Variation, Variability, and the Origin of the Avian Endocranium: Insights from the Anatomy of Alioramus altai (Theropoda: Tyrannosauroidea)

Abstract: The internal braincase anatomy of the holotype of Alioramus altai, a relatively small-bodied tyrannosauroid from the Late Cretaceous of Mongolia, was studied using high-resolution computed tomography. A number of derived characters strengthen the diagnosis of this taxon as both a tyrannosauroid and a unique, new species (e.g., endocranial position of the gasserian ganglion, internal ramification of the facial nerve). Also present are features intermediate between the basal theropod and avialan conditions that optimize as the ancestral condition for Coelurosauria—a diverse group of derived theropods that includes modern birds. The expression of several primitive theropod features as derived character states within Tyrannosauroidea establishes previously unrecognized evolutionary complexity and morphological plasticity at the base of Coelurosauria. It also demonstrates the critical role heterochrony may have played in driving patterns of endocranial variability within the group and potentially reveals stages in the evolution of neuroanatomical development that could not be inferred based solely on developmental observations of the major archosaurian crown clades. We discuss the integration of paleontology with variability studies, especially as applied to the nature of morphological transformations along the phylogenetically long branches that tend to separate the crown clades of major vertebrate groups.


The Miocene Tagay locality of Olkhon Island (Lake Baikal, Eastern Siberia)a multidisciplinary approach

Abstract:
Lake Baikal is the largest intracontinental freshwater basin of Central Asia and the deepest lake on earth. It stands out for its geologic history ranging back to the Late Cretaceous, and for the development of its unique aquatic fauna including numerous endemic elements (Mats et al. 2011) . The biggest island of Lake Baikal, the Olkhon Island, is part of the Baikal National Park, which is included in the list of the UNESCO World Heritage Sites (Fig. 1 ).
In Paleogene and Neogene times the Olkhon Island was still part of the Siberian mainland at the western margin of the Baikal depression. Similar geologic and geomorphologic features characterise the landscapes, such as denudated plateaus, where streams had deeply cut into the crystalline basement. The valleys and shallow basins were filled by reworked terrigenous sediments, locally producing rich fossil deposits. The uplift of landscapes around the Baikal depression and deepening of Lake Baikal was driven by tectonic processes in the course of the Neogene. Successively, the Olkhon Island started to separate from the Siberian hinterland, and became completely isolated during the Pleistocene (Mats et al. 2011) .
Tagay, one of the most important Miocene fossil sites, is located at the Tagay Bay of Lake Baikal, at the north-western part of Olkhon Island. For a long time this region has been known for its interesting geology and geomorphology and for the highly diverse fossil fauna and flora preserved in lacustrine sediments of the Miocene Tagay Formation (Logatchev et al.

olkhon island
issue
mylagaulidae
fossiliferous horizon
rodent fauna


A Chronostratigraphic Framework for the Rise of the Ediacaran Macrobiota: New Constraints from Mistaken Point Ecological Reserve, Newfoundland

Abstract: The Conception and St. John’s Groups of southeastern Newfoundland contain some of the oldest known fossils of the Ediacaran macrobiota. The Mistaken Point Ecological Reserve UNESCO World Heritage Site is an internationally recognized locality for such fossils and hosts early evidence for both total group metazoan body fossils and metazoan-style locomotion. The Mistaken Point Ecological Reserve sedimentary succession includes ∼1500 m of fossil-bearing strata containing numerous dateable volcanogenic horizons, and therefore offers a crucial window into the rise and diversification of early animals. Here we present six stratigraphically coherent radioisotopic ages derived from zircons from volcanic tuffites of the Conception and St. John’s Groups at Mistaken Point Ecological Reserve. The oldest architecturally complex macrofossils, from the upper Drook Formation, have an age of 574.17 ± 0.66 Ma (including tracer calibration and decay constant uncertainties). The youngest rangeomorph fossils from Mistaken Point Ecological Reserve, in the Fermeuse Formation, have a maximum age of 564.13 ± 0.65 Ma. Fossils of the famous “E” Surface are confirmed to be 565.00 ± 0.64 Ma, while exceptionally preserved specimens on the “Brasier” Surface in the Briscal Formation are dated at 567.63 ± 0.66 Ma. We use our new ages to construct an age-depth model for the sedimentary succession, constrain sedimentary accumulation rates, and convert stratigraphic fossil ranges into the time domain to facilitate integration with time-calibrated data from other successions. Combining this age model with compiled stratigraphic ranges for all named macrofossils within the Mistaken Point Ecological Reserve succession, spanning 76 discrete fossil-bearing horizons, enables recognition and interrogation of potential evolutionary signals. Peak taxonomic diversity is recognized within the Mistaken Point and Trepassey Formations, and uniterminal rangeomorphs with undisplayed branching architecture appear several million years before multiterminal, displayed forms. Together, our combined stratigraphic, paleontological, and geochronological approach offers a holistic, time-calibrated record of evolution during the mid–late Ediacaran Period and a framework within which to consider other geochemical, environmental, and evolutionary data sets.

ediacaran macrobiota
newfoundland
zircon


New chronology for Ksâr ‘Akil (Lebanon) supports Levantine route of modern human dispersal into Europe

Abstract: Significance Bayesian modeling of AMS radiocarbon dates on the marine mollusk Phorcus turbinatus from Ksâr ‘Akil (Lebanon) indicates that the earliest presence of Upper Paleolithic (UP) modern humans in the Levant predates 45,900 cal B.P. Similarities in early UP lithic technology and material culture suggest population dispersals between the Levant and Europe around 50,000–40,000 cal B.P. Our data confirm the presence of modern humans carrying a UP toolkit in the Levant prior to any known European modern human fossils and allow rejection of recent claims that European UP modern humans predate those in the Levant. This result, in turn, suggests the Levant served as a corridor for the dispersal of modern humans out of Africa and into Eurasia. Modern human dispersal into Europe is thought to have occurred with the start of the Upper Paleolithic around 50,000–40,000 y ago. The Levantine corridor hypothesis suggests that modern humans from Africa spread into Europe via the Levant. Ksâr ‘Akil (Lebanon), with its deeply stratified Initial (IUP) and Early (EUP) Upper Paleolithic sequence containing modern human remains, has played an important part in the debate. The latest chronology for the site, based on AMS radiocarbon dates of shell ornaments, suggests that the appearance of the Levantine IUP is later than the start of the first Upper Paleolithic in Europe, thus questioning the Levantine corridor hypothesis. Here we report a series of AMS radiocarbon dates on the marine gastropod Phorcus turbinatus associated with modern human remains and IUP and EUP stone tools from Ksâr ‘Akil. Our results, supported by an evaluation of individual sample integrity, place the EUP layer containing the skeleton known as “Egbert” between 43,200 and 42,900 cal B.P. and the IUP-associated modern human maxilla known as “Ethelruda” before ∼45,900 cal B.P. This chronology is in line with those of other Levantine IUP and EUP sites and demonstrates that the presence of modern humans associated with Upper Paleolithic toolkits in the Levant predates all modern human fossils from Europe. The age of the IUP-associated Ethelruda fossil is significant for the spread of modern humans carrying the IUP into Europe and suggests a rapid initial colonization of Europe by our species.

chronology
ksâr
modern human dispersal
colonization


Dental microwear texture analysis of Homo sapiens sapiens: Foragers, farmers, and pastoralists.

Abstract:
OBJECTIVES
The current study seeks to determine if a sample of foragers, farmers, and pastoralists are distinguishable based on their dental microwear texture signatures.

MATERIALS AND METHODS
The study included a sample of 719 individuals from 51 archeological sites (450 farmers, 192 foragers, 77 pastoralists). All were over age 12 and sexes were pooled. Using a Sensofar® white-light confocal profiler we collected dental microwear texture analysis (DMTA) data from a single first or second molar from each individual. We leveled and cleaned data clouds following standard procedures and analyzed the data with Sfrax® and Toothfrax® software. The DMTA variables were complexity and anisotropy. Statistics included ANOVA with partial eta squared and Hedges's g. We also performed a follow-up K-means cluster analysis.

RESULTS
We found significant differences between foragers and farmers and pastoralists for complexity and anisotropy, with foragers having greater complexity than either the farmers or the pastoralists. The farmers and pastoralists had greater anisotropy than the foragers. The Old World foragers had significantly higher anisotropy values than New World foragers. Old and New World farmers did not differ. Among the Old World farmers, those dating from the Neolithic through the Late Bronze Age had higher complexity values than those from the Iron Age through the medieval period. The cluster analysis discerned foragers and farmers but also indicated similarity between hard food foragers and hard food farmers.

DISCUSSION
Our findings reaffirm that DMTA is capable of distinguishing human diets. We found that foragers and farmers, in particular, differ in their microwear signatures across the globe. There are some exceptions, but nothing that would be unexpected given the range of human diets and food preparation techniques. This study indicates that in general DMTA is an efficacious means of paleodietary reconstruction in humans.

forager
pastoralist
dental microwear
microwear pattern
dietary habit


Early Asterozoan (Echinodermata) Diversification: A Paleontologic Quandary

Abstract: Abstract The Asterozoa as traditionally recognized is monophyletic, although ancestry within the Echinodermata is unknown. The asterozoan class Somasteroidea is most readily recognized by presence of series of simple ossicles termed virgals that extend laterally from each ambulacral ossicle. Virgal series reduction to two or three together with ossicular specializations provide apomorphies of the class Stenuroidea (new ranking). Both asteroid-like and ophiuroid-like configurations as well as expressions less suggestive of those of the surviving classes emerged within stenuroids during an early period of diversification. The classes Ophiuroidea and Asteroidea are separate lineages marked by virgal series reduction to a single ossicle and other ambulacral column specializations. It is uncertain whether one or both surviving classes were derived directly from somasteroids or originated through stenuroids. All three of the derived asterozoan classes can be argued to be either monophyletic and thereby justifying class status, or alternatively either paraphyletic or polyphyletic and thereby indicative of multiple plesions; here, monophyletic class-level status is favored for all three.


