Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars

Abstract: Ancient lake system at Gale crater Since 2012, the Curiosity rover has been diligently studying rocky outcrops on Mars, looking for clues about past water, climate, and habitability. Grotzinger et al. describe the analysis of a huge section of sedimentary rocks near Gale crater, where Mount Sharp now stands (see the Perspective by Chan). The features within these sediments are reminiscent of delta, stream, and lake deposits on Earth. Although individual lakes were probably transient, it is likely that there was enough water to fill in low-lying depressions such as impact craters for up to 10,000 years. Wind-driven erosion removed many of these deposits, creating Mount Sharp. Science, this issue p.10.1126/science.aac7575, see also p. 167 Mount Sharp now stands where there was once a large intercrater lake system. [Also see Perspective by Chan] INTRODUCTION Remote observational data suggest that large bodies of standing water existed on the surface of Mars in its early history. This would have required a much wetter climate than that of the present, implying greater availability of water on a global basis and enhanced potential for global habitability. However, based on assumptions of a vast water inventory and models of atmospheric erosion, theoretical studies suggest a climate that was wetter but not by enough to sustain large lakes, even in depressions such as impact craters. RATIONALE The Mars Science Laboratory mission’s rover, Curiosity, provides the capability to test hypotheses about Mars’s past climate. The focus of the mission is the exploration of a ~5-km-high mountain, Aeolis Mons (informally known as Mount Sharp), located near the center of the ~140-km-wide Gale impact crater. Mount Sharp is underlain by hundreds of meters of sedimentary rock strata deposited ~3.6 billion to 3.2 billion years ago. These sediments accumulated in aqueous environments, recording the history of Mars’s ancient climate. Because of Curiosity’s ability to study these strata where they are exposed near the base of Mount Sharp, we can directly test the hypothesis that large impact craters were capable of accumulating and storing water as lakes for substantial periods of time. RESULTS Over the course of 2 years, Curiosity studied dozens of outcrops distributed along a ~9-km transect that also rose ~75 m in elevation. Image data were used to measure the geometry and grain sizes of strata and to survey the textures associated with sediment deposition and diagenesis. Erosion of Gale’s northern crater wall and rim generated gravel and sand that were transported southward in shallow streams. Over time, these stream deposits advanced toward the crater interior, transitioning downstream into finer-grained (sand-sized), southward-advancing delta deposits. These deltas marked the boundary of an ancient lake where the finest (mud-sized) sediments accumulated, infilling both the crater and its internal lake basin. After infilling of the crater, the sedimentary deposits in Gale crater were exhumed, probably by wind-driven erosion, creating Mount Sharp. The ancient stream and lake deposits are erosional remnants of superimposed depositional sequences that once extended at least 75 m, and perhaps several hundreds of meters, above the current elevation of the crater floor. Although the modern landscape dips northward away from Mount Sharp, the ancient sedimentary deposits were laid down along a profile that projected southward beneath Mount Sharp and indicate that a basin once existed where today there is a mountain. CONCLUSION Our observations suggest that individual lakes were stable on the ancient surface of Mars for 100 to 10,000 years, a minimum duration when each lake was stable both thermally (as liquid water) and in terms of mass balance (with inputs effectively matching evaporation and loss of water to colder regions). We estimate that the stratigraphy traversed thus far by Curiosity would have required 10,000 to 10,000,000 years to accumulate, and even longer if overlying strata are included. Though individual lakes may have come and gone, they were probably linked in time through a common groundwater table. Over the long term, this water table must have risen at least tens of meters to enable accumulation of the delta and lake deposits observed by Curiosity in Gale crater. Inclined strata in the foreground dip southward toward Mount Sharp and represent ancient delta deposits. These deposits transition into strata in the mid-field that were deposited in ancient lakes. The buttes and mesas in the background contain younger deposits that overlie and postdate the lake deposits beneath Mount Sharp. The outcrop in the foreground is about 6 m wide, and the buttes and mesas in the background are hundreds of meters wide and tens of meters high. The image has been white-balanced. [Credit: NASA/Caltech/JPL/MSSS] The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).

lake deposit
gale crater
mars
diagenesis


Change and Stasis in the Iberian Middle Paleolithic

Abstract: The European Mousterian has traditionally been portrayed as a long period of technological stasis as opposed to the technotypological dynamism of Upper Paleolithic cultures. The classic debate on Mousterian variability explained interassemblage differences either by ethnic, cultural, functional, and chronological or by paleoenvironmental causes, but variability was based on typological considerations. Recently, technological factors have been introduced in discussions over time trends and geographic differences in the Mousterian. This paper will address the topic by reviewing technological strategies in the Iberian Middle Paleolithic. Three sites from northeastern Spain are chosen as a case study to address the existence of directional patterns in the Iberian Mousterian. We conclude that albeit diachronic variability exists, it does not show patterning, which suggests stochastic variation rather than directional change in the technological strategies of Iberian Neanderthals.

stasis
iberian middle paleolithic
strategy


VARIATIONS IN THE MORPHOLOGY OF EMU (DROMAIUS NOVAEHOLLANDIAE) TRACKS REFLECTING DIFFERENCES IN WALKING PATTERN AND SUBSTRATE CONSISTENCY: ICHNOTAXONOMIC IMPLICATIONS

Abstract: Abstract:  Fossil footprints appear in a variety of preservational states, each revealing a different morphology that can give rise to misidentification and misinterpretations. Comparative ichnological work was conducted using living emus (Dromaius novaehollandiae). It was clearly demonstrated that the morphological variation that occurred in footprints of the same animal, walking in the same manner, was caused by variation in substrate consistency. Dry sand substrates are unlikely to preserve any anatomical details of the foot, whereas damp sand or mud of firm consistency preserves a high level of anatomical detail. The finest anatomical details, such as skin impressions, are only preserved in firm mud or clay. In semi‐fluid to fluid mud the track walls collapse, destroying the shape of the footprint. Increased speed of progression affects the shape of the footprint dramatically as the distal ends of the digits become more deeply impressed in the substrate during acceleration. Plantigrade stance adopted by the emu while feeding produces highly elongated footprints. Applying these observations to the study of fossil footprints demonstrates that great care should be paid to the original sedimentary conditions at the time of track making, as well as to the stance and gait of the trackmaker.

morphology
dromaius novaehollandiae
substrate consistency
trackmaker


Counting individuals in mammalian fossil assemblages from fluvial environments

Abstract: Many paleoecological analyses utilize estimates of the relative abundances of taxa in fossil or subfossil assemblages. Such estimates depend upon determination of the number of individuals present or some other measure of the amount of material collected for each taxon. I assess the validity of methods currently used to estimate numbers of individuals per taxon in mammalian assemblages. For any method of counting selected, the underlying assumptions about the probability of association among skeletal elements should correspond to processes of accumulation for the assemblage, as inferred from its taphonomic characteristics. No method is appropriate for all mammalian assemblages. Equating the number of individuals with the number of specimens per taxon is the appropriate method when formerly articulated material has been widely dispersed and has accumulated as isolated specimens. Determining the minimum number of individuals represented by multiple skeletal elements is appropriate when material originally accumulated in articulation. For mammalian assemblages from Middle Siwalik (late Miocene) sediments of Pakistan, different methods of counting are appropriate for assemblages from different sedimentary environments. For assemblages produced by current transport, I counted each specimen as a single individual. For assemblages produced by the activities of predators and scavengers, I determined the minimum number of individuals. Two taphonomic processes that influence the degree of association among skeletal remains are mortality and transport. Taphonomic histories that combine different causes of mortality and different conditions of transport produce fossil assemblages with expected taphonomic characteristics. These include the amount of articulated material, the spatial distribution of specimens, the presence of hydraulic sorting, the frequency of juvenile remains, and patterns of bone damage. Taphonomic characteristics of fossil assemblages do not permit all combinations of mortality and transport to be distinguished. Processes of transport generally obscure taphonomic characteristics imposed by different agents of mortality. INTRODUCTION

fossil assemblage
environment
minimum number


Warming and Cooling: The Medieval Climate Anomaly in Africa and Arabia

Abstract: The Medieval Climate Anomaly (MCA) is a well-recognized climate perturbation in many parts of the world, with a core period of 1000–1200 Common Era. Here we present a palaeotemperature synthesis for the MCA in Africa and Arabia, based on 44 published localities. The data sets have been thoroughly correlated and the MCA trends palaeoclimatologically mapped. The vast majority of available Afro-Arabian onshore sites suggest a warm MCA, with the exception of the southern Levant where the MCA appears to have been cold. MCA cooling has also been documented in many segments of the circum-Africa-Arabian upwelling systems, as a result of changes in the wind systems which were leading to an intensification of cold water upwelling. Offshore cores from outside upwelling systems mostly show warm MCA conditions. The most likely key drivers of the observed medieval climate change are solar forcing and ocean cycles. Conspicuous cold spikes during the earliest and latest MCA may help to discriminate between solar (Oort Minimum) and ocean cycle (Atlantic Multidecadal Oscillation, AMO) influence. Compared to its large share of nearly one quarter of the world's landmass, data from Africa and Arabia are significantly underrepresented in global temperature reconstructions of the past 2,000 years. Onshore data are still absent for most regions in Africa and Arabia, except for regional data clusters in Morocco, South Africa, the East African Rift, and the Levant coast. In order to reconstruct land palaeotemperatures more robustly over Africa and Arabia, a systematic research program is needed.


