link.
Wednesday, December 24, 2014
The Paleoenvironment of Oligocene Paleogene Patagonia
Reconstruction of a fossil forest reveals details of the palaeoecology, palaeoenvironments and climatic conditions in the late Oligocene of South America
Authors:
Brea et al
Abstract:
This research focuses on the three-dimensional reconstruction of an in situ forest based on fossil wood assemblages recovered in the Rancahué Formation (Upper Oligocene), Neuquén, Argentina. Atherospermataceae, Lauraceae, Nothofagaceae, Eucryphiaceae, Cunoniaceae and Myrtaceae specimens are described. The mapping of a forest floor section and in situ tree diameters enabled the estimation of the following palaeoecological quantitative data: tree density, dominance, basal area, biomass, diametric classes, canopy height, and age classes. Palaeoclimatical data was determined on the basis of physiognomic anatomical features using multivariate anatomical analyses. These results were compared with other proxies including Carlquist's index, Coexistence Approach (CA), Nearest Living Relatives (NLRs), and growth-rings analyses. The structural data from the Aluminé forest inferred from these analyses includes: tree density of 463–701 trees/ha, mean height of 15.22 m, dominance of the genus Nothofagoxylon (89.66 m2/ha), total basal area of 158.20 m2/ha, biomass between 43 and 712 tn/ha and mean age of 223 years (specimens between 31 and 700 years old). These results are comparable to those of mature low-to-middle altitude extant forests dominated by Nothofagus and developed under humid-temperate conditions. Based on the NLRs method, the Aluminé forest has a floristic composition similar to the present-day Valdivian forest. The persistence of Nothofagus as the dominant element in temperate rainforests correlates with regimes where large-scale disturbances, such as volcanism and earthquakes are prevalent. The fossil taxa are closely related to the extant Laurelia, Persea, Eucryphia, Nothofagus, Weinmannia, Myrceugenia and Luma. The forest shows intermixed deciduous and evergreen elements, and taxa with shade-intolerance and intermediate shade tolerance. Also, the majority of these taxa need soils with available water. The integrated analysis of multiple sets of proxy data suggests that the late Oligocene forest grew under temperate and humid climate, while the eco-anatomical features and sedimentary data provide information about the environmental stress conditions of its development and the violent causes of burial.
NASA's Maven Finds Hints of Martian Atmospheric Loss due to Solar Wind
Early discoveries by NASA's newest Mars orbiter are starting to reveal key features about the loss of the planet's atmosphere to space over time.
The findings are among the first returns from NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission, which entered its science phase on Nov. 16. The observations reveal a new process by which the solar wind can penetrate deep into a planetary atmosphere. They include the first comprehensive measurements of the composition of Mars' upper atmosphere and electrically charged ionosphere. The results also offer an unprecedented view of ions as they gain the energy that will lead to their to escape from the atmosphere.
"We are beginning to see the links in a chain that begins with solar-driven processes acting on gas in the upper atmosphere and leads to atmospheric loss," said Bruce Jakosky, MAVEN principal investigator with the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. "Over the course of the full mission, we'll be able to fill in this picture and really understand the processes by which the atmosphere changed over time."
On each orbit around Mars, MAVEN dips into the ionosphere - the layer of ions and electrons extending from about 75 to 300 miles above the surface. This layer serves as a kind of shield around the planet, deflecting the solar wind, an intense stream of hot, high-energy particles from the sun.
Scientists have long thought that measurements of the solar wind could be made only before these particles hit the invisible boundary of the ionosphere. MAVEN's Solar Wind Ion Analyzer, however, has discovered a stream of solar-wind particles that are not deflected but penetrate deep into Mars' upper atmosphere and ionosphere.
Interactions in the upper atmosphere appear to transform this stream of ions into a neutral form that can penetrate to surprisingly low altitudes. Deep in the ionosphere, the stream emerges, almost Houdini-like, in ion form again. The reappearance of these ions, which retain characteristics of the pristine solar wind, provides a new way to track the properties of the solar wind and may make it easier to link drivers of atmospheric loss directly to activity in the upper atmosphere and ionosphere.
link.