Evolution of high tooth replacement rates in theropod dinosaurs

Abstract: Tooth replacement rate is an important contributor to feeding ecology for polyphyodont animals. Dinosaurs exhibit a wide range of tooth replacement rates, mirroring their diverse craniofacial specializations, but little is known about broad-scale allometric or evolutionary patterns within the group. In the current broad but sparse dinosaurian sample, only three non-avian theropod tooth replacement rates have been estimated. We estimated tooth formation and replacement rates in three additional non-avian theropod dinosaurs, the derived latest Cretaceous abelisaurid Majungasaurus and the more generalized Late Jurassic Allosaurus and Ceratosaurus. We created the largest dental histological and CT dataset for any theropod dinosaur, sectioning and scanning over a dozen toothed elements of Majungasaurus and several additional elements from the other two genera. Using this large sample, we created models of tooth formation time that allow for theropod replacement rates to be estimated non-destructively. In contrast to previous results for theropods, we found high tooth replacement rates in all three genera, with Allosaurus and Ceratosaurus rates of ~100 days and 56 days for Majungasaurus. The latter rate is on par with those of derived herbivorous dinosaurs including some neosauropods, hadrosaurids, and ceratopsians. This elevated rate may be a response to high rates of tooth wear in Majungasaurus. Within Dinosauria, there is no relationship between body mass and tooth replacement rate and no trends in replacement rate over time. Rather, tooth replacement rate is clade-specific, with elevated rates in abelisaurids and diplodocoids and lower rates in coelurosaurs.

tooth replacement rate
theropod dinosaur
dinosauria
body mass
tooth development


CASTING, REPLICATION, AND ANAGLYPH STEREO IMAGING OF MICROSCOPIC DETAIL IN FOSSILS, WITH EXAMPLES FROM CONODONTS AND OTHER JAWLESS VERTEBRATES

Abstract:
Sophisticated techniques, such as computed tomography and scanning light microscopy, now allow palaeontologists to image the microscopic details of fossils even when scanning electron microscopy cannot be used. Occasionally these techniques are not always applicable, and where this is the case, methods involving fossil replication offer an alternative. I describe here a series of techniques for moulding, casting, imaging, and three-dimensional illustration of microfossils (or microscopic details of larger fossils). For moulding fossils (or casting mouldic specimens), room temperature vulcanizing silicon rubber provides a strong and flexible medium with low levels of shrinkage. RTV rubbers are also capable of replicating microscopic details of only a few micrometres. Similarly, epoxy resins are rigid, durable, and long lasting. In combination with RTV silicon rubber moulds, epoxy casts offer higher levels of resolution than any other medium. Details of specific RTV rubbers and epoxy resins that are widely available and work well with small fossils are provided.
For imaging, the advantages of stereophotography to illustrate fossils have long been appreciated, but the use of stereo-pairs is limited by their maximum size (generally only 5 or 6 centimetres). With the widespread availability of powerful image editing software, it is now a straightforward matter to produce anaglyph stereo images of any size. I provide step-by-step instructions and a set of actions to automate the process in Adobe Photoshop®. Anaglyph stereo images can be extremely useful research tools in their own right, but combined with electronic communication and publication they offer a simple and inexpensive means for illustrating fossils, and their microscopic details, in three-dimensions.

microscopic detail
conodont
advantage
instruction


Late Pleistocene northward-dispersing Bison antiquus from the Bighill Creek Formation, Gallelli Gravel Pit, Alberta, Canada, and the fate of Bison occidentalis

Abstract: Late Pleistocene bison skeletal remains from the Gallelli Gravel Pit in the Bighill Creek Formation at Calgary, Alberta, document at least two individuals, including the largest postglacial bison reported from North America south of Beringia. Two partial crania, dated to 11 290 and 10 100 14 C years BP, are referred to the southern species Bison antiquus Leidy, indicating northward movement from the midcontinent as ice retreat opened a corridor between Laurentide and Cor- dilleran ice. Their large size suggests a dispersal phenotype exploiting newly available territory. DNA evidence links the 11 290-year-old bison to Clade 1, which includes modern B. bison. This supports in situ evolution of B. bison from B. antiquus through the intermediate usually called B.''occidentalis''. Bison of B. ''occidentalis'' character appeared in Al- berta about 10 ka BP, and the DNA evidence counters the suggestion of a migratory wave from Beringia. The B. occiden- talis type specimen is from Alaska, so this name may be inappropriate for southern populations. Radiocarbon dates suggest that the Bighill Creek Formation paleofauna comprises two faunules separated in time by the Younger Dryas cli- matic episode. Resume´ : Les restes de squelettes de bisons datant du Pleistocene tardif trouves dans la graviere Gallelli dans la Formation de Bighill Creek aCalgary, en Alberta, representent au moins deux individus, dont le plus gros bison postglaciaire trouve´ en Amerique du Nord au sud de la Beringie. Deux cranes partiels, datesa ` 11 290 et 10 100 annees 14 C avant le present correspondraient a l'espece meridionale Bison antiquus Leidy, indiquant un mouvement vers le nord a partir du milieu du continent alors que le retrait de la glace ouvrait un corridor entre la glace laurentidienne et la glace de la Cordillere. Leur grande taille suggere un phenotype de dispersion exploitant un territoire recemment disponible. Les preuves fournies par l'ADN relient le bison de 11 290 ans au Clade 1, lequel comprend le B. bison moderne. Cela soutient l'evolution in situ du B. bison apartir de B. antiquus en passant par l'intermediaire habituellement appeleB. « occidentalis ». Un bison B. « occidentalis » s'est retrouveen Alberta il y environ 10 ka avant le present et les preuves d'ADN opposent la suggestion d'une vague migratoire a partir de la Beringie. Le specimen de type B. occidentalis provient de l'Alaska; ce nom ne con- viendrait donc pas aux populations du sud. Selon les datations au radiocarbone, la paleofaune de la Formation de Bighill Creek comprendrait deux faunules separees dans le temps par l'episode climatique du Dryas recent. (Traduit par la Redaction)

bison
bighill creek formation
gallelli gravel pit
alberta


Twentieth century sea surface temperature and salinity variations at Timor inferred from paired coral δ18O and Sr/Ca measurements

Abstract: The Indonesian Throughflow (ITF), which represents the global ocean circulation connecting the Pacific Warm Pool to the Indian Ocean, strongly influences the Indo-Pacific climate. ITF monitoring since the late 1990s using mooring buoys have provided insights on seasonal and interannual time scales. However, the absence of longer records limits our perspective on its evolution over the past century. Here, we present sea surface temperature (SST) and salinity (SSS) proxy records from Timor Island located at the ITF exit passage via paired coral δ18O and Sr/Ca measurements spanning the period 1914–2004. These high-resolution proxy based climate data of the last century highlights improvements and cautions when interpreting paleoclimate records of the Indonesian region. If the seasonality of SST and SSS is not perfectly in phase, the application of coral Sr/Ca thermometry improves SST reconstructions compared to estimates based on coral δ18O only. Our records also underline the importance of ocean advection besides rainfall on local SSS in the region. Although the El Nino/Southern Oscillation (ENSO) causes larger anomalies relative to the Indian Ocean Dipole (IOD), Timor coral-based SST and SSS records robustly correlate with IOD on interannual time scales, whereas ENSO only modifies Timor SST. Similarly, Timor SST and SSS are strongly linked to Indian Ocean decadal-scale variations that appear to lead Timor oceanographic conditions by about 1.6–2 years. Our study sheds new light on the complex signatures of Indo-Pacific climate modes on SST and SSS dynamics of the ITF.


High Diversity, Low Disparity and Small Body Size in Plesiosaurs (Reptilia, Sauropterygia) from the Triassic–Jurassic Boundary

Abstract: Invasion of the open ocean by tetrapods represents a major evolutionary transition that occurred independently in cetaceans, mosasauroids, chelonioids (sea turtles), ichthyosaurs and plesiosaurs. Plesiosaurian reptiles invaded pelagic ocean environments immediately following the Late Triassic extinctions. This diversification is recorded by three intensively-sampled European fossil faunas, spanning 20 million years (Ma). These provide an unparalleled opportunity to document changes in key macroevolutionary parameters associated with secondary adaptation to pelagic life in tetrapods. A comprehensive assessment focuses on the oldest fauna, from the Blue Lias Formation of Street, and nearby localities, in Somerset, UK (Earliest Jurassic: 200 Ma), identifying three new species representing two small-bodied rhomaleosaurids (Stratesaurus taylori gen et sp. nov.; Avalonnectes arturi gen. et sp. nov) and the most basal plesiosauroid, Eoplesiosaurus antiquior gen. et sp. nov. The initial radiation of plesiosaurs was characterised by high, but short-lived, diversity of an archaic clade, Rhomaleosauridae. Representatives of this initial radiation were replaced by derived, neoplesiosaurian plesiosaurs at small-medium body sizes during a more gradual accumulation of morphological disparity. This gradualistic modality suggests that adaptive radiations within tetrapod subclades are not always characterised by the initially high levels of disparity observed in the Paleozoic origins of major metazoan body plans, or in the origin of tetrapods. High rhomaleosaurid diversity immediately following the Triassic-Jurassic boundary supports the gradual model of Late Triassic extinctions, mostly predating the boundary itself. Increase in both maximum and minimum body length early in plesiosaurian history suggests a driven evolutionary trend. However, Maximum-likelihood models suggest only passive expansion into higher body size categories.


