuropteran family Parakseneuridae fam. nov. with three new genera and 15 new species from the Middle Jurassic of Daohugou (Inner Mongolia, China) and the Early/Middle Jurassic of Sai-Sagul (Kyrgyzstan): Parakseneura undula gen. et sp. nov., P. albomacula gen. et sp. nov., P. curvivenis gen. et sp. nov., P. nigromacula gen. et sp. nov., P. nigrolinea gen. et sp. nov., P. albadelta gen. et sp. nov., P. cavomaculata gen. et sp. nov., P. inflata gen. et sp. nov., P. metallica gen. et sp. nov., P. emarginata gen. et sp. nov., P. directa gen. et sp. nov., Pseudorapisma jurassicum gen. et sp. nov., P. angustipenne gen. et sp. nov., P. maculatum gen. et sp. nov. (Daohugou); Shuraboneura ovata gen. et sp. nov. (Sai-Sagul). The family comprises large neuropterans with most primitive wing venation in the order indicated by the presence of ScA and AA1+2, and the dichotomous branching of MP, CuA, CuP, AA3+4, AP1+2. The phylogenetic position of Parakseneuridae was investigated using a phylogenetic analysis of morphological scoring for 33 families of extinct and extant Neuropterida combined with DNA sequence data for representatives of all extant families. Parakseneuridae were recovered in a clade with Osmylopsychopidae, Prohemerobiidae, and Ithonidae. Conclusions/Significance The presence of the presumed AA1+2 in wings of Parakseneuridae is a unique plesiomorphic condition hitherto unknown in Neuropterida, the clade comprising Neuroptera, Megaloptera, Raphidioptera. The relative uncertainty of phylogenetic position of Parakseneuridae and the majority of other families of Neuroptera reflects deficient paleontological data, especially from critical important periods for the order, earliest Triassic and latest Triassic/earliest Jurassic.

primitive wing venation
phylogenetic position
neuropterida
ithonidae


Structure, ontogeny, and moulting of the olenid trilobite Ctenopyge (Eoctenopyge) angusta Westergård, 1922 from the upper Cambrian of Västergötland, Sweden

Abstract: The genus Ctenopyge is known mainly from disarticulated sclerites and from rare complete specimens flattened in shales. Hitherto, very few specimens have been found preserved intact and in three dimensions. In a recently discovered fauna, however, in the Peltura minor Subzone in Västergötland, central Sweden, there occur several species of Ctenopyge, of which many are complete and superbly preserved; moreover they occur at all stages of growth. Of these the abundant Ctenopyge (Eoctenopyge) angusta Westergård, 1922 is described and reconstructed here as an adult, and the entire ontogeny is documented for all post–protaspid growth stages. Many characters typical of the adult, such as the long genal spines and the caudal spine, develop very early in ontogeny, and the relative dimensions of the cranidium do not greatly change during growth. Macropleural spines, however, develop later. The transitory pygidium, relatively large and shield–shaped in the early meraspid, later becomes very small as the ten thoracic segments are liberated; a median spine develops on the last thoracic segment only at the holaspid stage. Instar groupings can be clearly distinguished for the early stages. Recurrent associations of sclerites are interpreted as moulting configurations. As reconstructed, the genal spines are horizontal and parallel with the extended thorax; an adaptation which presumably allowed the trilobite to rest on the sea floor.


Membrane Lipid Composition of the Moderately Thermophilic Ammonia-Oxidizing Archaeon “Candidatus Nitrosotenuis uzonensis” at Different Growth Temperatures

Abstract: For Thaumarchaeota, the ratio of their glycerol dialkyl glycerol tetraether (GDGT) lipids depends on growth temperature, a premise that forms the basis of the widely applied TEX86 paleotemperature proxy. A thorough understanding of which GDGTs are produced by which Thaumarchaeota and what the effect of temperature is on their GDGT composition is essential for constraining the TEX86 proxy. “Ca. Nitrosotenuis uzonensis” is a moderately thermophilic thaumarchaeote enriched from a thermal spring, setting it apart in its environmental niche from the other marine mesophilic members of its order. Indeed, we found that the GDGT composition of “Ca. Nitrosotenuis uzonensis” cultures was distinct from those of other members of its order and was more similar to those of other thermophilic, terrestrial Thaumarchaeota. This suggests that while phylogeny has a strong influence on GDGT distribution, the environmental niche that a thaumarchaeote inhabits also shapes its GDGT composition. ABSTRACT “Candidatus Nitrosotenuis uzonensis” is the only cultured moderately thermophilic member of the thaumarchaeotal order Nitrosopumilales (NP) that contains many mesophilic marine strains. We examined its membrane lipid composition at different growth temperatures (37°C, 46°C, and 50°C). Its lipids were all membrane-spanning glycerol dialkyl glycerol tetraethers (GDGTs), with 0 to 4 cyclopentane moieties. Crenarchaeol (cren), the characteristic thaumarchaeotal GDGT, and its isomer (crenʹ) were present in high abundance (30 to 70%). The GDGT polar headgroups were mono-, di-, and trihexoses and hexose/phosphohexose. The ratio of glycolipid to phospholipid GDGTs was highest in the cultures grown at 50°C. With increasing growth temperatures, the relative contributions of cren and crenʹ increased, while those of GDGT-0 to GDGT-4 (including isomers) decreased. TEX86 (tetraether index of tetraethers consisting of 86 carbons)-derived temperatures were much lower than the actual growth temperatures, further demonstrating that TEX86 does not accurately reflect the membrane lipid adaptation of thermophilic Thaumarchaeota. As the temperature increased, specific GDGTs changed relative to their isomers, possibly representing temperature adaption-induced changes in cyclopentane ring stereochemistry. Comparison of a wide range of thaumarchaeotal core lipid compositions revealed that the “Ca. Nitrosotenuis uzonensis” cultures clustered separately from other members of the NP order and the Nitrososphaerales (NS) order. While phylogeny generally seems to have a strong influence on GDGT distribution, our analysis of “Ca. Nitrosotenuis uzonensis” demonstrates that its terrestrial, higher-temperature niche has led to a lipid composition that clearly differentiates it from other NP members and that this difference is mostly driven by its high crenʹ content. IMPORTANCE For Thaumarchaeota, the ratio of their glycerol dialkyl glycerol tetraether (GDGT) lipids depends on growth temperature, a premise that forms the basis of the widely applied TEX86 paleotemperature proxy. A thorough understanding of which GDGTs are produced by which Thaumarchaeota and what the effect of temperature is on their GDGT composition is essential for constraining the TEX86 proxy. “Ca. Nitrosotenuis uzonensis” is a moderately thermophilic thaumarchaeote enriched from a thermal spring, setting it apart in its environmental niche from the other marine mesophilic members of its order. Indeed, we found that the GDGT composition of “Ca. Nitrosotenuis uzonensis” cultures was distinct from those of other members of its order and was more similar to those of other thermophilic, terrestrial Thaumarchaeota. This suggests that while phylogeny has a strong influence on GDGT distribution, the environmental niche that a thaumarchaeote inhabits also shapes its GDGT composition.

candidatus nitrosotenuis uzonensis
different growth temperature
membrane lipid composition


Evolutionary innovation and ecology in marine tetrapods from the Triassic to the Anthropocene

