Calcium isotopic patterns in enamel reflect different nursing behaviors among South African early hominins

Abstract: Calcium isotopic ratios in dental enamel of South African hominins reveal taxon-dependent nursing behaviors. Nursing is pivotal in the social and biological evolution of hominins, but to date, early-life behavior among hominin lineages is a matter of debate. The calcium isotopic compositions (δ44/42Ca) of tooth enamel can provide dietary information on this period. Here, we measure the δ44/42Ca values in spatially located microsized regions in tooth enamel of 37 South African hominins to reconstruct early-life dietary-specific variability in Australopithecus africanus, Paranthropus robustus, and early Homo. Very low δ44/42Ca values (<−1.4‰), indicative of milk consumption, are measured in early Homo but not in A. africanus and P. robustus. In these latter taxa, transitional or adult nonmilk foods must have been provided in substantial quantities relative to breast milk rapidly after birth. The results suggest that early Homo have continued a predominantly breast milk–based nursing period for longer than A. africanus and P. robustus and have consequently more prolonged interbirth interval.

enamel
nursing behavior
hominin
milk consumption


Indicators of locomotor habits in xenarthrans: Evidence for locomotor heterogeneity among fossil sloths

Abstract: ABSTRACT A striking diversity in limb morphology among fossil sloths suggests that the traditional distinction between extant “tree” sloths and fossil “ground” sloths merits closer scrutiny. Morphologically, xenarthrans (sloths, anteaters, and armadillos) are divergent from other mammalian orders. However, morphological shape indices of aspects of the elbow, hip, and knee joints that clearly discriminate locomotor modes in primates, carnivores, and bovids also succeed in differentiating the fully arboreal, semiarboreal, and terrestrial genera of anteaters. When compared to this extant data base, fossil sloths from both the Pleistocene radiation of the Antilles and the Santacrucian radiation of Argentina exhibit a range of values for these indices comparable to those of primates and anteaters. These results indicate that the diversity of limb structure in fossil sloths is associated with variation in posture and locomotor habits including arboreality, semiarboreality, and terrestriality.

locomotor habit
fossil sloth
sloth
index


Complexity and diversity of eyes in Early Cambrian ecosystems

Abstract:
Here we report exceptionally preserved non-biomineralized compound eyes of a non-trilobite arthropod Cindarella eucalla from the lower Cambrian Chengjiang Lagersta ¨tte, China. The specimen represents the oldest microanatomical evidence confirming the occurrence of highly developed vision in the early Cambrian, over 2,000 ommatidia in each eye. Moreover, a quantitative analysis of the distribution of eyes related to life habit, feeding types, and phyla respectively, from the Chengjiang biota indicates that specimens with eyes mostly belong to the arthropods, and they usually were actively mobile epifaunal and nektonic forms as hunters or scavengers. Arthropods took the lead in evolution of 'good vision' and domination in Cambrian communities, which supports the hypothesis that the origin and evolution of 'good vision' was a key trait that promoted preferential diversification and formed the foundation of modern benthic ecosystems in the early Cambrian ocean.
T he pervasiveness, intricacy, and complexity of animal eyes has long attracted the attention of scientists. The diverse types of extant eyes reflect the selective advantages of using light as a source of information throughout evolution 1 . It is largely accepted that proper vision originated in the early Cambrian during the initial radiation of many animal groups 2-4 , known as the Cambrian explosion [5] [6] [7] . The evolution of powerful vision has been proposed as a trigger for the Cambrian explosion of animals 8, 9 . However, the evolutionary origin and diversity of types of eyes still remains obscure. The record of early eyes is exceptionally sparse because most eyes are composed of soft tissue that does not usually fossilize, so much detail has been lost in mud and deep time. The availability of Cambrian Konservat-Lagersta ¨tten 5, 10, 11 with exceptional preservation offers the possibility to shed new light on the origin of eyes. The occurrence of eyes within the Chengjiang biota (approximately 520 million years ago) shows a remarkable variety of visual systems, which represent the earliest eyes in the metazoan fossil record [10] [11] [12] [13] [14] . More than 230 animal species have been described in the Chengjiang biota, representing at least 18 animal phyla and a variety of taxonomically enigmatic forms 15 , including primitive vertebrates 16 , which have great potential for understanding origination and evolution of visual systems in different animal phyla and their influence on the development of ecological communities in deep time. Here we report exceptionally preserved non-biomineralized eyes, preserved together with the body, of a non-trilobite arthropod Cindarella eucalla 10,17 from the early Cambrian Chengjiang biota, revealing the detailed structures of compound eyes. Together with a quantitative analysis of the distribution of eyes related to life habit, feeding types, and phyla, based on abundance data collected from a Chengjiang biota locality, we then explore the evolution of vision and its influence on ecological communities in the early Cambrian ocean.
Specimens of exceptionally preserved Cindarella eucalla with eyes as well as abundance data of the Chengjiang biota (86 species, 9941 individuals) were collected from a single quarry during study of a narrow stratigraphic interval from the lower Cambrian Maotianshan Shale in the Mafang section (N 24u469, E 102u359), Haikou, Yunnan Province, China, where one of the richest Chengjiang fossil deposits exists 18 . The fossils at the Mafang section feature an abundance and diversity of well-preserved soft-bodied animals that were subjected to limited or no pre-burial transportation and limited post-burial decay 18 . These fossils therefore present a record of the living soft-bodied animal community and provide unparalleled materials for understanding community paleoecology in the early Cambrian. In this abundance data analysis, we focus on the quantitative distribution of eyes and their relationship to phyla and ecological groups. For each taxon, its individual abundance and the presence/absence of macroscopic eye organs has been recorded (Supplementary Table 1 ).

eye
ecosystem
chengjiang biota
complexity


Systematic revision of the Protostegidae, with a redescription of Calcarichelys gemma Zangerl, 1953

Abstract: ABSTRACT A revised classification is proposed for the Protostegidae. This revision is aided significantly by a redescription of Calcarichelys gemma Zangerl, 1953 based on a nearly complete specimen from the Mooreville Chalk (Campanian) of Alabama. The phylogenetic relationships of “Protostega” eaglefordensis are unresolved but it does not belong in the genus Protostega. Protostega dixie and Protostega potens are junior synonyms of Protostega gigas. Archelon copei is placed in a new genus, Microstega, and is included with Archelon ischyros, Calcarichelys gemma, Chelosphargis advena, and Protostega gigas in the family Protostegidae. The protostegids have the following synapomorphies: absence of the foramen palatinum posterius; a basioccipital with knob-like processes fitting into sockets on the posterior end of the pterygoids; the presence of only one suprapygal; and a T-shaped entoplastron that is not sutured to the other plastral elements. Evidence exists for a larger group containing Desmatochelys, Rhino...

revision
protostegidae
calcarichelys gemma zangerl
archelon ischyro


Neogene sloth assemblages (Mammalia, Pilosa) of the Cocinetas Basin (La Guajira, Colombia): implications for the Great American Biotic Interchange

Abstract: We describe sloth assemblages from the Cocinetas Basin (La Guajira peninsula, Colombia), found in the Neogene Castilletes and Ware formations, located in northernmost South America, documenting otherwise poorly known biotas. The tentative referral of a specimen to a small megatherioid sloth, Hyperleptus?, from the early–middle Miocene Castilletes Formation, suggests affinities of this fauna with the distant Santa Cruz Formation and documents a large latitudinal distribution for this taxon. The late Pliocene Ware Formation is much more diverse, with five distinct taxa representing every family of ‘ground sloths’. This diversity is also remarkable at the ecological level, with sloths spanning over two orders of magnitude of body mass and probably having different feeding strategies. Being only a few hundred kilometres away from the Isthmus of Panama, and a few hundred thousand years older than the classically recognized first main pulse of the Great American Biotic interchange (GABI 1), the Ware Formation furthermore documents an important fauna for the understanding of this major event in Neogene palaeobiogeography. The sloths for which unambiguous affinities were recovered are not closely related to the early immigrants found in North America before GABI 1.

sloth assemblage
cocinetas basin
american biotic interchange


A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda)

Abstract:
Diplodocoidea includes some of the first well-known sauropod dinosaurs, including such late 19th century and early 20th century discoveries as Apatosaurus, Diplodocus, and Dicraeosaurus. As a consequence of their long history of study, the basic set of suprageneric diplodocoid interrelationships is well resolved, and the diagnostic features of each genus are well established. However, intergeneric relationships are less resolved, including the relationships of putatively basal taxa like Amphicoelias and Haplocanthosaurus, the flagellicaudatan Suuwassea, and the highly specialized rebbachisaurids. For the rebbachisaurids, this uncertainty is coupled with a recent surge in the discovery of new taxa. Comparative cladistic methods demonstrate that character and taxon sampling need to be improved before greater phylogenetic resolution can be expected. Here, I present a new phylogenetic analysis that resolves many of the outstanding questions regarding the relationships within Diplodocoidea and examines palaeobiogeographical trends within the group. Suuwassea is recovered as a basal dicraeosaurid (the only Laurasian member of the group), and two distinct clades of rebbachisaurids are identified: a group closely allied with Nigersaurus and a clade associated with Limaysaurus. Amphicoelias, Amazonsaurus, and Haplocanthosaurus are provisionally placed as successively less-derived taxa at the base of Diplodocoidea. A North American origin for Diplodocoidea and Flagellicaudata is hypothesized based on the geographical and temporal distribution of those taxa. Rebbachisaurid taxa demonstrate a South American/African vicariance pattern, but the timing of the event pre-dates the proposed final rifting of those continents by c. 40 million years; the meaning of this discrepancy is uncertain.