Ontogeny and intraspecific variation of the early Cambrian trilobite Olenellus gilberti, with implications for olenelline phylogeny and macroevolutionary trends in phenotypic canalization

Abstract: Morphological variation within the Early Cambrian olenelline trilobite Olenellus gilberti from the Pioche Formation of Nevada is partitioned into ontogenetic, static (non-ontogenetic), and taphonomic components, providing clearer understanding of the nature and sources of the variation. Such understanding is crucial for improved systematic, phylogenetic and evolutionary analyses of early trilobites. Compaction caused a significant change in mean form and an increase in shape variance, distorting many aspects of biological shape and shape variation. Morphologically mature specimens exhibited variation in many quantitative and qualitative aspects of cephalic morphology, in the distribution of prothoracic axial nodes, and in the number of opisthothoracic segments. The variance of two log-transformed size measures does not significantly increase over the first five sampled instars, a pattern interpretable either as the oldest known case of targeted growth in animal history, or as evidence of strong selection during early ontogeny. The magnitude of static cephalic shape variation does not significantly change during late ontogeny, also indicative either of developmental regulation of form or of selection against deviant phenotypes. The dominant structure of cephalic static shape variation is similar to the pattern of shape change during late portions of ontogeny: intraspecific heterochrony might therefore have been an important contributor to size-independent shape variation. For many traits, the developmental system was not well buffered against internal and/or external variation so that the resulting phenotype was not tightly canalized in the condition of those traits. Intraspecific variation in such traits is rarely documented in later (especially post-Cambrian) trilobites, consistent with the claim that developmental systems of early trilobites were relatively poorly canalized. However, other aspects of cephalic growth are consistent with having been under tight developmental regulation, which would not be indicative of general developmental ‘sloppiness’. This cautions against generalizing observations from a limited number of traits to the entire organism.

intraspecific variation
trilobite
ontogeny


Cryptospore Assemblages from the Ordovician/silurian Boundary in the Puna Region, North‐west Argentina

Abstract: Palynomorph assemblages have been recovered from deposits believed to straddle the Ordovician/Silurian boundary, from the upper member of the Salar del Rincón Formation, in the Puna region of north‐west Argentina. The palynomorph assemblages are dominated by terrestrial cryptospores, but also contain marine elements (acritarchs, prasinophycean algae and chitinozoans). The cryptospore assemblages are similar in composition to those described from coeval deposits worldwide, suggesting that the producers were cosmopolitan and tolerated a wide range of climatic conditions. They are correlated with the Imperfectotriletes spp. Interval Biozone (sub‐biozone α) of the Imperfectotriletes spp.‐Laevolancis divellomedia Assemblage Biozone, indicating a Hirnantian (latest Ordovician) age. Acritarchs include late Ordovician species such as Eupoikilosusa striata and Villosacapsula cf. setosapellicula, that coexist with the Llandovery species Dactylofusa estillis. Based on lithological and palynological evidence, an early Llandovery, or a late Hirnantian (post‐glacial) age is proposed for the basal part of the upper member of the Salar del Rincón Formation.

ordovician
silurian boundary
north‐w argentina


Calcium isotopes offer clues on resource partitioning among Cretaceous predatory dinosaurs

Abstract: Large predators are overabundant in mid-Cretaceous continental dinosaur assemblages of North Africa. Such unbalanced ecosystem structure involves, among predatory dinosaurs, typical abelisaurid or carcharodontosaurid theropods co-occurring with long-snouted spinosaurids of debated ecology. Here, we report calcium (Ca) isotope values from tooth enamel (expressed as δ44/42Ca) to investigate resource partitioning in mid-Cretaceous assemblages from Niger (Gadoufaoua) and Morocco (Kem Kem Beds). In both assemblages, spinosaurids display a distinct isotopic signature, the most negative in our dataset. This distinct taxonomic clustering in Ca isotope values observed between spinosaurids and other predators provides unambiguous evidence for niche partitioning at the top of the trophic chains: spinosaurids foraged on aquatic environments while abelisaurid and carcharodontosaurid theropods relied almost exclusively on terrestrial resources.


Dental microwear textural analysis as an analytical tool to depict individual traits and reconstruct the diet of a primate.

Abstract:
OBJECTIVES
Dental microwear is a promising tool to reconstruct animals' diet because it reflects the interplay between the enamel surface and the food items recently consumed. This study examines the sources of inter-individual variations in dietary habits in a free-ranging population of mandrills (Mandrillus sphinx) using a combination of feeding monitoring and in vivo dental microwear textural analysis (DMTA).

METHODS
We investigated the impact of seasonality and individual traits on four DMTA parameters. In parallel, we further studied the influence of the physical properties of the food items consumed on these four parameters, using three proxies (mechanical properties, estimates of phytolith and external grit contents).

RESULTS
We found that seasonality, age, and sex all impact DMTA parameters but those results differ depending on the facet analyzed (crushing vs. shearing facets). Three DMTA parameters (anisotropy, complexity, and heterogeneity of complexity) appear sensitive to seasonal variations and anisotropy also differs between the sexes while textural fill volume tends to vary with age. Moreover, the physical properties of the food items consumed vary seasonally and also differ depending on individual sex and age.

CONCLUSION
Considering the interplay between the tested variables and both dental microwear and diet, we reaffirm that food physical properties play a major role in microwear variations. These results suggest that DMTA parameters may provide valuable hints for paleoecological reconstruction using fragmentary fossil dental remains.

tool
individual trait
dmta
dental microwear


Tooth histology, attachment, and replacement in the Ichthyopterygia reviewed in an evolutionary context

Abstract: Ichthyosaurs, an extinct group of Mesozoic marine diapsids, show a relatively small range of tooth crown morphologies. With few exceptions, members of the group bear a large number of conical teeth and show only minor heterodonty within a jaw. This uniformity in gross morphology masks a high degree of variation in both the quantity and arrangement of the mineralized tooth tissues. Here, we describe tooth tissue structure and distribution in derived ichthyosaurs. We synthesize these new observations with the historical literature, to map changes in the quantity and arrangement of tooth tissues. These changes affected tooth attachment, tooth replacement, plicidentine morphology, and the amount and distribution of cellular cementum. The amount of variation detected in features relating to ichthyosaurian dentition is not surprising given the geological longevity and morphological disparity of the group, but does emphasize the importance of extensive taxon sampling in studies of tooth histology and evolution. This study is important in that it incorporates morphological and histological information in a phylogenetic and developmental context, something that is rarely done for marine reptile dentitions.


Evolutionary origins and development of saw-teeth on the sawfish and sawshark rostrum (Elasmobranchii; Chondrichthyes)

Abstract: A well-known characteristic of chondrichthyans (e.g. sharks, rays) is their covering of external skin denticles (placoid scales), but less well understood is the wide morphological diversity that these skin denticles can show. Some of the more unusual of these are the tooth-like structures associated with the elongate cartilaginous rostrum ‘saw’ in three chondrichthyan groups: Pristiophoridae (sawsharks; Selachii), Pristidae (sawfish; Batoidea) and the fossil Sclerorhynchoidea (Batoidea). Comparative topographic and developmental studies of the ‘saw-teeth’ were undertaken in adults and embryos of these groups, by means of three-dimensional-rendered volumes from X-ray computed tomography. This provided data on development and relative arrangement in embryos, with regenerative replacement in adults. Saw-teeth are morphologically similar on the rostra of the Pristiophoridae and the Sclerorhynchoidea, with the same replacement modes, despite the lack of a close phylogenetic relationship. In both, tooth-like structures develop under the skin of the embryos, aligned with the rostrum surface, before rotating into lateral position and then attaching through a pedicel to the rostrum cartilage. As well, saw-teeth are replaced and added to as space becomes available. By contrast, saw-teeth in Pristidae insert into sockets in the rostrum cartilage, growing continuously and are not replaced. Despite superficial similarity to oral tooth developmental organization, saw-tooth spatial initiation arrangement is associated with rostrum growth. Replacement is space-dependent and more comparable to that of dermal skin denticles. We suggest these saw-teeth represent modified dermal denticles and lack the ‘many-for-one’ replacement characteristic of elasmobranch oral dentitions.

saw-teeth
sawfish
sawshark
placoid scale
oral dentition


Holes and grooves: the contribution of microscopy and taphonomy to the problem of art origins.

Abstract: Optical and scanning electron microscopy, comparative anatomy, data from modern and Pleistocene carnivore accumulations, and analysis of archeological materials show that some of the pieces interpreted by various scholars as engraved or perforated bones from European Lower and Middle Paleolithic sites (such as Pech de l'Azé II, Stránska Skála, Kulna, Bois Roche and Cueva Morin) are not early manifestations of non-utilitarian behavior. Putative engravings are in fact vascular grooves, while perforated pieces are partially-digested bones regurgitated by hyenas. The current debate on art origins has often been centered on the symbolic value and cognitive implications of these and similar pieces without a first-hand analysis of the objects to provide convincing demonstration of the human origins of the marks. Such demonstration is a necessary prerequisite to any discussion of their significance for the evolution of symbolic behavior.


Rodents of the Bridgerian (Middle Eocene) Elderberry Canyon Local Fauna of Eastern Nevada

Abstract: Emry, Robert J., and William W. Korth. Rodents of the Bridgerian (Middle Eocene) Elderberry Canyon Local Fauna of Eastem Nevada. Smithsonian Contributions to Paleobiology, number 67, 14 pages, 5 figures, 1989.—The Elderberry Canyon Local Fauna, presently represented by more than 40 vertebrate taxa, including at least 30 mammals, occurs in carbonate rocks assigned to the Sheep Pass Formation, near Ely, Nevada. Among the mammals, nine rodent species, representing four families, are recognized. Reithroparamys delicatissimus, and R. cf. R. huerfanensis are species previously known from the Rocky Mountain region; Microparamys sambucus and Pauromys exallos are new species assigned to genera commonly occurring in Eocene faimas elsewhere; Elymys complexus is a new genus and species of minute rodent thought to be related to Simimys and questionably assigned to the family Zapodidae; Sciuravus, Mattimys, and Knightomys are represented by material not assignable to species; and another unidentified ischyromyid completes the roster of rodents presently known in the assemblage. The fauna as a whole, and the rodents in particular, share the greatest homotaxial similarity with early Bridgerian (early middle Eocene) faimas elsewhere, allowing a confident early Bridgerian age assignment for the Elderberry Canyon Local Fauna. The composition of this rodent assemblage suggests that faunal interchange was relatively unrestricted from southem California through Nevada to the Rocky Mountain region in Bridgerian time. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The trilobite Phaecops rana Green. Lilwary of Cwigrcss Cataloging in Publication DaU Emry, Robert J. Rodents of the Bridgerian (middle Eocene) Elderberry Canyon local fauna of Eastern Nevada. (Smithsonian COTitributions to paleobiology ; no. 67) Bibliography p. SupL of Docs, no.: SI 1.30:67 1. Rodents, Fossil—Nevada—Elderberry Canyoa 2. Paleontology—^Eocene. I. Korth, William W. II. Title. III. Series. QE701.S56 no. 67 560 s [569'.323] 89-600114 [QE882.R6]


Direct correlation of millennial‐scale changes in western North American vegetation and climate with changes in the California Current System over the past ∼60 kyr

Abstract: Terrestrial (pollen) and marine climate proxies from seven sediment cores taken on the continental margin of western North America between 32° and 43°N show systematically related short-term changes superposed on Milankovitch-scale oscillations of the past 60 kyr. During oxygen isotope stage 3, brief warming events in California and Oregon appear correlative with interstadial events in waters offshore, as do the rapid climate oscillations of the last glacial transition (∼14–∼10 ka). Estimated temperature depression of the coastal lowlands ranges from >10°C in southern California to ∼5°C in Oregon during the last glacial. The absence of long-distance migration of Pacific coastal plant assemblages concurs with marine evidence that southward movement of the polar front during the last glacial maximum was limited. Correlative changes in terrestrial and marine ecosystems imply that broad reorganizations of circulation in the northeast Pacific Ocean were synchronous with reorganizations of atmospheric circulation over western North America.