Abstract: Similar shapes inhabit the sea Over biological history, several different groups of vertebrate tetrapods have reinvaded the marine environment. Although these groups are widely distributed among reptiles, mammals, amphibians, and birds, the shapes they have evolved are remarkably similar. Kelley and Pyenson review the literature on marine vertebrate groups over time and describe the innovations that facilitated the evolution of these marine forms, the environmental conditions that selected for such convergence of form, and the threats they face from future environment change. Science, this issue 10.1126/science.aaa3716 The demands of a marine environment induced similar adaptations across multiple invasions of different vertebrate groups. BACKGROUND More than 30 different lineages of amphibians, reptiles, birds, and mammals have independently invaded oceans ecosystems. Prominent examples include ichthyosaurs and mosasaurs during the Mesozoic (252 to 66 million years ago) and penguins and sea otters during the Cenozoic (66 million years ago to the present). In today’s oceans, marine tetrapods are ecologically important consumers with trophic influence disproportionate to their abundance. They have occupied apex roles in ocean food webs for more than 250 million years, through major changes in ocean and climate, and through mass extinctions. Major paleontological discoveries in the past 40 years have clarified the early land-sea transitions for some marine tetrapods (e.g., whales, sea cows), although the terrestrial origins of many lineages remain obscure. Incipient invasions appear frequently in marine tetrapod history, but such early transitions account for only a small proportion of the total fossil record of successful marine lineages, which in some cases persist for hundreds of millions of years. ADVANCES Marine tetrapods provide ideal models for testing macroevolutionary hypotheses because the repeated transitions between land and sea have driven innovation, convergence, and diversification against a backdrop of changing marine ecosystems and mass extinctions. Recent investigations across a broad range of scales—from molecules to food webs—have clarified the phylogenetic scope, timing, and ecological consequences of these repeated innovations. Studies of the physiology and functional morphology of living species have illuminated the constraints and tradeoffs that shape the pathway of initial marine invasions. Comparative studies on muscle myoglobin concentration or the evolution of sex determination mechanisms, for example, have revealed rampant convergence for these adaptive traits in the marine realm. Exceptionally preserved fossils have also revealed insights into reproductive biology, soft tissue structures, and trophic interactions. Fossils provide critical baselines for understanding historical changes in marine communities and diversity through time, and these baselines remain vital for evaluating the ongoing and severe anthropogenic disturbance to marine tetrapod populations and marine ecosystems as a whole. OUTLOOK Technological advances in remote sensing and biologging will continue to provide crucial insights into the macroecology of marine tetrapods below the water’s edge. Field data, when combined with extensive vouchers represented in museum collections, provide the basis for integrative models of the function and ecology of these logistically challenging organisms. Placed in a phylogenetic comparative framework, these data can enable tests of hypotheses about macroevolutionary patterns. Although perpetually incomplete, new fossil discoveries continue to improve our understanding of the early land-sea transitions in lineages and reveal past ecologies that could not have otherwise been predicted. Emerging imaging, molecular, and isotopic techniques provide an opportunity to expand the investigational scope for studying extinct taxa and to inform our understanding of how living species evolved. Lastly, resolving the full evolutionary scope of marine tetrapod history provides context for the origins of modern ecological patterns and interactions, which are fundamentally being altered by human activities. A unified view of marine tetrapod evolution. Circles mark initial invasions of marine tetrapod groups. Extinct and extant lineages are denoted by open and solid circles, respectively (yellow, amphibians; green, nonavian reptiles; blue, birds; red, mammals). Top curve summarizes marine tetrapod fossil richness through time. Schematic limb drawings demonstrate convergent hydrodynamic forelimbs in marine tetrapods (top to bottom): sea lion, whale, penguin, sea turtle, mosasaur, ichthyosaur. Ma, millions of years ago. Many top consumers in today’s oceans are marine tetrapods, a collection of lineages independently derived from terrestrial ancestors. The fossil record illuminates their transitions from land to sea, yet these initial invasions account for a small proportion of their evolutionary history. We review the history of marine invasions that drove major changes in anatomy, physiology, and ecology over more than 250 million years. Many innovations evolved convergently in multiple clades, whereas others are unique to individual lineages. The evolutionary arcs of these ecologically important clades are framed against the backdrop of mass extinctions and regime shifts in ocean ecosystems. Past and present human disruptions to marine tetrapods, with cascading impacts on marine ecosystems, underscore the need to link macroecology with evolutionary change.


Biodiversity–ecosystem functioning relationships in long-term time series and palaeoecological records: deep sea as a test bed

Abstract: The link between biodiversity and ecosystem functioning (BEF) over long temporal scales is poorly understood. Here, we investigate biological monitoring and palaeoecological records on decadal, centennial and millennial time scales from a BEF framework by using deep sea, soft-sediment environments as a test bed. Results generally show positive BEF relationships, in agreement with BEF studies based on present-day spatial analyses and short-term manipulative experiments. However, the deep-sea BEF relationship is much noisier across longer time scales compared with modern observational studies. We also demonstrate with palaeoecological time-series data that a larger species pool does not enhance ecosystem stability through time, whereas higher abundance as an indicator of higher ecosystem functioning may enhance ecosystem stability. These results suggest that BEF relationships are potentially time scale-dependent. Environmental impacts on biodiversity and ecosystem functioning may be much stronger than biodiversity impacts on ecosystem functioning at long, decadal–millennial, time scales. Longer time scale perspectives, including palaeoecological and ecosystem monitoring data, are critical for predicting future BEF relationships on a rapidly changing planet.

palaeoecological record
deep sea
test bed
time-series data


Biomechanics of the rostrum in crocodilians: a comparative analysis using finite-element modeling.

Abstract: This article reports the use of simple beam and finite-element models to investigate the relationship between rostral shape and biomechanical performance in living crocodilians under a range of loading conditions. Load cases corresponded to simple biting, lateral head shaking, and twist feeding behaviors. The six specimens were chosen to reflect, as far as possible, the full range of rostral shape in living crocodilians: a juvenile Caiman crocodilus, subadult Alligator mississippiensis and Crocodylus johnstoni, and adult Caiman crocodilus, Melanosuchus niger, and Paleosuchus palpebrosus. The simple beam models were generated using morphometric landmarks from each specimen. Three of the finite-element models, the A. mississippiensis, juvenile Caiman crocodilus, and the Crocodylus johnstoni, were based on CT scan data from respective specimens, but these data were not available for the other models and so these--the adult Caiman crocodilus, M. niger, and P. palpebrosus--were generated by morphing the juvenile Caiman crocodilus mesh with reference to three-dimensional linear distance measured from specimens. Comparison of the mechanical performance of the six finite-element models essentially matched results of the simple beam models: relatively tall skulls performed best under vertical loading and tall and wide skulls performed best under torsional loading. The widely held assumption that the platyrostral (dorsoventrally flattened) crocodilian skull is optimized for torsional loading was not supported by either simple beam theory models or finite-element modeling. Rather than being purely optimized against loads encountered while subduing and processing food, the shape of the crocodilian rostrum may be significantly affected by the hydrodynamic constraints of catching agile aquatic prey. This observation has important implications for our understanding of biomechanics in crocodilians and other aquatic reptiles.

crocodilian
finite-element modeling
assumption
biomechanic


Australia's first fossil marsupial mole (Notoryctemorphia) resolves controversies about their evolution and palaeoenvironmental origins

Abstract: Fossils of a marsupial mole (Marsupialia, Notoryctemorphia, Notoryctidae) are described from early Miocene deposits in the Riversleigh World Heritage Area, northwestern Queensland, Australia. These represent the first unequivocal fossil record of the order Notoryctemorphia, the two living species of which are among the world's most specialized and bizarre mammals, but which are also convergent on certain fossorial placental mammals (most notably chrysochlorid golden moles). The fossil remains are genuinely ‘transitional', documenting an intermediate stage in the acquisition of a number of specializations and showing that one of these—the dental morphology known as zalambdodonty—was acquired via a different evolutionary pathway than in placentals. They, thus, document a clear case of evolutionary convergence (rather than parallelism) between only distantly related and geographically isolated mammalian lineages—marsupial moles on the island continent of Australia and placental moles on most other, at least intermittently connected continents. In contrast to earlier presumptions about a relationship between the highly specialized body form of the blind, earless, burrowing marsupial moles and desert habitats, it is now clear that archaic burrowing marsupial moles were adapted to and probably originated in wet forest palaeoenvironments, preadapting them to movement through drier soils in the xeric environments of Australia that developed during the Neogene.

marsupial mole
notoryctemorphia
australia


The Still Bay and Howiesons Poort at Sibudu and Blombos: Understanding Middle Stone Age Technologies

Abstract: The classification of archaeological assemblages in the Middle Stone Age of South Africa in terms of diversity and temporal continuity has significant implications with respect to recent cultural evolutionary models which propose either gradual accumulation or discontinuous, episodic processes for the emergence and diffusion of cultural traits. We present the results of a systematic technological and typological analysis of the Still Bay assemblages from Sibudu and Blombos. A similar approach is used in the analysis of the Howiesons Poort (HP) assemblages from Sibudu seen in comparison with broadly contemporaneous assemblages from Rose Cottage and Klasies River Cave 1A. Using our own and published data from other sites we report on the diversity between stone artifact assemblages and discuss to what extent they can be grouped into homogeneous lithic sets. The gradual evolution of debitage techniques within the Howiesons Poort sequence with a progressive abandonment of the HP technological style argues against the saltational model for its disappearance while the technological differences between the Sibudu and Blombos Still Bay artifacts considerably weaken an interpretation of similarities between the assemblages and their grouping into the same cultural unit. Limited sampling of a fragmented record may explain why simple models of cultural evolution do not seem to apply to a complex reality.

still bay
howiesons poort
middle stone age


What makes an ophiuroid? A morphological study of the problematic Ordovician stelleroid Stenaster and the palaeobiology of the earliest asteroids and ophiuroids

Abstract: Abstract Extant asteroids and ophiuroids [Echinodermata] are distinguished by differences in arm support, water vascular system structures and in details of arm and jaw structure. However, some lower Palaeozoic taxa show combinations of both asteroid-like and ophiuroid-like characters and their morphology and functional biology is poorly understood. This paper redescribes one such taxon, the middle-upper Ordovician stellate echinoderm Stenaster and clarifies its phylogenetic status. Characters in common with extant and Ordovician ophiuroids, include arm support due primarily to ambulacral ossicles, presence of extensive longitudinal arm musculature, a mobile jaw and an internalised radial water vessel with internalised podial pores. In addition, Stenaster lacks several characters which are conventionally considered to be asteroid-like, for example an axillary, madreporite, marginal ossicles and a true ambulacral groove. However, in overall shape Stenaster is remarkably asteroid-like, showing short, broad-based arms shared podial basins and a small disc. A cladistic analysis of early asteroids, ophiuroids and somasteroid taxa consistently places Stenaster within the ophiuroids and suggests secondary convergence to asteroids. In functional terms, Stenaster is interpreted as an ophiuroid which has secondarily adopted a semi-infaunal, deposit-feeding mode of life, analogous to that of some extant paxillosid asteroids.