© 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 161, 872–915.

phylogenetic analysis
diplodocoidea
suuwassea
basal dicraeosaurid


Quantitative analysis of dental microwear in hadrosaurid dinosaurs, and the implications for hypotheses of jaw mechanics and feeding

Abstract: Understanding the feeding mechanisms and diet of nonavian dinosaurs is fundamental to understanding the paleobiology of these taxa and their role in Mesozoic terrestrial ecosystems. Various methods, including biomechanical analysis and 3D computer modeling, have been used to generate detailed functional hypotheses, but in the absence of either direct observations of dinosaur feeding behavior, or close living functional analogues, testing these hypotheses is problematic. Microscopic scratches that form on teeth in vivo during feeding are known to record the relative motion of the tooth rows to each other during feeding and to capture evidence of tooth–food interactions. Analysis of this dental microwear provides a powerful tool for testing hypotheses of jaw mechanics, diet, and trophic niche; yet, quantitative analysis of microwear in dinosaurs has not been attempted. Here, we show that analysis of tooth microwear orientation provides direct evidence for the relative motions of jaws during feeding in hadrosaurid ornithopods, the dominant terrestrial herbivores of the Late Cretaceous. Statistical testing demonstrates that Edmontosaurus teeth preserve 4 distinct sets of scratches in different orientations. In terms of jaw mechanics, these data indicate an isognathic, near-vertical posterodorsal power stroke during feeding; near-vertical jaw opening; and propalinal movements in near anterior and near posterior directions. Our analysis supports the presence of a pleurokinetic hinge, and the straightness and parallelism of scratches indicate a tightly controlled occlusion. The dominance of scratched microwear fabrics suggests that Edmontosaurus was a grazer rather than a browser.

dental microwear
hadrosaurid dinosaur
jaw mechanic
tooth
powerful tool


Experimental maturation of feathers: implications for reconstructions of fossil feather colour

Abstract: Fossil feathers often preserve evidence of melanosomes—micrometre-scale melanin-bearing organelles that have been used to infer original colours and patterns of the plumage of dinosaurs. Such reconstructions acknowledge that evidence from other colour-producing mechanisms is presently elusive and assume that melanosome geometry is not altered during fossilization. Here, we provide the first test of this assumption, using high pressure–high temperature autoclave experiments on modern feathers to simulate the effects of burial on feather colour. Our experiments show that melanosomes are retained despite loss of visual evidence of colour and complete degradation of other colour-producing structures (e.g. quasi-ordered arrays in barbs and the keratin cortex in barbules). Significantly, however, melanosome geometry and spatial distribution are altered by the effects of pressure and temperature. These results demonstrate that reconstructions of original plumage coloration in fossils where preserved features of melanosomes are affected by diagenesis should be treated with caution. Reconstructions of fossil feather colour require assessment of the extent of preservation of various colour-producing mechanisms, and, critically, the extent of alteration of melanosome geometry.

feather
fossilization
melanosome
barb
experimental maturation


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

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

ecology
marine tetrapod
tetrapod
ocean
mass extinction


PALEOGENE EVOLUTION OF PRECIPITATION IN NORTHEASTERN CHINA SUPPORTING THE MIDDLE EOCENE INTENSIFICATION OF THE EAST ASIAN MONSOON

Abstract: ABSTRACT The timing of the development of the East Asian monsoon in the geologic past is critically important for paleoclimatological studies, yet few quantitative data are available. Based on palynomorphs from six formations, supplemented by leaf fossils from one of these formations in Fushun, northeastern China, we present a quantitative estimate of the evolution of precipitation in this area during the middle Paleocene–late Eocene. The results demonstrate that seasonal precipitation prevailed during the interval, suggesting that the monsoonal system had already developed by this time. Comparing Paleogene climatic results from different latitudes in eastern China, we conclude that the East Asian monsoon must have been significantly enhanced after the late middle Eocene (∼41–40 Ma), due to increased precipitation differentiation between wet and dry months as shown in the present study. The influence of both the uplift of the Da Hinggan Mountains in northeastern Asia on regional topography and the India-Asia collision globally may have contributed to early monsoon intensification by their influence on air mass movement and associated precipitation patterns in the monsoonal realm.

precipitation
northeastern china
east asian monsoon
monsoonal system


Drowning, extinction, and subsequent facies development of the Devonian Hönne Valley Reef (northern Rhenish Massif, Germany)

Abstract: The Hagen-Balve Reef is one of the largest Devonian carbonate complexes in the Rhenish Massif exposed in many former or active, economically significant quarries, especially in the Hönne Valley region at its eastern end. The timing and patterns of reef drowning, final extinction, and the middle Frasnian to middle Famennian post-reefal facies history, including details of the global Kellwasser Crisis, were studied based on two boreholes (HON_1101 and B102) and one outcrop at the Beul near Eisborn. More than 100 conodont samples provided a fine biostratigraphic framework and included new forms left in open nomenclature. The ca. upper 80 m of the new Asbeck Member of the Hagen-Balve Formation consists of relatively monotonous lagoonal successions assigned to four microfacies types. The local diversity of reef builders, mostly stromatoporoids, is low. Fenestral microbialites indicate very shallow and rather hostile back-reef settings. Near the Middle/Upper Devonian boundary, the eustatic pulses of the global Frasnes Events led to a significant backstepping of the reef margin, with reef core/outer slope facies overlying lagoonal facies. This flooding drastically reduced the carbonate accumulation rate and enabled the invasion of drowned back-reef areas by open-water organisms, such as polygnathid conodonts. Within this Eisborn Member, five microfacies types and numerous subtypes are distinguished including lowdiversity "coral gardens" and a final, top lower Frasnian parabiostrome dominated by tabulate and colonial rugose corals. There was no cap stage ("Iberg Facies"). Two phases of the Basal Frasnes Event are marked by dark, organic rich limestones with subordinate reef builders. Based on conodont fauna from overlying nodular limestones of the new, (hemi-)pelagic Beul Formation, the final Hönne Valley reef extinction was caused by the eustatic Middlesex Event at the lower/middle Frasnian boundary. Within the Beul Formation, eight subphotic submarine rise microfacies types are distinguished. After a lower middle Frasnian phase of extreme condensation, rich conodont faunas enable the recognition of most upper Frasnian to middle Famennian zones. The global semichatovae Event led to a regionally unique intercalation by four phases of organic-rich, laminated black shales and intervening thin limestones in core HON_1101. The Lower Kellwasser Event is represented in HON_1101 by atypical, moderately C org -rich, recrystallized, peloidal ostracod-mollusk pack-grainstones. The Upper Kellwasser level begins with an ostracod bloom, followed either by recrystallized mollusk wacke-packstones (HON_1101) or laminated, argillaceous mudstones (B102). The first indicates a rarely documented shallow subphotic, better oxygenated setting than typical Upper Kellwasser facies. As elsewhere, the top-Frasnian conodont extinction was severe. The lower/middle Famennian carbonate microfacies of the Beul Formation is relatively monotonous and typical for an oxic, pelagic submarine rise. The youngest recorded nodular limestones fall in the Palmatolepis marginifera utahensis Zone. Regionally uniform lydites of the Hardt Formation show that the local palaeotopography was levelled before the base of the This article is a contribution to the special issue "The Rhenish Massif: More than 150 years of research in a Variscan mountain chain" *

reef
rhenish massif
hagen-balve reef complex
ardennes shelf


Bone microstructure and developmental plasticity in birds and other dinosaurs

Abstract: Patterns of bone microstructure have frequently been used to deduce dynamics and processes of growth in extant and fossil tetrapods. Often, the various types of primary bone tissue have been associated with different bone deposition rates and more recently such deductions have extended to patterns observed in dinosaur bone microstructure. These previous studies are challenged by the findings of the current research, which integrates an experimental neontological approach and a paleontological comparison. We use tetracycline labeling and morphometry to study the variability of bone deposition rates in Japanese quail (Coturnix japonica) growing under different experimental conditions. We compare resulting patterns in bone microstructure with those found in fossil birds and other dinosaurs. We found that a single type of primary bone varies significantly in rates of growth in response to environmental conditions. Ranging between 10–50 μm per day, rates of growth overlap with the full range of bone deposition rates that were previously associated with different patterns of bone histology. Bone formation rate was significantly affected by environmental/experimental conditions, skeletal element, and age. In the quail, the experimental conditions did not result in formation of lines of arrested growth (LAGs). Because of the observed variation of bone deposition rates in response to variation in environmental conditions, we conclude that bone deposition rates measured in extant birds cannot simply be extrapolated to their fossil relatives. Additionally, we observe the variable incidence of LAGs and annuli among several dinosaur species, including fossil birds, extant sauropsids, as well as nonmammalian synapsids, and some extant mammals. This suggests that the ancestral condition of the response of bone to environmental conditions was variable. We propose that such developmental plasticity in modern birds may be reduced in association with the shortened developmental time during the later evolution of the ornithurine birds. J. Morphol. 254:232–246, 2002. © 2002 Wiley‐Liss, Inc.

plasticity
other dinosaur
bone microstructure
blood vessel


The ecological consequences of megafaunal loss: giant tortoises and wetland biodiversity