The fate of nitrogen in the Orbulina universa foraminifera‐symbiont system determined by nitrogen isotope analyses of shell‐bound organic matter

Abstract: To trace the flow of nitrogen through the foraminifera‐symbiont system, juvenile specimens of the symbiont‐bearing planktonic foraminifera, Orbulina universa were collected by SCUBA divers off the coast of Santa Catalina Island, California, and grown in filtered seawater solutions spiked with 15N‐labeled nitrate. Our work isolated each pathway of this symbiotic system to determine the amount of nitrogen translocated to the foraminifera from its endosymbionts and its captured diet. Our model results show that when the nitrate uptake by the symbionts is at a maximum, between 50 and 57% of the foraminiferal nitrogen was translocated from the symbionts and the remainder was derived from the captured diet. In nitrate‐deficient environments, when the symbiont nitrate uptake was at a minimum, ∼90–100% of the nitrogen was transferred to the foraminifer by the symbionts from the recycled nitrogen (NH4+) pool. In nitrate‐deficient conditions, the primary role of the captured diet may be to provide the system with phosphorous. Highly efficient nutrient use is particularly important to the foraminifera‐symbiont system, especially when nutrient concentrations are low. The results indicate a limited correlation between the isotopic composition of the NO3− in the culture solutions and the Δ15n values of the foraminifera. However, the δ15n values of the foraminifera much more strongly reflect the δ15n values of the NH4+ recycled through the system. It appears that recycled nitrogen (NH4+) is a more important source of nitrogen to the symbionts and the foraminifera than nitrate; therefore, the δ15n values of the foraminifera may not reflect the isotopic composition of the surface‐water nutrients. Understanding the nitrogen flow within modern foraminifera‐symbiont associations is also important to ancient marine systems, because symbiont‐bearing foraminifera are ubiquitous in the fossil record. This study shows that analysis of individual, symbiont‐bearing foraminifera species is a necessary first step toward the development of more reliable use of nitrogen isotopes for paleoceanographic reconstructions.

nitrogen
foraminifera‐symbiont system
foraminifera
endosymbiont


The craniomandibular anatomy of the early archosauriform Euparkeria capensis and the dawn of the archosaur skull

Abstract: Archosauria (birds, crocodilians and their extinct relatives) form a major part of terrestrial ecosystems today, with over 10 000 living species, and came to dominate the land for most of the Mesozoic (over 150 Myr) after radiating following the Permian–Triassic extinction. The archosaur skull has been essential to this diversification, itself diversified into myriad forms. The archosauriform Euparkeria capensis from the Middle Triassic (Anisian) of South Africa has been of great interest since its initial description in 1913, because its anatomy shed light on the origins and early evolution of crown Archosauria and potentially approached that of the archosaur common ancestor. Euparkeria has been widely used as an outgroup in phylogenetic analyses and when investigating patterns of trait evolution among archosaurs. Although described monographically in 1965, subsequent years have seen great advances in the understanding of early archosaurs and in imaging techniques. Here, the cranium and mandible of Euparkeria are fully redescribed and documented using all fossil material and computed tomographic data. Details previously unclear are fully described, including vomerine dentition, the epiptergoid, number of premaxillary teeth and palatal arrangement. A new diagnosis and cranial and braincase reconstruction is provided, and an anatomical network analysis is performed on the skull of Euparkeria and compared with other amniotes. The modular composition of the cranium suggests a flexible skull well adapted to feeding on agile food, but with a clear tendency towards more carnivorous behaviour, placing the taxon at the interface between ancestral diapsid and crown archosaur ecomorphology, corresponding to increases in brain size, visual sensitivity, upright locomotion and metabolism around this point in archosauriform evolution. The skull of Euparkeria epitomizes a major evolutionary transition, and places crown archosaur morphology in an evolutionary context.

anatomy
archosauriform euparkeria capensis
archosaur skull
archosauria


Terrestrial Origin of Viviparity in Mesozoic Marine Reptiles Indicated by Early Triassic Embryonic Fossils

Abstract: Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia), which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic). This exceptional specimen captures an articulated embryo in birth position, with its skull just emerged from the maternal pelvis. Its headfirst birth posture, which is unlikely to be a breech condition, strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view. The tail-first birth posture in derived ichthyopterygians, convergent with the conditions in whales and sea cows, therefore is a secondary feature. The unequivocally marine origin of viviparity is so far not known among amniotes, a subset of vertebrate animals comprising mammals and reptiles, including birds. Therefore, obligate marine amniotes appear to have evolved almost exclusively from viviparous land ancestors. Viviparous land reptiles most likely appeared much earlier than currently thought, at least as early as the recovery phase from the end-Permian mass extinction.

viviparity
early triassic
ichthyopterygian
terrestrial origin


Global decline in ocean ventilation, oxygenation, and productivity during the Paleocene-Eocene Thermal Maximum: Implications for the benthic extinction

Abstract: The prominent global warming event at the Paleocene-Eocene boundary (55 Ma), referred to as the Paleocene-Eocene Thermal Maximum (PETM), was characterized by rapid temperature increase and changes in the global carbon cycle in

productivity
paleocene-eocene thermal maximum
petm


Adults only. Reindeer hunting at the middle palaeolithic site salzgitter lebenstedt, northern Germany.

Abstract: The Middle Palaeolithic site Salzgitter Lebenstedt (northern Germany), excavated in 1952, is well known because of its well-preserved faunal remains, dominated by adult reindeer (Rangifer tarandus). The archaeological assemblage accumulated in an arctic setting in an earlier part of the last (Weichsel) glacial (OIS5-3). The site is remarkable because of the presence of unique Middle Palaeolithic bone tools and the occurrence of the northernmost Neanderthal remains, but this paper focuses on an analysis of its reindeer assemblage. The results indicate autumn hunting of reindeer by Middle Palaeolithic hominids. After the hunt, carcasses were butchered and in subsequent marrow processing of the bones a selection against young and sub-adult animals occurred. Adults were clearly preferred, and from their bones, again, poorer marrow bones were neglected. This focus on primeness of resources has been documented in other domains of Neanderthal behaviour, but Salzgitter Lebenstedt is the best example yet known in terms of systematic and routinized processing of game. The Salzgitter Lebenstedt assemblage displays some remarkable similarities to the Late Glacial reindeer assemblages from the Ahrensburg tunnel valley sites. The subsequent review of the evidence on subsistence strategies from earlier periods of the European Palaeolithic shows that hunting of large mammals may have been a part of the behavioural repertoire of the Middle Pleistocene occupants of Europe from the earliest occupation onwards. At the same time, it is suggested that these early hunting strategies were incorporated in ways of moving through landscapes ("settlement systems") which were different from what we know from the middle parts of the Upper Palaeolithic onwards.

reindeer
northern germany
occupation
adult


Computational biomechanical analyses demonstrate similar shell-crushing abilities in modern and ancient arthropods

Abstract: The biology of the American horseshoe crab, Limulus polyphemus, is well documented—including its dietary habits, particularly the ability to crush shell with gnathobasic walking appendages—but virtually nothing is known about the feeding biomechanics of this iconic arthropod. Limulus polyphemus is also considered the archetypal functional analogue of various extinct groups with serial gnathobasic appendages, including eurypterids, trilobites and other early arthropods, especially Sidneyia inexpectans from the mid-Cambrian (508 Myr) Burgess Shale of Canada. Exceptionally preserved specimens of S. inexpectans show evidence suggestive of durophagous (shell-crushing) tendencies—including thick gnathobasic spine cuticle and shelly gut contents—but the masticatory capabilities of this fossil species have yet to be compared with modern durophagous arthropods. Here, we use advanced computational techniques, specifically a unique application of 3D finite-element analysis (FEA), to model the feeding mechanics of L. polyphemus and S. inexpectans: the first such analyses of a modern horseshoe crab and a fossil arthropod. Results show that mechanical performance of the feeding appendages in both arthropods is remarkably similar, suggesting that S. inexpectans had similar shell-crushing capabilities to L. polyphemus. This biomechanical solution to processing shelly food therefore has a history extending over 500 Myr, arising soon after the first shell-bearing animals. Arrival of durophagous predators during the early phase of animal evolution undoubtedly fuelled the Cambrian ‘arms race’ that involved a rapid increase in diversity, disparity and abundance of biomineralized prey species.

arthropod
horseshoe crab
finite-element analysis
fea
mechanical performance


Computer Simulations Imply Forelimb-Dominated Underwater Flight in Plesiosaurs

Abstract: Plesiosaurians are an extinct group of highly derived Mesozoic marine reptiles with a global distribution that spans 135 million years from the Early Jurassic to the Late Cretaceous. During their long evolutionary history they maintained a unique body plan with two pairs of large wing-like flippers, but their locomotion has been a topic of debate for almost 200 years. Key areas of controversy have concerned the most efficient biologically possible limb stroke, e.g. whether it consisted of rowing, underwater flight, or modified underwater flight, and how the four limbs moved in relation to each other: did they move in or out of phase? Previous studies have investigated plesiosaur swimming using a variety of methods, including skeletal analysis, human swimmers, and robotics. We adopt a novel approach using a digital, three-dimensional, articulated, free-swimming plesiosaur in a simulated fluid. We generated a large number of simulations under various joint degrees of freedom to investigate how the locomotory repertoire changes under different parameters. Within the biologically possible range of limb motion, the simulated plesiosaur swims primarily with its forelimbs using an unmodified underwater flight stroke, essentially the same as turtles and penguins. In contrast, the hindlimbs provide relatively weak thrust in all simulations. We conclude that plesiosaurs were forelimb-dominated swimmers that used their hind limbs mainly for maneuverability and stability.


A New Fossil Species of Boa Linnaeus, 1758 (Squamata, Boidae), from the Pleistocene of Marie-Galante Island (French West Indies)

Abstract:
ABSTRACT
 Several studies have reported the occurrence of fossil remains of a now extinct Boa snake from the upper Pleistocene of Marie-Galante Island, French West Indies. However, these remains have never been fully investigated and no complete description of this possible new species has been published. In this paper, we try to bridge this gap by providing a detailed morphological study of the Boa remains discovered in the three major fossil deposits of Marie-Galante Island. Our study reveals the specific morphological aspects of this fossil snake and allows us to identify it as a new species, Boa blanchardensis. We also reconstructed its body size, carried out a paleohistological investigation, and suggest that this snake may have been a dwarf species. We then discuss the possible explanation for the extinction of this snake on Marie-Galante Island and possibly also on other Guadeloupe islands.

pleistocene
marie-galante island
fossil snake


When Did Carcharocles megalodon Become Extinct? A New Analysis of the Fossil Record

Abstract: Carcharocles megalodon (“Megalodon”) is the largest shark that ever lived. Based on its distribution, dental morphology, and associated fauna, it has been suggested that this species was a cosmopolitan apex predator that fed on marine mammals from the middle Miocene to the Pliocene (15.9–2.6 Ma). Prevailing theory suggests that the extinction of apex predators affects ecosystem dynamics. Accordingly, knowing the time of extinction of C. megalodon is a fundamental step towards understanding the effects of such an event in ancient communities. However, the time of extinction of this important species has never been quantitatively assessed. Here, we synthesize the most recent records of C. megalodon from the literature and scientific collections and infer the date of its extinction by making a novel use of the Optimal Linear Estimation (OLE) model. Our results suggest that C. megalodon went extinct around 2.6 Ma. Furthermore, when contrasting our results with known ecological and macroevolutionary trends in marine mammals, it became evident that the modern composition and function of modern gigantic filter-feeding whales was established after the extinction of C. megalodon. Consequently, the study of the time of extinction of C. megalodon provides the basis to improve our understanding of the responses of marine species to the removal of apex predators, presenting a deep-time perspective for the conservation of modern ecosystems.

shark
pliocene
early paleocene
apex predatory selachian


Commensal anomiid bivalves on Late Cretaceous heteromorph ammonites from south‐west Japan