A new turtle from the La Colonia Formation (Campanian–Maastrichtian), Patagonia, Argentina, with remarks on the evolution of the vertebral column in turtles

Abstract: Abstract:  Patagoniaemys gasparinae gen. et sp. nov. is a new stem turtle found in central Patagonia, Chubut Province, Argentina, in outcrops of the La Colonia Formation (Campanian–Maastrichtian). This is a turtle of relatively large size (carapace length c. 70 cm), and the preserved remains of the holotype consist of skull fragments and several postcranial elements including a nearly complete vertebral column. A phylogenetic analysis shows Patagoniaemys gasparinae gen. et sp. nov. forming a monophyletic group with Otwayemys cunicularius and Mongolochelys efremovi, as a sister group to Meiolaniidae. A comprehensive review confirms that formed cervical vertebrae appeared independently several times during turtle evolution: in the clade that includes Patagoniaemys gasparinae gen. et sp. nov. and Meiolaniidae, in some baenids, in the total group Pleurodira and in crown group Cryptodira. Likewise, formed caudal vertebrae appeared several times in turtle evolution.

turtle
campanian–maastrichtian
vertebral column


A large mimotonid from the Middle Eocene of China sheds light on the evolution of lagomorphs and their kin

Abstract:
Mimotonids share their closest affinity with lagomorphs and were a rare and endemic faunal element of Paleogene mammal assemblages of central Asia. Here we describe a new species, Mimolagus
aurorae from the Middle Eocene of Nei Mongol (China). This species belongs to one of the most enigmatic genera of fossil Glires, previously known only from the type and only specimen from the early Oligocene of Gansu (China). Our finding extends the earliest occurrence of the genus by at least 10 million years in the Paleogene of Asia, which closes the gap between Mimolagus and other mimotonids that are known thus far from middle Eocene or older deposits. The new species is one of the largest known pre-Oligocene Glires. As regards duplicidentates, Mimolagus is comparable with the largest Neogene continental leporids, namely hares of the genus Lepus. Our results suggest that ecomorphology of this species was convergent on that of small perissodactyls that dominated faunas of the Mongolian Plateau in the Eocene, and probably a result of competitive pressure from other Glires, including a co-occurring mimotonid, Gomphos.


An antiarch placoderm shows that pelvic girdles arose at the root of jawed vertebrates

Abstract: Almost all gnathostomes or jawed vertebrates (including osteichthyans, chondrichthyans, ‘acanthodians’ and most placoderms) possess paired pectoral and pelvic fins. To date, it has generally been believed that antiarch placoderms (extinct armoured jawed fishes from the Silurian–Devonian periods) lacked pelvic fins. The putative absence of pelvic fins is a key character bearing on the monophyly or paraphyly of placoderms. It also has far-reaching implications for studying the sequence of origin of pelvic girdles versus that of movable jaws in the course of vertebrate evolution. Parayunnanolepis xitunensis represents the only example of a primitive antiarch with extensive post-thoracic preservation, and its original description has been cited as confirming the primitive lack of pelvic fins in early antiarchs. Here, we present a revised description of Parayunnanolepis and offer the first unambiguous evidence for the presence of pelvic girdles in antiarchs. As antiarchs are placed at the base of the gnathostome radiation in several recent studies, our finding shows that all jawed vertebrates (including antiarch placoderms) primitively possess both pectoral and pelvic fins and that the pelvic fins did not arise within gnathostomes at a point subsequent to the origin of jaws.

antiarch placoderm
pelvic girdle
osteichthyan


Seed morphology of modern and fossil Ampelocissus (Vitaceae) and implications for phytogeography.

Abstract: Seeds are useful in distinguishing among extant genera of Vitaceae and provide a good basis for interpretation of fossil remains in reconstructing the evolutionary and phytogeographic history of this putatively basal Rosid family. Seeds of Ampelocissus s.l. including Pterisanthes and Nothocissus are distinguished from those of all other vitaceous genera by long, parallel ventral infolds and a centrally positioned oval chalazal scar. Principal component analysis facilitates recognition of four Ampelocissus s.l. seed morphotypes differentiated by dorsiventral thickness, width of ventral infolds, chalazal depth, and degree of dorsal surface rugosity. While these intergrade, their end-member morphologies are distinctive and coincide well with inflorescence morphology, extant geographic distribution, and ecology. Seven fossil morphospecies are recognized. Ampelocissus parvisemina sp. n. (Paleocene of North Dakota; Eocene of Oregon) and A. auriforma Manchester (Eocene of Oregon) resemble extant Central American species; A. bravoi Berry (Eocene of Peru) is similar to one group of Old World extant species; and A. parachandleri sp. n. (Eocene of Oregon) and the three European fossil species A. chandleri (Kirchheimer) comb. n., A. lobatum (Chandler) comb. n., and A. wildei sp. n. (Eocene to Miocene) resemble another group of extant Old World Ampelocissus. All these fossils occur outside the present geographic range of the genus, reflecting warmer climates and former intercontinental links.

vitaceae
ventral infold
oval chalazal scar
seed


Clay assemblage and oxygen isotopic constraints on the weathering response to the Paleocene-Eocene thermal maximum, east coast of North America

Abstract: The Paleocene-Eocene thermal maximum, a transient global warming event, is character- ized by extensive evidence of a more active hydrological cycle. This includes a widespread pulse of kaolinite accumulation on continental margins, viewed as the by-product of either enhanced chemical weathering consistent with much more humid conditions and/or increased erosion of previously deposited laterites. The former would be more consistent with year- round humid conditions, whereas the latter might be indicative of extreme seasonal precipi- tation patterns. To assess these hypotheses, we present a new high-resolution clay mineral assemblage and oxygen isotope record from Bass River, a site on the New Jersey margin (east coast of North America), which shows a sharp rise in the abundance of kaolinite beginning a few thousand years before the onset of the carbon isotope excursion (CIE). The δ 18 O of the <2-µm-size fraction exhibits a shift toward lower values during the event. On the basis of a coeval shift in clay assemblages, the shift in δ 18 O Clays can be explained by a shift in the relative percent of the primary clay phases rather than a change in the isotopic composition of kaolinite, as would be expected if the kaolinite had been produced primarily during the Paleocene-Eocene thermal maximum. This fi nding points to accelerated exhumation and ero- sion of kaolinitic soils, most likely Cretaceous laterites.

paleocene-eocene thermal maximum
east coast
chemical weathering
clay assemblage


Craniodental morphology and diet of Leptarctus oregonensis (Mammalia, Carnivora, Mustelidae) from the Mascall Formation (Miocene) of central Oregon

Abstract:
Abstract.
 The Leptarctinae are an enigmatic subfamily of mustelids present in North America and Eurasia during the Miocene (Arikareean to Hemphillian North American Land Mammal Ages). Their diet and ecology have been particularly controversial. Some workers have suggested they were similar to koalas, whereas others suggested they were crushing omnivores analogous to raccoons. Leptarctus oregonensis Stock, 1930, a poorly known leptarctine from the early Barstovian, is represented by fragmented cranial elements and isolated teeth from the Mascall Formation of Oregon, and some fairly complete but undescribed material from the Olcott Formation of western Nebraska. Herein, we describe the first well-preserved skull of L. oregonensis from the type formation. Based on this new specimen, we confirm that L. oregonensis is a distinct species from L. primus Leidy, 1856 and L. ancipidens White, 1941 that is characterized by a distinct morphology of its tympanic projections and first upper molars. We are also able to describe intraspecific variation within L. oregonensis coinciding with the geographic distribution of the specimens (Oregon and Nebraska). The most variable characters are concentrated in the morphology of the frontals and the upper fourth premolar. Additional specimens will be needed to settle the debate over sexual dimorphism in this species, but this new specimen suggests that Leptarctus oregonensis, despite being one of the smallest members of the Leptarctinae, was an animal-dominated omnivore with considerable crushing ability.

leptarctus oregonensis
carnivora
miocene


Cretaceous-Paleogene Dinoflagellate Biostratigraphy and the Age of the Clayton Formation, Southeastern Missouri, USA