Abstract: The giant tortoises of the Galápagos have become greatly depleted since European discovery of the islands in the 16th Century, with populations declining from an estimated 250 000 to between 8000 and 14 000 in the 1970s. Successful tortoise conservation efforts have focused on species recovery, but ecosystem conservation and restoration requires a better understanding of the wider ecological consequences of this drastic reduction in the archipelago's only large native herbivore. We report the first evidence from palaeoecological records of coprophilous fungal spores of the formerly more extensive geographical range of giant tortoises in the highlands of Santa Cruz Island. Upland tortoise populations on Santa Cruz declined 500–700 years ago, likely the result of human impact or possible climatic change. Former freshwater wetlands, a now limited habitat-type, were found to have converted to Sphagnum bogs concomitant with tortoise loss, subsequently leading to the decline of several now-rare or extinct plant species.

ecological consequence
giant tortoise
decline


Interpreting ecology and behaviour from the vertebrate fossil track record

Abstract: Fossil tracks represent a direct window onto the lives of extinct organisms, being formed and preserved in situ. Because track morphology is determined by limb motion, foot anatomy and substrate consistency, studies of fossil tracks can provide insight into producer, behaviour and palaeoenvironment. However, each determining factor is subject to variation, either continuous or discrete, and this variation may be co-dependent, making it difficult to correctly interpret a track. In addition to variance from the track-forming variables, tracks and tracksites are subject to further obfuscation because of time averaging, even before the effects of weathering, erosion and exposure are accounted for. This paper presents a discussion of the factors that may confound interpretation of fossil tracks, trackways and tracksites, and reviews experimental studies that have attempted to elucidate and eliminate these sources of confusion.

behaviour
track morphology
foot
substrate property


Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period

Abstract: The fossil record of the terminal Ediacaran Period is typified by the iconic index fossil Cloudina and its relatives. These tube-dwellers are presumed to be primitive metazoans, but resolving their phylogenetic identity has remained a point of contention. The root of the problem is a lack of diagnostic features; that is, phylogenetic interpretations have largely centered on the only available source of information—their external tubes. Here, using tomographic analyses of fossils from the Wood Canyon Formation (Nevada, USA), we report evidence of recognizable soft tissues within their external tubes. Although alternative interpretations are plausible, these internal cylindrical structures may be most appropriately interpreted as digestive tracts, which would be, to date, the earliest-known occurrence of such features in the fossil record. If this interpretation is correct, their nature as one-way through-guts not only provides evidence for establishing these fossils as definitive bilaterians but also has implications for the long-debated phylogenetic position of the broader cloudinomorphs.

cloudinomorph
terminal ediacaran period
relative


The Origin and Evolutionary Biology of Pinnipeds: Seals, Sea Lions, and Walruses

Abstract: The oldest definitive pinniped fossils date from approximately 30.6–23 million years ago (Ma) in the North Pacific. Pinniped monophyly is consistently supported; the group shares a common ancestry with arctoid carnivorans, either ursids or musteloids. Crown pinnipeds comprise the Otariidae (fur seals and sea lions), Odobenidae (walruses), and Phocidae (seals), with paraphyletic “enaliarctines” falling outside the crown group. The position of extinct Desmatophocidae is debated; they are considered to be closely related to both otariids and odobenids or, alternatively, to phocids. Both otariids and odobenids are known from the North Pacific, diverging approximately 19 Ma, with phocids originating in the North Atlantic or Paratethys region 19–14 Ma. Our understanding of pinniped paleobiology has been enriched by studies that incorporate anatomical and behavioral data into a phylogenetic framework. There is now evidence for sexual dimorphism in the earliest pinnipeds, heralding polygynous breeding systems, followed by increased body sizes, diving capabilities, and diverse feeding strategies in later-diverging phocid and otarioid lineages.

seal
sea lion
north pacific
otariidae
body size


Quantifying the dark data in museum fossil collections as palaeontology undergoes a second digital revolution

Abstract: Large-scale analysis of the fossil record requires aggregation of palaeontological data from individual fossil localities. Prior to computers, these synoptic datasets were compiled by hand, a laborious undertaking that took years of effort and forced palaeontologists to make difficult choices about what types of data to tabulate. The advent of desktop computers ushered in palaeontology's first digital revolution—online literature-based databases, such as the Paleobiology Database (PBDB). However, the published literature represents only a small proportion of the palaeontological data housed in museum collections. Although this issue has long been appreciated, the magnitude, and thus potential significance, of these so-called ‘dark data’ has been difficult to determine. Here, in the early phases of a second digital revolution in palaeontology—the digitization of museum collections—we provide an estimate of the magnitude of palaeontology's dark data. Digitization of our nine institutions' holdings of Cenozoic marine invertebrate collections from California, Oregon and Washington in the USA reveals that they represent 23 times the number of unique localities than are currently available in the PBDB. These data, and the vast quantity of similarly untapped dark data in other museum collections, will, when digitally mobilized, enhance palaeontologists’ ability to make inferences about the patterns and processes of past evolutionary and ecological changes.

dark data
palaeontology
digital revolution
digitization


The relative importance of directional change, random walks, and stasis in the evolution of fossil lineages

Abstract: The nature of evolutionary changes recorded by the fossil record has long been controversial, with particular disagreement concerning the relative frequency of gradual change versus stasis within lineages. Here, I present a large-scale, statistical survey of evolutionary mode in fossil lineages. Over 250 sequences of evolving traits were fit by using maximum likelihood to three evolutionary models: directional change, random walk, and stasis. Evolution in these traits was rarely directional; in only 5% of fossil sequences was directional evolution the most strongly supported of the three modes of change. The remaining 95% of sequences were divided nearly equally between random walks and stasis. Variables related to body size were significantly less likely than shape traits to experience stasis. This finding is in accord with previous suggestions that size may be more evolutionarily labile than shape and is consistent with some but not all of the mechanisms proposed to explain evolutionary stasis. In general, similar evolutionary patterns are observed across other variables, such as clade membership and temporal resolution, but there is some evidence that directional change in planktonic organisms is more frequent than in benthic organisms. The rarity with which directional evolution was observed in this study corroborates a key claim of punctuated equilibria and suggests that truly directional evolution is infrequent or, perhaps more importantly, of short enough duration so as to rarely register in paleontological sampling.

directional change
stasis
fossil lineage
maximum likelihood
body size


Beyond Coprinisphaera: fossil nests of dung beetles

Abstract: Forty-two remains of fossil nests of dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae), which were recorded in four formations of the Cenozoic of South America, are described herein for the first time. Most of them are represented by nesting chambers containing a fossil brood ball (Coprinisphaera). However, in the most remarkable cases, parts of the burrows constructed by the parents and/ or the vertical emergence burrows constructed by the offspring are preserved too. The preservation of the dung beetle nests is very unusual but more recurrent in younger formations probably because of the short-term action of the diagenetic processes. Considering that the construction of brood balls always involves the construction of nests, the ichnotaxonomical proposal is that the remains of fossil nests should be considered as 'structures associated with Coprinisphaera' and added to the diagnosis to avoid the proliferation of names. The study of the fossil nests provides new palaeoetological inferences for dung beetles, such as the Nesting Pattern of the trace makers of Coprinisphaera tonnii and Coprinisphaera akatanka, and how phylogenetically related were they with the extant necrophagous species of the genera Coprophanaeus and Canthon, respectively. Additionally, the fossil evidence suggests that simple nests of dung beetles predate compound nests. □ Fossil brood balls, nesting behaviour, nesting chambers, Scarabaeinae, trace fossils.

coprinisphaera
fossil nest
dung beetle
brood ball
extant necrophagous specie


Neanderthal Extinction by Competitive Exclusion

Abstract: Background Despite a long history of investigation, considerable debate revolves around whether Neanderthals became extinct because of climate change or competition with anatomically modern humans (AMH). Methodology/Principal Findings We apply a new methodology integrating archaeological and chronological data with high-resolution paleoclimatic simulations to define eco-cultural niches associated with Neanderthal and AMH adaptive systems during alternating cold and mild phases of Marine Isotope Stage 3. Our results indicate that Neanderthals and AMH exploited similar niches, and may have continued to do so in the absence of contact. Conclusions/Significance The southerly contraction of Neanderthal range in southwestern Europe during Greenland Interstadial 8 was not due to climate change or a change in adaptation, but rather concurrent AMH geographic expansion appears to have produced competition that led to Neanderthal extinction.

climate change
europe
neanderthal extinction
cause


Studies on Skeleton formation in reptiles. IV. The homology of the reptilian (amniote) astragalus revisited

Abstract: ABSTRACT In extant turtles and lepidosaurs, the astragalus forms from a single ossification center in a tarsale proximale resulting from fusion of originally separate chondrogenic condensations in the proximal tarsus. In crocodiles, the astragalus also ossifies from a single center although the cartilaginous precursors of astragalus and calcaneum do not fuse to form a tarsale proximale. Developmental stages of the parareptilian Mesosaurus document a similar ossification pattern, as do ontogenic series of a number of fossil diapsid reptiles. There is no consistent evidence of ontogenetic fusion of a “tibiale,” intermedium, and centrale to form the astragalus of Captorhinus. The development of the amniote astragalus contrasts with variable patterns of fusion of originally separate proximal tarsal ossifications in anthracosaurian amphibians and in Diadectes. It is concluded that the reptilian (and probably also the mammalian) astragalus is a neomorph, which resulted from ontogenetic repatterning and is diagn...


