PALEOBOTANY AND SEDIMENTOLOGY OF LATE OLIGOCENE TERRESTRIAL STRATA FROM THE NORTHWESTERN ETHIOPIAN PLATEAU

Abstract: This paper describes the sedimentology and paleobotany of a Late Oligocene (27.36 ± 0.11 Ma) succession of volcaniclastic strata from the Margargaria River region, northwestern Ethiopian Plateau. Sedimentology indicates fluvial deposition of clay-and silt-rich strata during the early sedimentary phases, whereas organic-rich deposits and massive and fluvially-reworked ash layers are increasingly more common in the middle and upper parts of the succession, respectively. Periods of interrupted deposition are indicated by three paleosol types present in the basal and middle parts of the succession. Paleobotany documents an exclusively angiosperm flora typical of riparian environments in the lower parts of the succession, and a flora dominated by ferns and a few angiosperm taxa typical of disturbed environments in the middle and upper parts. Sedimentology and paleobotany, combined, indicate a riparian environment inhabited by angiosperms for the lower part of the succession, characterized by rather calm deposition by meandering streams. The middle and upper parts of the succession represent transient environments colonized by pioneer vegetation consisting of a diverse fern community and fewer pioneer angiosperms, characterized by deposition of organic-and ash-rich strata in situ in ephemeral ponds and by small-scale crevasse-like channels and by aereal means on the landscape, respectively. Physiographic changes are interpreted to have resulted directly from the influence of volcanism on the surface environment. In summary, this study shows that the volcanic activity associated with the elevation of the northwestern Ethiopian Plateau during the Oligocene repeatedly influenced the development of plant communities and paleoenvironments, favoring the succession of heterogeneous ecosystems on short temporal and spatial scales. Finally, this study is the first that combines paleobotanical and sedimentological data for paleoenvironmental reconstruction and understanding of plant community dynamics in Paleogene deposits from Africa, and it demonstrates the advantages of a multiproxy approach for assessment of paleoecosystem dynamics on an unstable landscape.

sedimentology
oligocene
northwestern ethiopian plateau


Strontium isotope stratigraphy and paleomagnetic age constraints on the evolution history of coral reef islands, northern South China Sea

Abstract: Understanding the history of the response of coral reefs to past climate changes can provide valuable information for predicting the future response of modern reefs. However, dating such ancient biotic carbonate is still challenging because of its sensitivity to diagenetic alteration processes, scarcity of well-preserved fossils, and low magnetic mineral content. There have been a long debates about the origin and evolutionary history of coral reefs in the northern South China Sea, mainly due to the lack of direct and reliable age constraints. This provides us with a good opportunity to verify the practicability of different dating approaches, especially the strontium (Sr) isotope analysis of bulk carbonate. Here, we retrieved a 972.55-m-long core from the Xisha Islands to provide a credible chronologic constraint on the carbonate platform evolution. The lithostratigraphy, strontium isotope stratigraphy, and magnetostratigraphy were analyzed throughout the whole reef sequence. The lithostratigraphic results show that the 873.55 m reef sequence developed on an ancient volcaniclastic basement and experienced multiple evolutionary phases. The 87Sr/86Sr results of all 100 bulk carbonate samples vary from 0.708506 to 0.709168 and show a monotonic increase with decreasing depth, except for a few outliers. Trace-element criteria and stable isotope (δ18O and δ13C) methods were applied to these bulk carbonate samples, and results imply that the primary or near-primary seawater 87Sr/86Sr values were likely preserved, although different degrees of diagenetic alteration occurred. In addition, the paleomagnetic results indicate 10 normal polarity and eight reversed polarity magnetozones. Based on the 87Sr/86Sr ratios of the selected 58 samples and paleomagnetic reconstruction of polarity reversals, the bottom of the reef sequence is dated to 19.6 Ma, and the observed polarity chronozones extend from chron C6 (19.722–18.748 Ma) at 866.60 m to present at the top. Based on the new data, we propose a new chronologic framework for the evolutionary history of the reef islands, where: (1) the reefs initiated in the early Miocene (19.6 Ma) and were drowned until 16.26 Ma; (2) during 16.26–10.66 Ma, lagoon to lagoon slope environments prevailed; (3) the lagoon environment progressively transformed into a reef crest environment from 10.66 to 4.36 Ma and 4.36 to 1.59 Ma; and (4) the reef started to be drowned again during 1.59–0 Ma. Our study provides a new and reliable chronologic constraint on the general evolutionary history of the reef islands in the northern South China Sea. Furthermore, the 87Sr/86Sr results from bulk carbonate indicate that strontium isotope stratigraphy is a powerful dating tool only when rigid sample selection, sequential leaching procedures, and strict trace-element and isotopic criteria are applied.

reef island
south china sea
strontium isotope stratigraphy


Calcaneal proportions in primates and locomotor inferences in Anchomomys and other Palaeogene Euprimates

Abstract: Foot proportions, and in particular the lengthening of the tarsal elements, play a fundamental role in the discussion on the locomotor adaptations of Palaeogene primates. The elongation of the distal portion of the tarsus, particularly the anterior part of the calcaneus, is frequently interpreted as an adaptation to leaping and has played a fundamental role in the reconstruction of the locomotor adaptations of the earliest primates. Here, we report an allometric analysis of calcaneal proportions in primates and other mammals, in order to determine the actual differences in calcaneal proportions. This analysis reveals that primates as a group display a relatively longer distal calcaneus, relative to both total calcaneal length and body mass, when compared with other mammals. Contrary to current expectations, morphofunctional analysis indicates that a moderate degree of calcaneal elongation is not an adaptation to leaping, but it is merely a compensatory mechanism to recover the lost load arm (metatarsal length) when the foot adopts a grasping function, in order to maintain the same locomotor efficiency. Leaping can be inferred only when anterior calcaneal length departs from the scaling of non-specialized primate groups. The role of leaping on the inferred locomotor repertoire of earliest primates needs to be revised considering the results of this work.

primate
foot
leaping
calcaneal proportion


Dominican amber net-winged beetles suggest stable paleoenvironment as a driver for conserved morphology in a paedomorphic lineage

Abstract: Paedomorphosis is a heterochronic syndrome in which adult individuals display features of their immature forms. In beetles, this phenomenon occurs widely in the superfamily Elateroidea, including the net-winged beetles (Lycidae), and, due to the usual flightlessness of paedomorphic females, it is hypothesized to cause speciation rates higher than in non-paedomorphic lineages. However, some fossils of paedomorphic lycids do not support this with palaeobiological data. Discovery of new Lycidae fossils attributed to the West Indian extant paedomorphic genus Cessator Kazantsev in the Dominican amber also suggests morphological stasis within this genus in the Greater Antilles. We describe Cessator anachronicus Ferreira and Ivie, sp. nov. based on adult males, as well as the first ever recorded fossil net-winged beetle larva of the same genus. We propose that the relatively young age of the studied fossils combined with the stable conditions in the forest floor of the Greater Antilles through the last tens of million years could explain the exceptionally conserved morphology in the net-winged beetles affected by the paedomorphic syndrome.

net-winged beetle
morphology
paedomorphosis
elateroidea
dominican amber


Increased Atmospheric SO2 Detected from Changes in Leaf Physiognomy across the Triassic–Jurassic Boundary Interval of East Greenland

Abstract: The Triassic–Jurassic boundary (Tr–J; ∼201 Ma) is marked by a doubling in the concentration of atmospheric CO2, rising temperatures, and ecosystem instability. This appears to have been driven by a major perturbation in the global carbon cycle due to massive volcanism in the Central Atlantic Magmatic Province. It is hypothesized that this volcanism also likely delivered sulphur dioxide (SO2) to the atmosphere. The role that SO2 may have played in leading to ecosystem instability at the time has not received much attention. To date, little direct evidence has been presented from the fossil record capable of implicating SO2 as a cause of plant extinctions at this time. In order to address this, we performed a physiognomic leaf analysis on well-preserved fossil leaves, including Ginkgoales, bennettites, and conifers from nine plant beds that span the Tr–J boundary at Astartekløft, East Greenland. The physiognomic responses of fossil taxa were compared to the leaf size and shape variations observed in nearest living equivalent taxa exposed to simulated palaeoatmospheric treatments in controlled environment chambers. The modern taxa showed a statistically significant increase in leaf roundness when fumigated with SO2. A similar increase in leaf roundness was also observed in the Tr–J fossil taxa immediately prior to a sudden decrease in their relative abundances at Astartekløft. This research reveals that increases in atmospheric SO2 can likely be traced in the fossil record by analyzing physiognomic changes in fossil leaves. A pattern of relative abundance decline following increased leaf roundness for all six fossil taxa investigated supports the hypothesis that SO2 had a significant role in Tr–J plant extinctions. This finding highlights that the role of SO2 in plant biodiversity declines across other major geological boundaries coinciding with global scale volcanism should be further explored using leaf physiognomy.

atmospheric so2
atmosphere
leaf physiognomy
east greenland
environment chamber


Ontogeny and microstructure of the enigmatic Cambrian tommotiid Sunnaginia Missarzhevsky, 1969

Abstract: Abstract:  The tommotiids are a significant component of the earliest skeletal animal remains in the fossil record, occurring in large numbers in the Lower Cambrian. Sclerites of the tommotiid genus Sunnaginia have been implicated as integral to hypotheses regarding the evolution of the brachiopod body plan, with a morphology intermediate between the unspecialized sclerites of the tubular Eccentrotheca and the specialized sclerites of the tannuolinids. Abundant Sunnaginia ?imbricata sclerites, of a broad ontogenetic spectrum, were recovered from the Comley Limestone, Lower Cambrian (Stages 3–4), Shropshire, UK and compared to Sunnaginia imbricata from the Aldan River, Siberia (uppermost Tommotian). New microstructural data, collected using synchrotron radiation X‐ray tomographic microscopy, reveal a unique microstructure for Sunnaginia ?imbricata sclerites among the tommotiids; interlamellar cavities spanned by a series of continuous pillars, giving a colonnaded appearance contrasting to that of S. imbricata. These data refute the inclusion of Eccentrotheca within the Sunnaginiidae and highlight the need for a revision of suprageneric classification of the tommotiids. Rather, structural similarities between Sunnaginia sclerites and those of the tannuolinids suggest a close affinity to this group. Recent phylogenetic hypotheses place the tannuolinids as stem‐linguliform brachiopods, with Paterimitra plus the paterinid (and possibly rhynchonelliform) brachiopods as their sister group. Our new data therefore resolve Sunnaginia as close to the node defining crown‐Brachiopoda. However, the characters supporting this phylogenetic scheme cannot be consistently applied to all taxa, nor do they define a series of nested clades. We therefore suggest that a more thorough phylogenetic analysis is required in the light of the data presented here and other recent descriptions.