Abstract: Sedimentary deposits in Stoddard County, southeastern Missouri, reveal a K-Pg transition sequence represented by the uppermost Maastrichtian Owl Creek Formation and the Paleocene Clayton Formation. The Clayton Formation is characterized by a basal fossiliferous coquinite that contains reworked late Maastrichtian macrofossils. Dinoflagellate biostratigraphy is used to determine the age of the coquinite layer and specifically whether or not it is an end-K tsunamite deposit resulting from the Chicxulub impact event. Results indicate a mixed assemblage of late Maastrichtian and early Danian dinocysts within the basal coquinite of the Clayton Formation. Maastrichtian dinocyst taxa identified are Riculacysta amplexa, Pierceites pentagonus, Phelodinium tricuspe and Dinogymnium sp. and dinocysts utilized as global indicators of the basal Danian, also present in the coquinite, consist of Senoniasphaera inornata, Carpatella cornuta, Damassadinium californicum, and Lanternosphaeridium reinhardtii. A gray mud occurring above the coquinite in the middle of the Clayton Formation contains the mid-Danian dinoflagellate Senegalinium iterlaaense. Collectively, these data suggest that the coquinite was deposited well after the K-Pg event but before the middle Danian. The mixed assemblage of Late Cretaceous and Paleocene dinocysts preserved in the coquinite weakens the hypothesis that it is an end-K tsunamite deposit and suggests instead that it may result from a long-term transgressive lag. We also extend the stratigraphic range of the Paleocene Senegalinium simplex downward into the uppermost Maastrichtian.

dinoflagellate biostratigraphy
clayton formation
owl creek formation


Evolution of reproductive strategies in dictyopteran insects – clues from ovipositor morphology of extinct roachoids

Abstract: Dictyoptera, which comprises cockroaches, termites and mantids, is a quite successful group of insects in evolutionary terms with a long fossil record—roachoid insects were already abundant 315 million years ago in the Carboniferous forests. One of the most remarkable autapomorphies of extant dictyopterans, and possibly a major factor for their persisting success, is the ability to produce oothecae. Despite the robustness of this sort of egg package, fossils of oothecae are very rare, the oldest direct evidences being from the Cretaceous Crato Formation in Brazil (115 mya). The ability to produce oothecae is presumably linked to a specific ovipositor morphology, including a significant length reduction. Hence, ovipositor morphology can indirectly inform about the reproductive strategy of a species. Herein we describe the ovipositor morphology of various fossil forms of dictyopteran insects. Early fossil roachoids, in contrast to the modern forms, possessed a very long and prominent ovipositor, reminiscent of the ovipositor in orthopterans (Ensifera), indicating that these forms laid individual, rather small eggs into a substrate. We present examples from different fossil deposits, which show the entire range of ovipositor morphologies, from very long forms over forms with ovipositors partly reduced in length to modern-appearing morphologies. Most remarkably, different shapes of ovipositors seem to be present in roachoids in the fauna of the 115 million years old Crato Formation—species with long prominent ovipositors co-existed with species with a reduced short and broad ovipositor. Additionally, females that carry oothecae attached to their abdomen indicate a third type of ovipositor: a further reduced ovipositor as seen in modern forms, which already allowed the internal production of oothecae.

reproductive strategy
dictyopteran insect
ovipositor morphology
cockroach
abdoman


Dental microwear texture reflects dietary tendencies in extant Lepidosauria despite their limited use of oral food processing

Abstract: Lepidosauria show a large diversity in dietary adaptations, both among extant and extinct tetrapods. Unlike mammals, Lepidosauria do not engage in sophisticated mastication of their food and most species have continuous tooth replacement, further reducing the wear of individual teeth. However, dietary tendency estimation of extinct lepidosaurs usually rely on tooth shape and body size, which allows only for broad distinction between faunivores and herbivores. Microscopic wear features on teeth have long been successfully applied to reconstruct the diet of mammals and allow for subtle discrimination of feeding strategies and food abrasiveness. Here, we present, to our knowledge, the first detailed analysis of dental microwear texture on extant lepidosaurs using a combination of 46 surface texture parameters to establish a framework for dietary tendency estimation of fossil reptilian taxa. We measured dental surface textures of 77 specimens, belonging to herbivorous, algaevorous, frugivorous, carnivorous, ovivorous, insectivorous, molluscivorous, as well as omnivorous species. Carnivores show low density and shallow depth of furrows, whereas frugivores are characterized by the highest density of furrows. Molluscivores show the deepest wear features and highest roughness, herbivores have lower surface roughness and shallower furrows compared to insectivores and omnivores, which overlap in all parameters. Our study shows that despite short food–tooth interaction, dental surface texture parameters enable discrimination of several feeding strategies in lepidosaurs. This result opens new research avenues to assess diet in a broad variety of extant and extinct non-mammalian taxa including dinosaurs and early synapsids.

lepidosauria
dental microwear texture
reptile
dietary guild
dmta


Influence of Microbial Biofilms on the Preservation of Primary Soft Tissue in Fossil and Extant Archosaurs

Abstract: Background Mineralized and permineralized bone is the most common form of fossilization in the vertebrate record. Preservation of gross soft tissues is extremely rare, but recent studies have suggested that primary soft tissues and biomolecules are more commonly preserved within preserved bones than had been presumed. Some of these claims have been challenged, with presentation of evidence suggesting that some of the structures are microbial artifacts, not primary soft tissues. The identification of biomolecules in fossil vertebrate extracts from a specimen of Brachylophosaurus canadensis has shown the interpretation of preserved organic remains as microbial biofilm to be highly unlikely. These discussions also propose a variety of potential mechanisms that would permit the preservation of soft-tissues in vertebrate fossils over geologic time. Methodology/Principal Findings This study experimentally examines the role of microbial biofilms in soft-tissue preservation in vertebrate fossils by quantitatively establishing the growth and morphology of biofilms on extant archosaur bone. These results are microscopically and morphologically compared with soft-tissue extracts from vertebrate fossils from the Hell Creek Formation of southeastern Montana (Latest Maastrichtian) in order to investigate the potential role of microbial biofilms on the preservation of fossil bone and bound organic matter in a variety of taphonomic settings. Based on these analyses, we highlight a mechanism whereby this bound organic matter may be preserved. Conclusions/Significance Results of the study indicate that the crystallization of microbial biofilms on decomposing organic matter within vertebrate bone in early taphonomic stages may contribute to the preservation of primary soft tissues deeper in the bone structure.

microbial biofilm
primary soft tissue
organic matter
crystallization
vertebrate bone


A Gondwanan origin of passerine birds supported by DNA sequences of the endemic New Zealand wrens

Abstract: Zoogeographic, palaeontological and biochemical data support a Southern Hemisphere origin for passerine birds, while accumulating molecular data suggest that most extant avian orders originated in the mid–Late Cretaceous. We obtained DNA sequence data from the nuclear c–myc and RAG–1 genes of the major passerine groups and here we demonstrate that the endemic New Zealand wrens (Acanthisittidae) are the sister taxon to all other extant passerines, supporting a Gondwanan origin and early radiation of passerines. We propose that (i) the acanthisittids were isolated when New Zealand separated from Gondwana (ca. 82–85 Myr ago), (ii) suboscines, in turn, were derived from an ancestral lineage that inhabited western Gondwana, and (iii) the ancestors of the oscines (songbirds) were subsequently isolated by the separation of Australia from Antarctica. The later spread of passerines into the Northern Hemisphere reflects the northward migration of these former Gondwanan elements.

gondwanan origin
passerine bird
new zealand wren


Abstract: A sea-level index point (SLIP) estimates relative sea level (RSL) at a specified time and place, with an associated uncertainty. In the preceding chapters, numerous examples have been provided detailing how to collect sea-level indicators from different geomorphic settings (Chapters 3–10) and the means to interpret them (Chapters 12–22). Various methods of dating SLIPs (Chapters 23–27) have been discussed, as well as how to use modeling to account for compaction or changes in tidal range (Chapters 29 and 30). In order to compare SLIPs collected by differing techniques, it is necessary to analyze their associated errors in an objective and uniform way. SLIPs that are represented as discrete, errorless data points in age/ elevation space may lead to erroneous inferences of RSL fluctuations that often reflect inherent uncertainties in the underlying data. The usefulness of geological sea-level data increases significantly if they are subjected to a rigorous error analysis with well-quantified uncertainties. As a consequence, SLIPs have played a major role in the last decades in estimating future sea-level change by establishing long-term background rates of vertical land motion (e.g., Engelhart et al., 2009) and in refining glacial isostatic adjustment (GIA) models (e.g., Lambeck et al., 1998; Peltier et al., 2002; Milne et al., 2005; Vink et al., 2007). The database approach is a method for analyzing large numbers of SLIPs with all data stored according to a well-defined error protocol. A sea-level database can elucidate regional variations in past RSL which are of interest to a wide range of topics such as ice-sheet dynamics, archeology, Earth rheology, and future sea-level change. Multiple approaches to database construction have been used worldwide (e.g., Flemming, 1982; Shennan and Horton, 2002; Toscano and Macintyre, 2003; Dutton and Lambeck, 2012; Engelhart and Horton, 2012; Yu et al., 2012), all with unique strategies and emphases. In this chapter we present a comprehensive protocol for analyzing and standardizing sealevel data, including a format for constructing a sea-level database that captures all the relevant variables. In particular, we build on the work initiated by the Durham University group in the 1980s (e.g., Shennan, 1989) that culminated in a comprehensive sea-level database for the UK (Shennan and Horton, 2002). The hallmark of the UK sea-level database is the evaluation in a systematic fashion of a large range of variables to produce SLIPs and limiting data points. Here we expand upon this approach, especially by quantifying dating errors and by incorporating both modern-day and paleotidal modeling. The overarching philosophy is to include as much of the original, “raw” data as possible, and to maximize caution in assigning errors. The latter implies that assigned errors are often larger than in previous analyses of similar data. The database described here was developed within the framework of studies of RSL change since the Last Glacial Maximum (LGM) along the US Gulf and Atlantic coasts. However, the methods can be applied worldwide as they are suitable for a Chapter 34 A protocol for a geological sea-level database