First evidence of azhdarchid pterosaurs from the Late Cretaceous of Hungary

Abstract: New remains of an azhdarchid pterosaur were discovered from the Upper Cretaceous (Santonian) Csehbánya Formation at the Iharkút vertebrate locality in the Bakony Mountains, western Hungary. Among the isolated bones, consisting principally of 21 symphyseal jaw fragments, four cervical vertebrae, a right radius, and some fragmentary limb bones, is a complete articulated mandible that represents one of the best-preserved mandibular material of any presently known azhdarchid pterosaur. The complete edentulous jaw, referred to Bakonydraco galaczi gen. et sp. nov. posesses several features diagnostic for azhdarchids which prove that Bakonydraco belongs to this group. The cervical vertebrae exhibit azhdarchid features and consequently are referred to as Azhdarchidae indet. The discovery of these fossils helps to understand the construction of the azhdarchid mandible and provides new insight for studying the feeding style of the edentulous azhdarchid pterosaurs.

azhdarchid pterosaur
santonian
bakonydraco


Genomic and archaeological evidence suggest a dual origin of domestic dogs

Abstract: A dogged investigation of domestication The history of how wolves became our pampered pooches of today has remained controversial. Frantz et al. describe high-coverage sequencing of the genome of an Irish dog from the Bronze Age as well as ancient dog mitochondrial DNA sequences. Comparing ancient dogs to a modern worldwide panel of dogs shows an old, deep split between East Asian and Western Eurasian dogs. Thus, dogs were domesticated from two separate wolf populations on either side of the Old World. Science, this issue p. 1228 Dogs may have been domesticated independently in Eastern and Western Eurasia from distinct wolf populations. The geographic and temporal origins of dogs remain controversial. We generated genetic sequences from 59 ancient dogs and a complete (28x) genome of a late Neolithic dog (dated to ~4800 calendar years before the present) from Ireland. Our analyses revealed a deep split separating modern East Asian and Western Eurasian dogs. Surprisingly, the date of this divergence (~14,000 to 6400 years ago) occurs commensurate with, or several millennia after, the first appearance of dogs in Europe and East Asia. Additional analyses of ancient and modern mitochondrial DNA revealed a sharp discontinuity in haplotype frequencies in Europe. Combined, these results suggest that dogs may have been domesticated independently in Eastern and Western Eurasia from distinct wolf populations. East Eurasian dogs were then possibly transported to Europe with people, where they partially replaced European Paleolithic dogs.


Flowering after disaster: Early Danian buckthorn (Rhamnaceae) flowers and leaves from Patagonia

Abstract: Southern-Hemisphere terrestrial communities from the early Paleocene are poorly known, but recent work on Danian plant fossils from the Salamanca Formation in Chubut Province, Argentina are providing critical data on earliest Paleocene floras. The fossils described here come from a site in the Salamanca Formation dating to ca. 1 million years or less after the end-Cretaceous extinction event; they are the first fossil flowers reported from the Danian of South America, and possible the entire Southern Hemisphere. They are compressions and impressions in flat-laminated light gray shale, and they belong to the family Rhamnaceae (buckthorns). Flowers of Notiantha grandensis gen. et sp. nov. are pentamerous, with distinctly keeled calyx lobes projecting from the hypanthium, clawed and cucullate emarginate petals, antepetalous stamens, and a pentagonal floral disk that fills the hypanthium. Their phylogenetic position was evaluated using a molecular scaffold approach combined with morphological data. Results indicate that the flowers are most like those of extant ziziphoid Rhamnaceae. The associated leaves, assigned to Suessenia grandensis gen. et sp. nov. are simple and ovate, with serrate margins and three acrodromous basal veins. They conform to the distinctive leaves of some extant Rhamnaceae in the ziziphoid and ampelozizyphoid clades. These fossils provide the first unequivocal megafossil evidence of Rhamnaceae in the Southern Hemisphere, demonstrating that Rhamnaceae expanded beyond the tropics by the earliest Paleocene. Given previous reports of rhamnaceous pollen in the late Paleogene and Neogene of Antarctica and southern Australia, this new occurrence increases the possibility of high-latitude dispersal of this family between South America and Australia via Antarctica during the Cenozoic.

buckthorn
rhamnaceae
salamanca formation
flower


Abstract: Kear, B.P., Fordyce, R.E., Hiller, N. & Siversson, M., December 2017. A palaeobiogeographical synthesis of Australasian Mesozoic marine tetrapods. Alcheringa 42, 461-486. ISSN 0311-5518. THE LAST 15 years has witnessed a blossoming of research on Australasian Mesozoic marine tetrapod fossils. Much of this work has focused on amniotes, particularly those from the prolific Lower Cretaceous (Aptian–Albian) Lagerstätten of the Eromanga Basin in central and eastern Australia, and Upper Cretaceous (Campanian–Maastrichtian) sequences of the North and South islands of New Zealand. However, rare and less popularized remains have also been found in Lower Triassic–mid-Cretaceous rocks from Australia, New Zealand and the Chatham Islands, and on the tectonically proximal landmasses of New Caledonia and Timor. Currently identified taxa include estuarine–paralic rhytidostean, brachyopid, capitosaurian and trematosaurian temnospondyls from the earliest Triassic (Induan–Olenekian), Middle–Late Triassic (Anisian–Norian) eosauropterygians, and mixosaurian, shastasaurian and euichthyosaurian ichthyosaurians, Early–Middle Jurassic (Sinemurian–Bajocian) ichthyosaurians, together with plesiosauroid and rhomaleosaurid-like plesiosaurians, and diverse Early (Aptian–Albian) through to Late Cretaceous (Campanian–Maastrichtian) elasmosaurid, leptocleidid, polycotylid, probable cryptoclidid and pliosaurid plesiosaurians, as well as ophthalmosaurid ichthyosaurians, sea turtles incorporating protostegids, and mosasaurid squamates. This faunal succession evidences almost continuous occupation of southern high-palaeolatitude seas, and repeated endemic diversifications (including nascent members of some key lineages) amongst emigrant cosmopolitan clades. The primary dispersal routes are likely to have been peri-Gondwanan, with coastal migrations along the western Tethys and polar margins of the Panthalassan Ocean. However, augmentation by increasing continental fragmentation and seaway corridor connectivity probably occurred from the Middle Jurassic to Late Cretaceous. Latest Cretaceous mosasaurid and elasmosaurid taxa also reveal regional affinities with the emergent western Pacific and Weddellian austral bioprovinces. The extreme rarity, or complete absence, of many major groups prevalent elsewhere in Gondwana (e.g., tanystropheids, Triassic sauropterygians, bothremydid marine turtles, thalattosuchians and dyrosaurid crocodylomorphs) is conspicuous, and might be related to stratigraphical/collecting biases, or the predominantly higher-palaeolatitude, cooler-water Mesozoic palaeogeography of the Australasian region. Although the burgeoning record is substantial, much still awaits discovery and adequate documentation; thus Australasia is still one of the most exciting prospects for future insights into the global history of Mesozoic marine tetrapods. Benjamin P. Kear* [benjamin.kear@em.uu.se] Museum of Evolution, Uppsala University, Norbyvägen 16, SE-752 36 Uppsala, Sweden; R. Ewan Fordyce [ewan.fordyce@otago.ac.nz] Department of Geology, University of Otago, Post Box 56, Dunedin 9054, New Zealand; Norton Hiller [norton.hiller@gmail.com] Canterbury Museum, Rolleston Avenue, Christchurch 8013, New Zealand; Mikael Siversson [mikael.siversson@museum.wa.gov.au] Western Australian Museum, 49 Kew Street, Welshpool, Western Australia 6106.

palaeobiogeographical synthesis
australasian mesozoic
marine tetrapod


Tarsal morphology of the pleuraspidotheriid mammal Hilalia from the middle Eocene of Turkey

Abstract: Pleuraspidotheriids are a group of primitive ungulate mammals that, until recently, were thought to be restricted to the late Paleocene of Western Europe. It has been hypothesized that this family actually survived in Central Anatolia until at least the middle Eocene. However, these anachronistically young Anatolian “survivors”, including the genus Hilalia, were previously documented mainly by dental remains. Here, we describe the previously unknown astragalus of Hilalia saribeya, which confirms the pleuraspidotheriid affinities of the genus, and supports phylogenetic reconstructions that place Hilalia as the sister group of Pleuraspidotherium. The morphology of the astragalus suggests sub-cursorial plantigrade locomotion for H. saribeya, although its tarsal morphology remains generalized enough that scansorial capabilities cannot be ruled out. The evolution of Hilalia is addressed in the context of the apparent geographic isolation of Central Anatolia during the Eocene. The endemic character of the mammalian fauna of Central Anatolia during the middle Eocene emphasizes how the complex paleogeography of the northern margin of Neotethys impacted local biotas in a region situated at the crossroads of very distinctive biogeographic zones.

pleuraspidotheriid
hilalia
late paleocene
tarsal morphology


The ichnogenus Lumbricaria Münster from the Upper Jurassic of Germany interpreted as faecal strings of ammonites

Abstract: The trace fossil Lumbricaria Münster is a common constituent of the Upper Jurassic lithographic limestones in southern Germany. Despite having been recognized more than 300 years ago, its nature and producer remain enigmatic. Controversial interpretations of Lumbricaria regard it either as the remains of worms, or as cololites (i.e. faecal material preserved in the gut) or coprolites (i.e. ejected faecal material) of worms, fish, holothurians or cephalopods. A morphological analysis of the type material and numerous specimens reveals two basic morphotypes of Lumbricaria, conformable with the ichnospecies L. intestinum (loosely confined, intertwined to elongate) and L. colon (well confined, densely entangled). Transitions and combinations between both ichnospecies exist and are the result of taphonomic effects. A comparison with modern analogues favours cephalopods (in particular nautiloids or ammonites) as the most likely producers of Lumbricaria, an interpretation that is supported by the finding of an Upper Jurassic nautiloid cast preserving a Lumbricaria‐like faecal string within its body chamber. Ammonites are the likely producers of Lumbricaria from the Upper Jurassic of Germany.