New paromomyids (Mammalia, Primates) from the Paleocene of southwestern Alberta, Canada, and an analysis of paromomyid interrelationships

Abstract: Abstract. Paromomyidae are one of several families of plesiadapiforms that flourished during the Paleocene in North America soon after the extinction of non-avian dinosaurs some 66 million years ago. Although they are often among the best-represented plesiadapiforms in mammalian faunas in both North America and Europe, the early history of paromomyids is poorly understood, and their fossil record at higher latitudes is comparatively depauperate. We report here on the discovery of two new species of paromomyids from Paleocene deposits in southwestern Alberta: Edworthia greggi new species is the second known species of the basal paromomyid Edworthia Fox, Scott, and Rankin, 2010 whereas Ignacius glenbowensis new species is among the most abundantly represented species of Ignacius Matthew and Granger, 1921. These new discoveries document, for the first time, parts of the upper dentition of Edworthia, and the new species of Ignacius represents the first new, pre-Clarkforkian species of the genus to be described in nearly 100 years. A comprehensive phylogenetic analysis of nearly all known paromomyid taxa (including the new species described herein) recovered both species of Edworthia near the base of the paromomyid tree in a polytomy with Paromomys depressidens Gidley, 1923 and a paraphyletic Ignacius. The new paromomyids from Alberta not only increase the known taxonomic diversity of Edworthia and Ignacius but also add significantly to knowledge of the dental anatomy of these poorly known genera and further add to a uniquely Canadian complement of Paleocene plesiadapiforms.

paleocene
southwestern alberta
plesiadapiform
new paromomyid


Diversity dynamics of Ordovician bryozoa

Abstract: This study presents a compilation of the temporal distribution of 200 bryozoan genera during the Ordovician. Bryozoans appeared in the earliest Ordovician (Tremadoc), diversified rapidly until the late Sandbian, and then suffered three distinct extinctions in the Late Ordovician. In the early Katian, the first significant extinction eliminated 22.7% of bryozoan genera. That was the highest taxonomic loss in the Ordovician; however, due to high origination rates, the magnitude of this extinction was the lowest among the three extinctions. The second extinction wave occurred in the late Katian, resulting in taxonomic loss of 22.4%. This event can be estimated as the most severe for bryozoans during the Ordovician because of extremely low origination rates what resulted in the highest net decrease of diversity. The third extinction of bryozoans occurred during the Hirnantian resulting in the lowest taxonomic loss (16.5%) and intermediate net decrease of diversity. The diversity dynamics of bryozoans in the Ordovician was apparently controlled by climatic changes, provinciality and food availability.

bryozoa
sandbian
diversity dynamic
ordovician period


The Winton Formation flora (Albian–Cenomanian, Eromanga Basin): implications for vascular plant diversification and decline in the Australian Cretaceous

Abstract: The youngest Australian equisetaleans and bennettitaleans are identified within the latest Albian to early Cenomanian Winton Formation flora based on new impression fossils from the Winton district, Eromanga Basin, western Queensland. Typical Winton Formation floras are also confirmed near Isisford and Morney Plains in eastern and central Eromanga Basin. The Winton Formation flora contains over 50 macrofossil plant taxa and marks the transition from seed-fern/conifer to angiosperm dominance in the Australian floristic succession. The pattern of clade representation in Australian late Mesozoic fossil assemblages suggests a causal link between angiosperm diversification and the decline of key understorey and mid-storey plants, particularly equisetaleans, seed-ferns, ginkgophytes and some fern families, through the mid-Cretaceous.

winton formation flora
eromanga basin
conifer


Abstract: Gordodon kraineri is a new genus and species of edaphosaurid eupelycosaur known from an associated skull, lower jaw and incomplete postcranium found in the early Permian Bursum Formation of Otero County, New Mexico, USA. It has a specialized dental apparatus consisting of large, chisel-like incisors in the front of the jaws separated by a long diastema from relatively short rows of peg-like maxillary and dentary cheek teeth. The dorsal vertebrae of Gordodon have long neural spines that bear numerous, randomly arranged, small, thorn-like tubercles. The tubercles on long neural spines place Gordodon in the Edaphosauridae, and the dental apparatus and distinctive tubercles on the neural spines distinguish it from the other edaphosaurid genera—Edaphosaurus, Glaucosaurus, Lupeosaurus and Ianthasaurus. Gordodon is the oldest known tetrapod herbivore with a dentary diastema, extending the temporal range of that anatomical feature back 95 million years from the Late Triassic. The dental apparatus of Gordodon indicates significantly different modes of ingestion and intraoral transport of vegetable matter than took place in Edaphosaurus and thus represents a marked increase in disparity among edaphosaurids. There were two very early pathways to tetrapod herbivory in edaphosaurid evolution, one toward generalized browsing on high-fiber plant items (Edaphosaurus) and the other (Gordodon) toward more specialized browsing, at least some of it likely on higher nutrient, low fiber plant items. Gordodon shows a surprisingly early specialization of the dental apparatus and indicates how incomplete our knowledge is of edaphosaurid evolution, disparity and diversity. Spencer G. Lucas. New Mexico Museum of Natural History, 1801 Mountain Road N. W., Albuquerque, 87104 New Mexico, USA. spencer.lucas@state.nm.us Larry F. Rinehart. New Mexico Museum of Natural History, 1801 Mountain Road N. W., Albuquerque, http://zoobank.org/BA32DBE6-21CD-4CA3-A663-CB750B1A723F Lucas, Spencer G., Rinehart, Larry F., and Celeskey, Matthew D. 2018. The oldest specialized tetrapod herbivore: A new eupelycosaur from the Permian of New Mexico, USA. Palaeontologia Electronica 21.3.39A 1-42. https://doi.org/10.26879/899 palaeo-electronica.org/content/2018/2343-new-eupelycosaur Copyright: November 2018 Paleontological Society. This is an open access article distributed under the terms of Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0), which permits users to copy and redistribute the material in any medium or format, provided it is not used for commercial purposes and the original author and source are credited, with indications if any changes are made. creativecommons.org/licenses/by-nc-sa/4.0/ LUCAS, RINEHART, & CELESKEY: NEW EUPELYCOSAUR 87104 New Mexico, USA. larry.rinehart@earthlink.net Matthew D. Celeskey. New Mexico Museum of Natural History, 1801 Mountain Road N. W., Albuquerque, 87104 New Mexico, USA. matt.celeskey@hmnh.org

tetrapod herbivore
new eupelycosaur
gordodon
edaphosauridae


Dinosaur Speed Demon: The Caudal Musculature of Carnotaurus sastrei and Implications for the Evolution of South American Abelisaurids

Abstract: In the South American abelisaurids Carnotaurus sastrei, Aucasaurus garridoi, and, to a lesser extent Skorpiovenator bustingorryi, the anterior caudal ribs project at a high dorsolateral inclination and have interlocking lateral tips. This unique morphology facilitated the expansion of the caudal hypaxial musculature at the expense of the epaxial musculature. Distinct ridges on the ventrolateral surfaces of the caudal ribs of Aucasaurus garridoi are interpreted as attachment scars from the intra caudofemoralis/ilio-ischiocaudalis septa, and confirm that the M. caudofemoralis of advanced South American abelisaurids originated from a portion of the caudal ribs. Digital muscle models indicate that, relative to its overall body size, Carnotaurus sastrei had a substantially larger M. caudofemoralis than any other theropod yet studied. In most non-avian theropods, as in many extant sauropsids, the M. caudofemoralis served as the primary femoral retractor muscle during the locomotive power stroke. This large investment in the M. caudofemoralis suggests that Carnotaurus sastrei had the potential for great cursorial abilities, particularly short-burst sprinting. However, the tightly interlocking morphology of the anterior caudal vertebrae implies a reduced ability to make tight turns. Examination of these vertebral traits in evolutionary context reveals a progressive sequence of increasing caudofemoral mass and tail rigidity among the Abelisauridae of South America.

carnotaurus sastrei
abelisaurid
caudal vertebrae


Revision of the Athyrisininae, Siluro‐devonian Brachiopods from China and Russia

Abstract: Athyrisinine brachiopods from the Upper Silurian of Russia and the Lower–Middle Devonian of China and north Vietnam include over 70 species belonging to Athyrisina and Parathyrisina; generic and subfamilial diagnoses are emended. Five genera are considered synonyms of Athyrisina and three of Parathyrisina. A neotype is selected and illustrated for Athyrisina squamosa, the type species of Athyrisina. Four nomina nova, Athyrisinaxui, Parathyrisina wani, P. minima, and P. cheni, are suggested as new substitute names for Athyrisina tumida Wang, in Xu et al. 1978 (primary homonymy), Athyrisinoides ganxiensis Wan, in Xu et al. 1978, Parathyrisina minor Zhang, in Zhang and Fu 1983, and Athyrisinoides tudilingensis Chen, 1979 (secondary homonyms) respectively. A new genus, Bruntosina, is described from the Emsian to Eifelian of the Qinling region. A new subfamily, Homeathyridinae, is erected within the Athyrididae with Homeathyris, Pseudohomeospira, and Squamathyris included, revised and their diagnoses emended. Homeathyris incisus sp. nov. is described from the Ludfordian of Novaya Zemlya. Ikella is revised and excluded from the athyrisinins. The origin and dispersal of the homeathyridins and the athyrisinins are discussed.