protocol
geological sea-level database
uncertainty


Geocarb III: A Revised Model of Atmospheric CO2 over Phanerozoic Time

Abstract: Revision of the GEOCARB model (Berner, 1991, 1994) for paleolevels of atmospheric CO2, has been made with emphasis on factors affecting CO2 uptake by continental weathering. This includes: (1) new GCM (general circulation model) results for the dependence of global mean surface temperature and runoff on CO2, for both glaciated and non-glaciated periods, coupled with new results for the temperature response to changes in solar radiation; (2) demonstration that values for the weathering-uplift factor fR(t) based on Sr isotopes as was done in GEOCARB II are in general agreement with independent values calculated from the abundance of terrigenous sediments as a measure of global physical erosion rate over Phanerozoic time; (3) more accurate estimates of the timing and the quantitative effects on Ca-Mg silicate weathering of the rise of large vascular plants on the continents during the Devonian; (4) inclusion of the effects of changes in paleogeography alone (constant CO2 and solar radiation) on global mean land surface temperature as it affects the rate of weathering; (5) consideration of the effects of volcanic weathering, both in subduction zones and on the seafloor; (6) use of new data on the d 13 C values for Phanerozoic limestones and organic matter; (7) consideration of the relative weather- ing enhancement by gymnosperms versus angiosperms; (8) revision of paleo land area based on more recent data and use of this data, along with GCM-based paleo-runoff results, to calculate global water discharge from the continents over time. Results show a similar overall pattern to those for GEOCARB II: very high CO2 values during the early Paleozoic, a large drop during the Devonian and Carbonifer- ous, high values during the early Mesozoic, and a gradual decrease from about 170 Ma to low values during the Cenozoic. However, the new results exhibit considerably higher CO2 values during the Mesozoic, and their downward trend with time agrees with the independent estimates of Ekart and others (1999). Sensitivity analysis shows that results for paleo-CO2 are especially sensitive to: the effects of CO2 fertilization and temperature on the acceleration of plant-mediated chemical weathering; the quantitative effects of plants on mineral dissolution rate for constant temperature and CO2; the relative roles of angiosperms and gymnosperms in accelerating rock weather- ing; and the response of paleo-temperature to the global climate model used. This emphasizes the need for further study of the role of plants in chemical weathering and the application of GCMs to study of paleo-CO2 and the long term carbon cycle.

atmospheric co2
phanerozoic time
geocarb model


A new ankylosaurine dinosaur from the Judith River Formation of Montana, USA, based on an exceptional skeleton with soft tissue preservation

Abstract: The terrestrial Judith River Formation of northern Montana was deposited over an approximately 4 Myr interval during the Campanian (Late Cretaceous). Despite having been prospected and collected continuously by palaeontologists for over a century, few relatively complete dinosaur skeletons have been recovered from this unit to date. Here we describe a new genus and species of ankylosaurine dinosaur, Zuul crurivastator, from the Coal Ridge Member of the Judith River Formation, based on an exceptionally complete and well-preserved skeleton (ROM 75860). This is the first ankylosaurin skeleton known with a complete skull and tail club, and it is the most complete ankylosaurid ever found in North America. The presence of abundant soft tissue preservation across the skeleton, including in situ osteoderms, skin impressions and dark films that probably represent preserved keratin, make this exceptional skeleton an important reference for understanding the evolution of dermal and epidermal structures in this clade. Phylogenetic analysis recovers Zuul as an ankylosaurin ankylosaurid within a clade of Dyoplosaurus and Scolosaurus, with Euoplocephalus being more distantly related within Ankylosaurini. The occurrence of Z. crurivastator from the upper Judith River Formation fills a gap in the ankylosaurine stratigraphic and geographical record in North America, and further highlights that Campanian ankylosaurines were undergoing rapid evolution and stratigraphic succession of taxa as observed for Laramidian ceratopsids, hadrosaurids, pachycephalosaurids and tyrannosaurids.

ankylosaurine dinosaur
judith river formation
exceptional skeleton


A Revision of Plesiobaena (Testudines: Baenidae) and an Assessment of Baenid Ecology Across the K/T Boundary

Abstract: Abstract Over the course of the last two decades, the baenid taxon Plesiobaena has typically been thought to consist of two named species, Plesiobaena antiqua (Campanian) and Plesiobaena putorius (Paleocene), along with an unnamed species from the Maastrichtian, but the interrelationship of these three taxa was never explored in an explicit phylogenetic context. Herein we present or re-describe a number of relevant specimens and provide a cladistic analysis of Baenidae using species only as terminal taxa. The phylogenetic analysis clearly reveals that Plesiobaena in the traditional sense is a paraphyletic assemblage relative to the clade formed by Gamerabaena sonsalla and Palatobaena spp., thus demanding some nomenclatural adjustments. In particular, Plesiobaena putorius is moved to a new genus, Cedrobaena, and the unnamed taxon from the Maastrichtian is formally named Peckemys brinkman. Many of the new Cedrobaena putorius and Peckemys brinkman specimens described herein were found at the Turtle Graveyard locality in Slope County, North Dakota, along with four other turtle taxa, increasing the turtle diversity of this locality to at least six taxa. Although this indicates that Turtle Graveyard is the world's most diverse fossil turtle thanatocoenosis, a comparable diversity is found in modern river systems in the southeastern United States today. Our phylogenetic analysis indicates that seven out of nine latest Cretaceous baenid turtle lineages survived into the Paleocene, four of which are interpreted as being durophagous.

plesiobaena
baenidae
phylogenetic analysis


The long‐lived mollusc Arctica islandica: A new paleoceanographic tool for the reconstruction of bottom temperatures for the continental shelves of the northern North Atlantic Ocean

Abstract: The carbonate shell of the bivalve Arctica islandica has been recognized, for more than a decade, as a potentially important marine geochemical biorecorder owing to this species' great longevity (200+ years) and wide geographic distribution throughout the northern North Atlantic Ocean, a region vital to global climate and ocean circulation. However, until now this potential has not been realized owing to the difficulty of precisely sampling the shell of this slow growing species. Using newly available automated microsampling techniques combined with micromass stable isotope mass spectrometry, a stable oxygen isotope record (1956–1957 and 1961–1970) has been obtained from a live-captured, 38-year-old A. islandica specimen collected near the former position of the Nantucket Shoals Lightship (41°N. 69°W). The shell's δ18O signal is compared with an expected signal derived from ambient bottom temperature and salinity data recorded at the lightship for the same period. The results show that A islandica's δ18O record (1) is in phase with its growth banding, confirming the annual periodicity of this species' growth bands, (2) is in oxygen isotopic equilibrium with the ambient seawater, (3) shows a consistent shell growth shutdown temperature of ∼6°C. which translates into an ∼8-month (May–December) shell growth period at this location, and (4) records the ambient bottom temperature with a precision of ∼±1.2°C. These results add important information on the life history of this commercially important shellfish species and demonstrate that A. islandica shells can be used to reconstruct inter- and intra-annual records of the continental shelf bottom temperature.

bottom temperature
north atlantic ocean
oxygen
continental shelf


Redescription of Arganasaurus (Metoposaurus) azerouali (Dutuit) comb. nov. from the Upper Triassic of the Argana Basin (Morocco), and the first phylogenetic analysis of the Metoposauridae (Amphibia, Temnospondyli)