Abstract: The heteromorph ammonite Pravitoceras sigmoidale from the Upper Cretaceous Seidan Formation (Izumi Group) in south‐west Japan is frequently encrusted by sessile anomiid bivalves. Fossils of P. sigmoidale with anomiids are often concentrated at the top of or just above turbidite sandstones. Projecting retroversal hooks and apertures of P. sigmoidale are usually intact, and some individuals are associated with jaw apparatuses near apertures. Anomiids are found on both sides and ventral peripheries of P. sigmoidale conchs, attached predominantly to body chambers. These modes of occurrence suggest that the encrustation by anomiids occurred not on post‐mortem floating or sunken carcasses but on live conchs and that these organisms were rapidly buried by turbidity current deposits shortly after death. Attachment to both flanks and ventral peripheries of the retroversal hooks may indicate that at least adult individuals of P. sigmoidale did not lie on the sea floor and did not drag their body chambers. It is suggested that fully mature individuals of this ammonite species lived for a long period of time after having formed the retroversal hook because a few generations of anomiids have colonized a single body chamber. Such colonization by anomiids is also observed on Didymoceras awajiense, which is considered to be the closely related ancestral species of P. sigmoidale. This anomiid–heteromorph ammonite commensal relationship might continue to persist in descendants during the course of evolution of these heteromorph ammonites.

anomiid bivalve
heteromorph
south‐w japan


The role of ocean thermal expansion in Last Interglacial sea level rise

Abstract: A compilation of paleoceanographic data and a coupled atmosphere‐ocean climate model were used to examine global ocean surface temperatures of the Last Interglacial (LIG) period, and to produce the first quantitative estimate of the role that ocean thermal expansion likely played in driving sea level rise above present day during the LIG. Our analysis of the paleoclimatic data suggests a peak LIG global sea surface temperature (SST) warming of 0.7 ± 0.6°C compared to the late Holocene. Our LIG climate model simulation suggests a slight cooling of global average SST relative to preindustrial conditions (ΔSST = −0.4°C), with a reduction in atmospheric water vapor in the Southern Hemisphere driven by a northward shift of the Intertropical Convergence Zone, and substantially reduced seasonality in the Southern Hemisphere. Taken together, the model and paleoceanographic data imply a minimal contribution of ocean thermal expansion to LIG sea level rise above present day. Uncertainty remains, but it seems unlikely that thermosteric sea level rise exceeded 0.4 ± 0.3 m during the LIG. This constraint, along with estimates of the sea level contributions from the Greenland Ice Sheet, glaciers and ice caps, implies that 4.1 to 5.8 m of sea level rise during the Last Interglacial period was derived from the Antarctic Ice Sheet. These results reemphasize the concern that both the Antarctic and Greenland Ice Sheets may be more sensitive to temperature than widely thought.


The Palaeozoic colonization of the water column and the rise of global nekton

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

water column
nekton
devonian nekton revolution


Revision and re-description of Micropeltis isseli Airaghi, 1901 (Echinodermata: Echinoidea)

Abstract: Re-discovery of the holotype of ''Micropeltis '' isseli Airaghi, 1901, in the collection of the Museo di Paleontologia (University of Genova), allowed for a reassessment of its morphological features and revision of its systematic placement. The discovery of ambulacral plate compounding that is compatible with that of phymosomatids, in combination with its pore arrangement and tuberculation pattern, indicates that this species should be transferred to the genus Phymotaxis. Comparison with museum collections from the type area allowed for clarification of the type-locality and stratum. The specimen most likely derives from the Tortonian Marne di S. Agata Fossili beds exposed at Bocca d'Asino, northeast of Stazzano, which is in line with Airaghi's statement in the original description (in contrast to the original plate caption). This indicates that Phymotaxis isseli is the youngest representative of the echinoid order phymosomatida known to date, extending its range to the Late Miocene.


Small Theropod Teeth from the Late Cretaceous of the San Juan Basin, Northwestern New Mexico and Their Implications for Understanding Latest Cretaceous Dinosaur Evolution

Abstract: Studying the evolution and biogeographic distribution of dinosaurs during the latest Cretaceous is critical for better understanding the end-Cretaceous extinction event that killed off all non-avian dinosaurs. Western North America contains among the best records of Late Cretaceous terrestrial vertebrates in the world, but is biased against small-bodied dinosaurs. Isolated teeth are the primary evidence for understanding the diversity and evolution of small-bodied theropod dinosaurs during the Late Cretaceous, but few such specimens have been well documented from outside of the northern Rockies, making it difficult to assess Late Cretaceous dinosaur diversity and biogeographic patterns. We describe small theropod teeth from the San Juan Basin of northwestern New Mexico. These specimens were collected from strata spanning Santonian – Maastrichtian. We grouped isolated theropod teeth into several morphotypes, which we assigned to higher-level theropod clades based on possession of phylogenetic synapomorphies. We then used principal components analysis and discriminant function analyses to gauge whether the San Juan Basin teeth overlap with, or are quantitatively distinct from, similar tooth morphotypes from other geographic areas. The San Juan Basin contains a diverse record of small theropods. Late Campanian assemblages differ from approximately co-eval assemblages of the northern Rockies in being less diverse with only rare representatives of troodontids and a Dromaeosaurus-like taxon. We also provide evidence that erect and recurved morphs of a Richardoestesia-like taxon represent a single heterodont species. A late Maastrichtian assemblage is dominated by a distinct troodontid. The differences between northern and southern faunas based on isolated theropod teeth provide evidence for provinciality in the late Campanian and the late Maastrichtian of North America. However, there is no indication that major components of small-bodied theropod diversity were lost during the Maastrichtian in New Mexico. The same pattern seen in northern faunas, which may provide evidence for an abrupt dinosaur extinction.

late cretaceous
northwestern new mexico
theropod tooth


The Magnitude and Duration of Late Ordovician–Early Silurian Glaciation

Abstract: Carbonate isotopes reveal a link between past ocean temperatures and mass extinction. Understanding ancient climate changes is hampered by the inability to disentangle trends in ocean temperature from trends in continental ice volume. We used carbonate “clumped” isotope paleothermometry to constrain ocean temperatures, and thereby estimate ice volumes, through the Late Ordovician–Early Silurian glaciation. We find tropical ocean temperatures of 32° to 37°C except for short-lived cooling by ~5°C during the final Ordovician stage. Evidence for ice sheets spans much of the study interval, but the cooling pulse coincided with a glacial maximum during which ice volumes likely equaled or exceeded those of the last (Pleistocene) glacial maximum. This cooling also coincided with a large perturbation of the carbon cycle and the Late Ordovician mass extinction.


Phylogeography of the second plague pandemic revealed through analysis of historical Yersinia pestis genomes

Abstract: The second plague pandemic, caused by Yersinia pestis, devastated Europe and the nearby regions between the 14th and 18th centuries AD. Here we analyse human remains from ten European archaeological sites spanning this period and reconstruct 34 ancient Y. pestis genomes. Our data support an initial entry of the bacterium through eastern Europe, the absence of genetic diversity during the Black Death, and low within-outbreak diversity thereafter. Analysis of post-Black Death genomes shows the diversification of a Y. pestis lineage into multiple genetically distinct clades that may have given rise to more than one disease reservoir in, or close to, Europe. In addition, we show the loss of a genomic region that includes virulence-related genes in strains associated with late stages of the pandemic. The deletion was also identified in genomes connected with the first plague pandemic (541–750 AD), suggesting a comparable evolutionary trajectory of Y. pestis during both events.

second plague pandemic
yersinia pestis
genome


Issues of theory and method in the analysis of Paleolithic mortuary behavior: A view from Shanidar Cave

Abstract: Mortuary behavior (activities concerning dead conspecifics) is one of many traits that were previously widely considered to have been uniquely human, but on which perspectives have changed markedly in recent years. Theoretical approaches to hominin mortuary activity and its evolution have undergone major revision, and advances in diverse archeological and paleoanthropological methods have brought new ways of identifying behaviors such as intentional burial. Despite these advances, debates concerning the nature of hominin mortuary activity, particularly among the Neanderthals, rely heavily on the rereading of old excavations as new finds are relatively rare, limiting the extent to which such debates can benefit from advances in the field. The recent discovery of in situ articulated Neanderthal remains at Shanidar Cave offers a rare opportunity to take full advantage of these methodological and theoretical developments to understand Neanderthal mortuary activity, making a review of these advances relevant and timely.

mortuary behavior
shanidar cave
neanderthals
excavation


Quantitative uncertainty analyses of ancient atmospheric CO2 estimates from fossil leaves

Abstract: The relationship between atmospheric CO2 and ancient climate is of fundamental importance for gauging the climate sensitivity of the Earth system to a changing CO2 regime. One of the most widely adopted paleobiological CO2 proxies for reconstructing Earth's atmospheric CO2 history exploits the inverse relationship between leaf stomatal index, the fraction of leaf epidermal cells that are stomatal structures, and atmospheric CO2. However, fossil leaf-based CO2 reconstructions make a priori assumptions about the form of the empirical relationship between SI and CO2 required for transfer functions and have failed to correctly propagate error terms. These effects can translate into erroneous interpretations that undermine the value of the proxy. Here we report the development and application of a rigorous generalized statistical framework overcoming these limitations that generates probability density functions for each atmospheric CO2 estimate. The utility of our statistical tools is demonstrated by showing how they revise earlier atmospheric CO2 estimates from fossil cuticles of Ginkgo and Metasequoia trees during the early Eocene and middle Miocene warm periods upwards by +150 to 250 ppm to 450 to 700 ppm. The revised CO2 reconstructions therefore help to resolve the paradox of warm Paleogene and Neogene “greenhouse” climates co-existing with near present-day levels of CO2 and support the emerging view from independent paleoclimate studies for a high climate sensitivity of the Earth system. The statistical tools presented are sufficiently versatile to permit their use in other investigations of paleoCO2 estimates from fossil leaves.

atmospheric co2 estimate
fossil leave
middle miocene
ppm


Carbon isotope stratigraphy across the Silurian–Devonian transition in Podolia, Ukraine: evidence for a global biogeochemical perturbation