Benthic phosphorus regeneration, net primary production, and ocean anoxia: A model of the coupled marine biogeochemical cycles of carbon and phosphorus

Abstract: We examine the relationships between ocean ventilation, primary production, water column anoxia, and benthic regeneration of phosphorus using a mass balance model of the coupled marine biogeochemical cycles of carbon (C) and phosphorus (P). The elemental cycles are coupled via the Redfield C/P ratio of marine phytoplankton and the C/P ratio of organic matter preserved in marine sediments. The model assumes that on geologic timescales, net primary production in the oceans is limited by the upwelling of dissolved phosphorus to the photic zone. The model incorporates the dependence on bottom water oxygenation of the regeneration of nutrient phosphorus from particulate matter deposited at the water-sediment interface. Evidence from marine and lacustrine settings, modern and ancient, demonstrates that sedimentary burial of phosphorus associated with organic matter and ferric oxyhydroxides decreases when bottom water anoxia-dysoxia expands. Steady state simulations show that a reduction in the rate of thermohaline circulation, or a decrease of the oxygen content of downwelling water masses, intensifies water column anoxia-dysoxia and at the same time increases surface water productivity. The first effect reflects the declining supply of oxygen to the deeper parts of the ocean. The second effect is caused by the enhanced benthic regeneration of phosphorus from organic matter and ferric oxyhydroxides. Sedimentary burial of organic carbon and authigenic calcium phosphate mineral (francolite), on the other hand, is promoted by reduced ocean ventilation. According to the model, global-scale anoxia-dysoxia leads to a more efficient recycling of reactive phosphorus within the ocean system. Consequently, higher rates of primary production and organic carbon burial can be achieved, even when the continental supply of reactive phosphorus to the oceans remains unchanged.

phosphorus
regeneration
net primary production
ocean
marine biogeochemical cycle


Mesozoic salamanders and albanerpetontids of Middle Asia, Kazakhstan, and Siberia

Abstract: Mesozoic terrestrial deposits containing diverse vertebrate assemblages are widely distributed in Siberia (central and eastern part of Russia), Middle Asia (Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan), and Kazakhstan. Twelve formations of Middle Jurassic (Bathonian) to Late Cretaceous (Campanian) age in the region contain salamanders (six in Middle Asia, two in Siberia and four in Kazakhstan). In contrast to the situation in Euramerica, albanerpetontids are extremely rare in the Mesozoic of Asia, where their fossil record is limited to the Khodzhakul (Cenomanian) and Bissekty (Turonian) formations, both in Uzbekistan. Salamanders in Siberia are known from the Bathonian Itat Formation in the Krasnoyarsk Region (the stem salamander Urupia monstrosa and two undescribed taxa-a new stem salamander and a possible crown-group salamander) and from the Aptian-Albian Ilek Formation in Kemerovo Province and the Krasnoyarsk Region (the crown-group salamander Kiyatriton leshchinskiyi and Caudata indet.). In the Jurassic of Middle Asia, the stem salamanders Kokartus honorarius and Karauridae indet. are known from the Bathonian-Callovian Balabansai Formation in Kyrgyzstan. Younger records in Middle Asia are restricted to only two Late Cretaceous genera of crown-group salamanders: the possible cryptobranchoid Nesovtriton in the Bissekty Formation (Turonian) and the cryptobranchid Eoscapherpeton in the Khodzhakul, Dzharakuduk, Bissekty, and Aitym formations (collectively Cenomanian-Campanian) in Uzbekistan and the Yalovach Formation (Santonian) in Tajikistan. In Kazakhstan, salamanders are known from the Kimmeridgian Karabastau Formation (the stem salamander Karaurus sharovi), the Turonian Zhirkindek Formation (Caudata indet.), the Santonian-Campanian Bostobe Formation (the cryptobranchid Eoscapherpeton, the possible proteid "Bishara backa" and Caudata indet.) and the Campanian Darbasa Formation (the cryptobranchid Eoscapherpeton). Cenomanian-Campanian vertebrate assemblages in Middle Asia and Kazakhstan are characterised by dominance of the cryptobranchid Eoscapherpeton.


Male spike strobiles with Gnetum affinity from the Early Cretaceous in western Liaoning, Northeast China

Abstract: A fossil with Gnetum affinity was found in the Jianshangou Member (Barremian Age) of the Yixian Formation (Lower Cretaceous Epoch) of the Jehol Group in western Liaoning, northeastern China. The single fossil specimen is represented by both elongate‐cylindrical male spike strobiles which borne within a nodal bract of cauliflorous branch. The spike strobiles have apparent nodes, invisible internodes, and numerous verticillate involucral collars. The microsporangiate units within involucral collars are not seen. The male spike strobiles with verticillate involucral collars occur exclusively in Gnetum; hence, the fossil strobiles are attributed to a new taxon, Khitania columnispicata gen. & sp. nov., being closely related to Gnetum. The general isotopic dating suggests an age of Barremian, ca. 125–122 million years (Myr) ago for the Jianshangou Member. The palaeoecological and palaeoclimatic inference based on the compositions of flora and fauna, and lithological characters of the fossil locality suggests that the fossil plants grew in a subtropical mesophytic forest and under a warmer climate. The remains of male spike strobiles are the first record of gnetalean macrofossil. It documents the evolution of the distinct gnetoid morphology and indicates a wider range of distribution of Gnetaceae in the Early Cretaceous than present day.

gnetum affinity
western liaoning
gnetaceae
male spike strobile


Ancient DNA analysis identifies marine mollusc shells as new metagenomic archives of the past

Abstract: Marine mollusc shells enclose a wealth of information on coastal organisms and their environment. Their life history traits as well as (palaeo‐) environmental conditions, including temperature, food availability, salinity and pollution, can be traced through the analysis of their shell (micro‐) structure and biogeochemical composition. Adding to this list, the DNA entrapped in shell carbonate biominerals potentially offers a novel and complementary proxy both for reconstructing palaeoenvironments and tracking mollusc evolutionary trajectories. Here, we assess this potential by applying DNA extraction, high‐throughput shotgun DNA sequencing and metagenomic analyses to marine mollusc shells spanning the last ~7,000 years. We report successful DNA extraction from shells, including a variety of ancient specimens, and find that DNA recovery is highly dependent on their biomineral structure, carbonate layer preservation and disease state. We demonstrate positive taxonomic identification of mollusc species using a combination of mitochondrial DNA genomes, barcodes, genome‐scale data and metagenomic approaches. We also find shell biominerals to contain a diversity of microbial DNA from the marine environment. Finally, we reconstruct genomic sequences of organisms closely related to the Vibrio tapetis bacteria from Manila clam shells previously diagnosed with Brown Ring Disease. Our results reveal marine mollusc shells as novel genetic archives of the past, which opens new perspectives in ancient DNA research, with the potential to reconstruct the evolutionary history of molluscs, microbial communities and pathogens in the face of environmental changes. Other future applications include conservation of endangered mollusc species and aquaculture management.


A Serravallian (Middle Miocene) shark fauna from Southeastern Spain and its palaeoenvironment significance

Abstract: Abstract The study of a new Serravallian (Middle Miocene) locality from the Southeastern Spain has yielded a shark assemblage characterized by microremains of at least seven taxa (Deania calcea, †Isistius triangulus, †Squaliolus cf. S. schaubi, †Paraetmopterus sp., Pristiophorus sp., Scyliorhinus sp. and a cf. Squaliformes indet) of three different orders (Squaliformes, Pristiophoriformes and Carcharhiniformes). In addition, associated macroremains have also been found, including teeth of †Cosmopolitodus hastalis, Isurus sp., Hemipristis serra, Odontaspis sp., Carcharhinus spp. and †Otodus (Megaselachus) megalodon. The assemblage contains taxa with disparate environmental preferences including not only neritic and epipelagic sharks but also an important number of meso and bathypelagic representatives. The migration of deep water taxa to shallower waters through submarine canyons/coastal upwelling is proposed as the most plausible cause for explaining the origin of such assemblage. Interestingly, the composition of the deep-water taxa here reported contrast with the chondrichthyans assemblages from the Pliocene and extant Mediterranean communities. This entails a complex biogeographic history, where the Messinian salinity crisis strongly affected the posterior evolution of the Mediterranean ecosystems but some other factors, such us the existence of anoxic events during the Quaternary, could have also played an important role.

middle miocene
southeastern spain
extensive fossil record


Quantifying the effect of shade on cuticle morphology and carbon isotopes of sycamores: present and past

Abstract: Abstract Premise Reconstructing the light environment and architecture of the plant canopy from the fossil record requires the use of proxies, such as those derived from cell wall undulation, cell size, and carbon isotopes. All approaches assume that plant taxa will respond predictably to changes in light environments. However, most species‐level studies looking at cell wall undulation only consider “sun” or “shade” leaves; therefore, we need a fully quantitative taxon‐specific method. Methods We quantified the response of cell wall undulation, cell size, and carbon isotopes of Platanus occidentalis using two experimental setups: (1) two growth chambers at low and high light and (2) a series of outdoor growth experiments using green and black shade cloth at different densities. We then developed and applied a proxy for daily light integral (DLI) to fossil Platanites leaves from two early Paleocene floras from the San Juan Basin in New Mexico. Results All traits responded to light environment. Cell wall undulation was the most useful trait for reconstructing DLI in the geological record. Median reconstructed DLI from early Paleocene leaves was ~44 mol m−2 d−1, with values from 28 to 54 mol m−2 d−1. Conclusions Cell wall undulation of P. occidentalis is a robust, quantifiable measurement of light environment that can be used to reconstruct the paleo‐light environment from fossil leaves. The distribution of high DLI values from fossil leaves may provide information on canopy architecture; indicating that either (1) most of the canopy mass is within the upper portion of the crown or (2) leaves exposed to more sunlight are preferentially preserved.


Climate change, not human population growth, correlates with Late Quaternary megafauna declines in North America

Abstract:
The disappearance of many North American megafauna at the end of the Pleistocene is a contentious topic. While the proposed causes for megafaunal extinction are varied, most researchers fall into three broad camps emphasizing human overhunting, climate change, or some combination of the two. Understanding the cause of megafaunal extinctions requires the analysis of through-time relationships between climate change and megafauna and human population dynamics. To do so, many researchers have used summed probability density functions (SPDFs) as a proxy for through-time fluctuations in human and megafauna population sizes. SPDFs, however, conflate process variation with the chronological uncertainty inherent in radiocarbon dates. Recently, a new Bayesian regression technique was developed that overcomes this problem-Radiocarbon-dated Event-Count (REC) Modelling.
Here we employ REC models to test whether declines in North American megafauna species could be best explained by climate changes, increases in human population densities, or both, using the largest available database of megafauna and human radiocarbon dates. Our results suggest that there is currently no evidence for a persistent through-time relationship between human and megafauna population levels in North America. There is, however, evidence that decreases in global temperature correlated with megafauna population declines.

decline
north america
cause
megafaunal extinction
climate change


Trilobite abnormalities

Abstract: ABSTRACT There is abundant evidence of injury, teratology and pathological conditions in trilobites although it is commonly difficult to distinguish between their morphological results. Many injuries were probably sustained during moulting, with spines, bilamellar fringes and narrow gaps between dorsal exoskeleton and doublure being most vulnerable. Some injuries were the result of predaceous attack and provide important clues to the trophic structure of Palaeozoic communities. Many injuries show evidence of repair. Some supposedly teratological conditions, most notably the number of paradoxidid thoracic segments, are so common that they must be considered part of normal variation. Others represent genetic mutation or ontogenetic malfunction, the latter possibly externally induced. Undoubted pathological conditions are restricted to swellings and borings presumably caused by parasitic infestation. Abnormalities affecting lateral areas are more common than those involving the rachis and glabella and this probably reflects both greater mortality when the axial region is involved, and greater vulnerability of peripheral regions to predaceous and moulting damage. The first explanation also accounts for the rarity of cephalic abnormalities compared to those of the pygidium.