Scorpion taphonomy: criteria for distinguishing fossil scorpion molts and carcasses

Abstract: Abstract The ability to distinguish fossil arthropod carcasses from their molts is necessary for a more complete understanding of the arthropod fossil record and for more accurately assessing the role of fossil arthropods in paleoecosystems. Taphonomic characteristics, e.g., recurrent patterns of disarticulation of exoskeletal elements, are the primary data that have been used to differentiate fossil exuvia and fossil carcasses among arthropods. This study documents recurrent taphonomic patterns in modern scorpion carcasses and molts and extends these patterns to the fossil record to define criteria by which fossil scorpion molts might be distinguished from fossil scorpion carcasses. The three most useful and statistically significant characters in making the scorpion carcass/molt distinction are: position of the chelicerae (drawn in or extended); position of walking legs (folded or splayed); and body line (straight or curved). Two other characteristics, the position of pedipalps and presence or absence of telescoped segments, approach statistical significance and are also potentially useful. Disarticulation data are not as useful for distinguishing fossil scorpion molts and carcasses, because there are no statistically significant differences in length of time to total disarticulation or in the sequence of disarticulation between scorpion molts and carcasses. Among extant arthropods, scorpions possess the body plan most similar to that of the extinct eurypterids. Therefore, the taphonomic criteria developed for distinguishing fossil scorpion molts and carcasses may have implications for understanding molting among eurypterids.


Nomenclature, Comparative Anatomy, and Evolution of the Reflected Lamina of the Angular in Non-Mammalian Synapsids

Abstract: ABSTRACT The reflected lamina of the angular has long been portrayed as a key component in understanding the evolution of the mammalian mandible and middle ear, yet the function of this structure in non-mammalian therapsids remains uncertain. We undertake a broad scale survey of two aspects of the reflected lamina that have been poorly characterized: the ridges and fossae on its lateral surface and the extent of the underlying angular cleft. These two features were visualized in a wide range of therapsids using CT data from the literature and blue light surface scanning. Most species exhibit a clade-specific pattern of surface topography, although dicynodonts are highly variable. A striking similarity in the general number and orientation of fossae and ridges is seen between the otherwise disparate therapsid clades, and we propose homologies in these surface features across Therapsida. These features may serve as useful phylogenetic characters in analyses of the relationships among the major therapsid clades. The angular cleft does not underlie all of what is often referred to as the ‘reflected lamina’ in the literature, and an updated definition of this term is provided. Several therapsid groups independently expanded the angular cleft to further separate the reflected lamina from the angular body. We discuss some functional consequences of our findings and note inconsistency between proposed clade-specific muscle attachment sites and the presence of homologous fossae and ridges across much of Therapsida.

comparative anatomy
angular
non-mammalian synapsid


The palaeobiology of belemnites – foundation for the interpretation of rostrum geochemistry

Abstract: Belemnites are an extinct group of Mesozoic coleoid cephalopods with a fossil record ranging from the early Late Triassic [about 240 million years ago (Mya)] to the Cretaceous/Palaeogene boundary (65 Mya). Belemnites were widely distributed, highly abundant and diverse, and an important component of Mesozoic marine food webs. Their internal shells, specifically their low‐Mg calcite rostra, have been used as palaeoenvironmental carbonate archives for the last 70 years. This is primarily due to the assumption that the rostrum calcite formed in equilibrium with the oxygen isotope composition of ambient sea water. Of prime importance for the reliable interpretation of isotope data derived from these biogenic carbonates is a robust reconstruction of the palaeobiology of their producers. Here we provide a critical assessment of published reconstructions of belemnite soft‐body organization and their lifestyle and habitats. Different lines of evidence, including sedimentological, geochemical, morphological, and biomechanical data, point towards an outer shelf habitat of belemnites, for some taxa also including the littoral area. Belemnite habitat temperatures, oxygen content, salinities, and life span are constrained based on observations of the ecology and life history of modern coleoids. Belemnite habitat depth might have been largely controlled by food and temperature, with a temperature optimum between 10°C and 30°C. The distribution of modern coleoids is for most species restricted to well‐oxygenated water masses and a salinity between 27 and 37 psu. The trophic position of belemnites as both predators and prey is documented by unique fossil finds of stomach contents and soft tissue preservation, such as jaws, hooks, and ink sacs. Belemnites were medium‐sized predators in the epipelagic zone (not deeper than ∼200 m) hunting for crustaceans, other cephalopods, and fishes. Taxa with elongated rostra probably were fast and highly manoeuvrable swimmers. Forms with conical rostra represent slow but highly manoeuvrable swimmers, and forms with depressed rostra likely had a bottom‐related life habit. Predators of adult belemnites were sharks, bony fishes, and marine reptiles. Belemnites, like most of the modern coleoids, were relatively short lived, most likely living only for 1–2 years. Understanding the biomineralization of belemnite rostra is highly relevant for an improved interpretation of their geochemistry. Here we confirm that belemnite rostra are composed of low Mg‐calcite fibres, but they do not contain distinct types of laminae. These fibres are composed of two distinct calcite phases. One phase is a filigree network of tetrahedral organic‐rich calcite and the second phase is represented by organic‐poor calcite.

palaeobiology
belemnite
extinct group
palaeoenvironmental reconstruction


Closing the gap between rocks and clocks using total-evidence dating

Abstract: Total-evidence dating (TED) allows evolutionary biologists to incorporate a wide range of dating information into a unified statistical analysis. One might expect this to improve the agreement between rocks and clocks but this is not necessarily the case. We explore the reasons for such discordance using a mammalian dataset with rich molecular, morphological and fossil information. There is strong conflict in this dataset between morphology and molecules under standard stochastic models. This causes TED to push divergence events back in time when using inadequate models or vague priors, a phenomenon we term ‘deep root attraction’ (DRA). We identify several causes of DRA. Failure to account for diversified sampling results in dramatic DRA, but this can be addressed using existing techniques. Inadequate morphological models also appear to be a major contributor to DRA. The major reason seems to be that current models do not account for dependencies among morphological characters, causing distorted topology and branch length estimates. This is particularly problematic for huge morphological datasets, which may contain large numbers of correlated characters. Finally, diversification and fossil sampling priors that do not incorporate all the available background information can contribute to DRA, but these priors can also be used to compensate for DRA. Specifically, we show that DRA in the mammalian dataset can be addressed by introducing a modest extra penalty for ghost lineages that are unobserved in the fossil record, for instance by assuming rapid diversification, rare extinction or high fossil sampling rate; any of these assumptions produces highly congruent divergence time estimates with a minimal gap between rocks and clocks. Under these conditions, fossils have a stabilizing influence on divergence time estimates and significantly increase the precision of those estimates, which are generally close to the dates suggested by palaeontologists. This article is part of the themed issue ‘Dating species divergences using rocks and clocks’.

rock
clock
total-evidence
conflict
standard stochastic model


Early Jurassic bennettitalean reproductive structures of Romania

Abstract: The Romanian Early Jurassic (Hettangian-Sinemurian) floras represent a key element of the Eurosinian Province in which the Williamsoniaceae (Bennettitales) are well represented by vegetative remains (leaves, stems, roots) and reproductive structures. Up to the present, Early Jurassic bennettitalean reproductive structures have been found at only two localities in Romania: Anina and Doman. These localities belong to the Reşiţa Basin, Getic Nappe, South Carpathians, Romania, with Anina considered to be the best Romanian Early Jurassic locality in terms of diversity and preservation of fossil plants and animals, i.e. a fossil Lagerstätte. This paper deals with all bennettitalean reproductive structures identified to date. These belong to the Steierdorf Formation, Valea Tereziei Member, and are Sinemurian in age. In total, 32 rare hand specimens (compressions and casts) have been studied and the following taxa identified: Williamsonia banatica

reproductive structure
romania
early jurassic bennettitalean


ZooArchNet: Connecting zooarchaeological specimens to the biodiversity and archaeology data networks

Abstract: Interdisciplinary collaborations and data sharing are essential to addressing the long history of human-environmental interactions underlying the modern biodiversity crisis. Such collaborations are increasingly facilitated by, and dependent upon, sharing open access data from a variety of disciplinary communities and data sources, including those within biology, paleontology, and archaeology. Significant advances in biodiversity open data sharing have focused on neontological and paleontological specimen records, making available over a billion records through the Global Biodiversity Information Facility. But to date, less effort has been placed on the integration of important archaeological sources of biodiversity, such as zooarchaeological specimens. Zooarchaeological specimens are rich with both biological and cultural heritage data documenting nearly all phases of human interaction with animals and the surrounding environment through time, filling a critical gap between paleontological and neontological sources of data within biodiversity networks. Here we describe technical advances for mobilizing zooarchaeological specimen-specific biological and cultural data. In particular, we demonstrate adaptations in the workflow used by biodiversity publisher VertNet to mobilize Darwin Core formatted zooarchaeological data to the GBIF network. We also show how a linked open data approach can be used to connect existing biodiversity publishing mechanisms with archaeoinformatics publishing mechanisms through collaboration with the Open Context platform. Examples of ZooArchNet published datasets are used to show the efficacy of creating this critically needed bridge between biological and archaeological sources of open access data. These technical advances and efforts to support data publication are placed in the larger context of ZooarchNet, a new project meant to build community around new approaches to interconnect zoorchaeological data and knowledge across disciplines.

zooarchaeological specimen
biodiversity
zooarchnet


An early chondrichthyan and the evolutionary assembly of a shark body plan

Abstract: Although relationships among the major groups of living gnathostomes are well established, the relatedness of early jawed vertebrates to modern clades is intensely debated. Here, we provide a new description of Gladbachus, a Middle Devonian (Givetian approx. 385-million-year-old) stem chondrichthyan from Germany, and one of the very few early chondrichthyans in which substantial portions of the endoskeleton are preserved. Tomographic and histological techniques reveal new details of the gill skeleton, hyoid arch and jaws, neurocranium, cartilage, scales and teeth. Despite many features resembling placoderm or osteichthyan conditions, phylogenetic analysis confirms Gladbachus as a stem chondrichthyan and corroborates hypotheses that all acanthodians are stem chondrichthyans. The unfamiliar character combination displayed by Gladbachus, alongside conditions observed in acanthodians, implies that pre-Devonian stem chondrichthyans are severely under-sampled and strongly supports indications from isolated scales that the gnathostome crown group originated at the latest by the early Silurian (approx. 440 Ma). Moreover, phylogenetic results highlight the likely convergent evolution of conventional chondrichthyan conditions among earliest members of this primary gnathostome division, while skeletal morphology points towards the likely suspension feeding habits of Gladbachus, suggesting a functional origin of the gill slit condition characteristic of the vast majority of living and fossil chondrichthyans.