Abstract: Abstract The carbon and oxygen isotope composition of marine carbonates (δ13C and δ18O, respectively) are studied in the fossiliferous, stratigraphically well-constrained and remarkably expanded successions of Podolia, SW Ukraine, spanning the Silurian–Devonian transition. Significant isotopic shifts are directly comparable to previously published global secular trends in well-preserved brachiopod calcite isotopic ratios from this region, and therefore may be taken as a reliable primary record of seawater δ13C changes. The sections reveal a major positive δ13C excursion, with an amplitude above 6 ‰, beginning in the upper Pridoli and reaching peak values as heavy as +4.2 ‰ in the lowermost Lochkovian. This turnover in carbon cycling is followed by a general trend toward more negative δ13C values in the upper Lochkovian. The Podolian isotopic signals provide strong support for the previously inferred global biogeochemical perturbation across the Silurian–Devonian transition, reflecting a complex combination of palaeogeographical, biogeochemical and evolutionary processes in the late Caledonian geodynamic setting, with a likely undervalued role of the expanding vegetation in vast near-coastal shallows and deltas.

silurian–devonian transition
global biogeochemical perturbation
succession


What big eyes you have: the ecological role of giant pterygotid eurypterids

Abstract: Eurypterids are a group of extinct chelicerates that ranged for over 200 Myr from the Ordovician to the Permian. Gigantism is common in the group; about 50% of families include taxa over 0.8 m in length. Among these were the pterygotids (Pterygotidae), which reached lengths of over 2 m and were the largest arthropods that ever lived. They have been interpreted as highly mobile visual predators on the basis of their large size, enlarged, robust chelicerae and forward-facing compound eyes. Here, we test this interpretation by reconstructing the visual capability of Acutiramus cummingsi (Pterygotidae) and comparing it with that of the smaller Eurypterus sp. (Eurypteridae), which lacked enlarged chelicerae, and other arthropods of similar geologic age. In A. cummingsi, there is no area of lenses differentiated to provide increased visual acuity, and the interommatidial angles (IOA) do not fall within the range of high-level modern arthropod predators. Our results show that the visual acuity of A. cummingsi is poor compared with that of co-occurring Eurypterus sp. The ecological role of pterygotids may have been as predators on thin-shelled and soft-bodied prey, perhaps in low-light conditions or at night.

ecological role
chelicerae
lense
acuity
ioa


Calibrated Tree Priors for Relaxed Phylogenetics and Divergence Time Estimation

Abstract: Abstract The use of fossil evidence to calibrate divergence time estimation has a long history. More recently, Bayesian Markov chain Monte Carlo has become the dominant method of divergence time estimation, and fossil evidence has been reinterpreted as the specification of prior distributions on the divergence times of calibration nodes. These so-called “soft calibrations” have become widely used but the statistical properties of calibrated tree priors in a Bayesian setting hashave not been carefully investigated. Here, we clarify that calibration densities, such as those defined in BEAST 1.5, do not represent the marginal prior distribution of the calibration node. We illustrate this with a number of analytical results on small trees. We also describe an alternative construction for a calibrated Yule prior on trees that allows direct specification of the marginal prior distribution of the calibrated divergence time, with or without the restriction of monophyly. This method requires the computation of the Yule prior conditional on the height of the divergence being calibrated. Unfortunately, a practical solution for multiple calibrations remains elusive. Our results suggest that direct estimation of the prior induced by specifying multiple calibration densities should be a prerequisite of any divergence time dating analysis.

divergence time estimation
calibration
choice


Leg 183 synthesis: Kerguelen plateau-broken ridge-a large igneous province

Abstract:
The Kerguelen Plateau and Broken Ridge form a large igneous
province (LIP) in the southern Indian Ocean. The main objectives of
Ocean Drilling Program Leg 183 were to understand the origin and evolution
of this LIP and the impact of its formation on the environment.
Igneous basement (33 to 233 m of penetration) has been recovered
from 11 drill sites on the LIP, and 7 are Leg 183 sites. Studies of the basement
and sediment cores lead to the following conclusions.
1. Formation of the LIP postdated breakup between India and Antarctica,
with eruption ages (40Ar/39Ar) ranging from ~119 Ma in the southern Kerguelen Plateau (SKP) to ~34 Ma in the northern Kerguelen Plateau. Apparently, peaks in magmatic output (~0.9 km3/yr) occurred in the intervals of 119–110 and 105–95 Ma.
Although an important caveat is that we have access only to
uppermost basement of a thick (~20 km) igneous crust, these
results are inconsistent with massive volcanism associated with
a single plume head and continental breakup.
2. The uppermost igneous basement is dominantly tholeiitic
basalt. Based on the physical characteristics of the lava flows,
which indicate subaerial eruption, and the occurrence of overlying
terrestrially derived sediments containing wood fragments,
fern remains, and terrestrial palynoflora, much of the LIP was
above sea level when magmatic output was high.
3. The geochemical characteristics of basalt forming the LIP are unlike mid-ocean-ridge basalt (MORB). There are, however significant geochemical differences between tholeiitic basalt
erupted at each site. These differences are attributed to varying
proportions of components derived from the Kerguelen plume,
depleted MORB-related asthenosphere, and continental lithosphere.
4. Based on radiogenic isotopic ratios and incompatible element
abundances, tholeiitic basalt of Cretaceous age from spatially
diverse locations (Site 738 in the SKP, Site 1137 on Elan Bank,
Site 747 in the Central Kerguelen Plateau (CKP), and Site 1142
on Broken Ridge) contains up to ~5% of a component derived
from continental crust. The Proterozoic-age zircon and monazite
in clasts of garnet-biotite gneiss in a conglomerate intercalated
with basalt at Site 1137 demonstrate that continental crust fragments
are present in the Indian Ocean lithosphere.
5. Surprising new results for oceanic LIPs are the dominance of
alkalic lavas, trachybasalt to trachyte and rhyolite, at Skiff Bank
and the pyroclastic deposits present on Skiff Bank, Elan Bank,
and the CKP. Explosive subaerial volcanism at high latitudes can
contribute volatiles to the stratosphere; therefore, LIP volcanism
may have had a significant environmental impact.
6. Flora and fauna preserved in Kerguelen Plateau sediments
provide a long-term record of the plateau’s environment, beginning
with terrestrial and shallow-marine deposition followed by
equable Cretaceous paleoceanographic conditions, the abrupt
Cretaceous/Tertiary boundary, the Late Paleocene Thermal
Maximum, and cooling of the Southern Ocean through Tertiary
time.


The Wagner Parsimony using morphological characters: a new method for palaeosynecological studies

Abstract: Abstract The limits and difficulties related to the tools currently in use for palaeosynecological comparisons of faunas or floras of different geological periods are discussed. The new method of the Wagner parsimony Applied to Palaeosynecology Using Morphology (WAPUM method), is defined and tested on morphological characters gathered from two insect groups Odonatoptera and Thripida. The difficulties related to the monophyly of the taxonomic groups used in the more traditional approaches are no longer a problem when using the WAPUM method. In the WAPUM a character is ‘presence versus absence of species bearing a morphological structure’. The results obtained from use of the WAPUM minimize the number of changes among character states. Application of the WAPUM could reveal signals to confirm or object the currently available scenarios for the global changes in the evolution of past diversity and disparity of organisms (major changes or global crises of diversity).

wagner parsimony
palaeosynecology
geological period
thripida


Dietary palaeoecology of an Early Cretaceous armoured dinosaur (Ornithischia; Nodosauridae) based on floral analysis of stomach contents

Abstract: The exceptionally well-preserved holotype of the armoured dinosaur Borealopelta markmitchelli (Ornithischia; Nodosauridae) from the Early Cretaceous (Clearwater Formation) of northern Alberta preserves a distinct mass within the abdominal cavity. Fourteen independent criteria (including: co-allochthony, anatomical position, gastroliths) support the interpretation of this mass as ingested stomach contents—a cololite. Palynomorphs in the cololite are a subset of the more diverse external sample. Analysis of the cololite documents well-preserved plant material dominated by leaf tissue (88%), including intact sporangia, leaf cross-sections and cuticle, but also including stems, wood and charcoal. The leaf fraction is dominated (85%) by leptosporangiate ferns (subclass Polypodiidae), with low cycad–cycadophyte (3%) and trace conifer foliage. These data represent the most well-supported and detailed direct evidence of diet in an herbivorous dinosaur. Details of the dietary palaeoecology of this nodosaur are revealed, including: selective feeding on ferns; preferential ingestion of leptosporangiate ferns to the exclusion of Osmundaceae and eusporangiate ferns such as Marattiaceae; and incidental consumption of cycad–cycadophyte and conifer leaves. The presence of significant (6%) charcoal may represent the dietary use of recently burned conifer forest undergoing fern succession, early evidence of a fire succession ecology, as is associated with many modern large herbivores.

nodosauridae
stomach content
plant material
herbivorous dinosaur
dietary palaeoecology


Revision of the Early Devonian psammosteids from the “Placoderm Sandstone”: Implications for their body shape reconstruction

Abstract: The Early Devonian psammosteid agnathans (Guerichosteus and Hariosteus) originally described by Tarlo (1964, 1965) from the so-called “Placoderm Sandstone” are revised. The newly collected material from the Holy Cross Mountains allows detailed reexamination and provides new anatomical information. The morphology and ornamentation of the plates supports the establishment of the genera Guerichosteus and Hariosteus. However, G. kotanskii, G. kulczyckii and G. lefeldi should be considered as junior synonyms of Guerichosteus kozlowskii. Hariosteus lobanowskii, erected by Tarlo (1964), is considered here as invalid (nomen dubium) and H. kotanskii is included with Hariosteus kielanae. The three-dimensional scanning of plates belonging to Guerichosteus allows for a more detailed description and reconstruction. In cross section the deep ventral part of the trunk is V-shaped in contrast to previous U-shaped restorations. Probably, the Early Devonian psammosteid, Drepanaspis gemuendenesis in particular, shared this body shape. Marek Dec. Institute of Palaeobiology, Polish Academy of Sciences, Twarda 51/55, 00-818 Warszawa, Poland. mdec@wp.pl

psammosteids
placoderm sandstone
body shape
guerichosteus kozlowskii


The Great American Biotic Interchange revisited: a new perspective from the stable isotope record of Argentine Pampas fossil mammals

Abstract: This study aims at assessing resource and habitat use, niche occupation and trophic interactions from a stable isotope perspective on fossil mammals from the Argentine Pampas during the Great American Biotic Interchange (GABI). We present stable isotope data of more than 400 samples belonging to 10 mammalian orders and spanning a temporal range from ~9.5 Ma to ~12 ky. Rodents, notoungulates and pilosians record an increase in the consumption of C4 plants, whereas litopterns and cingulates show δ13C values that remain mostly within a C3-dominated diet. Our stable isotope data indicates that the expansion of C4 vegetation opened up new niche opportunities, probably alleviating resource competition among endemic taxa. Gomphothere, equid and camelid δ13C records show a broad variability pointing to consumption of C3 and mixed C3-C4 vegetation. This flexible dietary behavior may have facilitated the successful settlement of immigrant groups in South America. In the case of carnivorous taxa, Late Miocene pre-GABI endemic sparassodonts consumed prey from C3 environments, whereas immigrant carnivorans preferred prey from mixed C3-C4 areas. Our research contributes to the study of the GABI from a different perspective as stable isotope records permit to characterize, from a (semi)quantitative standpoint, ecological traits within extinct fauna.

american biotic interchange
stable isotope record
south america
new discovery


The dawn of a dynasty : life strategies of Cambrian and Ordovician brachiopods.