Abstract: A systematic revision of the temnospondyl ‘Metoposaurus’ azerouali Dutuit from the Late Triassic of the Argana Basin (Western High Atlas, Morocco) is presented. The type material is redescribed in detail, and a preliminary phylogenetic analysis – the first one dealing with all metoposaurid species – is also conducted in order to test its position within the Metoposauridae. Our analysis places ‘Metoposaurus’ azerouali as sister‐taxon to Arganasaurus lyazidi in a robust clade supported by two unambiguous synapomorphies (bulge‐like tabular horn and exoccipital process visible in dorsal view) and two ambiguous synapomorphies (cultriform process of uniform width and subtriangular posterior Meckelian fenestra). We therefore propose the new combination Arganasaurus azerouali comb. nov. for the species ‘M.’ azerouali. Our analysis also confirms that the central Laurasian genus Metoposaurus is monophyletic but not the genus Koskinonodon, which deserves its own systematic revision. By consequent, the Late Triassic rich vertebrate fauna from the Argana Basin comprises the metoposauroid Almasaurus habazzi, the basal metoposaurid Dutuitosaurus ouazzoui, and the genus Arganasaurus which is represented by the type species A. lyazidi and A. azerouali comb. nov. Combined with the stratigraphical and geographical occurrences of the taxa, our phylogenetic analysis suggests that metoposaurids may have appeared during the Longobardian (late Ladinian) in central Pangea. Their diversification may be linked to the Carnian Pluvial Episode. At least, their extinction may have occurred during the Rhaetian because of the aridification of the climate and/or competition with amniotes.

argana basin
phylogenetic analysis
metoposauridae


Molecular Decay of the Tooth Gene Enamelin (ENAM) Mirrors the Loss of Enamel in the Fossil Record of Placental Mammals

Abstract: Vestigial structures occur at both the anatomical and molecular levels, but studies documenting the co-occurrence of morphological degeneration in the fossil record and molecular decay in the genome are rare. Here, we use morphology, the fossil record, and phylogenetics to predict the occurrence of “molecular fossils” of the enamelin (ENAM) gene in four different orders of placental mammals (Tubulidentata, Pholidota, Cetacea, Xenarthra) with toothless and/or enamelless taxa. Our results support the “molecular fossil” hypothesis and demonstrate the occurrence of frameshift mutations and/or stop codons in all toothless and enamelless taxa. We then use a novel method based on selection intensity estimates for codons (ω) to calculate the timing of iterated enamel loss in the fossil record of aardvarks and pangolins, and further show that the molecular evolutionary history of ENAM predicts the occurrence of enamel in basal representatives of Xenarthra (sloths, anteaters, armadillos) even though frameshift mutations are ubiquitous in ENAM sequences of living xenarthrans. The molecular decay of ENAM parallels the morphological degeneration of enamel in the fossil record of placental mammals and provides manifest evidence for the predictive power of Darwin's theory.

enamel
placental mammal
aardvark
sloth
molecular decay


Coupling of millennial‐scale changes in sea surface temperature and precipitation off northeastern Brazil with high‐latitude climate shifts during the last glacial period

Abstract: [1] High-resolution records of alkenone-derived sea surface temperatures and elemental Ti/Ca ratios from a sediment core retrieved off northeastern Brazil (4°S) reveal short-term climate variability throughout the past 63,000 a. Large pulses of terrigenous sediment discharge, caused by increased precipitation in the Brazilian hinterland, coincide with Heinrich events and the Younger Dryas period. Terrigenous input maxima related to Heinrich events H6–H2 are characterized by rapid cooling of surface water ranging between 0.5° and 2°C. This signature is consistent with a climate model experiment where a reduction of the Atlantic meridional overturning circulation (AMOC) and related North Atlantic cooling causes intensification of NE trade winds and a southward movement of the Intertropical Convergence Zone, resulting in enhanced precipitation off northeastern Brazil. During deglaciation the surface temperature evolution at the core site predominantly followed the Antarctic warming trend, including a cooling, prior to the Younger Dryas period. An abrupt temperature rise preceding the onset of the Bolling/Allerod transition agrees with model experiments suggesting a Southern Hemisphere origin for the abrupt resumption of the AMOC during deglaciation caused by Southern Ocean warming and associated with northward flow anomalies of the South Atlantic western boundary current.

sea surface temperature
precipitation
northeastern brazil
sediment core


Global late Quaternary megafauna extinctions linked to humans, not climate change

Abstract: The late Quaternary megafauna extinction was a severe global-scale event. Two factors, climate change and modern humans, have received broad support as the primary drivers, but their absolute and relative importance remains controversial. To date, focus has been on the extinction chronology of individual or small groups of species, specific geographical regions or macroscale studies at very coarse geographical and taxonomic resolution, limiting the possibility of adequately testing the proposed hypotheses. We present, to our knowledge, the first global analysis of this extinction based on comprehensive country-level data on the geographical distribution of all large mammal species (more than or equal to 10 kg) that have gone globally or continentally extinct between the beginning of the Last Interglacial at 132 000 years BP and the late Holocene 1000 years BP, testing the relative roles played by glacial–interglacial climate change and humans. We show that the severity of extinction is strongly tied to hominin palaeobiogeography, with at most a weak, Eurasia-specific link to climate change. This first species-level macroscale analysis at relatively high geographical resolution provides strong support for modern humans as the primary driver of the worldwide megafauna losses during the late Quaternary.

quaternary megafauna extinction
climate change
mammal specie
pleistocene


Revision of the oryctocephalid trilobite genera Arthricocephalus Bergeron and Oryctocarella Tomashpolskaya and Karpinski (Cambrian) from South China and Siberia

Abstract:
Abstract.
 Restudy of the limestone slab containing the type suite of Arthricocephalus chauveaui Bergeron, 1899 (Trilobita), the type species of Arthricocephalus Bergeron, 1899, shows that specimens of three species, each representing a separate genus, are present on the slab and were likely included in the original concept of the species. Besides A. chauveaui, the slab contains specimens of Oryctocarella duyunensis (Qian, 1961) and Duyunaspis duyunensis Zhang and Qian in Zhou et al., 1977. Bergeron (1899) illustrated one exoskeleton from the type suite of A. chauveaui only and apparently based much of his written description on that specimen. This specimen was clearly intended to be the type specimen of A. chauveaui. Subsequently, Lane et al. (1988) designated another specimen, which was not originally illustrated, as the lectotype, and this specimen is referable to Oryctocarella duyunensis. As revised here, Bergeron's illustrated specimen should be regarded as the lectotype of A. chauveaui. Such designation stabilizes the concepts of both Arthricocephalus and A. chauveaui. Arthricocephalites Qian in Lu et al., 1974 and Haliplanktos Blaker and Peel, 1997 are regarded as junior synonyms of Arthricocephalus. Oryctocarella Tomashpolskaya and Karpinski, 1961, which was previously regarded as a junior synonym of Arthricocephalus, is revived as a valid genus. Oryctocarella includes a number of species previously assigned to Arthricocephalus. The type species of both Arthricocephalus and Oryctocarella, together with related species, are described on the basis of new material.

oryctocarella tomashpolskaya
karpinski
south china
balangia


Small carbonaceous fossils (SCFs) from North Greenland: new light on metazoan diversity in early Cambrian shelf environments

Abstract: The Sirius Passet Lagerstätte of North Greenland is one of the oldest records of soft‐bodied metazoan‐dominated ecosystems from the early Cambrian. The Lagerstätte site itself is restricted to just a single c. 1‐km‐long outcrop located offshore from the shelf margin, in an area affected by metamorphic alteration during the Ellesmerian Orogeny (Devonian – Early Carboniferous). The recent recovery of small carbonaceous fossils (SCFs) to the south, in areas that escaped the effects of this deformation, has substantially expanded the known coverage of organic preservation into shallower water depositional settings in this region. Here, we describe additional SCF assemblages from the siliciclastic shelf succession of the Buen Formation (Cambrian Series 2, stages 3–4; c. 515 Ma), expanding the previously documented SCF biota. Newly recovered material indicates a rich diversity of non‐mineralizing metazoans, chiefly represented by arthropod remains. These include the filtering and grinding elements of a sophisticated crustacean feeding apparatus (the oldest crustacean remains reported to date), alongside an assortment of bradoriid sclerites, including almost complete, 3D valves, which tie together a number of SCFs previously found in isolation. Other metazoan remains include various trilobite cuticles, diverse scalidophoran sclerites, and a range of metazoan fragments of uncertain affinity. This shallower water assemblage differs substantially from the Sirius Passet biota, which is dominated by problematic euarthropod stem‐group members and sponges. Although some of these discrepancies are attributable to taphonomic or temporal factors, these lateral variations in taxonomic composition also point to significant palaeoenvironmental and/or palaeoecological controls on early Cambrian metazoan communities.

north greenland
cambrian series
small carbonaceous fossil


A new varanopid synapsid from the early Permian of Oklahoma and the evolutionary stasis in this clade

Abstract: Varanopids are a basal clade of small- to medium-sized non-therapsid synapsids, whose range extends from the late Pennsylvanian to the late middle Permian, and are found in North America, Russia, Europe and South Africa. The greatest varanopid diversity is observed at the fossiliferous cave deposits near Richards Spur, Oklahoma, well known for the preservation of a complex early Permian upland community. Two previously described varanopids, Mycterosaurus and Varanops, are known only from fragmentary disarticulated material at Richards Spur. A third putative varanopid, Basicranodon fortsillensis, represented by a partial parasphenoid, has been synonymized with Mycterosaurus longiceps. This study reports on a new varanopid taxon, represented by substantially more complete material, including three nearly complete skulls. Such comprehensive cranial material allows for a detailed study of the taxon and its relationship to other varanopids. This new varanopid bears great morphological similarity to Mesenosaurus romeri from the middle Permian Mezen River Basin of northern Russia. Phylogenetic analysis recovers a sister relationship between this taxon and Me. romeri. This relationship, in conjunction with a detailed morphological comparison, supports the placement of this taxon within Mesenosaurus, as a new species, Me. efremovi. These results reveal an unexpected extension of the geographical and temporal range of Mesenosaurus, contributing to our understanding of varanopid dispersal. The extended persistence of this basal clade of predatory synapsids, underscored by the apparent evolutionary stasis of this genus, is unusual among Palaeozoic tetrapods. This phenomenon implies an exceptionally high degree of extended ecological resilience across major faunal and environmental transitions.