chondrichthyan
germany
phylogenetic analysis
acanthodian


Bilaterally symmetric axes with rhizoids composed the rooting structure of the common ancestor of vascular plants

Abstract: There are two general types of rooting systems in extant land plants: gametophyte rhizoids and sporophyte root axes. These structures carry out the rooting function in the free-living stage of almost all land plant gametophytes and sporophytes, respectively. Extant vascular plants develop a dominant, free-living sporophyte on which roots form, with the exception of a small number of taxa that have secondarily lost roots. However, fossil evidence indicates that early vascular plants did not develop sporophyte roots. We propose that the common ancestor of vascular plants developed a unique rooting system—rhizoidal sporophyte axes. Here we present a synthesis and reinterpretation of the rootless sporophytes of Horneophyton lignieri, Aglaophyton majus, Rhynia gwynne-vaughanii and Nothia aphylla preserved in the Rhynie chert. We show that the sporophyte rooting structures of all four plants comprised regions of plagiotropic (horizontal) axes that developed unicellular rhizoids on their underside. These regions of axes with rhizoids developed bilateral symmetry making them distinct from the other regions which were radially symmetrical. We hypothesize that rhizoidal sporophyte axes constituted the rooting structures in the common ancestor of vascular plants because the phylogenetic positions of these plants span the origin of the vascular lineage. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.


Abstract: Skelton P., 1973. Aragonitic shell structures in the rudist Biradiolites, and some palaeobiological inferences. (Sur la preservation de structures aragonitiques dans la coquille du genre Biradiolites (Rudiste) — Implications paleobiologiques). Des echantillons de Biradiolites angulosissimus Toucas, provenant du Santonien du Massif de la Ste Baume, montrent dans leur coquille des structures aragonitiques. Trois couches peuvent etre distinguees : — Une couche externe formee de prismes de calcite, compacte dans la -valve gauche, cellulaire dans la valve droite. — Une couche moyenne aragonitique de structure "crosse d-lamellar" doublant la couche externe a l'interieur de la cavite generale formant les dents de la valve gauche, et les fossettes de la valve droite. — Une couche interne aragonitique de structure "complex crossed-lamellar", comblant le fond de la cavite generale, et constituant les apophyses myophores. En outre on observe des prismes myostracaux d'aragonite bien developpes sur les apophyses myophores, et egalement entre les couches moyennes et interne de la valve droite, et sur la surface ventrale de l'appareil cardinal de la valve gauche. Le stade initial est de type spirogyre avec une charniere de type monopleuride et probablement un ligament de type diceratide. Ces caracteres disparaissent au stade adulte. La couche calci tique n'apparait que tardivement. La preservation de l'Aragonite semble favorisee par le caractere reducteur des sediments. Les muscles adducteurs de B. angulosissimus etaient tres courts. Il n'y avait pas de fusion entre les deux lobes du manteau sur la commissure des deux valves. Les Biradiolitinae sont proches des Monopleuridae. La couche calcitique semble etre une addition ontogenique et n'existe peut etre pas chez les ancetres des Rudistes.

rudist biradiolites
palaeobiological inference
aragonitic shell structure


A New Genus and Species of Extinct Ground Shark, †Diprosopovenator Hilperti, Gen. Et Sp. Nov. (Carcharhiniformes, †Pseudoscyliorhinidae, Fam. Nov.), from The Upper Cretaceous of Germany

Abstract: ABSTRACT We describe a new genus and species of extinct ground shark, †Diprosopovenator hilperti, gen. et sp. nov. (Elasmobranchii, Carcharhiniformes), based on a single incomplete skeleton with dentition recovered from basinal marine late Cenomanian (Metoicoceras geslinianum ammonite zone) organic-rich deposits of northern Germany. The new carcharhiniform is characterized by a unique combination of dental morphologies, indicating close architectural resemblance to the family Scyliorhinidae (catsharks). However, the very distinct tooth root morphology readily separates the new taxon from all other scyliorhinids. The extinct Cretaceous carcharhiniform †Pseudoscyliorhinus (represented by †Ps. schwarzhansi and †Ps. reussi) shares tooth root morphologies and vascularization patterns with †Diprosopovenator, gen. nov. We hypothesize that these two sharks form part of an extinct group of carcharhiniforms characterized by a distinct root morphology (viz., low hemiaulacorhize roots with very flat and strongly flared basal faces protruding below the crown labially and mesiodistally and with a well-developed central labiobasal notch). Consequently, we propose a new family of Late Cretaceous carcharhiniforms, †Pseudoscyliorhinidae, fam. nov., to include the new taxon, as well as †Pseudoscyliorhinus. †Pseudoscyliorhinidae, fam. nov., shows a wide European distribution during the Late Cretaceous, ranging from the early Cenomanian to the late Campanian. The longevity of Scyliorhinidae, with a fossil record extending back into the Middle Jurassic, however, remains ambiguous and unresolved; therefore, it may be best to regard the assignment of fossil taxa to Scyliorhinidae as currently uncertain pending further taxonomic work.

new genus
extinct ground shark
†pseudoscyliorhinidae


A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum

Abstract: Background The origin of sauropod dinosaurs is one of the major landmarks of dinosaur evolution but is still poorly understood. This drastic transformation involved major skeletal modifications, including a shift from the small and gracile condition of primitive sauropodomorphs to the gigantic and quadrupedal condition of sauropods. Recent findings in the Late Triassic–Early Jurassic of Gondwana provide critical evidence to understand the origin and early evolution of sauropods. Methodology/Principal Findings A new sauropodomorph dinosaur, Leonerasaurus taquetrensis gen. et sp. nov., is described from the Las Leoneras Formation of Central Patagonia (Argentina). The new taxon is diagnosed by the presence of anterior unserrated teeth with a low spoon-shaped crown, amphicoelous and acamerate vertebral centra, four sacral vertebrae, and humeral deltopectoral crest low and medially deflected along its distal half. The phylogenetic analysis depicts Leonerasaurus as one of the closest outgroups of Sauropoda, being the sister taxon of a clade of large bodied taxa composed of Melanorosaurus and Sauropoda. Conclusions/Significance The dental and postcranial anatomy of Leonerasaurus supports its close affinities with basal sauropods. Despite the small size and plesiomorphic skeletal anatomy of Leonerasaurus, the four vertebrae that compose its sacrum resemble that of the large-bodied primitive sauropods. This shows that the appearance of the sauropod-type of sacrum predated the marked increase in body size that characterizes the origins of sauropods, rejecting a causal explanation and evolutionary linkage between this sacral configuration and body size. Alternative phylogenetic placements of Leonerasaurus as a basal anchisaurian imply a convergent acquisition of the sauropod-type sacrum in the new small-bodied taxon, also rejecting an evolutionary dependence of sacral configuration and body size in sauropodomorphs. This and other recent discoveries are showing that the characteristic sauropod body plan evolved gradually, with a step-wise pattern of character appearance.

new sauropodomorph dinosaur
jurassic
sauropod-type sacrum


Taphonomic experiments resolve controls on the preservation of melanosomes and keratinous tissues in feathers

Abstract: Fossils are a key source of data on the evolution of feather structure and function through deep time, but their ability to resolve macroevolutionary questions is compromised by an incomplete understanding of their taphonomy. Critically, the relative preservation potential of two key feather components, melanosomes and keratinous tissue, is not fully resolved. Recent studies suggesting that melanosomes are preferentially preserved conflict with observations that melanosomes preserve in fossil feathers as external moulds in an organic matrix. To date, there is no model to explain the latter mode of melanosome preservation. We addressed these issues by degrading feathers in systematic taphonomic experiments incorporating decay, maturation and oxidation in isolation and combination. Our results reveal that the production of mouldic melanosomes requires interactions with an oxidant and is most likely to occur prior to substantial maturation. This constrains the taphonomic conditions under which melanosomes are likely to be fossilized. Critically, our experiments also confirm that keratinous feather structures have a higher preservation potential than melanosomes under a range of diagenetic conditions, supporting hitherto controversial hypotheses that fossil feathers can retain degraded keratinous structures.

experiment melanosome feather mould oxidant


Body-shape diversity in Triassic–Early Cretaceous neopterygian fishes: sustained holostean disparity and predominantly gradual increases in teleost phenotypic variety

Abstract: Abstract. Comprising Holostei and Teleostei, the ∼ 32,000 species of neopterygian fishes are anatomically disparate and represent the dominant group of aquatic vertebrates today. However, the pattern by which teleosts rose to represent almost all of this diversity, while their holostean sister-group dwindled to eight extant species and two broad morphologies, is poorly constrained. A geometric morphometric approach was taken to generate a morphospace from more than 400 fossil taxa, representing almost all articulated neopterygian taxa known from the first 150 million years—roughly 60%—of their history (Triassic-Early Cretaceous). Patterns of morphospace occupancy and disparity are examined to: (1) assess evidence for a phenotypically “dominant” holostean phase; (2) evaluate whether expansions in teleost phenotypic variety are predominantly abrupt or gradual, including assessment of whether early apomorphy-defined teleosts are as morphologically conservative as typically assumed; and (3) compare diversification in crown and stem teleosts. The systematic affinities of dapediiforms and pycnodontiforms, two extinct neopterygian clades of uncertain phylogenetic placement, significantly impact patterns ofmorphological diversification. For instance, alternative placements dictate whether or not holosteans possessed statistically higher disparity than teleosts in the Late Triassic and Jurassic. Despite this ambiguity, all scenarios agree that holosteans do not exhibit a decline in disparity during the Early Triassic–Early Cretaceous interval, but insteadmaintain their Toarcian–Callovian variety until the end of the Early Cretaceouswithout substantial further expansions.After a conservative Induan–Carnian phase, teleosts colonize (and persistently occupy) novel regions of morphospace in a predominantly gradual manner until the Hauterivian, after which expansions are rare. Furthermore, apomorphy-defined teleosts possess greater phenotypic variety than typically assumed. Comparison of crown and stem teleost partial disparity indicates that, despite a statistically significant increase in crown teleost disparity between the Late Jurassic and earliest Cretaceous, stem teleosts remained important long-term contributors to overall teleost disparity during this time.