Early Use of Pressure Flaking on Lithic Artifacts at Blombos Cave, South Africa

Abstract: Ancient Innovations Pressure flaking is a method of forming points, grooves, and notches on stone tools in which a tool is pressed up against another stone, instead of striking it. It has been thought to be a fairly recent innovation, arising in the Upper Paleolithic 20,000 or so years ago. Mourre et al. (p. 659), show that tools from Blombos Cave, dating to about 75,000 years ago, have grooves and patterns resembling production by heat treatment followed by pressure flaking. Replication experiments were performed using similar source material followed by microscopic study of the tools. Despite the evidence for an early innovation, it seems that pressure flaking was not used widely elsewhere until much later; thus, such early innovations may have been sporadic ephemeral. Tools dating to ~75,000 years ago show evidence of pressure flaking, long before the technique became widespread. Pressure flaking has been considered to be an Upper Paleolithic innovation dating to ~20,000 years ago (20 ka). Replication experiments show that pressure flaking best explains the morphology of lithic artifacts recovered from the ~75-ka Middle Stone Age levels at Blombos Cave, South Africa. The technique was used during the final shaping of Still Bay bifacial points made on heat‐treated silcrete. Application of this innovative technique allowed for a high degree of control during the detachment of individual flakes, resulting in thinner, narrower, and sharper tips on bifacial points. This technology may have been first invented and used sporadically in Africa before its later widespread adoption.

pressure flaking
lithic artifact
blombos cave
point


An Early Instance of Upper Palaeolithic Personal Ornamentation from China: The Freshwater Shell Bead from Shuidonggou 2

Abstract: We report the discovery and present a detailed analysis of a freshwater bivalve from Shuidonggou Locality 2, layer CL3. This layer is located c. 40 cm below layer CL2, which has yielded numerous ostrich eggshell beads. The shell is identified as the valve of a Corbicula fluminea. Data on the occurrence of this species in the Shuidonggou region during Marine Isotope Stage 3 and taphonomic analysis, conducted in the framework of this study, of a modern biocoenosis and thanatocoenosis suggest that the archeological specimen was collected at one of the numerous fossil or sub-fossil outcrops where valves of this species were available at the time of occupation of level CL3. Experimental grinding and microscopic analysis of modern shells of the same species indicate that the Shuidonggou shell was most probably ground on coarse sandstone to open a hole on its umbo, attach a thread, and use the valve as a personal ornament. Experimental engraving of freshwater shells and microscopic analysis identify an incision crossing the archaeological valve outer surface as possible deliberate engraving. Reappraisal of the site chronology in the light of available radiocarbon evidence suggests an age of at least 34–33 cal kyr BP for layer CL3. Such estimate makes the C. fluminea recovered from CL3 one of the earliest instances of personal ornamentation and the earliest example of a shell bead from China.


La2010: a new orbital solution for the long-term motion of the Earth

Abstract: We present here a new solution for the astronomical computation of the orbital motion of the Earth spanning from 0 to −250 Myr. The main improvement with respect to our previous numerical solution La2004 is an improved adjustment of the parameters and initial conditions through a fit over 1 Myr to a special version of the highly accurate numerical ephemeris INPOP08 (Integration Numerique Planetaire de l'Observatoire de Paris). The precession equations have also been entirely revised and are no longer averaged over the orbital motion of the Earth and Moon. This new orbital solution is now valid over more than 50 Myr in the past or into the future with proper phases of the eccentricity variations. Owing to the chaotic behavior, the precision of the solution decreases rapidly beyond this time span, and we discuss the behavior of various solutions beyond 50 Myr. For paleoclimate calibrations, we provide several different solutions that are all compatible with the most precise planetary ephemeris. We have thus reached the time where geological data are now required to discriminate between planetary orbital solutions beyond 50 Myr.

new orbital solution
solution
motion
past


The Ladder of Life Detection

Abstract: Abstract We describe the history and features of the Ladder of Life Detection, a tool intended to guide the design of investigations to detect microbial life within the practical constraints of robotic space missions. To build the Ladder, we have drawn from lessons learned from previous attempts at detecting life and derived criteria for a measurement (or suite of measurements) to constitute convincing evidence for indigenous life. We summarize features of life as we know it, how specific they are to life, and how they can be measured, and sort these features in a general sense based on their likelihood of indicating life. Because indigenous life is the hypothesis of last resort in interpreting life-detection measurements, we propose a small but expandable set of decision rules determining whether the abiotic hypothesis is disproved. In light of these rules, we evaluate past and upcoming attempts at life detection. The Ladder of Life Detection is not intended to endorse specific biosignatures or instruments for life-detection measurements, and is by no means a definitive, final product. It is intended as a starting point to stimulate discussion, debate, and further research on the characteristics of life, what constitutes a biosignature, and the means to measure them.


Old African fossils provide new evidence for the origin of the American crocodiles

Abstract: Molecular and morphological phylogenies concur in indicating that the African lineages formerly referred to Crocodylus niloticus are the sister taxon the four Neotropical crocodiles (Crocodylus intermedius, C. moreleti, C. acutus and C. rhombifer), implying a transoceanic dispersal from Africa to America. So far the fossil record did not contribute to identify a possible African forerunner of the Neotropical species but, curiously, the oldest remains referred to the African C. niloticus are Quaternary in age, whereas the oldest American fossils of Crocodylus are older, being dated to the early Pliocene, suggesting that another species could be involved. We re-described, also thanks to CT imaging, the only well-preserved topotipic skull of Crocodylus checchiai Maccagno, 1947 from the late Miocene (Messinian) African site of As Sahabi in Libya. As previously suggested on the basis of late Miocene material from Tanzania, C. checchiai is a valid, diagnosable species. According to our phylogenetic analyses, C. checchiai is related to the Neotropical taxa and could be even located at the base of their radiation, therefore representing the missing link between the African and the American lineages.


X-ray microscopy reveals endophallic structures in a new species of the ground beetle genus Trechus Clairville, 1806 from Baltic amber (Coleoptera, Carabidae, Trechini)

Abstract: Abstract The third fossil species of the genus Trechus Clairville, 1806 is described from Baltic amber: Trechus exhibitorius sp. n. Details of external and internal morphology were analysed using X-ray micro-computed tomography (micro-CT) and important diagnostic features of the internal male genital sac (endophallus) are described in detail for the first time in a fossil ground beetle. Based on these data, we could assign Trechus exhibitorius sp. n. to Trechus sensu stricto and this new fossil species seems to represent a basal branch of a lineage comprising species diverse groups of extant Trechus mainly distributed in the Caucasus and Anatolia. Thus, our results support previous studies suggesting that Trechus is a phylogenetically old lineage already present in the Eocene with numerous species.


The Miocene: The Future of the Past

Abstract: The Miocene epoch (23.03–5.33 Ma) was a time interval of global warmth, relative to today. Continental configurations and mountain topography transitioned toward modern conditions, and many flora and fauna evolved into the same taxa that exist today. Miocene climate was dynamic: long periods of early and late glaciation bracketed a ∼2 Myr greenhouse interval—the Miocene Climatic Optimum (MCO). Floras, faunas, ice sheets, precipitation, pCO2, and ocean and atmospheric circulation mostly (but not ubiquitously) covaried with these large changes in climate. With higher temperatures and moderately higher pCO2 (∼400–600 ppm), the MCO has been suggested as a particularly appropriate analog for future climate scenarios, and for assessing the predictive accuracy of numerical climate models—the same models that are used to simulate future climate. Yet, Miocene conditions have proved difficult to reconcile with models. This implies either missing positive feedbacks in the models, a lack of knowledge of past climate forcings, or the need for re‐interpretation of proxies, which might mitigate the model‐data discrepancy. Our understanding of Miocene climatic, biogeochemical, and oceanic changes on broad spatial and temporal scales is still developing. New records documenting the physical, chemical, and biotic aspects of the Earth system are emerging, and together provide a more comprehensive understanding of this important time interval. Here, we review the state‐of‐the‐art in Miocene climate, ocean circulation, biogeochemical cycling, ice sheet dynamics, and biotic adaptation research as inferred through proxy observations and modeling studies.

miocene
warmth
flora
future climate scenario
concentration


Using a theoretical ecospace to quantify the ecological diversity of Paleozoic and modern marine biotas

Abstract: Abstract The process of evolution hinders our ability to make large-scale ecological comparisons—such as those encompassing marine biotas spanning the Phanerozoic—because the compared entities are taxonomically and morphologically dissimilar. One solution is to focus instead on life habits, which are repeatedly discovered by taxa because of convergence. Such an approach is applied to a comparison of the ecological diversity of Paleozoic (Cambrian–Devonian) and modern marine biotas from deep-subtidal, soft-substrate habitats. Ecological diversity (richness and disparity) is operationalized by using a standardized ecospace framework that can be applied equally to extant and extinct organisms and is logically independent of taxonomy. Because individual states in the framework are chosen a priori and not customized for particular taxa, the framework fulfills the requirements of a universal theoretical ecospace. Unique ecological life habits can be recognized as each discrete, n-dimensional combination of character states in the framework. Although the basic unit of analysis remains the organism, the framework can be applied to other entities—species, clades, or multispecies assemblages—for the study of comparative paleoecology and ecology. Because the framework is quantifiable, it is amenable to analytical techniques used for morphological disparity. Using these methods, I demonstrate that the composite Paleozoic biota is approximately as rich in life habits as the sampled modern biota, but that the life habits in the modern biota are significantly more disparate than those in the Paleozoic; these results are robust to taphonomic standardization. Despite broadly similar distributions of life habits revealed by multivariate ordination, the modern biota is composed of life habits that are significantly enriched, among others, in mobility, infaunality, carnivory, and exploitation of other organisms (or structures) for occupation of microhabitats.