The locomotory apparatus and paraxial swimming in fossil and living marine reptiles: comparing Nothosauroidea, Plesiosauria, and Chelonioidea

Abstract:
The terrestrial origins of the diapsid Sauropterygia and Testudines are uncertain, with the latter being highly controversially discussed to this day. For only 15 Ma, Nothosauroidea lived in shallow-marine seas of the Triassic. Contrastingly, the pelagic Plesiosauria evolved in the Late Triassic, dispersed globally, and inhabited the oceans of the Jurassic and Cretaceous for approximately 135 Ma. Since the Cretaceous (~ 100 Ma), Chelonioidea, the modern sea turtles, have populated the oceans. All three groups evolved aquatic paraxial locomotion. Nothosaurs swam with their foreflippers, supported by the swimming tail. Plesiosaurs are the only tetrapods to have ever evolved four hydrofoil-like flippers. The plesiosaur flipper beat cycle has been debated for nearly two centuries. The different proposed locomotory styles (rowing, rowing-flight, underwater flight) are discussed in this review. A fourth gait that is employed by Carettochelys insculpta, which combines rowing and flying, is introduced. The osteology of the locomotory apparatus of nothosaurs and plesiosaurs is reviewed and compared to that of extant underwater-flying Chelonioidea. In conclusion, underwater flight remains the favoured locomotory style for plesiosaurs. Also, the review reveals that nothosaur locomotion has largely remained unstudied. Further, our understanding of joint morphologies and mobilities of the foreflipper in nothosaurs, plesiosaurs, and even recent sea turtles, and of the hindflipper in plesiosaurs, is very limited. It is crucial to the discussion of locomotion, to find out, if certain limb cycles were even possible, as evidence seems to point to the improbability of a rowing motion because of limited humerus and femur long axis rotation in plesiosaurs.
Nothosauroidea • Plesiosauria • Chelonioidea • Mode of locomotion • Rowing • Underwater flight
Evolution of Nothosauroidea and Plesiosauria (Eosauropterygia) and Chelonioidea
Sauropterygia were amongst the first fossil reptiles subjected to paleontological research (de la Beche and Conybeare 1821; Owen 1840; von Meyer 1847-1855). Since then, researchers have studied not only their morphology and phylogeny, but also different aspects of their biology (

locomotory apparatus
plesiosauria
chelonioidea
flipper


Siphonal zone structure in the cuttlebone of Sepia officinalis

Abstract: The evolutionary process through which the siphonal zone of the cuttlebone of Sepia replaced the tubular siphuncle seen in other shelled cephalopods is poorly understood. Recently, porous connecting stripes, interpreted as homologous to connecting rings of tubular siphuncles, were revealed in Sepia (Acanthosepion) cf. savignyi (Geobios, 45:13-17, 2012). New data on the siphonal zone structure are herein demonstrated through SEM testing of 16 beach-collected cuttlebones of Sepia officinalis from Vale do Lobo, southern Portugal. In examined cuttlebones, the organic connecting stripes are mineralized along their peripheries where they are attached to septa by inorganic-organic porous contacting ridges. The contacting ridges consist of globular crystalline units within an organic matrix; each globule is a stack of rounded alternating organic and mineralized microlaminas parallel to the septal surface; mineralized microlaminas contain carbonate microgranules. Porous connecting stripes together with the contacting ridges may serve as transport routes for the cameral liquid used in buoyancy regulation. The contacting ridges appear to reinforce contacts between the connecting stripes and septa, and may strengthen shell resistance to changing environments. Lamella-fibrillar nacre in septa is demonstrated in Sepia for the first time. Comparison of Sepia and Spirula reveals the common character of their phragmocones, the slit-like shape of the permeable zones between chambers and the siphuncle. Narrowing of the permeable zones may provide shell resistance to high hydrostatic pressure; however, the essentially dissimilar relative length of the permeable zones may results in different capabilities of two genera for buoyancy regulation. In Sepia, long narrow porous inorganic-organic permeable connecting stripes and contacting ridges may allow for rapid buoyancy regulation which would lead to environmental plasticity and higher species diversity.

cuttlebone
sepia
siphonal zone structure


Optimized coral reconstructions of the Indian Ocean Dipole: An assessment of location and length considerations

Abstract: The Indian Ocean Dipole (IOD; or Indian Ocean Zonal Mode) is a coupled ocean-atmosphere climate oscillation that has profound impacts on rainfall distribution across the Indian Ocean region. Instrumental records provide a reliable representation of IOD behavior since 1958, while coral reconstructions currently extend the IOD history back to 1846. Large fluctuations in the number and intensity of positive IOD events over time are evident in these records, but it is unclear to what extent this represents multidecadal modulation of the IOD or an anthropogenically forced change in IOD behavior. In this study we explore the suitability of coral records from single-site locations in the equatorial Indian Ocean for capturing information about the occurrence and magnitude of positive IOD (pIOD) events. We find that the optimum location for coral reconstructions of the IOD occurs in the southeastern equatorial Indian Ocean, along the coast of Java and Sumatra between ~3 and 7°S. Here the strong ocean cooling and atmospheric drying during pIOD events are unambiguously recorded in coral oxygen isotope records, which capture up to 50% of IOD variance. Unforced experiments with coupled climate models suggest that potential biases in coral estimates of pIOD frequency are skewed toward overestimating pIOD recurrence intervals and become larger with shorter reconstruction windows and longer pIOD recurrence times. Model output also supports the assumption of stationarity in sea surface temperature relationships in the optimum IOD location that is necessary for paleoclimate reconstructions. This study provides a targeted framework for the future generation of paleoclimate records, including optimized coral reconstructions of past IOD variability.

coral reconstruction
indian ocean dipole
paleoclimate reconstruction
iod variability


Dental microwear and stable isotopes inform the paleoecology of extinct hominins.

Abstract: Determining the diet of an extinct species is paramount in any attempt to reconstruct its paleoecology. Because the distribution and mechanical properties of food items may impact postcranial, cranial, mandibular, and dental morphologies related to their procurement, ingestion, and mastication, these anatomical attributes have been studied intensively. However, while mechanical environments influence skeletal and dental features, it is not clear to what extent they dictate particular morphologies. Although biomechanical explanations have been widely applied to extinct hominins in attempts to retrodict dietary proclivities, morphology may say as much about what they were capable of eating, and perhaps more about phylogenetic history, than about the nature of the diet. Anatomical attributes may establish boundary limits, but direct evidence left by the foods that were actually (rather than hypothetically) consumed is required to reconstruct diet. Dental microwear and the stable light isotope chemistry of tooth enamel provide such evidence, and are especially powerful when used in tandem. We review the foundations for microwear and biogeochemistry in diet reconstruction, and discuss this evidence for six early hominin species (Ardipithecus ramidus, Australopithecus anamensis, Au. afarensis, Au. africanus, Paranthropus robustus, and P. boisei). The dietary signals derived from microwear and isotope chemistry are sometimes at odds with inferences from biomechanical approaches, a potentially disquieting conundrum that is particularly evident for several species.

paleoecology
extinct hominin
paranthropus robustus
several specie
dental microwear


Ancient mitochondrial genomes from Chinese cave hyenas provide insights into the evolutionary history of the genus Crocuta

Abstract: Cave hyenas (genus Crocuta) are extinct bone-cracking carnivores from the family Hyaenidae and are generally split into two taxa that correspond to a European/Eurasian and an (East) Asian lineage. They are close relatives of the extant African spotted hyenas, the only extant member of the genus Crocuta. Cave hyenas inhabited a wide range across Eurasia during the Pleistocene, but became extinct at the end of the Late Pleistocene. Using genetic and genomic datasets, previous studies have proposed different scenarios about the evolutionary history of Crocuta. However, causes of the extinction of cave hyenas are widely speculative and samples from China are severely understudied. In this study, we assembled near-complete mitochondrial genomes from two cave hyenas from northeastern China dating to 20 240 and 20 253 calBP, representing the youngest directly dated fossils of Crocuta in Asia. Phylogenetic analyses suggest a monophyletic clade of these two samples within a deeply diverging mitochondrial haplogroup of Crocuta. Bayesian analyses suggest that the split of this Asian cave hyena mitochondrial lineage from their European and African relatives occurred approximately 1.85 Ma (95% CI 1.62–2.09 Ma), which is broadly concordant with the earliest Eurasian Crocuta fossil dating to approximately 2 Ma. Comparisons of mean genetic distance indicate that cave hyenas harboured higher genetic diversity than extant spotted hyenas, brown hyenas and aardwolves, but this is probably at least partially due to the fact that their mitochondrial lineages do not represent a monophyletic group, although this is also true for extant spotted hyenas. Moreover, the joint female effective population size of Crocuta (both cave hyenas and extant spotted hyenas) has sustained two declines during the Late Pleistocene. Combining this mitochondrial phylogeny, previous nuclear findings and fossil records, we discuss the possible relationship of fossil Crocuta in China and the extinction of cave hyenas.

mitochondrial genome
hyena
evolutionary history
genus crocuta
late pleistocene


Comparative Taphonomy, Taphofacies, and Bonebeds of the Mio-Pliocene Purisima Formation, Central California: Strong Physical Control on Marine Vertebrate Preservation in Shallow Marine Settings