neopterygian fish
teleost
phenotypic variety


Komodo monitor (Varanus komodoensis) feeding behavior and dental function reflected through tooth marks on bone surfaces, and the application to ziphodont paleobiology

Abstract: Abstract Most functional interpretations of ziphodont dentition are based on limited morphometric, behavioral, and taphonomic studies, but few are based on controlled observations of a modern ziphodont consumer. The purpose of this study is to determine through controlled feeding observations if the behaviors indicative of a ziphodont consumer are reflected by tooth marks left on bone surfaces by Varanus komodoensis, the Komodo monitor. We document feeding behavior, expand upon dental function, and correlate these aspects with tooth mark production. We also discuss the significance and limits of applying these data to fossil assemblages. Goat carcasses were fed to 11 captive individuals. V. komodoensis modifies bone surfaces extensively. Individuals exhibit a “medial-caudal arc” when defleshing, followed by inertial swallowing. Bone crushing was not observed. The vast majority of tooth marks are scores, with pits being significantly less common. Tooth furrows and punctures are rare. “Edge marks” are produced on flat elements. Marks are elongate and narrow, with variable lengths and curvature. Over one-third of the marks occur within parallel clusters. Striations are evident on 5% of all marks. Both feeding behavior and tooth marks indicate that ziphodont crowns are ideal for defleshing by being drawn distally through a carcass. Crowns are poorly built for crushing, and within-bone nutrients are acquired through swallowing. Mark production is a by-product of the distal crown movement during the flesh removal process. Scores are the consequence of apical dragging. Edge marks and striated scores result respectively from distal and mesial carinae contact. Mark curvature is the consequence of arcing motions. Parallel clusters may result from repetitive defleshing strokes and/or from multiple crown contacts during a stroke. These observations can be used to draw functional, behavioral, and taphonomic interpretations from fossil assemblages. When they are provisionally applied to theropod tooth marks, similar crown function and defleshing behavior with little bone crushing is apparent. Differences occur concerning mark frequency and curvature, relating potentially to taphonomic biases and rostral motion, respectively.

varanus komodoensis
tooth mark
bone surface
dentition
carcass


Morphology of the oldest fossil subfamily of Limoniidae (Diptera, Architipulinae) in the light of exceptionally preserved Mesozoic material

Abstract:
Based on known fossil evidence the extinct subfamily Architipulinae is considered to be the oldest evolutionary group of the Limoniidae, the largest family within the infraorder Tipulomorpha. The morphology of this subfamily, which includes 11 genera, has so far been based mainly on wing venation. New well-preserved representatives of the genus Cretolimonia Kalugina, 1986 were recovered from the Jurassic/Cretaceous boundary of Shevia and Daya, Transbaikalia, as well as from mid-Cretaceous amber from Kachin, Myanmar. This new material enriches our knowledge of the subfamily Architipulinae and of the genus Cretolimonia, and allows us to ascertain the detailed morphological structure of the female copulatory apparatus with spermathecae and the structure of the male hypopygium. The combination of detailed impression fossils with a specimen preserved three-dimensionally in resin has permitted study of the morphology of this Mesozoic fly genus almost to the level of modern genera. The paper includes descriptions of four new species of Cretolimonia: C. lukashevichae sp. nov., C. pseudojurassica sp. nov., C. dayana sp. nov. from sedimentary rocks, and C. mikolajczyki sp. nov. from Myanmar amber, supported with a key to all known species.
The Limoniidae (limoniid craneflies), with over 10,000 described extant species, is the largest family in the dipteran infraorder Tipulomorpha, and one of the largest among all Nematocera. It is currently divided into seven subfamilies, three of which are extinct (Architipulinae, Eotipulinae, Drinosinae), and four extant: Limnophilinae, Chioneinae, Dactylolabinae, and Limoniinae (Fig. 1 ). Based on the fossil data known to date Architipulinae is considered the oldest group of Limoniidae 1-7 , with the oldest representative Architipula youngi Krzemiński, 1992 dating from the Late Triassic of North America 3 . This species was used to calibrate the age of the Tipulomorpha clade in the phylogenetic tree of Diptera 8 . During the Jurassic, the family Limoniidae, including Architipulinae, underwent rapid radiation expressed in an abundant and diverse assemblage of genera and species 3,7,9-16 . In the Cretaceous, Architipulinae gradually became extinct, while other limoniid families had appeared in that time.
The subfamily Architipulinae includes 11 fossil genera:

diptera
architipulinae
late triassic
morphology
old group


Tropical sea surface temperatures for the past four centuries reconstructed from coral archives

Abstract: Most annually resolved climate reconstructions of the Common Era are based on terrestrial data, making it a challenge to independently assess how recent climate changes have affected the oceans. Here as part of the Past Global Changes Ocean2K project, we present four regionally calibrated and validated reconstructions of sea surface temperatures in the tropics, based on 57 published and publicly archived marine paleoclimate data sets derived exclusively from tropical coral archives. Validation exercises suggest that our reconstructions are interpretable for much of the past 400 years, depending on the availability of paleoclimate data within, and the reconstruction validation statistics for, each target region. Analysis of the trends in the data suggests that the Indian, western Pacific, and western Atlantic Ocean regions were cooling until modern warming began around the 1830s. The early 1800s were an exceptionally cool period in the Indo-Pacific region, likely due to multiple large tropical volcanic eruptions occurring in the early nineteenth century. Decadal-scale variability is a quasi-persistent feature of all basins. Twentieth century warming associated with greenhouse gas emissions is apparent in the Indian, West Pacific, and western Atlantic Oceans, but we find no evidence that either natural or anthropogenic forcings have altered El Nino–Southern Oscillation-related variance in tropical sea surface temperatures. Our marine-based regional paleoclimate reconstructions serve as benchmarks against which terrestrial reconstructions as well as climate model simulations can be compared and as a basis for studying the processes by which the tropical oceans mediate climate variability and change.

sea surface temperature
century
coral archive


Abstract: Hollis, C.J, Stickley, C.E., Bijl, P.K., Schiøler, P., Clowes, C.D., Li, X, Campbell, H. March 2017. The age of the Takatika Grit, Chatham Islands, New Zealand. Alcheringa 41, xxx–xxx. ISSN 0311-5518. The oldest Paleogene strata on Chatham Islands, east of New Zealand, are the phosphatized conglomerates and sandstones of the Takatika Grit that crops out on the northeastern coast at Tioriori and unconformably overlies the Chatham Schist. An intact Cretaceous–Paleogene boundary transition is not preserved at this locality. New biostratigraphic analysis of dinoflagellate, diatom and radiolarian microfossil assemblages confirms that the Takatika Grit is of late early–middle Paleocene (New Zealand Teurian stage) age but contains reworked microfossils of early Campanian (Early Haumurian) age. Vertebrate fossils found in this unit are inferred to be a mixture of reworked Cretaceous and in situ Paleocene bones and teeth. The overlying Tutuiri Greensand is of middle–late Paleocene age in its lower part and also contains reworked Cretaceous microfossils. Christopher J. Hollis [c.hollis@gns.cri.nz], Chris Clowes [c.clowes@gns.cri.nz], Xun Li [x.li@gns.cri.nz], Hamish Campbell [h.campbell@gns.cri.nz], GNS Science, PO Box 30-368, Lower Hutt 5040, New Zealand; Catherine Stickley, Evolution Applied Limited, 50 Mitchell Way, Upper Rissington, Cheltenham GL54 2PL, UK [catherine.stickley@gmail.com]; Peter Bijl [p.k.bijl@uu.nl], Marine Palynology and Paleoceanography, Department of Earth Sciences, Utrecht University, 3584 CS Utrecht, the Netherlands; Poul Schiøler [poul.schioler@mgpalaeo.com.au], Morgan Goodall Palaeo, Unit 1/5 Arvida St, Malaga, WA 6090, Australia.

takatika grit
chatham islands
new zealand


The Postcranial Anatomy of Diademodon tetragonus (Cynodontia, Cynognathia)

Abstract:
ABSTRACT
 A survey of the postcranial anatomy of a specimen of Diademodon tetragonus recovered from the Upper Omingonde Formation in Namibia resulted in the recognition of diagnostic characters in the axis, scapula, interclavicle, manubrium, sternebrae, humerus, ilium, ischium, and femur. Our comparative analysis shows that these and other postcranial features distinguish Diademodon tetragonus from other cynognathians. The presence of ossified sternal elements (manubrium and sternebrae) in Diademodon tetragonus stands out because they are otherwise only present in tritylodontids among nonmammaliaform cynodonts. It is suggested that this feature is not linked to body size but could be phylogenetically informative. A review of the postcranial anatomy of specimens previously identified as Diademodon and ?Cynognathus/ ?Diademodon shows that only a few of them can be assigned to Diademodon tetragonus.

postcranial anatomy
diademodon tetragonus
cynodontia


Exploring abnormal Cambrian-aged trilobites in the Smithsonian collection

Abstract: Biomineralised trilobite exoskeletons provide a 250 million year record of abnormalities in one of the most diverse arthropod groups in history. One type of abnormality—repaired injuries—have allowed palaeobiologists to document records of Paleozoic predation, accidental damage, and complications in moulting experienced by the group. Although Cambrian trilobite injuries are fairly well documented, the illustration of new injured specimens will produce a more complete understanding of Cambrian prey items. To align with this perspective, nine new abnormal specimens displaying healed injuries from the Smithsonian National Museum of Natural History collection are documented. The injury pattern conforms to the suggestion of lateralised prey defence or predator preference, but it is highlighted that the root cause for such patterns is obscured by the lumping of data across different palaeoecological and environmental conditions. Further studies of Cambrian trilobites with injuries represent a key direction for uncovering evidence for the Cambrian escalation event.

trilobite
exoskeleton
predation
injury
abnormal specimen


End-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change

Abstract: The cause of the end-Cretaceous (KPg) mass extinction is still debated due to difficulty separating the influences of two closely timed potential causal events: eruption of the Deccan Traps volcanic province and impact of the Chicxulub meteorite. Here we combine published extinction patterns with a new clumped isotope temperature record from a hiatus-free, expanded KPg boundary section from Seymour Island, Antarctica. We document a 7.8±3.3 °C warming synchronous with the onset of Deccan Traps volcanism and a second, smaller warming at the time of meteorite impact. Local warming may have been amplified due to simultaneous disappearance of continental or sea ice. Intra-shell variability indicates a possible reduction in seasonality after Deccan eruptions began, continuing through the meteorite event. Species extinction at Seymour Island occurred in two pulses that coincide with the two observed warming events, directly linking the end-Cretaceous extinction at this site to both volcanic and meteorite events via climate change.