ecological diversity
paleozoic
modern marine biota


Structure and function of a compound eye, more than half a billion years old

Abstract: Significance An exceptionally well-preserved arthropod fossil from near the base of the lower Cambrian shows the internal sensory structures of a compound eye, more than half a billion years old. The trilobite to which it belongs is found in a zone where the first complete organisms appear in the fossil record; thus, it is probably the oldest record of a visual system that ever will be available. This compound eye proved to possess the same kind of structure as the eyes of bees and dragonflies living today, but it lacks the lenses that are typical of modern eyes of this type. There is an elegant physical solution, however, of how to develop a quality image of modern type. Until now, the fossil record has not been capable of revealing any details of the mechanisms of complex vision at the beginning of metazoan evolution. Here, we describe functional units, at a cellular level, of a compound eye from the base of the Cambrian, more than half a billion years old. Remains of early Cambrian arthropods showed the external lattices of enormous compound eyes, but not the internal structures or anything about how those compound eyes may have functioned. In a phosphatized trilobite eye from the lower Cambrian of the Baltic, we found lithified remnants of cellular systems, typical of a modern focal apposition eye, similar to those of a bee or dragonfly. This shows that sophisticated eyes already existed at the beginning of the fossil record of higher organisms, while the differences between the ancient system and the internal structures of a modern apposition compound eye open important insights into the evolution of vision.


Estimating taxonomic diversity, extinction rates, and speciation rates from fossil data using capture-recapture models

Abstract: Methods currently used to estimate taxonomic extinction probabilities from fossil data generally assume that the probability of encountering a specimen in a particular stratum, given that the taxon was extant in the time period and location represented by the stratum, either equals 1.0 or else is a constant for all strata. Methods used to estimate taxonomic diversity (number of taxa) and speciation rate generally assume that encounter probabilities equal 1.0. We suspect that these assumptions are often false. Capture-recapture models were historically developed for estimation in the face of variable and unknown sampling probabilities. These models can thus be used to estimate parameters of interest from paleobiological data when encounter probabilities are unknown and variable over time. These models also permit estimation of sampling variances, and goodness-of-fit tests are available for assessing the fit of data to most models. Here we describe capture-recapture models which should be useful in paleobiological analyses and discuss the assumptions which underlie them. We illustrate these models with examples and discuss aspects of study design. We conclude that these models should prove useful in paleobiological analyses.

speciation rate
fossil data
capture-recapture model


Latitude, urbanization, age, and sex as risk factors for vitamin D deficiency disease in the Roman Empire.

Abstract:
OBJECTIVES
The aims of the study are to investigate the effects of latitude, settlement type, age, and sex on the prevalence of vitamin D deficiency disease in the Roman Empire using human skeletal remains from cemetery sites (1st to 6th cent. AD).

MATERIALS AND METHODS
Data from 2,787 individuals (1,143 subadults, 1,644 adults) from 18 cemeteries associated with 15 different settlements in the Mediterranean and north-western Europe were analyzed. Vitamin D deficiency disease (rickets, osteomalacia) was identified using standard paleopathological criteria. Multivariate statistical analysis was used analyze the effects of the variables of interest on the prevalence of vitamin D deficiency.

RESULTS
The overall prevalence of rickets in subadults (<20 years) was 5.7%, and 3.2% of adults showed osteomalacia and/or residual rickets. There was a positive association between rickets in subadults and latitude, with numerous cases of rickets among infants. There was no general association with sex or settlement type, although an elevated prevalence of rickets was observed at a cemetery associated with a settlement (Ostia, Italy), which had multi-storey buildings.

DISCUSSION
The association of rickets with latitude may reflect care practices that, in more northerly locations where solar radiation is less intense, placed infants at increased risk of insufficient sunlight exposure to permit adequate vitamin D biosynthesis. The elevated level of vitamin D deficiency at Ostia may reflect, at least in part, the lack of sunlight due to dense occupation of multi-storey blocks that prevented direct sunlight from reaching living quarters and the streets between these closely spaced buildings.

vitamin
deficiency disease
variable
latitude


Craniodental Morphology and Systematics of a New Family of Hystricognathous Rodents (Gaudeamuridae) from the Late Eocene and Early Oligocene of Egypt

Abstract: Background Gaudeamus is an enigmatic hystricognathous rodent that was, until recently, known solely from fragmentary material from early Oligocene sites in Egypt, Oman, and Libya. Gaudeamus' molars are similar to those of the extant cane rat Thryonomys, and multiple authorities have aligned Gaudeamus with Thryonomys to the exclusion of other living and extinct African hystricognaths; recent phylogenetic analyses have, however, also suggested affinities with South American caviomorphs or Old World porcupines (Hystricidae). Methodology/Principal Findings Here we describe the oldest known remains of Gaudeamus, including largely complete but crushed crania and complete upper and lower dentitions. Unlike younger Gaudeamus species, the primitive species described here have relatively complex occlusal patterns, and retain a number of plesiomorphic features. Unconstrained parsimony analysis nests Gaudeamus and Hystrix within the South American caviomorph radiation, implying what we consider to be an implausible back-dispersal across the Atlantic Ocean to account for Gaudeamus' presence in the late Eocene of Africa. An analysis that was constrained to recover the biogeographically more plausible hypothesis of caviomorph monophyly does not place Gaudeamus as a stem caviomorph, but rather as a sister taxon of hystricids. Conclusions/Significance We place Gaudeamus species in a new family, Gaudeamuridae, and consider it likely that the group originated, diversified, and then went extinct over a geologically brief period of time during the latest Eocene and early Oligocene in Afro-Arabia. Gaudeamurids are the only known crown hystricognaths from Afro-Arabia that are likely to be aligned with non-phiomorph members of that clade, and as such provide additional support for an Afro-Arabian origin of advanced stem and basal crown members of Hystricognathi.

hystricognathous rodent
gaudeamuridae
late eocene


Trilobite taphonomy and taxonomy; a problem and some implications

Abstract: Recent advances in trilobite taphonomy have highlighted the importance of sclerite preservation for understanding sedimentary processes and aspects of trilobite paleoecology (Speyer and Brett, 1985, 1986; Westrop, 1986; Babcock and Speyer, 1987; Speyer, 1987, 1988). The effect of taphonomy on trilobite taxonomy has received less attention. Consequently, it is not possible to evaluate the broader effects of taphonomy on our understanding of evolution and biogeography, and some recent studies of evolutionary patterns within the group (e.g., Foote, 1990, 1991, 1993) have been restricted to forms occurring within particular lithofacies. Numerous systematic papers discuss how preservation affects particular characters or character sets. Examples include the effects of compaction on sclerite morphology in specimens preserved in fine grain clastic sediments (e.g., Kiaer, 1917; Fortey, 1974), differences between carbonate and clastic preservation (e.g., Taylor, 1978), the differences in the morphology of internal and external molds (e.g., Jell, 1985), and how taphonomic artifacts have been mistaken for biological features (Hughes, 1993). However, such examples refer to specific instances, and are of limited use in evaluating the broader implications of taphonomy on trilobite taxonomy. As taphonomic conditions vary markedly between sedimentary environments, the effects of taphonomy on trilobite systematics are likely to be greatest on those taxa which occur in a wide range of lithofacies. Such taxa are often the most useful for providing inter-regional correlations and hence have critical significance for biogeography and biostratigraphy. Here I present a brief illustrative example of the potential effects of taphonomy on the taxonomy of one trilobite, the middle Cambrian conocoryphid Bailiella, and a discussion of the implications of this example for other areas of paleontology. Bailiella is an appropriate trilobite to use as an example for several reasons. Firstly, as an eyeless conocoryphid trilobite its morphology is distinct from that of many generalized "ptychopariid" trilobites, with which it is co-occurrent. Its distinctiveness allows us to be relatively confident of its identification, despite the taphonomic differences detailed below. Secondly, the genus is widespread and occurs in a variety of paleoenvironments. A revision of the systematics of Bailiella species from China, Vietnam, India and Siberia, indicates that the position of the facial suture (cutting the border) provides a consistent characteristic that can be used to recognize the species B. lantenoisi (see Zhang and Jell, 1987, pl. 35, figs. 1-7). This species is found both in shelfal carbonate settings (China and Siberia), where it is usually found as disarticulated sclerites, and in finegrain clastic slope deposits (Vietnam and India) where it occurs both as articulated dorsal shields and as disarticulated sclerites. These different preservation styles present alternative character suites to the systematist. For example, cranidia preserved in carbonates possess original relief and fine details of surface ornament. The preservation potential of these types of features is reduced in specimens preserved in shales, because the skeletal material is often absent and the specimens are compressed composite molds. The presence of articulated dorsal exoskeletons in this type of setting, however, provides a suite of characteristics that are not available for evaluation in specimens from shelf carbonates. Such characteristics include the number of thoracic segments, and the overall body proportions. Peter Jell and I are preparing a redescription of B. lantenoisi that lists some 38 "major" characters (Table 1). Parentheses are used here because the question of what constitutes a character is subjective in any systematic analysis (see Adrain and Chatterton, 1990), and character choice is especially difficult when the morphology includes both biological and preservational components. Another systematist would not describe an identical set of characters, but the magnitude of preservational factors documented below far outweighs slight differences of character interpretation. The greater number of characters listed for the cranidium (23) than for the remainder of the dorsal exoskeleton (15) (Table 1) reflects the concentration of distinctive morphological features on that sclerite. Of the 38 characters, only 14 appear to have resisted modification by preservational biases, and can be compared with confidence in specimens from all lithofacies settings (Table 1). Variation in any of these 14 characters could potentially be used to define different taxa, but apparently does not do so in this case. Of the remaining 24 characters we can be less confident. 18 characteristics can only be coded with confidence in specimens from carbonates preserving relief and fine detail, 4 are codable only in articulated dorsal shields, presently known only from slope settings, and 2 cannot be coded with confidence in either setting. Each of these 24 characteristics could potentially indicate taxonomic differences between B. lantenoisi collections preserved in different taphonomic settings. However, as these