Evidence from Paleolithic (Pleistocene Quaternary) Manot Cave, Israel of Heat Treating Stone Tools
Heating of flint debitage from Upper Palaeolithic contexts at Manot Cave, Israel: changes in atomic organization due to heating using infrared spectroscopy
Authors:
Weiner et al
Abstract:
The heat treatment of flint is known to change its mechanical properties and improve its fracture behaviour during knapping. Here we examine 20 flint artifacts from Upper Paleolithic contexts from Manot Cave, Israel, using Fourier transform infrared spectroscopy and compare them to geogenic flint beds from the walls inside the cave and from outcrops just above the cave. We show that the 512 and 467 cm−1 peaks are broader in most of the flint debitage pieces as compared to the geogenic flint, and that broadening of these peaks occurs when geogenic flint from the cave wall is heated. We also present an empirical simple method to monitor these changes.
Metatherian Mammals Nearly Wiped out by KT/K-Pg Extinction
The origin and early evolution of metatherian mammals: the Cretaceous record
Authors:
Wiliamson et al
Abstract:
Metatherians, which comprise marsupials and their closest fossil relatives, were one of the most dominant clades of mammals during the Cretaceous and are the most diverse clade of living mammals after Placentalia. Our understanding of this group has increased greatly over the past 20 years, with the discovery of new specimens and the application of new analytical tools. Here we provide a review of the phylogenetic relationships of metatherians with respect to other mammals, discuss the taxonomic definition and diagnosis of Metatheria, outline the Cretaceous history of major metatherian clades, describe the paleobiology, biogeography, and macroevolution of Cretaceous metatherians, and provide a physical and climatic background of Cretaceous metatherian faunas. Metatherians are a clade of boreosphendian mammals that must have originated by the Late Jurassic, but the first unequivocal metatherian fossil is from the Early Cretaceous of Asia. Metatherians have the distinctive tightly interlocking occlusal molar pattern of tribosphenic mammals, but differ from Eutheria in their dental formula and tooth replacement pattern, which may be related to the metatherian reproductive process which includes an extended period of lactation followed by birth of extremely altricial young. Metatherians were widespread over Laurasia during the Cretaceous, with members present in Asia, Europe, and North America by the early Late Cretaceous. In particular, they were taxonomically and morphologically diverse and relatively abundant in the Late Cretaceous of western North America, where they have been used to examine patterns of biogeography, macroevolution, diversification, and extinction through the Late Cretaceous and across the Cretaceous-Paleogene (K-Pg) boundary. Metatherian diversification patterns suggest that they were not strongly affected by a Cretaceous Terrestrial Revolution, but they clearly underwent a severe extinction across the K-Pg boundary.
A Hypothesis on the Evolution of Tetrapod Limbs
Urodelans, Ichthyostega and the origin of the tetrapod limb
Author:
Mednikov
Abstract:
Available information on the development of primitive urodele (Hynobiidae) limbs and limb structure in Devonian tetrapods provide the basis for formulating the hypothesis on the existence of a special phase, the phase of the biserial limb in tetrapod history. The limb of the Devonian amphibian Ichthyostega with two groups of digits, preaxial and postaxial, corresponds well to this phase. Based on the structure of the Ichthyostega limb, it is suggested that the fin type ancestral to terrestrial limbs was asymmetrical biserial, possessed a short axis, unbranched jointed preaxial radials deviating one by one from each mesomere of the axis, and unbranched jointed postaxial radials deviating from the distal mesomeres of the axis in two or more radials.
Is Australian Ediacaran NeoProterozoic Fossil Genus Aspidella Really a Holdfast Trace Fossil?