meteorite impact
climate change
end-cretaceous extinction


THE MIDDLE MIOCENE (LAVENTAN) QUEBRADA HONDA FAUNA, SOUTHERN BOLIVIA and A DESCRIPTION OF ITS NOTOUNGULATES

Abstract: Abstract:  The Laventan Quebrada Honda Fauna of southern Bolivia is one of the best sampled middle Miocene South American faunas. The present study describes the toxodontid, interatheriid and mesotheriid notoungulates from Quebrada Honda and summarizes the present state of knowledge of the fauna. Toxodontid specimens from Quebrada Honda include two isolated molars, one upper and one lower. The upper molar compares favourably with Paratrigodon and may represent a new species, but too little material is known to make an adequate diagnosis. The lower molar may pertain to the same taxon, or to a distinct species that is even more poorly represented. A new species of the interatheriid Miocochilius is described, M. federicoi, on the basis of a partial skull. It differs from M. anomopodus in its significantly smaller size (at least 20 per cent smaller based on linear upper molar dimensions); relatively wider P4 with deeper lingual sulcus; more prominent middle lobes on upper molars; and M3 with deeper lingual sulcus and more prominent metastyle (distal lobe). The generic allocation of this new species is considered tentative, pending a better understanding of the phylogenetic relationships among currently recognized species of Miocochilius and Protypotherium. Mesotheriids are represented at Quebrada Honda by a pair of poorly preserved mandibles that are referred to Plesiotypotherium minor, a species previously recorded from slightly older deposits near Cerdas, Bolivia. A newly revised faunal list for Quebrada Honda is compiled that includes 30 species of non‐volant mammals, 27 of which have been identified to at least genus level. This revised faunal list is used to compare Quebrada Honda to other well‐sampled middle–late Miocene faunas (including La Venta, Columbia; Collón‐Curá, Argentina; and Arroyo Chasicó, Argentina) using the Simpson Index of faunal similarity. In order to compensate for inadequately identified specimens (i.e. those not identified to genus level), minimum and maximum values of faunal similarly were estimated using two different sets of assumptions. The analysis indicates that the middle‐latitude Quebrada Honda Fauna is more similar to the slightly older high‐latitude fauna of Collón‐Curá than to the contemporaneous low‐latitude fauna of La Venta, suggesting that isolating mechanisms between the low and middle latitudes were in place during the early and/or middle Miocene. The relative paucity of taxa shared between Quebrada Honda and La Venta, despite their contemporaneity, suggests that the system of South American Land Mammal ‘Ages’ (SALMAs) may not be useful for biocorrelation between low‐latitude faunas and those from elsewhere in South America.

middle miocene
quebrada honda fauna
southern bolivia


Earliest Example of a Giant Monitor Lizard (Varanus, Varanidae, Squamata)

Abstract: Background Varanidae is a clade of tiny (<20 mm pre-caudal length [PCL]) to giant (>600 mm PCL) lizards first appearing in the Cretaceous. True monitor lizards (Varanus) are known from diagnostic remains beginning in the early Miocene (Varanus rusingensis), although extremely fragmentary remains have been suggested as indicating earlier Varanus. The paleobiogeographic history of Varanus and timing for origin of its gigantism remain uncertain. Methodology/Principal Findings A new Varanus from the Mytilini Formation (Turolian, Miocene) of Samos, Greece is described. The holotype consists of a partial skull roof, right side of a braincase, partial posterior mandible, fragment of clavicle, and parts of six vertebrae. A cladistic analysis including 83 taxa coded for 5733 molecular and 489 morphological characters (71 previously unincluded) demonstrates that the new fossil is a nested member of an otherwise exclusively East Asian Varanus clade. The new species is the earliest-known giant (>600 mm PCL) terrestrial lizard. Importantly, this species co-existed with a diverse continental mammalian fauna. Conclusions/Significance The new monitor is larger (longer) than 99% of known fossil and living lizards. Varanus includes, by far, the largest limbed squamates today. The only extant non-snake squamates that approach monitors in maximum size are the glass-snake Pseudopus and the worm-lizard Amphisbaena. Mosasauroids were larger, but exclusively marine, and occurred only during the Late Cretaceous. Large, extant, non-Varanus, lizards are limbless and/or largely isolated from mammalian competitors. By contrast, our new Varanus achieved gigantism in a continental environment populated by diverse eutherian mammal competitors.


Do sharks exhibit heterodonty by tooth position and over ontogeny? A comparison using elliptic Fourier analysis

Abstract: Tooth morphology is often used to inform the feeding ecology of an organism as these structures are important to procure and process dietary resources. In sharks, differences in morphology may facilitate the capture and handling of prey with different physical properties. However, few studies have investigated differences in tooth morphology over ontogeny, throughout the jaws of a single species, or among species at multiple tooth positions. Bull (Carcharhinus leucas), blacktip (Carcharhinus limbatus), and bonnethead sharks (Sphyrna tiburo) are coastal predators that exhibit ontogenetic dietary shifts, but differ in their feeding ecologies. This study measured tooth morphology at six positions along the upper and lower jaws of each species using elliptic Fourier analysis to make comparisons within and among species over their ontogeny. Significant ontogenetic differences were detected at four of the six tooth positions in bull sharks, but only the posterior position on the lower jaw appeared to exhibit a functionally relevant shift in morphology. No ontogenetic changes in morphology were detected in blacktip or bonnethead sharks. Intraspecific comparisons found that most tooth positions significantly differed from one another across all species, but heterodonty was greatest in bull sharks. Additionally, interspecific comparisons found differences among all species at each tooth position except between bull and blacktip sharks at two positions. These morphological patterns within and among species may have implications for prey handling efficiency, as well as in providing insight for paleoichthyology studies and reevaluating heterodonty in sharks.

heterodonty
tooth position
ontogeny
fourier analysis
dietary shift


Lucy's Flat Feet: The Relationship between the Ankle and Rearfoot Arching in Early Hominins

Abstract: Background In the Plio-Pleistocene, the hominin foot evolved from a grasping appendage to a stiff, propulsive lever. Central to this transition was the development of the longitudinal arch, a structure that helps store elastic energy and stiffen the foot during bipedal locomotion. Direct evidence for arch evolution, however, has been somewhat elusive given the failure of soft-tissue to fossilize. Paleoanthropologists have relied on footprints and bony correlates of arch development, though little consensus has emerged as to when the arch evolved. Methodology/Principal Findings Here, we present evidence from radiographs of modern humans (n = 261) that the set of the distal tibia in the sagittal plane, henceforth referred to as the tibial arch angle, is related to rearfoot arching. Non-human primates have a posteriorly directed tibial arch angle, while most humans have an anteriorly directed tibial arch angle. Those humans with a posteriorly directed tibial arch angle (8%) have significantly lower talocalcaneal and talar declination angles, both measures of an asymptomatic flatfoot. Application of these results to the hominin fossil record reveals that a well developed rearfoot arch had evolved in Australopithecus afarensis. However, as in humans today, Australopithecus populations exhibited individual variation in foot morphology and arch development, and “Lucy” (A.L. 288-1), a 3.18 Myr-old female Australopithecus, likely possessed asymptomatic flat feet. Additional distal tibiae from the Plio-Pleistocene show variation in tibial arch angles, including two early Homo tibiae that also have slightly posteriorly directed tibial arch angles. Conclusions/Significance This study finds that the rearfoot arch was present in the genus Australopithecus. However, the female Australopithecus afarensis “Lucy” has an ankle morphology consistent with non-pathological flat-footedness. This study suggests that, as in humans today, there was variation in arch development in Plio-Pleistocene hominins.

foot
distal tibiae
tibial arch angle
australopithecus
lucy


A New Saurichthyiform (Actinopterygii) with a Crushing Feeding Mechanism from the Middle Triassic of Guizhou (China)

Abstract: Background Equipped with an effective predatory feeding mechanism enhanced by large and sharp teeth, pointed snout and elongate body, saurichthyiform fishes are considered common fish-eaters in the early Mesozoic aquatic ecosystems. Additionally, because of the similar body plan across species, saurichthyiforms are also regarded evolutionally conservative, with few morphological and ecological changes during their long history. However, their phylogenetic affinity remains unclear as to whether they are chondrostean, neopterygian or stem-actinopteran, and likewise the intrarelationships of the group have rarely been explored. Methodology/Principal Findings Here we report a new saurichthyiform from the Middle Triassic of Guizhou, China, based on the well-preserved specimens including a 3-D braincase. The new taxon, Yelangichthys macrocephalus gen. et sp. nov., is unique among saurichthyiforms in having a peculiar neurocranium with a broad orbital tectum, paired posterior myodomes, a deep, transverse fossa in the posterodorsal part of the orbit, and a feeding mechanism structured for durophagy. Phylogenetic analysis places Yelangichthys gen. nov. at the most basal position in the Saurichthyiformes as the sister to Saurichthyidae, and a new family Yelangichthyidae is erected to include only Y. macrocephalus gen. et sp. nov. The monophyly of the Chondrostei comprising [Saurichthyiformes + Acipenseriformes] Birgeriiformes is supported, but not the monophyly of Saurichthys, the type genus of Saurichthyidae. With its outstanding osteological details, Yelangichthys gen. nov. greatly increases the neurocranial variations in saurichthyiforms, and its novel feeding structure suggests the consumption of hard-preys instead of fishes. Conclusions/Significance Our findings highlight the detailed osteology of a saurichthyiform braincase and its feeding design. We suggest that saurichthyiforms are closely allied to the Acipenseriformes. Saurichthyiforms were very diverse in the cranial osteology and they might have undergone a rapid evolutionary radiation via, for the new material here, transforming the feeding mechanism and thus exploiting the food resources unsuitable for other saurichthyiforms.

new saurichthyiform
feeding mechanism
middle triassic
phylogenetic analysis


Simulation of climate, ice sheets and CO 2 evolution during the last four glacial cycles with an Earth system model of intermediate complexity