Simulating sauropod manus-only trackway formation using finite-element analysis

Abstract: The occurrence of sauropod manus-only trackways in the fossil record is poorly understood, limiting their potential for understanding locomotor mechanics and behaviour. To elucidate possible causative mechanisms for these traces, finite-element analyses were conducted to model the indentation of substrate by the feet of Diplodocus and Brachiosaurus. Loading was accomplished by applying mass, centre of mass and foot surface area predictions to a range of substrates to model track formation. Experimental results show that when pressure differs between manus and pes, as determined by the distribution of weight and size of respective autopodia, there is a range of substrate shear strengths for which only the manus (or pes) produce enough pressure to deform the substrate, generating a track. If existing reconstructions of sauropod feet and mass distributions are correct, then different taxa will produce either manus- or pes-only trackways in specific substrates. As a result of this work, it is predicted that the occurrence of manus- or pes-only trackways may show geo-temporal correlation with the occurrence of body fossils of specific taxa.

sauropod manus-only trackway
manus-only trackway
finite-element analysis


Genetic contributions to variation in human stature in prehistoric Europe

Abstract: Significance Measurements of prehistoric human skeletal remains provide a record of changes in height and other anthropometric traits over time. Often, these changes are interpreted in terms of plastic developmental response to shifts in diet, climate, or other environmental factors. These changes can also be genetic in origin, but, until recently, it has been impossible to separate the effects of genetics and environment. Here, we use ancient DNA to directly estimate genetic changes in phenotypes and to identify changes driven not by genetics, but by environment. We show that changes over the past 35,000 y are largely predicted by genetics but also identify specific shifts that are more likely to be environmentally driven. The relative contributions of genetics and environment to temporal and geographic variation in human height remain largely unknown. Ancient DNA has identified changes in genetic ancestry over time, but it is not clear whether those changes in ancestry are associated with changes in height. Here, we directly test whether changes over the past 38,000 y in European height predicted using DNA from 1,071 ancient individuals are consistent with changes observed in 1,159 skeletal remains from comparable populations. We show that the observed decrease in height between the Early Upper Paleolithic and the Mesolithic is qualitatively predicted by genetics. Similarly, both skeletal and genetic height remained constant between the Mesolithic and Neolithic and increased between the Neolithic and Bronze Age. Sitting height changes much less than standing height—consistent with genetic predictions—although genetics predicts a small post-Neolithic increase that is not observed in skeletal remains. Geographic variation in stature is also qualitatively consistent with genetic predictions, particularly with respect to latitude. Finally, we hypothesize that an observed decrease in genetic heel bone mineral density in the Neolithic reflects adaptation to the decreased mobility indicated by decreased femoral bending strength. This study provides a model for interpreting phenotypic changes predicted from ancient DNA and demonstrates how they can be combined with phenotypic measurements to understand the relative contribution of genetic and developmentally plastic responses to environmental change.

contribution
stature
height
genetic contribution


Estimating the body mass of extinct ungulates: a study on the use of multiple regression

Abstract: The correlation between body mass and both skeletal and dental measures in living mammals has enabled paleontologists to obtain reliable estimates of body size for extinct species, usually using log-transformed bivariate least-squares regression equations. Multiple regression, however, has rarely been used for estimating the mass of extinct species, although this technique can clearly improve the predictive equations compared with those adjusted by simple regression. However, the use of multiple regression is problematical, because even those functions explaining a high percentage of the variance of the dependent variable (i.e. body mass) can show a rather limited predictive power. After analyzing which factors determine the predictive ability of multiple regression equations, we propose a new set of algorithms that allow the estimation of the body mass of extinct ungulates. These algorithms are finally applied to three Miocene ungulate species, Dinohippus leidyanus, Stenomylus hitchcocki and Aletomeryx scotti.

body mass
extinct ungulate
multiple regression


Time-calibrated molecular phylogeny of pteropods

Abstract: Pteropods are a widespread group of holoplanktonic gastropod molluscs and are uniquely suitable for study of long-term evolutionary processes in the open ocean because they are the only living metazoan plankton with a good fossil record. Pteropods have been proposed as bioindicators to monitor the impacts of ocean acidification and in consequence have attracted considerable research interest, however, a robust evolutionary framework for the group is still lacking. Here we reconstruct their phylogenetic relationships and examine the evolutionary history of pteropods based on combined analyses of Cytochrome Oxidase I, 28S, and 18S ribosomal rRNA sequences and a molecular clock calibrated using fossils and the estimated timing of the formation of the Isthmus of Panama. Euthecosomes with uncoiled shells were monophyletic with Creseis as the earliest diverging lineage, estimated at 41–38 million years ago (mya). The coiled euthecosomes (Limacina, Heliconoides, Thielea) were not monophyletic contrary to the accepted morphology-based taxonomy; however, due to their high rate heterogeneity no firm conclusions can be drawn. We found strong support for monophyly of most euthecosome genera, but Clio appeared as a polyphyletic group, and Diacavolinia grouped within Cavolinia, making the latter genus paraphyletic. The highest evolutionary rates were observed in Heliconoides inflatus and Limacina bulimoides for both 28S and 18S partitions. Using a fossil-calibrated phylogeny that sets the first occurrence of coiled euthecosomes at 79–66 mya, we estimate that uncoiled euthecosomes evolved 51–42 mya and that most extant uncoiled genera originated 40–15 mya. These findings are congruent with a molecular clock analysis using the Isthmus of Panama formation as an independent calibration. Although not all phylogenetic relationships could be resolved based on three molecular markers, this study provides a useful resource to study pteropod diversity and provides general insight into the processes that generate and maintain their diversity in the open ocean.


Dental functional traits of mammals resolve productivity in terrestrial ecosystems past and present

Abstract: We have recently shown that rainfall, one of the main climatic determinants of terrestrial net primary productivity (NPP), can be robustly estimated from mean molar tooth crown height (hypsodonty) of mammalian herbivores. Here, we show that another functional trait of herbivore molar surfaces, longitudinal loph count, can be similarly used to extract reasonable estimates of rainfall but also of temperature, the other main climatic determinant of terrestrial NPP. Together, molar height and the number of longitudinal lophs explain 73 per cent of the global variation in terrestrial NPP today and resolve the main terrestrial biomes in bivariate space. We explain the functional interpretation of the relationships between dental function and climate variables in terms of long- and short-term demands. We also show how the spatially and temporally dense fossil record of terrestrial mammals can be used to investigate the relationship between biodiversity and productivity under changing climates in geological time. The placement of the fossil chronofaunas in biome space suggests that they most probably represent multiple palaeobiomes, at least some of which do not correspond directly to any biomes of today's world.


Birth, obstetrics and human evolution

Abstract: There are several characteristics that set our species apart from other mammals. We are the only living or extant mammal that habitually walks on two legs. For our body size, we have the largest and the most complex brains of all animals. Humans depend on material culture or ‘tools’ for their survival. Humans universally communicate with each other through abstract symbols known as language. Finally, human females routinely seek assistance when they give birth. In fact, many have argued that midwifery or obstetrics, not prostitution, is the ‘oldest profession’. Fossil evidence shows that although two-legged walking, or bipedalism, traces its origin to the very beginning of human ancestry, tools and language appeared much more recently in human evolution. We will argue in this paper that, along with bipedalism, some aspects of the human pattern of birth trace their origin to the very beginning of human evolution. Based on fossil evidence from Africa, human paleontologists agree that the mammalian family to which humans belong, Hominidae (‘hominids’), originated approximately 5 million years ago. The crucial hallmarks of our earliest hominid ancestors are skeletal indicators of bipedalism. These markers appear clearly first in Australopithecus anamensis (ca. 4 million years ago) or possibly earlier. In spite of a human pattern of locomotion, these early members of the genus Australopithecus had brains that were smaller than modern humans—in proportion to their bodies—very similar to those of modern chimpanzees. Significant brain expansion did not begin until the origin of our genus, Homo, about 2.5 million years ago, when we also have evidence of the first stone tools. Evidence of language is not directly preserved in the fossil record but several investigators suggest that our ancestors were capable of the complex speech patterns that are part of all spoken languages today by at least 200,000 years ago. As noted above, we argue that assisted birth may be associated with bipedalism, and may thus be as old as the hominid family itself. However, assistance at birth is not the only significant birthrelated difference between humans and our close relatives in the primate order. The unusual way in which modern humans give birth is the result of a set of constraints imposed by bipedalism, a large brain, and ‘secondary altriciality’, or the delivery of the infant in a relatively helpless state. Birth in non-human primates

obstetric
human evolution
assistance
non-human primate
birth


Fossil lizards and worm lizards (Reptilia, Squamata) from the Neogene and Quaternary of Europe: an overview

Abstract: Lizards were and still are an important component of the European herpetofauna. The modern European lizard fauna started to set up in the Miocene and a rich fossil record is known from Neogene and Quaternary sites. At least 12 lizard and worm lizard families are represented in the European fossil record of the last 23 Ma. The record comprises more than 3000 occurrences from more than 800 localities, mainly of Miocene and Pleistocene age. By the beginning of the Neogene, a marked faunistic change is detectable compared to the lizard fossil record of Palaeogene Europe. This change is reflected by other squamates as well and might be related to an environmental deterioration occurring roughly at the Oligocene/ Miocene boundary. Nevertheless, the diversity was still rather high in the Neogene and started to decrease with the onset of the Quaternary glacial cycles. This led to the current impoverished lizard fauna, with the southward range shrinking of the most thermophilic taxa (e.g., agamids, amphisbaenians) and the local disappearance of other groups (e.g., varanids). Our overview of the known fossil record of European Neogene and Quaternary lizards and worm lizards highlighted a substantial number of either unpublished or poorly known occurrences often referred to wastebasket taxa. A proper study of these and other remains, as well as a better sampling of poorly explored time ranges (e.g., Pliocene, Holocene), is needed and would be of utmost importance to better understand the evolutionary history of these reptiles in Europe.