Lichen mimesis in mid-Mesozoic lacewings

Abstract: Animals mimicking other organisms or using camouflage to deceive predators are vital survival strategies. Modern and fossil insects can simulate diverse objects. Lichens are an ancient symbiosis between a fungus and an alga or a cyanobacterium that sometimes have a plant-like appearance and occasionally are mimicked by modern animals. Nevertheless, lichen models are almost absent in fossil record of mimicry. Here, we provide the earliest fossil evidence of a mimetic relationship between the moth lacewing mimic Lichenipolystoechotes gen. nov. and its co-occurring fossil lichen model Daohugouthallus ciliiferus. We corroborate the lichen affinity of D. ciliiferus and document this mimetic relationship by providing structural similarities and detailed measurements of the mimic’s wing and correspondingly the model’s thallus. Our discovery of lichen mimesis predates modern lichen-insect associations by 165 million years, indicating that during the mid-Mesozoic, the lichen-insect mimesis system was well established and provided lacewings with highly honed survival strategies.


A new genus of Devonian tetrapod from North‐East Greenland, with new information on the lower jaw of Ichthyostega

Abstract: Abstract:  A new genus and species of Devonian tetrapod has been identified from material collected in 1947 from the southern slope of Mt. Celsius, Ymer Ø, North‐East Greenland. The specimen preserves both lower jaws, partial palate, premaxillae and maxillae, with a natural mould of parts of the shoulder girdle. The new taxon, Ymeria denticulata, shows differences in dentition, skull ornament and lateral line expression from both Acanthostega and Ichthyostega, but it shows a closer resemblance to the latter. A cladistic analysis not only suggests that Ymeria lies adjacent to Ichthyostega on the tetrapod stem, but also reveals substantial topological instability. As the third genus and the fifth species of tetrapod identified from North‐East Greenland, it demonstrates the high diversity of Devonian tetrapods in that region.

new genus
ichthyostega
ymeria denticulata
low jaw


First Mesozoic Record of the Stingray Myliobatis wurnoensis from Mali and a Phylogenetic Analysis of Myliobatidae Incorporating Dental Characters

Abstract: New specimens, including the first record of lower dental plates, of the extinct myliobatid Myliubatis wurnoensis were recovered from the Maastrichtian (Late Cretaceous) of the Iullemmeden Basin, Mali, and are the oldest record of the taxon. We evaluated the phylogenetic position of this taxon with reference to other myliobatids (extinct and extant) using osteology and dentition. Our results indicate that Myliobatinae and Myliobatis are each paraphyletic, and that Aetobatus and Rhinoptera are monophyletic. We also found that taxa known only from the Cretaceous, Brachyrhizodus and Igdabatis, are highly nested within Myliobatidae. The phylogenetic position of these taxa unambiguously extends the origin of Myliobatidae and most of its representative taxa into the Mesozoic.

myliobatis
mali
myliobatidae
dental plate
maastrichtian


A new alligatoroid from the Eocene of Vietnam highlights an extinct Asian clade independent from extant Alligator sinensis

Abstract: During systematic paleontological surveys in the Na Duong Basin in North Vietnam between 2009 and 2012, well-preserved fossilized cranial and postcranial remains belonging to at least 29 individuals of a middle to late Eocene (late Bartonian to Priabonian age (39–35 Ma)) alligatoroid were collected. Comparative anatomical study of the material warrants the diagnosis of a new taxon, Orientalosuchus naduongensis gen. et sp. nov. The combined presence of an enlarged fifth maxillary tooth, prominent preorbital ridges, a large supraoccipital exposure on the skull table, a palatine-pterygoid suture anterior to the posterior end of the suborbital fenestra, and a pterygoid forming a neck surrounding the choana is unique to this species. Unlike previous phylogenies, our parsimony analysis recovers a monophyletic Late Cretaceous to Paleogene East to Southeastern Asian alligatoroid group, here named Orientalosuchina. The group includes Orientalosuchus naduongensis, Krabisuchus siamogallicus, Eoalligator chunyii, Jiangxisuchus nankangensis and Protoalligator huiningensis, all of them sharing a medial shifted quadrate foramen aerum. The recognition of this clade indicates at least two separate dispersal events from North America to Asia: one during the Late Cretaceous by Orientalosuchina and one by the ancestor of Alligator sinensis during the Paleogene or Neogene, the timing of which is poorly constrained.


Torvosaurus gurneyi n. sp., the Largest Terrestrial Predator from Europe, and a Proposed Terminology of the Maxilla Anatomy in Nonavian Theropods

Abstract: The Lourinhã Formation (Kimmeridgian-Tithonian) of Central West Portugal is well known for its diversified dinosaur fauna similar to that of the Morrison Formation of North America; both areas share dinosaur taxa including the top predator Torvosaurus, reported in Portugal. The material assigned to the Portuguese T. tanneri, consisting of a right maxilla and an incomplete caudal centrum, was briefly described in the literature and a thorough description of these bones is here given for the first time. A comparison with material referred to Torvosaurus tanneri allows us to highlight some important differences justifying the creation of a distinct Eastern species. Torvosaurus gurneyi n. sp. displays two autapomorphies among Megalosauroidea, a maxilla possessing fewer than eleven teeth and an interdental wall nearly coincidental with the lateral wall of the maxillary body. In addition, it differs from T. tanneri by a reduced number of maxillary teeth, the absence of interdental plates terminating ventrally by broad V-shaped points and falling short relative to the lateral maxillary wall, and the absence of a protuberant ridge on the anterior part of the medial shelf, posterior to the anteromedial process. T. gurneyi is the largest theropod from the Lourinhã Formation of Portugal and the largest land predator discovered in Europe hitherto. This taxon supports the mechanism of vicariance that occurred in the Iberian Meseta during the Late Jurassic when the proto-Atlantic was already well formed. A fragment of maxilla from the Lourinhã Formation referred to Torvosaurus sp. is ascribed to this new species, and several other bones, including a femur, a tibia and embryonic material all from the Kimmeridgian-Tithonian of Portugal, are tentatively assigned to T. gurneyi. A standard terminology and notation of the theropod maxilla is also proposed and a record of the Torvosaurus material from Portugal is given.

terminology
theropod
torvosaurus material


The Quilon Limestone, Kerala Basin, India: an archive for Miocene Indo-Pacific seagrass beds

Abstract: The facies of the fossiliferous Quilon Limestone in SW India is described for the first time in detail at the Padappakkara-type locality. Facies (fossiliferous, micrite-rich, bioturbated sediment with intercalated sand pockets) and faunal composition (epiphytic foraminifers, seagrass feeding Smaragdia gastropods, bioimmuration of celleporiform bryozoan colonies) indicate a seagrass environment. The large discoidal archaiasin foraminifer Pseudotaberina malabarica, in particular, is considered as a proxy for seagrass communities. Recent seagrasses have their centre of generic richness in the Indo-Pacific where they cover wide areas in the tidal and shallow sub-tidal zones. However, their geological record is only fragmentary and their palaeobiogeographic distribution has a big stratigraphical gap in the Miocene Western Indo-Pacific region. The described nannoplankton flora and planktonic foraminifers from the Quilon Formation demonstrate that the deposition of the studied seagrass bed occurred in nannoplankton biozone NN3. This timing suggests formation during the closure of the Tethyan Seaway. The Quilon Limestone is thus an early Western Indo-Pacific seagrass bed and an important step in reconstructing the history of seagrass communities. h Quilon Formation, Pseudotaberina malabarica, seagrass facies, Burdigalian, Indo-Pacific.

quilon limestone
kerala basin
seagrass environment


Experimental studies on microbial bioerosion at Lee Stocking Island, Bahamas and One Tree Island, Great Barrier Reef, Australia: implications for paleoecological reconstructions