Abstract: Abstract. In spite of significant progress in paleoclimate reconstructions and modelling of different aspects of the past glacial cycles, the mechanisms which transform regional and seasonal variations in solar insolation into long-term and global-scale glacial–interglacial cycles are still not fully understood – in particular, in relation to CO2 variability. Here using the Earth system model of intermediate complexity CLIMBER-2 we performed simulations of the co-evolution of climate, ice sheets, and carbon cycle over the last 400 000 years using the orbital forcing as the only external forcing. The model simulates temporal dynamics of CO2, global ice volume, and other climate system characteristics in good agreement with paleoclimate reconstructions. These results provide strong support for the idea that long and strongly asymmetric glacial cycles of the late Quaternary represent a direct but strongly nonlinear response of the Northern Hemisphere ice sheets to orbital forcing. This response is strongly amplified and globalised by the carbon cycle feedbacks. Using simulations performed with the model in different configurations, we also analyse the role of individual processes and sensitivity to the choice of model parameters. While many features of simulated glacial cycles are rather robust, some details of CO2 evolution, especially during glacial terminations, are sensitive to the choice of model parameters. Specifically, we found two major regimes of CO2 changes during terminations: in the first one, when the recovery of the Atlantic meridional overturning circulation (AMOC) occurs only at the end of the termination, a pronounced overshoot in CO2 concentration occurs at the beginning of the interglacial and CO2 remains almost constant during the interglacial or even declines towards the end, resembling Eemian CO2 dynamics. However, if the recovery of the AMOC occurs in the middle of the glacial termination, CO2 concentration continues to rise during the interglacial, similar to the Holocene. We also discuss the potential contribution of the brine rejection mechanism for the CO2 and carbon isotopes in the atmosphere and the ocean during the past glacial termination.

ice sheet
glacial cycle
earth system model


A crown‐group demosponge from the early Cambrian Sirius Passet Biota, North Greenland

Abstract: Calibration of the divergence times of sponge lineages and understanding of their phylogenetic history are hampered by the difficulty in recognizing crown versus stem groups in the fossil record. A new specimen from the lower Cambrian (Series 2, Stage 3; approximately 515 Ma) Sirius Passet Biota of North Greenland has yielded a diagnostic spicule assemblage of the extant demosponge lineages Haploscleromorpha and/or Heteroscleromorpha. The specimen has disarticulated approximately in situ, but represents an individual sponge that possessed monaxon spicules combined with a range of slightly smaller sigma, toxa and unique spiral morphologies. The combination of spicule forms, together with their relatively large size, suggests that the sponge represents the stem lineage of Haploscleromorpha + Heteroscleromorpha. This is the first crown‐group demosponge described from the early Cambrian and provides the most reliable calibration point currently available for phylogenetic studies.

crown‐group demosponge
sirius passet biota
north greenland


Proterotheriids and macraucheniids (Litopterna: Mammalia) from the Pampa Castillo Fauna, Chile (early Miocene, Santacrucian SALMA) and a new phylogeny of Proterotheriidae

Abstract: Here we describe the litopterns, a diverse and temporally long-ranging clade of South American native ‘ungulates’, of the early Miocene Pampa Castillo fauna from the Galera Formation in the Andean Cordillera of southern Chile, and present a new phylogeny of Proterotheriidae, the most speciose litoptern subgroup. Two proterotheriids occur at Pampa Castillo: Thoatherium, the northernmost and first record of this taxon outside Santa Cruz Province, Argentina, and Picturotherium, known previously solely from the Pinturas Formation of north-western Santa Cruz Province. Macraucheniidae are represented at Pampa Castillo by Theosodon. Collectively, these three taxa suggest an early Miocene (Santacrucian South American Land Mammal ‘Age’ (SALMA)) age for the fossil mammal fauna from Pampa Castillo, reinforcing previous biochronological interpretations. Results of a comprehensive phylogenetic analysis identify Megadolodus molariformis as the earliest-diverging member of Proterotheriidae, a name for which we propose a stem-based definition. Few multi-species proterotheriid genera were recovered as monophyletic in our analysis. Three ‘anisolambdid’ litopterns, initially assumed to represent outgroups, instead nest deeply within Proterotheriidae, implying long ghost lineages. The phylogenetic placement of the four proterotheriids from the middle Miocene La Venta fauna of Colombia sheds light on the poorly understood long-term isolation of tropical faunas and their degree of exchange with high-latitude regions. Santacrucian SALMA assemblages in Patagonia are notable in that older localities preferentially produce earlier-diverging proterotheriids. Older sites are also marked by a mix of brachyodont and hypsodont taxa, whereas younger sites yield strictly hypsodont forms, supporting the notion of increasing aridity in Patagonia through this interval. Proterotheriids alone cannot be used to discriminate between an early or late Santacrucian age for the Pampa Castillo fauna, but the brachyodonty of Picturotherium suggests a humid climate and closed habitats.

litopterna
pampa castillo fauna
proterotheriidae


Three-dimensional Morphology of the Ichnofossil Phycosiphon incertum and Its Implication for Paleoslope Inclination

Abstract: Abstract Details of the three-dimensional morphology of the ichnofossil Phycosiphon incertum collected from deposits on submarine slopes are reconstructed by processing a series of images obtained from polished sections of the samples. Samples were collected from the mudstone around a slump scar in the Paleocene Shiomi Formation, northern Japan, which is characterized by the occurrence of slump scars. The reconstructed morphology of Phycosiphon incertum is a meandering tube with a flattened ellipse cross section. The tubes are flattened in a plane oblique to the bedding surfaces and aligned along the same direction at both the interior and exterior of the slump scar. Flattening of the tubes was likely caused by sediment compaction, and the tube flattens toward the horizontal plane that is oblique to the bedding plane because of the paleoslope inclination. The difference between the bedding and flattening planes of the tubes of Phycosiphon incertum may imply paleoslope inclination. When the inclination of the bedding plane of the Shiomi Formation is corrected using the flattened surfaces, the bedding plane dips by 9° toward the southeast, which conforms to the paleocurrent direction of the turbidites. The morphology of Phycosiphon incertum can, therefore, be used as a paleoslope indicator.

ichnofossil phycosiphon incertum
paleoslope inclination
three-dimensional morphology


Triassic: the crucial period of post-Palaeozoic crinoid diversification

Abstract: After their near-extinction around the end of the Permian, crinoids recovered during the Triassic and reoccupied almost all ecological niches they had held in Palaeozoic times. Triassic crinoids comprise 33 genera in 12 well-defined families and 5 orders of the subclass Articulata; the systematic position of 4 additional families is unknown. The highest diversity was before the Mid Carnian Wet Intermezzo that caused the extinction of the order Encrinida. Major morphologic changes were connected with the adaptation to various benthic habitats and to pseudoplanktonic and eleutherozoic modes of life. Convergently, the cups of Encrinida and Holocrinida-Isocrinida became cryptodicyclic with large muscular radial facets, arm numbers increased from 5 to more than 300, and the arms of Encrinida became gradually biserial. The Encrinida remained permanently fixed to hardgrounds and acted as frame builders in bioherms. By encrusting bivalve mudstickers some dadocrinids also became secondary soft bottom dwellers. The holocrinid stem evolved preformed rupture points at the lower nodal facets, allowing these crinoids to attach intermittently by cirri. The pseudoplanktonic traumatocrinids evolved extremely long, flexible stems with multiple pore systems and terminal root cirri. Paracomatulids and eocomatulids reduced their stems and adapted to an eleutherozoic mode of life. Somphocrinids miniaturized and remodeled their skeleton towards lightweight construction and adapted to a planktonic life style. After the Triassic no fundamentally novel adaptation was added. Crinoidal limestones, as common in the Palaeozoic, had their last appearance in Middle Triassic times.

diversification
near-extinction
ecological niche
palaeozoic
triassic


Experimental disintegration of regular echinoids: roles of temperature, oxygen, and decay thresholds

Abstract: Laboratory experiments on regular echinoids indicate that low water temperatures retard organic decomposition far more effectively than anoxia, and that the primary role of anoxia in the preservation of articulated multi-element calcareous skeletons may be in excluding scavenging organisms. When tumbled at 20 rpm, specimens that were first allowed to decay for two days in warm seawater (30°C) disintegrated more than six times faster than specimens treated at room temperature (23°C) and more than an order of magnitude faster than specimens treated in cool water (11°C). In contrast, the effects of aerobic versus anerobic decay on disintegration rates were insignificant. The longer the period that specimens were allowed to decay before tumbling, the greater the rate at which specimens disintegrated, until a threshold time that appears to mark the decomposition of collagenous ligaments. This required a few days at 30°C, about two weeks at 23°C, and more than 4 weeks at 11°C for Strongylocentrotus. Up until this threshold, coronas disintegrate by a combination of cross-plate fractures and separation along plate sutures; cross-plate fractures thus can be taphonomic in origin and are not necessarily related to predation. Specimens decayed for longer-than-threshold periods of time disintegrate virtually instantaneously upon tumbling by sutural separation only. Undisturbed coronas can remain intact for months, sufficient time for epibiont occupation. Rates of disintegration were documented semi-quantitatively by recognizing seven stages of test disarticulation, and quantitatively by tensometer measures of test strength and toughness. The effects of temperature and oxygen on decay and the existence of a decay threshold in disintegration should apply at least in a qualitative sense to many other animals whose skeletons consist of multiple, collagen-bound elements. Regular echinoids should still be perceived as taphonomically fragile organisms, but our results suggest the potential for latitudinal as well as bathymetric gradients in the preservation of fossil echinoid faunas. Echinoid preservation under any given set of conditions should also be a function of taxonomic differences in test construction (particularly stereom interlocking along plate sutures) as suggested by previous workers, although our experiments indicate that these effects should only be significant among post-threshold specimens. A survey of regular echinoids from Upper Cretaceous white chalk facies of Britain substantiates the basic experimental patterns, yielding examples of all disarticulation stages and significant taxonomic differences in quality of preservation. A diverse array of borers and encrusters on fossil coronas also corroborates the post-mortem persistence of some tests on mid-latitude seafloors.


Repeated evolution of durophagy during ichthyosaur radiation after mass extinction indicated by hidden dentition

Abstract: Marine tetrapods quickly diversified and were established as marine top predators after the end-Permian Mass extinction (EPME). Ichthyosaurs were the forerunner of this rapid radiation but the main drivers of the diversification are poorly understood. Cartorhynchus lenticarpus is a basal ichthyosauriform with the least degree of aquatic adaptation, holding a key to identifying such a driver. The unique specimen appeared edentulous based on what was exposed but a CT scanning revealed that the species indeed had rounded teeth that are nearly perpendicular to the jaw rami, and thus completely concealed in lateral view. There are three dental rows per jaw ramus, and the root lacks infoldings of the dentine typical of ichthyopterygians. The well-developed and worn molariform dentition with three tooth rows supports the previous inference that the specimen is not of a juvenile. The premaxilla and the corresponding part of the dentary are edentulous. Molariform dentition evolved three to five times independently within Ichthyosauriformes in the Early and Middle Triassic. Convergent exploitation of hard-shelled invertebrates by different subclades of ichthyosauriforms likely fueled the rapid taxonomic diversification of the group after EPME.