Abstract: Brachiopods are among the first animal phyla to emerge from the Cambrian Explosion, rapidly diversifying to all major palaeocontinental blocks within 20 million years. The group underwent another steep rise in diversity during the Ordovician, and their relative abundance and diversity made them one of the most successful invertebrate groups during the entire Palaeozoic. During this time, brachiopods lived in a range of environments and represented a significant component of marine ecosystems, yet information regarding their modes of life and ecology is somewhat limited. Recent studies, primarily from the Chengjiang and Burgess Shale Lagerstatten, have revealed that by the Middle Cambrian (Series 3, Stage 5) brachiopods from across the phylum had already developed a range of ecological strategies and life modes. Cambrian brachiopods occupied distinct trophic niches on soft and hard substrates and exhibited at least five types of lifestyles: pedicle attachment, pedicle anchoring, cemented, free‐lying and semi‐infaunal. Comparisons with Ordovician benthic assemblages show that despite the explosion of brachiopod taxa witnessed in the Ordovician, with the exception of the appearance of burrowing brachiopods, life strategies of brachiopods remained largely the same. Indicating that the majority of life modes observed in brachiopods had rapidly evolved and was already in place prior to the Great Ordovician Biodiversity Event.

life strategy
ordovician
brachiopod
palaeozoic


Evolution, Systematics, and Phylogeography of Pleistocene Horses in the New World: A Molecular Perspective

Abstract: The rich fossil record of horses has made them a classic example of evolutionary processes. However, while the overall picture of equid evolution is well known, the details are surprisingly poorly understood, especially for the later Pliocene and Pleistocene, c. 3 million to 0.01 million years (Ma) ago, and nowhere more so than in the Americas. There is no consensus on the number of equid species or even the number of lineages that existed in these continents. Likewise, the origin of the endemic South American genus Hippidion is unresolved, as is the phylogenetic position of the “stilt-legged” horses of North America. Using ancient DNA sequences, we show that, in contrast to current models based on morphology and a recent genetic study, Hippidion was phylogenetically close to the caballine (true) horses, with origins considerably more recent than the currently accepted date of c. 10 Ma. Furthermore, we show that stilt-legged horses, commonly regarded as Old World migrants related to the hemionid asses of Asia, were in fact an endemic North American lineage. Finally, our data suggest that there were fewer horse species in late Pleistocene North America than have been named on morphological grounds. Both caballine and stilt-legged lineages may each have comprised a single, wide-ranging species.

horse
north america
genetic study
stilt-legged horse
mitochondrial dna


The osteology and paleoecology of the giant otter Enhydritherium terraenovae

Abstract: ABSTRACT The giant otter Enhydritherium terraenovae, a New World taxon thought to be related to both the Old World otter Enhydriodon and the extant sea otter Enhydra, was originally described on the basis of relatively limited material, mostly dental. However, an incomplete skeleton of E. terraenovae recovered from the early Hemphillian Moss Acres Racetrack site in northern Florida includes a skull, mandible, part of the axial skeleton, and most of both the fore- and hindlimbs, adding greatly to knowledge of this animal. On the basis of this new material, the osteology of this species is described in detail for the first time, with its diagnosis revised accordingly. This new osteological information, along with information about the nature of the Moss Acres Racetrack site, allows such paleoecological and functional aspects of E. terraenovae as habitat preference, mode of swimming, and diet to be inferred or interpreted in a detail previously impossible. E. terraenovae: 1) was a habitat generalist rather t...

osteology
otter enhydritherium terraenovae
florida


EOCENE RECORDS OF BEE FLIES (INSECTA, DIPTERA, BOMBYLIIDAE, COMPTOSIA): THEIR PALAEOBIOGEOGRAPHIC IMPLICATIONS AND REMARKS ON THE EVOLUTIONARY HISTORY OF BOMBYLIIDS

Abstract: Abstract:  The first fossil records of Holarctic representatives of the genus Comptosia Macquart, 1840 from the middle Eocene Messel Pit, Germany, and the upper Eocene of Florissant, USA, are reported. The fossil from Messel, Comptosia pria sp. nov., is represented by a well‐preserved wing, displaying characteristic wing venation, remains of the second wing and elements of the thorax. The Florissant fossil, C. miranda comb. nov., is preserved almost completely with both wings and most parts of the body visible. Extant members of the genus Comptosia are currently found only in Australia, and close relatives are known from southern South America. Previously this group of genera has been thought to be of Gondwanan origin, but these Eocene fossil representatives of Comptosia from the Holarctic region argue against this interpretation, and suggest that Comptosia and its relatives were more widespread in both Northern and Southern hemispheres during the Palaeogene. The fossil record of bee flies suggests a major radiation of bombyliids in the late Cretaceous or early Cenozoic. This assumption is supported by the comparatively young geological age of many bombyliid host taxa. A key factor driving the specialization of many bombyliid larvae on ground‐dwelling hosts may have been avoidance of competition with tachinid flies and parasitic hymenopterans.


A ‘Terror of Tyrannosaurs’: The First Trackways of Tyrannosaurids and Evidence of Gregariousness and Pathology in Tyrannosauridae

Abstract: The skeletal record of tyrannosaurids is well-documented, whereas their footprint record is surprisingly sparse. There are only a few isolated footprints attributed to tyrannosaurids and, hitherto, no reported trackways. We report the world’s first trackways attributable to tyrannosaurids, and describe a new ichnotaxon attributable to tyrannosaurids. These trackways are from the Upper Cretaceous (Campanian - Maastrichtian) of northeastern British Columbia, Canada. One trackway consists of three tridactyl footprints, and two adjacent trackways consist of two footprints each. All three trackways show animals bearing southeast within an 8.5 meter-wide corridor. Similarities in depth and preservation of the tyrannosaurid tracks indicate that these three trackways were made by track-makers walking concurrently in the same direction. These trackways add significantly to previous osteology-based hypotheses of locomotion and behavior in Tyrannosauridae by providing ichnologic support for gregariousness in tyrannosaurids, and the first record of the walking gait of tyrannosaurids.

gregariousness
tyrannosauridae
footprint
british columbia


Chaetopterid Tubes from Vent and Seep Sites: Implications for Fossil Record and Evolutionary History of Vent and Seep Annelids

Abstract: Vestimentiferan tube worms living at deep-sea hydrothermal vents and cold seeps have been considered as a clade with a long and continuing evolutionary history in these ecosystems. Whereas the fossil record appears to support this view, molecular age estimates do not. The two main features that are used to identify vestimentiferan tubes in the fossil record are longitudinal ridges on the tube's surface and a tube wall constructed of multiple layers. It is shown here that chaetopterid tubes from modern vents and seeps—as well as a number of fossil tubes from shallow-water environments—also show these two features. This calls for a more cautious interpretation of tubular fossils from ancient vent and seep deposits. We suggest that: current estimates for a relatively young evolutionary age based on molecular clock methods may be more reliable than the inferences of ancient “vestimentiferans” based on putative fossils of these worms; not all of these putative fossils actually belong to this group; and that tubes from fossil seeps should be investigated for chitinous remains to substantiate claims of their potential siboglinid affinities.

vent
evolutionary history
vestimentiferan


Redescription and palaeobiology of Palaeoscorpius devonicus Lehmann, 1944 from the Lower Devonian Hunsrück Slate of Germany

Abstract: Abstract:  Palaeoscorpius devonicus Lehmann, 1944 is known from only a single specimen, found in the Eschenbach Pit near Bundenbach in the Lower Devonian Hunsrück Slate of Germany. It is a key fossil, having been interpreted both as the most basal member of the Scorpiones and as one of the order’s most likely candidates for an aquatic mode of life. Prepared both ventrally and dorsally, some aspects of its morphology remain problematic. Here, with the aid of new techniques, including computed tomography, we present a re‐investigation of this scorpion’s anatomy and a new reconstruction, with a particular focus on the species’ original habitat. On the basis of the environmental interpretation of the Hunsrück Slate and the completeness of the specimen, previous authors concluded that P. devonicus was marine, but none offered convincing morphological evidence. Recent studies of the deposit’s environment suggest that the Hunsrück Sea was part of an intrashelf basin, relatively close to the coastline, and fossils of land plants show that terrestrial wash‐in occasionally occurred. Our revised interpretation of the fossil’s morphology demonstrates that the scorpion was most probably terrestrial. Internal mesosomal organs are interpreted as book lungs, but other terrestrial adaptations are lacking. The absence of both coxapophyses and gnathobases makes determining the scorpion’s feeding mechanism difficult. Interpreting the scorpion’s character states within a phylogenetic framework, especially the possible presence of book lungs, implies either that the plesiomorphic position of P. devonicus is no longer supported or that the development of book lungs had already taken place early in the scorpion lineage.

palaeoscorpius devonicus lehmann
germany
scorpion
possible presence


THE ALLIGATOROIDEA OF ARGENTINA: AN UPDATE OF ITS FOSSIL RECORD

Abstract: The fossil record of Alligatoroidea in Argentina is mainly represented by Caimaninae alligatorids. This lineage recorded two impor- tant moments in its natural history, one at the beginning of the Paleogene (Late Paleocene–Middle Eocene) and the other in the Neogene (Late Miocene). The most ancient record of alligatoroids in South America comes from the Early Paleocene of Patagonia. It includes basal forms of caimanines such as Necrosuchus ionensis, Eocaiman palaeocenicus, Eocaiman cavernensis, and probably a new species of alligatoroid, which provide key morphological information on the evolutionary and biogeographic history of these crocodylians. Another important moment of the evolutionary history of caimanines is the diversification of the lineage observed during the Miocene. Although there is some isolated cranial material of caimanines from the Late Miocene of northwestern Argentina, the most abundant and diverse fossil Miocene material comes from the northeast, from a level informally called “Conglomerado Osifero”. Two genera of caimanines are known from this stratigraphic level (Caiman and Mourasuchus) with at least five valid species. Here we present an update of the knowledge of Cenozoic alligatorids of Argentina, as a tribute to Zulma Gasparini for her invaluable contribution to the understanding of the crocodilian evolution in South America.