Abstract: Different kinds of experimental calcareous substrates were exposed at Lee Stocking Island (Bahamas) and One Tree Island (Great Barrier Reef, Australia) to study which endolithic bacteria, algae and fungi contribute to bioerosion and what their bioerosion rates are. The sites at Lee Stocking Island were several leeward shallow water and several windward shallow and deep-water positions (from the Acropora palmata reef at 2 m down to 275 m depth). At One Tree Island, the experiments were conducted in patch reefs treated with P and N to study the influence of mineral nutrients on bioerosion. The exposure periods ranged from 1 week to 2 years. The micritic carbonate substrates exposed on Lee Stocking Island contained 6 genera with 15 species of cyanobacteria, green and red algae, and different kinds of microendolithic heterotrophs. The mean values of bioerosion rates measured between 1 to 2 g/m 2 /y at 275 m and 520 g/m 2 /y at one of the leeward sites. The composition of the endolithic community and the bioerosion rates changed over time. At One Tree Island, shell pieces of Tridacna were used as substrate exposed for 5 months to endolith activity. Five genera and 6 species of cyanobacteria, green and red algae and different kinds of heterotrophic microendoliths were found with bioerosion rates of 20–30 g/m 2 /y. There are differences in abundance of taxa between Lee Stocking Island and One Tree Island. The introduction of nutrients had no apparent impact on the microborer community. Controlling factors for the distribution and abundance of microborers are mainly light, but also the kind of substrate and, possibly, the biogeographic position. The results support the paleoecological importance of microendoliths.

bioerosion
lee stocking island
great barrier reef


A New Saurolophine Dinosaur from the Latest Cretaceous of Far Eastern Russia

Abstract: Background Four main dinosaur sites have been investigated in latest Cretaceous deposits from the Amur/Heilongjiang Region: Jiayin and Wulaga in China (Yuliangze Formation), Blagoveschensk and Kundur in Russia (Udurchukan Formation). More than 90% of the bones discovered in these localities belong to hollow-crested lambeosaurine saurolophids, but flat-headed saurolophines are also represented: Kerberosaurus manakini at Blagoveschensk and Wulagasaurus dongi at Wulaga. Methodology/Principal Findings Herein we describe a new saurolophine dinosaur, Kundurosaurus nagornyi gen. et sp. nov., from the Udurchukan Formation (Maastrichtian) of Kundur, represented by disarticulated cranial and postcranial material. This new taxon is diagnosed by four autapomorphies. Conclusions/Significance A phylogenetic analysis of saurolophines indicates that Kundurosaurus nagornyi is nested within a rather robust clade including Edmontosaurus spp., Saurolophus spp., and Prosaurolophus maximus, possibly as a sister-taxon for Kerberosaurus manakini also from the Udurchukan Formation of Far Eastern Russia. The high diversity and mosaic distribution of Maastrichtian hadrosaurid faunas in the Amur-Heilongjiang region are the result of a complex palaeogeographical history and imply that many independent hadrosaurid lineages dispersed without any problem between western America and eastern Asia at the end of the Cretaceous.

new saurolophine dinosaur
far eastern russia
kerberosaurus manakini


Spinicaudatans and ostracods (Crustacea) from the Montceau Lagerstätte (Late Carboniferous, France): morphology and palaeoenvironmental significance

Abstract: Spinicaudatans and ostracods form two components of the diverse arthropod fauna from the Montceau Lagerstätte (Stephanian, France). Spinicaudatans are represented by Montcestheria orri gen. and sp. nov. and Euestheria feysi sp. nov., and ostracods by a single species, Carbonita sp. aff. salteriana (Jones, 1862). Allied forms such as Montcestheria sp. aff. orri, Montcestheria sp. and Euestheria cebennensis (Grand'Eury, 1890), all from coeval localities in France, are also described. Montcestheria gen. nov. has carapace features, external (possibly sexual) dimorphism, preserved soft parts (e.g. appendages, gut) and resting eggs similar to those of Recent spinicaudatans, suggesting comparable lifestyles, reproductive strategies and feeding modes. Detailed anatomical comparisons are made with Cyzicus tetracerus from Recent ephemeral freshwater ponds. The ostracods belong to the Superfamily Carbonitoidea, which is a recurrent component of Carboniferous non‐marine biotas. Spinicaudatan‐rich assemblages typically occur in several Westphalian–Stephanian Lagerstätten (including Montceau) and localities from Europe and North America, where freshwater conditions prevailed, indicating that the group had already colonized continental waters by the Late Carboniferous. Similarities with the fauna from Recent temporary freshwater ponds (e.g. low diversity/high density spinicaudatan‐ostracod populations, synchronous spinicaudatan populations developing from resting eggs, high diversity/low density insects, amphibians) suggest the presence of temporary or ephemeral aquatic environments at Montceau as part of a complex limnic ecosystem. Flooding may have been the main driving force by which faunal and floral elements drifted away from their respective biotopes into the depositional areas, thus explaining the co‐occurrence of terrestrial (e.g. myriapods, scorpions, plants), amphibian and aquatic (e.g. conchostracans and syncarids from temporary and permanent settings, respectively) elements in fossil assemblages.

ostracod
montceau lagerstätte
late carboniferous


Looking forward through the past: identification of 50 priority research questions in palaeoecology

Abstract: Priority question exercises are becoming an increasingly common tool to frame future agendas in conservation and ecological science. They are an effective way to identify research foci that advance the field and that also have high policy and conservation relevance. To date, there has been no coherent synthesis of key questions and priority research areas for palaeoecology, which combines biological, geochemical and molecular techniques in order to reconstruct past ecological and environmental systems on time‐scales from decades to millions of years. We adapted a well‐established methodology to identify 50 priority research questions in palaeoecology. Using a set of criteria designed to identify realistic and achievable research goals, we selected questions from a pool submitted by the international palaeoecology research community and relevant policy practitioners. The integration of online participation, both before and during the workshop, increased international engagement in question selection. The questions selected are structured around six themes: human–environment interactions in the Anthropocene; biodiversity, conservation and novel ecosystems; biodiversity over long time‐scales; ecosystem processes and biogeochemical cycling; comparing, combining and synthesizing information from multiple records; and new developments in palaeoecology. Future opportunities in palaeoecology are related to improved incorporation of uncertainty into reconstructions, an enhanced understanding of ecological and evolutionary dynamics and processes and the continued application of long‐term data for better‐informed landscape management. Synthesis. Palaeoecology is a vibrant and thriving discipline, and these 50 priority questions highlight its potential for addressing both pure (e.g. ecological and evolutionary, methodological) and applied (e.g. environmental and conservation) issues related to ecological science and global change.

priority research question
palaeoecology
dynamic


‘Fish’ (Actinopterygii and Elasmobranchii) diversification patterns through deep time

Abstract: Actinopterygii (ray‐finned fishes) and Elasmobranchii (sharks, skates and rays) represent more than half of today's vertebrate taxic diversity (approximately 33000 species) and form the largest component of vertebrate diversity in extant aquatic ecosystems. Yet, patterns of ‘fish’ evolutionary history remain insufficiently understood and previous studies generally treated each group independently mainly because of their contrasting fossil record composition and corresponding sampling strategies. Because direct reading of palaeodiversity curves is affected by several biases affecting the fossil record, analytical approaches are needed to correct for these biases. In this review, we propose a comprehensive analysis based on comparison of large data sets related to competing phylogenies (including all Recent and fossil taxa) and the fossil record for both groups during the Mesozoic–Cainozoic interval. This approach provides information on the ‘fish’ fossil record quality and on the corrected ‘fish’ deep‐time phylogenetic palaeodiversity signals, with special emphasis on diversification events. Because taxonomic information is preserved after analytical treatment, identified palaeodiversity events are considered both quantitatively and qualitatively and put within corresponding palaeoenvironmental and biological settings. Results indicate a better fossil record quality for elasmobranchs due to their microfossil‐like fossil distribution and their very low diversity in freshwater systems, whereas freshwater actinopterygians are diverse in this realm with lower preservation potential. Several important diversification events are identified at familial and generic levels for elasmobranchs, and marine and freshwater actinopterygians, namely in the Early–Middle Jurassic (elasmobranchs), Late Jurassic (actinopterygians), Early Cretaceous (elasmobranchs, freshwater actinopterygians), Cenomanian (all groups) and the Paleocene–Eocene interval (all groups), the latter two representing the two most exceptional radiations among vertebrates. For each of these events along with the Cretaceous‐Paleogene extinction, we provide an in‐depth review of the taxa involved and factors that may have influenced the diversity patterns observed. Among these, palaeotemperatures, sea‐levels, ocean circulation and productivity as well as continent fragmentation and environment heterogeneity (reef environments) are parameters that largely impacted on ‘fish’ evolutionary history, along with other biotic constraints.

actinopterygii
elasmobranchii
diversification pattern
vertebrate