Synchrotron imaging reveals bone healing and remodelling strategies in extinct and extant vertebrates

Abstract: Current understanding of bone healing and remodelling strategies in vertebrates has traditionally relied on morphological observations through the histological analysis of thin sections. However, chemical analysis may also be used in such interpretations, as different elements are known to be absorbed and used by bone for different physiological purposes such as growth and healing. These chemical signatures are beyond the detection limit of most laboratory-based analytical techniques (e.g. scanning electron microscopy). However, synchrotron rapid scanning–X-ray fluorescence (SRS–XRF) is an elemental mapping technique that uniquely combines high sensitivity (ppm), excellent sample resolution (20–100 µm) and the ability to scan large specimens (decimetre scale) approximately 3000 times faster than other mapping techniques. Here, we use SRS–XRF combined with microfocus elemental mapping (2–20 µm) to determine the distribution and concentration of trace elements within pathological and normal bone of both extant and extinct archosaurs (Cathartes aura and Allosaurus fragilis). Results reveal discrete chemical inventories within different bone tissue types and preservation modes. Chemical inventories also revealed detail of histological features not observable in thin section, including fine structures within the interface between pathological and normal bone as well as woven texture within pathological tissue.

bone healing
remodelling strategy
vertebrate


Taxonomic identification using virtual palaeontology and geometric morphometrics: a case study of Jurassic nerineoidean gastropods

Abstract: Taxonomic identification of fossils is fundamental to a wide range of geological and biological disciplines. Many fossil groups are identified based on expert judgement, which requires extensive experience and is not always available for the specific taxonomic group at hand. Nerineoideans, a group of extinct gastropods that formed a major component of Mesozoic shallow marine environments, have distinctive internal spiral folds that form the basis for their classification at the genus level. However, their identification is often inconsistent because it is based on a set of selected characters reliant upon individual interpretation. This study shows a non‐destructive and quantitative method for their identification using micro‐CT and geometric morphometrics. We examined and micro‐CT‐scanned nerineoidean specimens from five main families that dominated Europe, Arabia and Africa during the Middle–Late Jurassic. Optimal longitudinal slices were selected from the tomographic reconstructions or from images of polished cross‐sections compiled from fossil collections, published work and online databases. Internal whorl outlines were represented by 30 evenly distributed sliding semilandmarks and shape variations were studied using the Procrustes‐based geometric morphometrics method. Multivariate analysis shows that Ceritellidae and Ptygmatididae are distinct families, whereas Nerinellidae, Eunerineidae and Nerineidae fall within the same shape variance and cannot be distinguished based on internal whorl outlines. The suggested method can be applied to images from various sources as well as to poorly preserved specimens. Our case study demonstrates the importance of quantitatively re‐evaluating taxonomy in the fossil record, promoting the future utility of large datasets.

geometric morphometric
gastropod
taxonomic identification


Postcranial remains of Teraterpeton hrynewichorum (Reptilia: Archosauromorpha) and the mosaic evolution of the saurian postcranial skeleton

Abstract: Teraterpeton hrynewichorum is an unusual archosauromorph reptile from the Upper Triassic (Carnian) Evangeline Member of the Wolfville Formation in Nova Scotia (Canada). Its long snout has transversely broad, cusped ‘molariform’ teeth posteriorly and lacks teeth anteriorly. The temporal region of the cranium is ‘euryapsid’ with large upper and closed lower temporal fenestrae. A previously undescribed specimen referable to Teraterpeton includes a nearly complete pelvic girdle and both hind limbs. The ilium has a long, dorsoventrally deep anterior process similar to that of derived rhynchosaurs. The pelvis has a well-developed thyroid fenestra, a feature shared only by Tanystropheidae among Archosauromorpha. Metatarsal V is proximodistally short, resembling the condition in Tanystropheidae. The pedal unguals of Teraterpeton are strongly flattened mediolaterally, dorsoventrally deep and weakly curved, much like the manual unguals. We performed a phylogenetic analysis of a matrix comprising 61 taxa of Permo-Triassic diapsid reptiles and 337 characters, which supports the position of Teraterpeton as the sister-taxon of Trilophosaurus + Spinosuchus. In the current phylogeny, parsimony-based character optimization of the aforementioned character-states in Teraterpeton indicate that all were acquired independently from other saurian lineages. The unusual combination of postcranial features in Teraterpeton underscores the critical importance of comprehensive taxon sampling for understanding the mode of character change among Triassic diapsid reptiles and careful apomorphy-based identifications to faunal analyses.

teraterpeton hrynewichorum
archosauromorpha
postcranial skeleton
upper triassic
nova scotia


Morphometry of the teeth of western North American tyrannosaurids and its applicability to quantitative classification

Abstract: Gross tooth morphology and serration morphology were examined to determine a quantifiable method for classifying tyrannosaurid tooth crowns from western North America. From the examination of teeth in jaws, tyrannosaurid teeth could be qualitatively assigned to one of five types based on the cross-sectional shape of the base of the tooth and characteristics of the mesial carina. A principal component analysis (PCA) revealed that much of the variance in tooth shape was a result of isometry, but some gross morphological variables exhibited strong positive allometry. Non-size associated factors were also important in determining tooth shape, particularly when data on denticle dimensions were considered in the analysis. While PCA identified important factors in variation, PCA ordination plots did not cluster the teeth into distinct, separate groupings based on taxon or bone of origin. The group classification functions determined by discriminant analysis, though not universally successful for classifying unidentified isolated teeth of all tyrannosaurids, do identify bone of origin of adult Albertosaurus, Daspletosaurus, and Gorgosaurus teeth at a statistically acceptable level.

tyrannosaurid
tooth
pca
discriminant analysis


Osteology of Klamelisaurus gobiensis (Dinosauria, Eusauropoda) and the evolutionary history of Middle–Late Jurassic Chinese sauropods

Abstract: Fossil-rich deposits from the Middle and Late Jurassic of China have yielded a diverse array of sauropod dinosaurs, including numerous species referred to Mamenchisaurus and Omeisaurus. Despite an abundance of fossils and a proliferation of taxa, the anatomy of Middle–Late Jurassic Chinese sauropods remains poorly documented. Here, we comprehensively redescribe and illustrate Klamelisaurus gobiensis from the Middle–Late Jurassic Shishugou Formation of northwest China. Phylogenetic analyses conducted under parsimony and time-calibrated Bayesian optimality criteria consistently recover Klamelisaurus as a member of a predominantly Chinese radiation of exceptionally long-necked eusauropods that includes Mamenchisaurus spp., Chuanjiesaurus, Qijianglong and Wamweracaudia. In most analyses, this lineage also includes Euhelopus, reviving a ‘traditional’ Euhelopodidae and calling into question the macronarian affinities of Euhelopus. Klamelisaurus shares several features with Euhelopus that are unique to a subset of East Asian taxa or rare among sauropods, including a convex ventral margin of the prezygodiapophyseal lamina in middle–posterior cervical vertebrae, a ventrally bifurcated postzygodiapophyseal lamina in posterior cervical vertebrae, and development of a rugose projection extending anteriorly from the epipophysis into the spinodiapophyseal fossa in most cervical vertebrae. Anatomical comparisons of the cervical vertebrae of Klamelisaurus to several other sauropodomorphs and insights from myological studies of extant archosaurs strongly suggest that this latter structure, often considered part of an epipophyseal-prezygapophyseal lamina, is an epaxial muscle scar that is distinct from pneumatic structures of the lateral surface of the neural spine. The phylogenetic and comparative anatomical data presented here provide a foundation for future revision of the taxonomy and systematics of sauropods from the Junggar and Sichuan basins.

klamelisaurus gobiensis
middle–late jurassic
sauropod
mamenchisaurus
phylogenetic analysis


Long-term persistence of structured habitats: seagrass meadows as enduring hotspots of biodiversity and faunal stability

Abstract: Ecological studies indicate that structurally complex habitats support elevated biodiversity, stability and resilience. The long-term persistence of structured habitats and their importance in maintaining biodiverse hotspots remain underexplored. We combined geohistorical data (dead mollusc assemblages, ‘DA’) and contemporary surveys (live mollusc assemblages, ‘LA’) to assess the persistence of local seagrass habitats over multi-centennial timescales and to evaluate whether they acted as long-term drivers of biodiversity, stability and resilience of associated fauna. We sampled structured seagrass meadows and open sandy bottoms along Florida's Gulf Coast. Results indicated that: (i) LA composition differed significantly between the two habitat types, (ii) LA from seagrass sites were characterized by significantly elevated local biodiversity and significantly higher spatial stability, (iii) DA composition differed significantly between the two habitat types, and (iv) fidelity between LA and DA was significantly greater for seagrass habitats. Contemporary results support the hypotheses that local biodiversity and spatial stability of marine benthos are both elevated in structured seagrass habitats. Geohistorical results suggest that structured habitats persist as local hotspots of elevated biodiversity and faunal stability over centennial-to-millennial timescales; indicating that habitat degradation and concomitant loss within structurally complex marine systems is a key driver of declining biodiversity and resilience.

seagrass meadow
biodiversity
long-term persistence


Sequence stratigraphy, seismic stratigraphy, and seismic structures of the lower intermediate confining unit and most of the Floridan aquifer system, Broward County, Florida