Abstract: Background Taphonomic study of marine vertebrate remains has traditionally focused on single skeletons, lagerstätten, or bonebed genesis with few attempts to document environmental gradients in preservation. As such, establishment of a concrete taphonomic model for shallow marine vertebrate assemblages is lacking. The Neogene Purisima Formation of Northern California, a richly fossiliferous unit recording nearshore to offshore depositional settings, offers a unique opportunity to examine preservational trends across these settings. Methodology/Principal Findings Lithofacies analysis was conducted to place vertebrate fossils within a hydrodynamic and depositional environmental context. Taphonomic data including abrasion, fragmentation, phosphatization, articulation, polish, and biogenic bone modification were recorded for over 1000 vertebrate fossils of sharks, bony fish, birds, pinnipeds, odontocetes, mysticetes, sirenians, and land mammals. These data were used to compare both preservation of multiple taxa within a single lithofacies and preservation of individual taxa across lithofacies to document environmental gradients in preservation. Differential preservation between taxa indicates strong preservational bias within the Purisima Formation. Varying levels of abrasion, fragmentation, phosphatization, and articulation are strongly correlative with physical processes of sediment transport and sedimentation rate. Preservational characteristics were used to delineate four taphofacies corresponding to inner, middle, and outer shelf settings, and bonebeds. Application of sequence stratigraphic methods shows that bonebeds mark major stratigraphic discontinuities, while packages of rock between discontinuities consistently exhibit onshore-offshore changes in taphofacies. Conclusions/Significance Changes in vertebrate preservation and bonebed character between lithofacies closely correspond to onshore-offshore changes in depositional setting, indicating that the dominant control of preservation is exerted by physical processes. The strong physical control on marine vertebrate preservation and preservational bias within the Purisima Formation has implications for paleoecologic and paleobiologic studies of marine vertebrates. Evidence of preservational bias among marine vertebrates suggests that careful consideration of taphonomic overprint must be undertaken before meaningful paleoecologic interpretations of shallow marine vertebrates is attempted.

bonebed
marine vertebrate preservation
shark


Correlation of Late Miocene to Early Pliocene sequences between the Mediterranean and North Atlantic

Abstract: Ocean Drilling Program (ODP) Site 982 in the North Atlantic contains a complete latest Miocene to early Pliocene section that was tuned to the astronomical timescale by correlating the record of gamma ray attenuation (GRA) bulk density to summer insolation at 65°N and the benthic δ18O signal to orbital obliquity for the interval from 4.6 to 7.5 Ma. The astronomical tuning of the Site 982 record permits a direct bed-to-bed correlation to the cyclostratigraphy of Messinian sections in the Mediterranean [Krijgsman et al., 1999a, 2001]. The benthic δ18O signal at Site 982 records a latest Miocene glacial period that lasted from ∼6.26 to 5.50 Ma and consisted of 18 glacial-to-interglacial oscillations that were controlled by the 41-kyr cycle of obliquity. Although the intensification of glaciation at 6.26 Ma may have contributed to the restriction of the Mediterranean, it preceded the depositional onset of the lower evaporite unit at 5.96 Ma by some 300 kyr. The transition from Stage TG12 to TG11 at 5.5 Ma marks the end of the latest Miocene glacial period and precedes the Miocene/Pliocene boundary by 170 kyr. Although benthic δ18O values are relatively low and δ18O of bulk carbonate reaches a minimum at the Miocene/Pliocene boundary at 5.33 Ma, there is no single “event” that would indicate deglaciation and sea level rise as the cause of the reflooding of the Mediterranean. We conclude that glacioeustatic changes alone were not responsible for either the start or end of evaporite deposition during the Messinian, suggesting that tectonic or local climate changes in the Mediterranean region were the dominant cause(s).

late miocene
mediterranean
north atlantic
glaciation


An investigation of the genus Mesacanthus (Chordata: Acanthodii) from the Orcadian Basin and Midland Valley areas of Northern and Central Scotland using traditional morphometrics

Abstract: Mesacanthus is a common and speciose genus of acanthodian fish from Lower Old Red Sandstone and Middle Old Red Sandstone assemblages (representing the Lower Devonian and Middle Devonian respectively) and is well represented in many palaeoichthyology collections in the UK. Based upon descriptions given during the 19th century, specimens of the genus Mesacanthus from the Orcadian Basin and Midland Valley areas of Northern and Central Scotland have historically been referred to a number of different species; of these, the most frequently discussed in the literature are M. mitchelli, M. peachi and M. pusillus. In order to test the validity of these three species, traditional morphometric analyses were carried out on over 100 specimens of Mesacanthus, from both the Lower Devonian and the Middle Devonian, that cover the full range of known localities for these taxa in Northern and Central Scotland. Based upon morphological and morphometric comparisons, this investigation has found that at least two species of Mesacanthus are valid (M. mitchelli and M. pusillus) as specimens from the Lower Devonian and Middle Devonian have been shown to differ significantly in a number of important ways. However, no evidence has been found for the validity of the second and distinct Middle Devonian species, M. peachi.

genus mesacanthus
orcadian basin
central scotland
middle devonian specie


A new family of Cambrian rhynchonelliformean brachiopods (Order Naukatida) with an aberrant coral‐like morphology

Abstract: Tomteluva perturbata gen. et sp. nov. and Nasakia thulensis gen. et sp. nov., two new rhynchonelliformean brachiopod taxa, are described from carbonate beds from the lower middle Cambrian (Series 3, Stage 5) basinal Stephen Formation, Canada, and the upper lower Cambrian (Series 2, Stage 4) Henson Gletscher Formation, North Greenland, respectively. The two taxa are characterized by an unusual coral‐like morphology typified by a high conical ventral valve with an anteriorly curved umbo and a tube‐like structure inside the ventral valve, interpreted as pedicle tube. Both resemble the problematic late middle Cambrian (Drumian) species Anomalocalyx cawoodi Brock from Australia, whose systematic affiliation is controversial. Together, the three genera are interpreted as representatives of a new family of rhynchonelliformean brachiopods, the Tomteluvidae fam. nov., which is interpreted as an aberrant or derived taxon within the Order Naukatida. Convergence between the Tomteluvidae and the coralla of small solitary Cambrian coralimorphs, as well as the late Palaeozoic reef‐building richthofenioid brachiopods, might indicate adaptation to a similar life habits and environments. However, their small size (length 4 mm), well‐developed pedicle and perfect morphological symmetry make it more likely that tomteluvids lived attached to frondose algae or sponges, above the seafloor, in a similar fashion to the acrotretoid brachiopods with which they show a high degree of morphological convergence. Morphological features of the pedicle tube of N. thulensis suggest that the tomteluvid pedicle is homologous to that in modern rhynchonelliformean brachiopods. This is the first evidence of the pedicle type within the Naukatida and represents the oldest confirmation of a rhynchonellate pedicle.

new family
rhynchonelliformean brachiopod
order naukatida


Patterning of a compound eye on an extinct dipteran wing

Abstract: We have discovered unexpected similarities between a novel and characteristic wing organ in an extinct biting midge from Baltic amber, Eohelea petrunkevitchi, and the surface of a dipteran's compound eye. Scanning electron microscope images now reveal vestigial mechanoreceptors between the facets of the organ. We interpret Eohelea's wing organ as the blending of these two developmental systems: the formation and patterning of the cuticle in the eye and of the wing. Typically, only females in the genus carry this distinctive, highly organized structure. Two species were studied (E. petrunkevitchi and E. sinuosa), and the structure differs in form between them. We examine Eohelea's wing structures for modes of fabrication, material properties and biological functions, and the effective ecological environment in which these midges lived. We argue that the current view of the wing organ's function in stridulation has been misconstrued since it was described half a century ago.


Ordovician ostracods from east central Iran

Abstract: Ordovician ostracods are described for the first time from Iran, enhancing the record of this group from the Lower Palaeozoic of the Middle East. The ostracods occur in the Shirgesht Formation, in the east central part of the country, and comprise Ogmoopsis achaemenid sp. nov., Cerninella aryana sp. nov., Ordovizona amyitisae sp. nov., cf. Aechmina? ventadorni, Vogdesella sp., and podocope taxa tentatively identified as species of Longiscula, Pullvillites, and Rectella. These taxa were hitherto unknown from this region. The ostracod-bearing interval is associated with trilobites (Neseuretinus) and brachiopods (Nicolella) that suggest a late Middle Ordovician age. Although the ostracod fauna is small, it demonstrates biogeographical links at genus-level, and possibly at species-level, with the fauna of the late Middle Ordovician Travesout Formation of western France, which also lay in a peri-Gondwanan palaeogeographical setting. It also suggests the potential use of some ostracods as stratigraphical tools for correlating Ordovician rock successions between Europe and the Middle East.

shirgesht formation
ostracod fauna
ordovician ostracod


New trilophosaurid species demonstrates a decline in allokotosaur diversity across the Adamanian-Revueltian boundary in the Late Triassic of western North America

Abstract: Abstract Allokotosauria, including Trilophosauridae and Azendohsauridae, is an extinct archosauromorph group that reached a near-Pangean distribution in the Middle Triassic to Late Triassic and evolved a broad range of cranial and dental morphologies. Within the Chinle Formation of western North America, allokotosaurs span the Norian-aged Blue Mesa Member (Adamanian estimated holochronozone) and Sonsela Member (Adamanian and Revueltian estimated holochronozone). The Adamanian-Revueltian faunal assemblage transition is hypothesized to represent extinction and faunal turnover in large-bodied archosauromorphs, but poor sampling of known localities has obscured any similar patterns in tetrapods <1 m long. Trilophosaurids are the most common smaller-bodied herbivorous taxa found in Adamanian microvertebrate sites, with four species previously reported (Trilophosaurus buettneri, T. jacobsi, T. dornorum, and Spinosuchus caseanus). The presence of three new allokotosaur taxa in Adamanian microvertebrate sites, including a new species of trilophosaurid described here (Trilophosaurus phasmalophos sp. nov.) demonstrates the high diversity of this group in the Adamanian. Trilophosaurus phasmalophos occurs in microvertebrate-bearing horizons in the Jim Camp Wash beds of the Sonsela Member, making it the first unambiguous trilophosaurid reported from the Revueltian estimated holochronozone. Unlike in other trilophosaurids, the teeth are bicuspid, but the cusp and cingulum structure and complexity are similar to those of Trilophosaurus dornorum and T. jacobsi. The Adamanian-Revueltian boundary marks a reduction in allokotosaur diversity from five Adamanian taxa to one Revueltian taxon. This pattern of faunal turnover and extinction is similar to those of other large-bodied archosauromorph clades across the Adamanian-Revueltian boundary in the American Southwest. Systematic sampling of microvertebrate bonebeds at stratigraphic intervals across this boundary demonstrates that this turnover in allokotosaurs may reveal similar patterns in other groups that have been missed because of collecting biases towards larger-bodied vertebrate fossils.