The bivalved arthropod Tuzoia from the Balang Formation (Cambrian Stage 4) of Guizhou, China, and new observations on comparative species

Abstract: Tuzoia is a large, bivalved Cambrian arthropod having a widespread distribution in shallow‐shelf to deeper marine Lagerstätten; stratigraphically it ranges from Cambrian Series 2 through the Miaolingian Series. In the present study, three species are recognized from relatively deep‐water deposits of the Balang Formation (Cambrian Stage 4) of Guizhou, South China: Tuzoia sinensis Pan, 1957, T. bispinosa Yuan et Zhao, 1999 and T. lazizhaiensis sp. nov. The new species is unique in having 6–10 small marginal spines on the dorsal margin, an inflated anterior margin with three short, closely spaced marginal spines. These remains, which usually occur as disarticulated valves, are inferred to be parautochthonous. One new specimen of T. lazizhaiensis shows a stalked eye and antenna. New Tuzoia material from the Kaili Biota (Cambrian: Wuliuan Stage) of Guizhou, and from the Guanshan Biota (Cambrian Stage 4) of Yunnan, China, provide additional comparative information about the genus. Some new specimens of T. bispinosa from the Kaili Biota provide information on valve morphology and palaeoecology. One specimen of T. sinensis from the Guanshan Biota provides information on the appendages, and one specimen of T. tylodesa, from the Guanshan Biota adds provides information on the trunk and appendages.


The rise of the ruling reptiles and ecosystem recovery from the Permo-Triassic mass extinction

Abstract: One of the key faunal transitions in Earth history occurred after the Permo-Triassic mass extinction (ca 252.2 Ma), when the previously obscure archosauromorphs (which include crocodylians, dinosaurs and birds) become the dominant terrestrial vertebrates. Here, we place all known middle Permian–early Late Triassic archosauromorph species into an explicit phylogenetic context, and quantify biodiversity change through this interval. Our results indicate the following sequence of diversification: a morphologically conservative and globally distributed post-extinction ‘disaster fauna’; a major but cryptic and poorly sampled phylogenetic diversification with significantly elevated evolutionary rates; and a marked increase in species counts, abundance, and disparity contemporaneous with global ecosystem stabilization some 5 million years after the extinction. This multiphase event transformed global ecosystems, with far-reaching consequences for Mesozoic and modern faunas.

reptile
permo-triassic mass extinction
mass extinction
faunal transition
early triassic


Aquatic ecosystems in Miocene western Amazonia – marine ingressions vs. salt leaching

Abstract: Before the onset of the modern Amazon river system, north-western South America was shaped by an extensive wetland during the Miocene. This ‘Pebas mega-wetland’ kept a well renowned endemic mollusk and ostracod fauna, which initiated a persisting debate about marine ingressions reaching the center of Amazonia at that time. Due to high endemism, uniformitarian principles are hardly applicable to this biota but also other paleontological, sedimentological and geochemical information led to ambiguous paleoenvironmental interpretations. These results are based on ostracod and foraminiferal assemblages and the oxygen and carbon stable isotopy of their biogenic calcite from an outcrop at the cutbank of the Amazon river (NE-Peru, ~55 km S of Iquitos). While ostracods (e.g., Cyprideis) are able to calcify their carapaces along the entire salinity range, at least low saline conditions are a prerequisite for the biomineralization of calcareous foraminiferan tests. Hence, the finding of calcareous foraminifers (Ammonia, Elphidium), associated mainly with brackish water ostracods, indicates the presence of saline waters. In contrast, δ 18 Oand δ 13 C-analyses performed on co-occurring ostracod valves and foraminiferan tests yielded constantly very light ratios. Such values refer to a pure freshwater environment and are incompatible with the interference of isotopically heavier, marine waters or an evaporative stable isotope enrichment. Based on these opposing data, we hypothesize that the Pebas megawetland was episodically influenced by mineralized but isotopically light groundwater discharge. Possibly, the resulting specific hydrochemistry contributed not only to the evolution of the endemic Pebasian fauna but also facilitated the sporadic settlement of euryhaline foraminifers, which mimics short-lived marine incursions.

miocene
amazonia
marine ingression
saltwater organism
ground water release


Taxonomy-testing and the ‘Goldilocks Hypothesis’: morphometric analysis of species diversity in living and extinct Hispaniolan hutias

Abstract: Understanding the dynamics of the Late Quaternary Caribbean mammal extinction event is complicated by continuing uncertainty over the taxonomic status of many species. Hispaniola is one of the few Caribbean islands to retain native non-volant mammals; however, there has been little consensus over past or present levels of diversity in Hispaniolan hutias (Capromyidae: Plagiodontinae). Craniodental measurement data from modern hutia specimens, previously classified as both Plagiodontia aedium and P. hylaeum, display morphological differences between Hispaniola's northern and southern palaeo-islands using MANOVA and PCA. Although attempts to amplify mitochondrial DNA from the holotype of P. aedium were unsuccessful, this specimen is morphometrically associated with southern palaeo-island specimens. The mandibular size distribution of recent Plagiodontia specimens is unimodal, but the Late Quaternary mandibular size distribution is multimodal and displays much broader measurement spread, representing multiple extinct species. Finite Mixture Analysis was used to assess the best fit of different taxonomic hypotheses to the fossil mandibular size distribution. All retained FMA models include living hutias and P. spelaeum as distinct taxa; PCA further demonstrates that levels of morphological variation between modern hutia populations are lower than levels between living hutias and P. spelaeum, so that living hutias are interpreted as the single species P. aedium. Taxonomic differentiation for larger-bodied hutias is less well defined, but most retained models show only one larger species, for which the only available name is P. velozi. ‘Plagiodontia’ araeum is morphologically distinct from other species and is reassigned to Hyperplagiodontia. Hispaniola's plagiodontine fauna has lost its largest and smallest representatives; similar trends of body size selectivity in extinction risk are shown more widely across the Caribbean mammal fauna, possibly due to different regional anthropogenic threats (invasive mammals, hunting) affecting small-bodied and large-bodied mammals during the recent past. This apparent pattern of extinction selectivity is named the ‘Goldilocks Hypothesis’.

goldilocks hypothesis
hispaniolan hutia
invasive mammal


Oldest known avian footprints from Australia: Eumeralla Formation (Albian), Dinosaur Cove, Victoria

Abstract: Two thin‐toed tridactyl tracks in a fluvial sandstone bed of the Eumeralla Formation (Albian) at Dinosaur Cove (Victoria, Australia) were likely made by avian trackmakers, making these the oldest known fossil bird tracks in Australia and the only Early Cretaceous ones from Gondwana. These tracks, which co‐occur on the same surface with a slightly larger nonavian theropod track, are distinguishable by their anisodactyl form, hallux impressions and wide digit II–IV divarication angles. A lengthy hallux impression and other deformational structures associated with one track indicate foot movement consistent with an abrupt stop, suggesting its tracemaker landed after either flight or a hop. The single nonavian theropod track is similar to other tracks described from the Eumeralla Formation at another locality. The avian footprints are larger than most Early Cretaceous avian tracks recorded worldwide, indicating sizeable enantiornithine or ornithurine species in formerly polar environments of Australia. The avian tracks further supplement scant body fossil evidence of Early Cretaceous birds in southern Australia, which includes a furcula from the Wonthaggi Formation. Because of this discovery, Dinosaur Cove, previously known for its vertebrate body fossils, is added to a growing list of Early Cretaceous vertebrate tracksites in southern Australia.

footprint
eumeralla formation
dinosaur cove
impression


High-quality fossil dates support a synchronous, Late Holocene extinction of devils and thylacines in mainland Australia

Abstract: The last large marsupial carnivores—the Tasmanian devil (Sarcophilis harrisii) and thylacine (Thylacinus cynocephalus)—went extinct on mainland Australia during the mid-Holocene. Based on the youngest fossil dates (approx. 3500 years before present, BP), these extinctions are often considered synchronous and driven by a common cause. However, many published devil dates have recently been rejected as unreliable, shifting the youngest mainland fossil age to 25 500 years BP and challenging the synchronous-extinction hypothesis. Here we provide 24 and 20 new ages for devils and thylacines, respectively, and collate existing, reliable radiocarbon dates by quality-filtering available records. We use this new dataset to estimate an extinction time for both species by applying the Gaussian-resampled, inverse-weighted McInerney (GRIWM) method. Our new data and analysis definitively support the synchronous-extinction hypothesis, estimating that the mainland devil and thylacine extinctions occurred between 3179 and 3227 years BP.

devil
mainland australia
radiocarbon date