Abstract: Deep well injection and disposal of treated wastewater into the highly transmissive saline Boulder Zone in the lower part of the Floridan aquifer system began in 1971. The zone of injection is a highly transmissive hydrogeologic unit, the Boulder Zone, in the lower part of the Floridan aquifer system. Since the 1990s, however, treated wastewater injection into the Boulder Zone in southeastern Florida has been detected at three treated wastewater injection utilities in the brackish upper part of the Floridan aquifer system designated for potential use as drinking water. At a time when usage of the Boulder Zone for treated wastewater disposal is increasing and the utilization of the upper part of the Floridan aquifer system for drinking water is intensifying, there is an urgency to understand the nature of cross-formational fluid flow and identify possible fluid pathways from the lower to upper zones of the Floridan aquifer system. To better understand the hydrogeologic controls on groundwater movement through the Floridan aquifer system in southeastern Florida, the U.S. Geological Survey and the Broward County Environmental Planning and Community Resilience Division conducted a 3.5-year cooperative study from July 2012 to December 2015. The study characterizes the sequence stratigraphy, seismic stratigraphy, and seismic structures of the lower part of the intermediate confining unit aquifer and most of the Floridan aquifer system. Data obtained to meet the study objective include 80 miles of high-resolution, two-dimensional (2D), seismic-reflection profiles acquired from canals in eastern Broward County. These profiles have been used to characterize the sequence stratigraphy, seismic stratigraphy, and seismic structures in a 425-square-mile study area. Horizon mapping of the seismic-reflection profiles and additional data collection from well logs and cores or cuttings from 44 wells were focused on construction of three-dimensional (3D) visualizations of eight sequence stratigraphic cycles that compose the Eocene to Miocene Oldsmar, Avon Park, and Arcadia Formations. The mapping of these seismic-reflection and well data has produced a refined Cenozoic sequence stratigraphic, seismic stratigraphic, and hydrogeologic framework of southeastern Florida. The upward transition from the Oldsmar Formation to the Avon Park Formation and the Arcadia Formation embodies the evolution from (1) a tropical to subtropical, shallow-marine, carbonate platform, represented by the Oldsmar and Avon Park Formations, to (2) a broad, temperate, mixed carbonate-siliciclastic shallow marine shelf, represented by the lower part of the Arcadia Formation, and to (3) a temperate, distally steepened carbonate ramp represented by the upper part of the Arcadia Formation. In the study area, the depositional sequences and seismic sequences have a direct correlation with hydrogeologic units. The approximate upper boundary of four principal permeable units of the Floridan aquifer system (Upper Floridan aquifer, Avon Park permeable zone, uppermost major permeable zone of the Lower Floridan aquifer, and Boulder Zone) have sequence stratigraphic and seismic-reflection signatures that were identified on cross sections, mapped, or both, and therefore the sequence stratigraphy and seismic stratigraphy were used to guide the development of a refined spatial representation of these hydrogeologic units. In all cases, the permeability of the four permeable units is related to stratiform megaporosity generated by ancient dissolution of carbonate rock associated with subaerial exposure and unconformities at the upper surfaces of carbonate depositional cycles of several 1U.S. Geological Survey. 2Cherokee Nation Businesses, Contractor to the U.S. Geological Survey. 3Jarer Biostrat, Inc., Contractor to the U.S. Geological Survey. 4Walker Marine Geophysical Company, Contractor to the Miami-Dade County Water and Sewer Department. 2 Sequence Stratigraphy, Seismic Stratigraphy, and Seismic Structures of the Lower Intermediate Confining Unit. . . hierarchical scales ranging from high-frequency cycles to depositional sequences. Additionally, interparticle porosity also contributes substantially to the stratiform permeability in much of the Upper Floridan aquifer. Information from seismic stratigraphy allowed 3D geomodeling of hydrogeologic units— an approach never before applied to this area. Notably, the 3D geomodeling provided 3D visualizations and geocellular models of the depositional sequences, hydrostratigraphy, and structural features. The geocellular data could be used to update the hydrogeologic structure inherent to groundwater flow simulations that are designed to address the sustainability of the water resources of the Floridan aquifer system. Two kinds of pathways that could enable upward cross-formational flow of injected treated wastewater from the Boulder Zone have been identified in the 80 miles of high-resolution seismic data collected for this study: a near-vertical reverse fault and karst collapse structures. The single reverse fault, inferred to be of tectonic origin, is in extreme northeastern Broward County and has an offset of about 19 feet at the level of the Arcadia Formation. Most of the 17 karst collapse structures identified manifest as columniform, vertically stacked sagging seismic reflections that span early Eocene to Miocene age rocks equivalent to much of the Floridan aquifer system and the lower part of the overlying intermediate confining unit. In some cases, the seismic-sag structures extend upward into strata of Pliocene age. The seismic-sag structures are interpreted to have a semicircular shape in plan view on the basis of comparison to (1) other seismic-sag structures in southeastern Florida mapped with two 2D seismic cross lines or 3D data, (2) comparison to these structures located in other carbonate provinces, and (3) plausible extensional ring faults detected with multi-attribute analysis. The seismic-sag structures in the study area have heights as great as 2,500 vertical feet, though importantly, one spans about 7,800 feet. Both multi-attribute analysis and visual detection of offset of seismic reflections within the seismic-sag structures indicate faults and fractures are associated with many of the structures. Multi-attribute analysis highlighting chimney fluid pathways also indicates that the seismic-sag structures have a high probability for potential vertical cross-formational fluid flow along the faulted and fractured structures. A collapse of the seismic-sag structures within a deep burial setting evokes an origin related to hypogenic karst processes by ascending flow of subsurface fluids. In addition, paleo-epigenic karst related to major regional subaerial unconformities within the Florida Platform generated collapse structures (paleo-sinkholes) that are much smaller in scale than the cross-formational seismic-sag structures. Introduction The source of drinking water in southeastern Florida primarily comes from the shallow Biscayne aquifer of the surficial aquifer system, whereas the Upper Floridan aquifer of the deeper Floridan aquifer system provides only a relatively minor volume (figs. 1 and 2). The Biscayne aquifer is a sole source aquifer in southeastern Florida (Federal Register Notice, 1979) and, as a protective measure, the South Florida Water Management District’s Regional Water Availability Rule 1, adopted in 2007, limits urban water withdrawals from the Biscayne aquifer to pre-2006 levels (Broward Water Resources Task Force, 2010). In addition, legislation adopted by the State of Florida mandates the elimination of ocean outfalls of treated wastewater by 2025. These mandated changes have advanced the use of the more deeply buried Floridan aquifer system for the purposes of freshwater supply from the Upper Floridan aquifer and treated wastewater storage in the Boulder Zone of the Lower Floridan aquifer (fig. 2). The year 1971 marked the beginning of the use of deep well injection of treated wastewater into the highly transmissive Boulder Zone in southern Florida (fig. 2, Meyer, 1974). Since the 1990s, however, wastewater injection into the Boulder Zone in southeastern Florida has been detected at three treated wastewater injection utilities in the brackish (brackish water contains dissolved-solids concentrations that range from 1,000 to 10,000 milligrams per liter) upper part of the Floridan aquifer system designated for potential use as drinking water (Maliva and others, 2007; Walsh and Price, 2010). At a time when usage of the Boulder Zone for treated wastewater disposal is increasing and utilization of the upper brackish part of the Floridan aquifer system for drinking water is intensifying, the possibility of upward movement of treated wastewater brings new urgency to understanding the nature of cross-formational fluid flow and identifying possible fluid pathways from the Boulder Zone to the upper brackish part of the Floridan aquifer system. In Broward County, the Floridan aquifer system (figs. 1 and 2) is receiving increased attention as a result of regulatory restrictions on water-supply withdrawals and treated wastewater management practices. However, the integrity of the Floridan aquifer system for use either as a water-supply resource or wastewater repository (or both) is not well understood. Structural geologic anomalies (faults, fractures, and karst collapse structures) within the Floridan aquifer system in southeastern Florida are well documented (Cunningham and Walker, 2009; Cunningham and others, 2012; Reese and Cunningham, 2013, 2014; Cunningham, 2015) and present a potential risk for vertical cross-formational transport of undesirable fluids through the aquifer. The karst collapse structures are defined on seismic-reflection profiles as columniform, seismic-sag structures (McDonnell and others, 2007). Moreover, because of the risk posed by limited stratigraphic knowledge of the physic

seismic stratigraphy
aquifer system
sequence stratigraphy


Paleoceanography of the Late Cretaceous northwestern Tethys Ocean: Seasonal upwelling or steady thermocline?

Abstract: In this study we attempted to assess whether seasonal upwelling or a steady thermocline persisted at the western margin of the Tethys Ocean during the late Turonian–early Coniacian interval. For this scope, we employed novel and published stable oxygen isotope (δ18O) data of various organisms (bivalves, bivalves, brachiopods, fish and belemnites). New seasonally resolved temperature estimates were based on the δ18O record of sequentially sampled inoceramid (Inoceramus sp.) and rudist (Hippurites resectus) shells from the Scaglia Rossa and Gosau deposits of northern Italy and western Austria, respectively. Diagenetic screening was performed using reflected light, cathodoluminescence (CL), scanning electron microscopy (SEM) and stable isotope analysis. Originally preserved δ13C and δ18O values were used to characterize the lifestyle of the bivalves and detect vital effects that could have biased oxygen isotope-based temperature reconstructions. Inoceramid δ18O values provide–for the first time–information on temperatures of Tethyan benthic waters, which were, on average, 14.4 ± 0.6 °C and fluctuated seasonally within a range of less than 2 °C. Such a thermal regime is in line with the temperatures postulated for late Turonian boreal water masses and support the existence of a cold water supply from the North Atlantic to the Tethyan bottom. Bottom cooling, however, did not affect the shallow water environment. In fact, the rudist-based temperature estimates for shallow water environment revealed a mean annual range of 11 °C, between 24 and 35 °C (assuming a seasonally constant δ18Ow = 1.0 ‰), which are among the warmest temperatures recorded over the entire Late Cretaceous. Our findings, thus, suggest a strong thermal and food web decoupling between the two environments. The absence of a seasonal vertical homogenization of different water bodies suggests the existence of a steady thermocline and, therefore, contrasts with the presence of an active coastal upwelling in the region as hypothesized by previous authors.

tethys ocean
seasonal upwelling
steady thermocline


Pitfalls reconstructing the last common ancestor of chimpanzees and humans

Abstract: The morphological nature of the last common ancestor (LCA) of chimpanzees/bonobos and humans is a fascinating topic in human evolution. Available evidence suggests that both lineages share a LCA that lived in Africa ∼8–6 Myr. However, the hominoid fossil record of this time period is inadequate, prompting the use of novel methodological approaches to reconstruct the anatomy of this key ancestor. In a recent example, Young et al. (1) claim that “fossil hominin shoulders support an African ape-like last common ancestor of humans and chimpanzees.” Although I applaud these authors for implementing novel comparative methods to paleoanthropology, fundamental aspects of the experimental design were disregarded, leading to biased conclusions. Herein I provide constructive criticisms on that study, also addressing recurrent pitfalls in the field, to help redirect future research on human paleobiology.