allokotosaur diversity
late triassic
western north america
cusp


Upper Cretaceous volcanoclastic deposits from the Haţeg basin, south Carpathians (Romania): K-Ar ages and intrabasinal correlation

Abstract: In order to constrain the age of the Upper Cretaceous continental Densuş-Ciula Formation from the Haţeg basin, South Carpathians, and correlate it with the other continental unit that occurs in the region, the Sânpetru Formation, we separated and dated by the K-Ar method biotites and amphiboles from volcanoclastic deposits. The mineral phases analysed are from two tuff layers and volcanic bombs cropping out near Rachitova village. Two tuff layers from the Densuş-Ciula Formation give early Maastrichtian ages of 69.8±1.3 and 71.3±1.6 Ma, respectively. The ages determined for the tuff layers constrain the age of deposition for the Densuş-Ciula Formation and enable further correlations with the available palaeomagnetic data from the deposits occurring along the Sibişel Valley that belong to the Sânpetru Formation. The volcanic bombs collected near to Răchitova village are andesites and dacites. The age determined by K-Ar method on hornblende separated from a volcanic bomb is 82.7±1.5 Ma, which is older than the underlying Campanian marine deposits in turbidite facies. This suggests that the volcanic bombs were re-deposited during the early Maastrichtian. Thus, the volcanics found at Răchitova have at least two origins: one type is related to an explosive synsedimentary volcanic activity, and the other type is represented by older andesitic/dacitic bombs, which most probably originate from a volcanic centre situated in the Haţeg region.

volcanoclastic deposit
haţeg basin
south carpathians
maastrichtian age


The deep divergences of neornithine birds: a phylogenetic analysis of morphological characters

Abstract: Consensus is elusive regarding the phylogenetic relationships among neornithine (crown clade) birds. The ongoing debate over their deep divergences is despite recent increases in available molecular sequence data and the publication of several larger morphological data sets. In the present study, the phylogenetic relationships among 43 neornithine higher taxa are addressed using a data set of 148 osteological and soft tissue characters, which is one of the largest to date. The Mesozoic non‐neornithine birds Apsaravis, Hesperornis, and Ichthyornis are used as outgroup taxa for this analysis. Thus, for the first time, a broad array of morphological characters (including both cranial and postcranial characters) are analyzed for an ingroup densely sampling Neornithes, with crown clade outgroups used to polarize these characters. The strict consensus cladogram of two most parsimonious trees resultant from 1000 replicate heuristic searches (random stepwise addition, tree‐bisection‐reconnection) recovered several previously identified clades; the at‐one‐time contentious clades Galloanseres (waterfowl, fowl, and allies) and Palaeognathae were supported. Most notably, our analysis recovered monophyly of Neoaves, i.e., all neognathous birds to the exclusion of the Galloanseres, although this clade was weakly supported. The recently proposed sister taxon relationship between Steatornithidae (oilbird) and Trogonidae (trogons) was recovered. The traditional taxon “Falconiformes” (Cathartidae, Sagittariidae, Accipitridae, and Falconidae) was not found to be monophyletic, as Strigiformes (owls) are placed as the sister taxon of (Falconidae + Accipitridae). Monophyly of the traditional “Gruiformes” (cranes and allies) and ”Ciconiiformes” (storks and allies) was also not recovered. The primary analysis resulted in support for a sister group relationship between Gaviidae (loons) and Podicipedidae (grebes)—foot‐propelled diving birds that share many features of the pelvis and hind limb. Exclusion of Gaviidae and reanalysis of the data set, however, recovered the sister group relationship between Phoenicopteridae (flamingos) and grebes recently proposed from molecular sequence data.

deep divergence
phylogenetic analysis
morphological character
present study
mayr


Chitinase genes (CHIAs) provide genomic footprints of a post-Cretaceous dietary radiation in placental mammals

Abstract: Mammal genomes retain remnants of chitinase genes, pointing to dietary shifts in the wake of the K/Pg mass extinction. The end-Cretaceous extinction led to a massive faunal turnover, with placental mammals radiating in the wake of nonavian dinosaurs. Fossils indicate that Cretaceous stem placentals were generally insectivorous, whereas their earliest Cenozoic descendants occupied a variety of dietary niches. It is hypothesized that this dietary radiation resulted from the opening of niche space, following the extinction of dinosaurian carnivores and herbivores. We provide the first genomic evidence for the occurrence and timing of this dietary radiation in placental mammals. By comparing the genomes of 107 placental mammals, we robustly infer that chitinase genes (CHIAs), encoding enzymes capable of digesting insect exoskeletal chitin, were present as five functional copies in the ancestor of all placental mammals, and the number of functional CHIAs in the genomes of extant species positively correlates with the percentage of invertebrates in their diets. The diverse repertoire of CHIAs in early placental mammals corroborates fossil evidence of insectivory in Cretaceous eutherians, with descendant lineages repeatedly losing CHIAs beginning at the Cretaceous/Paleogene (K/Pg) boundary as they radiated into noninsectivorous niches. Furthermore, the timing of gene loss suggests that interordinal diversification of placental mammals in the Cretaceous predates the dietary radiation in the early Cenozoic, helping to reconcile a long-standing debate between molecular timetrees and the fossil record. Our results demonstrate that placental mammal genomes, including humans, retain a molecular record of the post-K/Pg placental adaptive radiation in the form of numerous chitinase pseudogenes.

chias
placental mammal
enzyme
early cenozoic
chitinase gene


Mode of life and hydrostatic stability of orthoconic ectocochleate cephalopods: hydrodynamic analyses of restoring moments from 3D-printed, neutrally buoyant models

Abstract: Theoretical 3D models were digitally reconstructed from a phragmocone section of Baculites compressus in order to investigate the hydrostatic properties of the orthoconic morphotype. These virtual models all had the capacity for neutral buoyancy (or nearly so) and were highly stable with vertical syn vivo orientations. Body chamber lengths exceeding approximately 40% of the shell length cause buoyancy to become negative with the given modeled proportions. The distribution of cameral liquid within the phragmocone does not change orientation and only slightly influences hydrostatic stability. The mass of cameral liquid required to completely reduce stability, permitting a non-vertical static orientation, would cause the living cephalopod to become negatively buoyant. A concave dorsum does not significantly change the mass distribution and results in a 5° dorsal rotation of the aperture from vertical. The restoring moments acting to return neutrally buoyant objects to their equilibrium position were investigated using 3D-printed models of Nautilus pompilius and Baculites compressus with theoretically equal masses and hydrostatic stabilities to their virtual counterparts. The N. pompilius behaved as an underdamped harmonic oscillator during restoration due to its low hydrostatic stability and drag relative to the B. compressus model. In contrast, the B. compressus model more quickly returns to its equilibrium position without oscillating (overdamped system). The thrust required to overcome such a large restoring moment was explored using several extant cephalopod analogues. Significant angles of displacement were only achieved with coleoid-like thrusts, which were unrealistically high despite the probable similarities in their locomotor design. These maximum bursts of thrust may have been too energetically expensive and would preclude an unusual form of locomotion in a non-vertical orientation. These results suggest baculitids and other orthocones with similar hydrostatic stabilities probably lived a nektic to quasiplanktic mode of life with a primarily vertical orientation and mobility.


A new Early Triassic gastropod genus and the recovery of gastropods from the Permian/Triassic extinction

Abstract: The common Early Triassic (Olenekian) gastropod Turbo rectecostatus from the upper Werfen Formation of the Alps is placed in the new genus Werfenella. Elimination of the wrong or outdated generic assignments of Late Palaeozoic and Early Mesozoic gastropods to archetypical genera such as Turbo, Trochus, or Natica (all with Recent type species) represents an important step toward understanding the evolutionary history of the gastropods across the Permian/Triassic mass-extinction event. The first appearance of Werfenella in the Olenekian, as well as the origination of other groups of gastropods, suggests an early turnover in the aftermath of the end-Permian mass extinction event. The relatively large size of Werfenella (up to 35 mm) sheds doubt on assertions that all Early Triassic gastropods are microgastropods (Lilliput effect). The new genus is placed in the caenogastropod family Purpurinidae and represents its earliest occurrence. However, a placement of Werfenella in the Archaeogastropoda (Vetigastropoda) is also possible because it resembles the paraturbinid genus Chartronella. The characteristic Werfenella rectecostata-Natiria costata gastropod association from the Werfen Formation is not found in the approximately contemporaneous Sinbad Limestone of the Moenkopi Formation (Utah, USA) nor elsewhere outside Europe. This suggests that the similarities between Olenekian gastropod faunas from the Tethys and western North America are more limited than previously thought.