alligatoroidea
argentina
update
miocene
south america


Fine Endmesolithic fish caviar meal discovered by proteomics in foodcrusts from archaeological site Friesack 4 (Brandenburg, Germany)

Abstract: The role of aquatic resources in ancient economies and paleodiet is important for understanding the evolution of prehistorical societies. Charred food remains from ancient pottery are valuable molecular evidence of dietary habits in antiquity. However, conventional archaeometric approaches applied in their analysis lack organismal specificity, are affected by abundant environmental contaminants, do not elucidate food processing recipes and are limited in the inland regions where diverse dietary resources are available. We performed proteomics analysis of charred organic deposits adhered on early ceramics from Mesolithic-Neolithic inland site Friesack 4 (Brandenburg, Germany). One of pots—a small coarse bowl radiocarbon dated to the end of the 5th millennium BC—was attributed to Endmesolithic pottery. Proteomics of foodcrust from this vessel identified fine carp roe meal and revealed details of a prehistorical culinary recipe. Ancient proteins were unequivocally distinguished from contemporary contaminants by computing deamidation ratios of glutamine residues. These data paint a broader picture of the site-specific exploitation of aquatic resources and contribute to better understanding of the dietary context of Neolithic transition in European inland.


Intra-Trackway Morphological Variations Due to Substrate Consistency: The El Frontal Dinosaur Tracksite (Lower Cretaceous, Spain)

Abstract: An ichnological and sedimentological study of the El Frontal dinosaur tracksite (Early Cretaceous, Cameros basin, Soria, Spain) highlights the pronounced intra-trackway variation found in track morphologies of four theropod trackways. Photogrammetric 3D digital models revealed various and distinct intra-trackway morphotypes, which reflect changes in footprint parameters such as the pace length, the track length, depth, and height of displacement rims. Sedimentological analyses suggest that the original substrate was non-homogenous due to lateral changes in adjoining microfacies. Multidata analyses indicate that morphological differences in these deep and shallow tracks represent a part of a continuum of track morphologies and geometries produced by a gradient of substrate consistencies across the site. This implies that the large range of track morphologies at this site resulted from similar trackmakers crossing variable facies. The trackways at the El Frontal site present an exemplary case of how track morphology, and consequently potential ichnotaxa, can vary, even when produced by a single trackmaker.


Early farmers from across Europe directly descended from Neolithic Aegeans

Abstract: Significance One of the most enduring and widely debated questions in prehistoric archaeology concerns the origins of Europe’s earliest farmers: Were they the descendants of local hunter-gatherers, or did they migrate from southwestern Asia, where farming began? We recover genome-wide DNA sequences from early farmers on both the European and Asian sides of the Aegean to reveal an unbroken chain of ancestry leading from central and southwestern Europe back to Greece and northwestern Anatolia. Our study provides the coup de grâce to the notion that farming spread into and across Europe via the dissemination of ideas but without, or with only a limited, migration of people. Farming and sedentism first appeared in southwestern Asia during the early Holocene and later spread to neighboring regions, including Europe, along multiple dispersal routes. Conspicuous uncertainties remain about the relative roles of migration, cultural diffusion, and admixture with local foragers in the early Neolithization of Europe. Here we present paleogenomic data for five Neolithic individuals from northern Greece and northwestern Turkey spanning the time and region of the earliest spread of farming into Europe. We use a novel approach to recalibrate raw reads and call genotypes from ancient DNA and observe striking genetic similarity both among Aegean early farmers and with those from across Europe. Our study demonstrates a direct genetic link between Mediterranean and Central European early farmers and those of Greece and Anatolia, extending the European Neolithic migratory chain all the way back to southwestern Asia.

europe
neolithic individual
early farmer


Mitochondrial DNA sequence analysis reveals multiple Pleistocene glacial refugia for Podarcis muralis (Laurenti, 1768) in the Italian Peninsula

Abstract: Abstract The genetic variability of the wall lizard, Podarcis muralis, was analysed in that part of its range regarded as its area of origin and also its expansion centre. The analysis was performed on partial cytochrome b sequences (405 bp) of 117 specimens representing 31 sampling locations from southern, central and northern Italy. The results of this study revealed 30 haplotypes in the Italian sample belonging to three main genetic lineages. The genetic divergence among haplotypes ranged from 0.2 to 6.6%, whereas the estimation of divergence times among mtDNA lineages highlighted a complex pattern of genetic differentiation with both Pleistocene and Pliocene divergences (3.2–0.7 Ma). These results put in evidence the role played by the pre-Pleistocene and Pleistocene palaeogeographic and palaeoclimatic events in shaping the genetic diversity of the wall lizard in Italy and confirm the role of this peninsula as glacial refuge. In addition, AMOVA analysis revealed the presence of geographically structured clades indicating the occurrence of multiple glacial refugia in Italy, thus supporting a refugia-within-refugia scenario for the wall lizard in Italy. Finally, the results of this study seem to indicate a lack of congruence between the four morphological subspecies currently recognised in the Italian Peninsula and the main genetic lineages detected.

glacial refugia
podarcis muralis
italian peninsula
genetic lineage


Early Human Speciation, Brain Expansion and Dispersal Influenced by African Climate Pulses

Abstract: Early human evolution is characterised by pulsed speciation and dispersal events that cannot be explained fully by global or continental paleoclimate records. We propose that the collated record of ephemeral East African Rift System (EARS) lakes could be a proxy for the regional paleoclimate conditions experienced by early hominins. Here we show that the presence of these lakes is associated with low levels of dust deposition in both West African and Mediterranean records, but is not associated with long-term global cooling and aridification of East Africa. Hominin expansion and diversification seem to be associated with climate pulses characterized by the precession-forced appearance and disappearance of deep EARS lakes. The most profound period for hominin evolution occurs at about 1.9 Ma; with the highest recorded diversity of hominin species, the appearance of Homo (sensu stricto) and major dispersal events out of East Africa into Eurasia. During this period, ephemeral deep-freshwater lakes appeared along the whole length of the EARS, fundamentally changing the local environment. The relationship between the local environment and hominin brain expansion is less clear. The major step-wise expansion in brain size around 1.9 Ma when Homo appeared was coeval with the occurrence of ephemeral deep lakes. Subsequent incremental increases in brain size are associated with dry periods with few if any lakes. Plio-Pleistocene East African climate pulses as evinced by the paleo-lake records seem, therefore, fundamental to hominin speciation, encephalisation and migration.

dispersal
african climate pulse
lake
hominin evolution


THE ANTIQUITY OF AFRICAN TORTOISES

Abstract: Tortoises (Testudinidae) are a diverse and highly specialized clade of terrestrial turtles that currently inhabit five continents. The global radiation of tortoises in the Paleogene, part of an explosive radiation of testudinoid turtles out of Asia, is poorly understood. The oldest known tortoises are from the late Paleocene of Mongolia (Parham, pers. obs. at PIN), and early in the Eocene they are known to have colonized North America and Europe (e.g., Hutchison, 1998; Lapparent de Broin, 2001). At some point in the early Paleogene they marched or floated to Africa. Today, the ancestors of those first invaders have evolved into the most diverse tortoise fauna in the world; Africa is home to 10 of the 13 extant genera (Iverson, 1992; Lapparent de Broin, 2000). One of the most poorly understood episodes in the early testudinid range expansion is the dispersal of tortoises into Africa. Fossil tortoises have been known from Africa since the beginning of the last century, when Andrews (1902) noted that a ‘‘gigantic land-tortoise’’ had been found by H. J. L. Beadnell. However, the age of these tortoises has never been firmly established, because early collecting records were not precise with regard to the specific quarries from which they were collected. Three species of Testudo were described (Andrews and Beadnell, 1903; Andrews, 1906) as having come from the upper Eocene ‘‘Fluviomarine’’ deposits of the Jebel Qatrani Formation in the Fayum Province of Egypt. In the intervening years, the Jebel Qatrani Formation came to be regarded as early Oligocene in age (e.g., Simons, 1968), then partly late Eocene and partly early Oligocene (Kappelman, 1992; Kappelman et al., 1992). No further testudinids have been reported from Egypt, although fragmentary testudinid fossils possibly close to the Egyptian taxon have been recovered from lower Oligocene sediments in Oman (Thomas et al., 1989; Lapparent de Broin, 2000). Most recently, Lapparent de Broin (2000) reviewed the African fossil record of turtles and conservatively reported the age of the Fayum tortoises as early Oligocene. Resolution of the age of Africa’s oldest tortoises has been difficult because specimens housed in European institutions (Natural History Museum, London, and Staatliches Museum, Stuttgart) lack detailed locality data, and more recent fieldwork in the area by E. L. Simons and crews (materials housed at Yale Peabody Museum, Cairo Geological Museum, and Duke University Primate Center, Durham, North Carolina) has not yielded remains of these comparatively rare reptiles. Reevaluation of older collections from the Jebel Qatrani Formation has uncovered the only African tortoise with associated stratigraphic data indicating a late Eocene age, allowing us to place this taxon in an updated geochronologic context and providing us with the opportunity to resolve several taxonomic issues regarding these specimens. Abbreviations Used AMNH, American Museum of Natural History, New York; BMNH, The Natural History Museum, London; CGM, Cairo Geological Museum, Cairo; PIN, Paleontological Institute, Moscow.