early triassic
gastropod
permian
lilliput effect


Abstract: The Mersin Ophiolitic Complex is situated in southern Turkey and contains the relics of the Palaeotethys and Neotethys Oceans and of the Huglu-Pindos basin. The succession exposed at the Tavusçayiri Block has been intensely studied but ostracods are still poorly documented. This paper illustrates and discusses the ostracods extracted from a radiolarian-rich limestone of the lower Tuvalian Spongotortilispinus moixi radiolarian Zone (Carnian, Late Triassic) intercalated with thick green tuffs. The moderately abundant assemblage (40 specimens) is composed of 29 species, 16 genera of seven families, including one new species: Bairdiacypris sorgunensis Forel sp. nov. This assemblage points to a moderately shallow subtidal environment submitted to short-lived environmental instabilities. In regards to the slightly older ostracods recently reported from the Tavusçayiri Block, the present record illustrates an upwards shallowing trend for the Carnian succession. All the taxa found are of typical MesozoicCenozoic affinity, in contrast to the slightly older assemblage from the Julian of the Tavusçayiri Block (Kilek section), which also include Palaeozoic taxa. This different pattern could relate either to the disappearance of Palaeozoic taxa during the intervening interval or to their survival only in relatively deeper waters. Finally, we also report the oldest known record of a boring trace on the surface of an ostracod valve, probably of predatory origin. It represents the first evidence of predation on micro-benthos in the Triassic and is in line with several recent studies attesting the establishment of boring predation in the Late Triassic. Marie-Béatrice Forel. MNHN-CNRS-SU, Muséum national d’Histoire naturelle, 8 rue Buffon (CP38), 75005 Paris, France. marie-beatrice.forel@mnhn.fr Péter Ozsvárt. MTA-MTM-ELTE, Research Group for Paleontology, P.O. Box 137, H 1431 Budapest, Hungary. ozsvart.peter@nhmus.hu Patrice Moix. Rue de la Combe 55, 1969 Eison, Switzerland. patricemoix@gmail.com http://zoobank.org/BDBCC335-201C-4197-949A-81747E64B3B8 Forel, Marie-Béatrice, Ozsvárt, Péter, and Moix, Patrice. 2018. Carnian (Late Triassic) ostracods from the Sorgun Ophiolitic Mélange (Southern Turkey): Taxonomy, palaeoenvironment, and evidence of predation. Palaeontologia Electronica 21.2.26A 1-23. https:// doi.org/10.26879/852 palaeo-electronica.org/content/2018/2262-carnian-ostracods-from-turkey Copyright: July 2018 Paleontological Society. This is an open access article distributed under the terms of Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0), which permits users to copy and redistribute the material in any medium or format, provided it is not used for commercial purposes and the original author and source are credited, with indications if any changes are made. creativecommons.org/licenses/by-nc-sa/4.0/ FOREL, OZSVÁRT, & MOIX: CARNIAN OSTRACODS FROM TURKEY

triassic
ostracod
southern turkey
palaeoenvironment


A New Morphological Phylogeny of the Ophiuroidea (Echinodermata) Accords with Molecular Evidence and Renders Microfossils Accessible for Cladistics

Abstract: Ophiuroid systematics is currently in a state of upheaval, with recent molecular estimates fundamentally clashing with traditional, morphology-based classifications. Here, we attempt a long overdue recast of a morphological phylogeny estimate of the Ophiuroidea taking into account latest insights on microstructural features of the arm skeleton. Our final estimate is based on a total of 45 ingroup taxa, including 41 recent species covering the full range of extant ophiuroid higher taxon diversity and 4 fossil species known from exceptionally preserved material, and the Lower Carboniferous Aganaster gregarius as the outgroup. A total of 130 characters were scored directly on specimens. The tree resulting from the Bayesian inference analysis of the full data matrix is reasonably well resolved and well supported, and refutes all previous classifications, with most traditional families discredited as poly- or paraphyletic. In contrast, our tree agrees remarkably well with the latest molecular estimate, thus paving the way towards an integrated new classification of the Ophiuroidea. Among the characters which were qualitatively found to accord best with our tree topology, we selected a list of potential synapomorphies for future formal clade definitions. Furthermore, an analysis with 13 of the ingroup taxa reduced to the lateral arm plate characters produced a tree which was essentially similar to the full dataset tree. This suggests that dissociated lateral arm plates can be analysed in combination with fully known taxa and thus effectively unlocks the extensive record of fossil lateral arm plates for phylogenetic estimates. Finally, the age and position within our tree implies that the ophiuroid crown-group had started to diversify by the Early Triassic.


Bizarre structures in dinosaurs: species recognition or sexual selection? A response to Padian and Horner

Abstract: Since the mid-1970s, most investigators have agreed that the ‘bizarre’ structures (here referred to as ‘exaggerated’ structures) of dinosaurs – for example, the horns and frills of ceratopsids, the crests of lambeosaurine hadrosaurids, the domes of pachycephalosaurs – functioned first and foremost as signalling and combat structures used in mate competition (Farlow D Hopson, 1975; Molnar, 1977; Spassov, 1979; Ostrom & Wellnhoffer, 1986; Sampson, 1997, 2001; Dodson, Forster & Sampson, 2004). Padian & Horner (2010) argue that the mate competition hypothesis is not supported by available evidence, citing in particular the lack of data documenting sexual dimorphism within dinosaur species. In place of the mate competition model, they present a challenging and novel alternative, suggesting these traits functioned as species recognition features for identifying conspecifics, thereby facilitating social interactions such as herding, mating and parental care. Padian & Horner offer a pair of tests for distinguishing paleontological examples of exaggerated traits evolving under the influence of species recognition from those resulting primarily from sexual selection. The first test relates to the patterns of diversification of exaggerated structures, predicted to be random under the influence of species recognition and directional if driven by sexual selection. The second test invokes evidence of geographic overlap of closely related, contemporaneous species, thought to be a necessary condition for the evolution of exaggerated structures under the influence of species recognition (in part so as to avoid unwanted matings). These authors argue that known examples of exaggerated structures among dinosaurs pass both of these tests, indicating that species recognition is the preferred (though not necessarily sole) explanation. Padian & Horner highlight a major problem common to most previous studies addressing the function of dinosaurian exaggerated structures – lack of phylogenetic context. Comprehensive testing of adaptation hypotheses requires mapping of relevant characters onto independently derived phylogenies in order to search for evidence of evolutionary assembly of the purported adaptation. They also underline the importance of assessing the full range of alternative hypotheses as rigorously as possible, rather than accepting one explanation as the default. We fully support both of these contentions. Nevertheless, we disagree with several of the paper’s central conclusions, including: (1) the necessary correlation of overt sexual dimorphism and sexual selection; (2) the required linkage between sexual selection with a directional pattern of diversification; (3) evidence for the geographical overlap of multiple closely related dinosaur taxa bearing exaggerated structures. In addition to countering these claims, we propose two alternative predictions that allow putative species recognition traits to be distinguished from sexually selected ones. With regard to the exaggerated structures of dinosaurs, the species recognition hypothesis fails both of these tests, and the sexual selection hypothesis remains by far the best-supported explanation. Citing Darwin (1871), Padian & Horner claim that sexual dimorphism is effectively the sine qua non of sexual selection. They argue further that the apparent absence of sexual dimorphism in dinosaurian exaggerated characters is Journal of Zoology

sexual selection
padian
horner
specie recognition trait


Hyena as a predator of small mammals? Taphonomic analysis from the site of Bois Roche, France

Abstract: Abstract. Feeding behaviors may differ between past and current predators due to differences in the environments inhabited by these species at different times. We provide an example of this behavioral variability in spotted hyena (Crocuta crocuta), for which our analysis of a late Pleistocene micromammal assemblage indicates that hyenas preyed upon small rodents, a feeding habit that is rarely observed today among hyenas. The Bois Roche cave site is situated at the edge of a low bluff overlooking the floodplain of a small stream in Cherves-Richemont (Charente, France). The deposits are dated by electron spin resonance (ESR) to about 69.7 ± 4.1 Ka. Excavations at the site recovered fossil bones and teeth of large and small mammals, together with hyena coprolites. Water screening of the sediments produced large accumulations of rodent remains with low taxonomic diversity. Small mammal bones were recovered from hyena coprolites as well. Descriptions of small mammal bone modification, both from the sediments and coprolites, are reported here. The analysis yielded a distinct taphonomic pattern representative of large carnivores (over 30 kg), which differs from any other modern or fossil predator-accumulated microfaunal assemblage taphonomically analyzed to date. To our knowledge, previous studies of hyena diet have not recorded high concentrations of a single-rodent prey species. Weconclude that the lowspecies diversity of this small mammal assemblage most likely relates to a local abundance of the prey species due to an outbreak in the rodent population, rather than from specialist predator behavior and hunting technique.


A new glimpse on trophic interactions of 100-million-year old lacewing larvae

Abstract: Larvae of lacewings (Neuroptera) are known to be fierce predators. According to the morphology of fossil forms thisseems to have been the case already in the Early Cretaceous. While being predators, lacewing larvae are also food itemsfor other organisms. Here we report two pieces of amber from Myanmar providing instances of such cases. In one amberpiece several isolated stylets of lacewing larvae are preserved closely associated together. The most likely interpretationis that a predator preying on lacewing larvae has regurgitated or defecated these non-digestible pieces, yet the identityof the predator remains unclear. The other amber piece preserves a larva resembling modern day larvae of split-footedlacewings (Nymphidae). The larva has projections on its trunk, allowing it to wear a camouflaging cloak. In the headregion, a mite (Acari) is attached to the larva; more precisely, the entire anterior body region of the mite is apparentlyinserted into the lacewing larva. The mite is smaller than the larva. It is known from the modern fauna that stage 1 larvaeof Ascalaphidae can be attacked also by rather small predators, such as ants. The mite can therefore well be interpretedas a true predator instead of a parasite, especially considering the unusual mode of attachment. We briefly review interactionsof lacewing larvae with other organisms represented in amber from Myanmar and add two new pieces to thepuzzle of reconstructing the trophic interactions in the 100-million-year old amber forest.


Nd and Pb isotope signatures of the clay-size fraction of Labrador Sea sediments during the Holocene: Implications for the inception of the modern deep circulation pattern

Abstract: Holocene on the basis of sediment supply variations. For the last 12 kyr, three sources have contributed to the sediment mixture: the North American Shield, the Pan-African and Variscan crusts, and the Mid-Atlantic Ridge. Clay isotope signatures indicate two mixtures of sediment sources. The first mixture (12.2–6.5 ka) is composed of material derived from the North American shield and from a ‘‘young’’ crustal source. From 6.5 ka onward the mixture is characterized by a young crustal component and by a volcanic component characteristic of the MidAtlantic Ridge. Since the significant decrease in proximal deglacial supplies, the evolution of the relative contributions of the sediment sources suggests major changes in the relative contributions of the deep water masses carried by the Western Boundary Undercurrent over the past 8.4 kyr. The progressive intensification of the Western Boundary Undercurrent was initially associated mainly with the transport of the Northeast Atlantic Deep Water mass until 6.5 ka and with the Denmark Strait Overflow Water thereafter. The establishment of the modern circulation at 3 ka suggests a reduced influence of the Denmark Strait Overflow Water, synchronous with the full appearance of the Labrador Seawater mass. Our isotopic data set emphasizes several changes in the relative contribution of the two major components of North Atlantic Deep Water throughout the Holocene. INDEX TERMS: 4267 Oceanography: General: Paleoceanography; 4558 Oceanography: Physical: Sediment transport; 1040 Geochemistry: Isotopic composition/chemistry; 9325 Information Related to Geographic Region: Atlantic Ocean; 9604 Information Related to Geologic Time: Cenozoic; KEYWORDS: clay-size fraction, sedimentary mixings, deep circulation, Nd and Pb isotopes, North Atlantic, Labrador Sea

clay-size fraction
holocene
western boundary undercurrent