Protein sequences bound to mineral surfaces persist into deep time

Abstract: Proteins persist longer in the fossil record than DNA, but the longevity, survival mechanisms and substrates remain contested. Here, we demonstrate the role of mineral binding in preserving the protein sequence in ostrich (Struthionidae) eggshell, including from the palaeontological sites of Laetoli (3.8 Ma) and Olduvai Gorge (1.3 Ma) in Tanzania. By tracking protein diagenesis back in time we find consistent patterns of preservation, demonstrating authenticity of the surviving sequences. Molecular dynamics simulations of struthiocalcin-1 and -2, the dominant proteins within the eggshell, reveal that distinct domains bind to the mineral surface. It is the domain with the strongest calculated binding energy to the calcite surface that is selectively preserved. Thermal age calculations demonstrate that the Laetoli and Olduvai peptides are 50 times older than any previously authenticated sequence (equivalent to ~16 Ma at a constant 10°C). DOI: http://dx.doi.org/10.7554/eLife.17092.001

mineral surface
longevity
eggshell
tanzania
protein sequence


On the duration of magnetochrons C24r and C25n and the timing of early Eocene global warming events: Implications from the Ocean Drilling Program Leg 208 Walvis Ridge depth transect

Abstract: [1] Five sections drilled in multiple holes over a depth transect of more than 2200 m at the Walvis Ridge (SE Atlantic) during Ocean Drilling Program (ODP) Leg 208 resulted in the first complete early Paleogene deep-sea record. Here we present high-resolution stratigraphic records spanning a ∼4.3 million yearlong interval of the late Paleocene to early Eocene. This interval includes the Paleocene-Eocene thermal maximum (PETM) as well as the Eocene thermal maximum (ETM) 2 event. A detailed chronology was developed with nondestructive X-ray fluorescence (XRF) core scanning records and shipboard color data. These records were used to refine the shipboard-derived spliced composite depth for each site and with a record from ODP Site 1051 were then used to establish a continuous time series over this interval. Extensive spectral analysis reveals that the early Paleogene sedimentary cyclicity is dominated by precession modulated by the short (100 kyr) and long (405 kyr) eccentricity cycles. Counting of precession-related cycles at multiple sites results in revised estimates for the duration of magnetochrons C24r and C25n. Direct comparison between the amplitude modulation of the precession component derived from XRF data and recent models of Earth's orbital eccentricity suggests that the onset of the PETM and ETM2 are related to a 100-kyr eccentricity maximum. Both events are approximately a quarter of a period offset from a maximum in the 405-kyr eccentricity cycle, with the major difference that the PETM is lagging and ETM2 is leading a 405-kyr eccentricity maximum. Absolute age estimates for the PETM, ETM2, and the magnetochron boundaries that are consistent with recalibrated radiometric ages and recent models of Earth's orbital eccentricity cannot be precisely determined at present because of too large uncertainties in these methods. Nevertheless, we provide two possible tuning options, which demonstrate the potential for the development of a cyclostratigraphic framework based on the stable 405-kyr eccentricity cycle for the entire Paleogene.


Viewpoints: feeding mechanics, diet, and dietary adaptations in early hominins.

Abstract: Inference of feeding adaptation in extinct species is challenging, and reconstructions of the paleobiology of our ancestors have utilized an array of analytical approaches. Comparative anatomy and finite element analysis assist in bracketing the range of capabilities in taxa, while microwear and isotopic analyses give glimpses of individual behavior in the past. These myriad approaches have limitations, but each contributes incrementally toward the recognition of adaptation in the hominin fossil record. Microwear and stable isotope analysis together suggest that australopiths are not united by a single, increasingly specialized dietary adaptation. Their traditional (i.e., morphological) characterization as "nutcrackers" may only apply to a single taxon, Paranthropus robustus. These inferences can be rejected if interpretation of microwear and isotopic data can be shown to be misguided or altogether erroneous. Alternatively, if these sources of inference are valid, it merely indicates that there are phylogenetic and developmental constraints on morphology. Inherently, finite element analysis is limited in its ability to identify adaptation in paleobiological contexts. Its application to the hominin fossil record to date demonstrates only that under similar loading conditions, the form of the stress field in the australopith facial skeleton differs from that in living primates. This observation, by itself, does not reveal feeding adaptation. Ontogenetic studies indicate that functional and evolutionary adaptation need not be conceptually isolated phenomena. Such a perspective helps to inject consideration of mechanobiological principles of bone formation into paleontological inferences. Finite element analysis must employ such principles to become an effective research tool in this context.

dietary adaptation
morphology
tooth
assumption


American mastodon extirpation in the Arctic and Subarctic predates human colonization and terminal Pleistocene climate change

Abstract: Significance New radiocarbon (14C) dates on American mastodon (Mammut americanum) fossils in Alaska and Yukon suggest this species suffered local extirpation before terminal Pleistocene climate changes or human colonization. Mastodons occupied high latitudes during the Last Interglacial (∼125,000–75,000 y ago) when forests were established. Ecological changes during the Wisconsinan glaciation (∼75,000 y ago) led to habitat loss and population collapse. Thereafter, mastodons were limited to areas south of the continental ice sheets, where they ultimately died out ∼10,000 14C years B.P. Extirpation of mastodons and some other megafaunal species in high latitudes was thus independent of their later extinction south of the ice. Rigorous pretreatment was crucial to removing contamination from fossils that originally yielded erroneously “young” 14C dates. Existing radiocarbon (14C) dates on American mastodon (Mammut americanum) fossils from eastern Beringia (Alaska and Yukon) have been interpreted as evidence they inhabited the Arctic and Subarctic during Pleistocene full-glacial times (∼18,000 14C years B.P.). However, this chronology is inconsistent with inferred habitat preferences of mastodons and correlative paleoecological evidence. To establish a last appearance date (LAD) for M. americanum regionally, we obtained 53 new 14C dates on 36 fossils, including specimens with previously published dates. Using collagen ultrafiltration and single amino acid (hydroxyproline) methods, these specimens consistently date to beyond or near the ∼50,000 y B.P. limit of 14C dating. Some erroneously “young” 14C dates are due to contamination by exogenous carbon from natural sources and conservation treatments used in museums. We suggest mastodons inhabited the high latitudes only during warm intervals, particularly the Last Interglacial [Marine Isotope Stage (MIS) 5] when boreal forests existed regionally. Our 14C dataset suggests that mastodons were extirpated from eastern Beringia during the MIS 4 glacial interval (∼75,000 y ago), following the ecological shift from boreal forest to steppe tundra. Mastodons thereafter became restricted to areas south of the continental ice sheets, where they suffered complete extinction ∼10,000 14C years B.P. Mastodons were already absent from eastern Beringia several tens of millennia before the first humans crossed the Bering Isthmus or the onset of climate changes during the terminal Pleistocene. Local extirpations of mastodons and other megafaunal populations in eastern Beringia were asynchrononous and independent of their final extinction south of the continental ice sheets.

arctic
human colonization
pleistocene climate change
continental ice sheet


Evidence for an African-Iberian mammal dispersal during the pre-evaporitic Messinian

Abstract: The accurate timing of biogeographic dispersal can be determined by examining the age of fossiliferous strata on either side of a physical barrier. Here we show that African mammals migrated to Iberia and European mammals migrated to North Africa at the same time before isolation of the Mediterranean Sea during the Messinian. The fossil site of Venta del Moro (Spain) exhibits western Europe’s most complete vertebrate fauna for the latest Miocene. Its uniquely cosmopolitan assemblage is evidence of faunal dispersals from Africa and Asia to Europe during the latest Miocene glaciation. A preliminary paleomagnetic study suggested an age of 5.8 Ma for this site, but our expanded magnetostratigraphy dates the site at 6.23 Ma. In addition, we recalibrated the paleomagnetic age of the Librilla site (Spain) and the North Africa site of Afoud-1 (Morocco) using the Astronomical Tuned Neogene Time Scale. Our results show a two-way African-Iberian mammal dispersal just before 6.2 Ma. These new ages indicate that an ephemeral land corridor existed between the two continents 250 k.y. before the onset of the Messinian Salinity Crisis, reflecting a tentative initial isolation of the Mediterranean Sea. This corridor developed after tectonics closed the Betic Seaway at 6.3 Ma and during the intensification of the latest Miocene glaciation at 6.26 Ma, when water circulation in the Mediterranean became very restricted.

african-iberian mammal dispersal
venta del moro
late miocene


Pseudogenization of the tooth gene enamelysin (MMP20) in the common ancestor of extant baleen whales

Abstract: Whales in the suborder Mysticeti are filter feeders that use baleen to sift zooplankton and small fish from ocean waters. Adult mysticetes lack teeth, although tooth buds are present in foetal stages. Cladistic analyses suggest that functional teeth were lost in the common ancestor of crown-group Mysticeti. DNA sequences for the tooth-specific genes, ameloblastin (AMBN), enamelin (ENAM) and amelogenin (AMEL), have frameshift mutations and/or stop codons in this taxon, but none of these molecular cavities are shared by all extant mysticetes. Here, we provide the first evidence for pseudogenization of a tooth gene, enamelysin (MMP20), in the common ancestor of living baleen whales. Specifically, pseudogenization resulted from the insertion of a CHR-2 SINE retroposon in exon 2 of MMP20. Genomic and palaeontological data now provide congruent support for the loss of enamel-capped teeth on the common ancestral branch of crown-group mysticetes. The new data for MMP20 also document a polymorphic stop codon in exon 2 of the pygmy sperm whale (Kogia breviceps), which has enamel-less teeth. These results, in conjunction with the evidence for pseudogenization of MMP20 in Hoffmann's two-toed sloth (Choloepus hoffmanni), another enamel-less species, support the hypothesis that the only unique, non-overlapping function of the MMP20 gene is in enamel formation.

common ancestor
baleen whale
tooth-specific gene
frameshift mutation
pseudogenization


Ontogenetic variability in crystallography and mosaicity of conodont apatite: implications for microstructure, palaeothermometry and geochemistry

Abstract: X-ray diffraction data from Silurian conodonts belonging to various developmental stages of the species Dapsilodus obliquicostatus demonstrate changes in crystallography and degree of nanocrystallite ordering (mosaicity) in both lamellar crown tissue and white matter. The exclusive use of a single species in this study, combined with systematic testing of each element type at multiple locations, provided insight into microstructural and crystallographic differentiation between element type (Sa, Sb-c, M) as well as between juveniles and adults. A relative increase in the unit cell dimensions a/c ratio of nanocrystallites during growth was apparent in areas demonstrating single-crystal behaviour, but no such relationship was seen in dominantly polycrystalline areas. Systematic variations in mosaicity were identified, with mosaicity (as a proxy for disorder) increasing during growth, as well as along elements from tip to base. These results provide potential insight into the integrity of conodont apatite as a recorder of palaeoseawater chemistry, as well as demonstrate the need to consider the influence of ontogeny and element type on the use of conodonts in palaeothermometry and geochemical investigations.

crystallography
conodont apatite
palaeothermometry
lamellar crown tissue