Taphonomy and Morphology of the Ediacara Form Genus Aspidella
Authors:
Tarhan et al
Abstract:
Aspidella, the disk-like Ediacaran form genus, is a common and globally-distributed member of the Ediacara Biota. In South Australia, it occurs prolifically (n greater than 1000) in locally dense assemblages on the bases of sandstone beds in the eponymous Ediacara Member of the Rawnsley Quartzite. Association with stalks, fronds and textured organic surfaces (TOS) has led to the interpretation of Aspidella as the holdfast of a frondose, Charniodiscus-like organism which lived with its holdfast secured within or under a sandy microbial mat and its stalk and frond protruding above the substrate and into the water column. As the dominant component of four fossiliferous beds and a minor component of most others, Aspidella exemplifies the bed-scale faunal heterogeneity characteristic of Ediacara fossil assemblages. Aspidella itself, moreover, is characterized by strong morphological variability, including variation in the presence or absence of particular distinct morphological features, variable preservation as internal and external molds, variable relief and a broad size range. However, the distribution of morphological characters is unrelated to either Aspidella specimen size or bed assemblage composition. Herein we demonstrate that this morphological diversity is an expression of neither ontogenetic nor species-level anatomical differences, but rather is the product of differential taphonomy related to variation in local substrate-related sedimentological and biogenic factors, particularly the presence or absence of TOS composed of the eukaryotic tubular organism Funisia.
Tuesday, December 23, 2014
Ukraine Formally Abandons Nonaligned Status
Ukraine's parliament on Tuesday voted to abandon the country's nonaligned status, a move that could be a step toward seeking membership in NATO.
Supporters of the move, which passed by a 303-9 vote, said it was justified by Russian aggression toward Ukraine, including the annexation of its Crimean Peninsula in March and Russian support for a separatist insurgency in eastern Ukraine, where some 4,700 people have been killed since the spring.
link.
Saudis' War on Frackers Gets REALLY Serious, Won't cut Production Even at $20/barrel
OPEC will not cut oil production even if the price drops to $20 a barrel and it is unfair to expect the cartel to reduce output if non-members do not, Saudi Arabia said.
"Whether it goes down to $20 a barrel, $40, $50, $60, it is irrelevant," the kingdom's Oil Minister Ali al-Naimi said in an interview with the Middle East Economic Survey (MEES), an industry weekly.
In unusually detailed comments, Naimi defended a decision by the Organization of the Petroleum Exporting Countries, whose lead producer is Saudi Arabia, last month to maintain a production ceiling of 30 million barrels per day.
The decision sent global crude prices tumbling, worsening a price drop that has seen them fall by around 50 percent since June.
Slower demand growth and a stronger dollar have also contributed to the slump.
link.
Indian Navy Wants American MQ-4C Triton Maritime Surveillance Drone
The Indian Navy has earlier shown interest in acquiring six to eight of the maritime variants of the US high altitude, long endurance (HALE) Unmanned Aerial Vehicles (UAV) for extended ocean surveillance. The drones have been upgraded as the MQ-4C Triton maritime surveillance platform for the U.S. Navy, providing real-time intelligence, surveillance and reconnaissance over vast ocean and coastal regions.
The Global Hawk has been deployed by the U.S. in Japan, and the U.S. this week approved the sale of four Global Hawks to South Korea. Australia and Japan too have expressed interest in these drones, though Australia later backed out because of the high price.
link.
US Navy Negotiating With Boeing to Slow Down EA-18G Growler Production to Preserve Production Line Through 2017
The U.S. Navy on Friday said it was in talks with Boeing Co about slowing production of its EA-18G electronic attack jets to keep the St. Louis facility running through the end of 2017, after Congress approved funding for 15 more planes.
The Navy is seeking to modify Boeing's existing contract for EA-18G jets, or Growlers, and F/A-18 Super Hornets to add the extra jets funded by Congress in the fiscal 2015 U.S. budget, said Rob Koon, spokesman for the Navy's Naval Air Systems Command.
President Obama on Tuesday signed the fiscal 2015 spending bill into law. It includes $1.46 billion for 15 more Growlers, and up to $100 million to cover the cost of slowing the current production rate from three to two aircraft a month.
By building two jets a month instead of three, Boeing will be able to stretch jet orders through the end of 2017, preserving the tooling and jobs associated with the line for as long as possible.
link.
China Building Airbase on Nanji Island Between Taiwan and Senkaku Islands
China is building airstrips on islands less than 200 miles from the contested Japanese Senkaku Islands, according to a report in Kyodo News.
Citing unnamed Chinese sources, the news agency reported that several landing strips have been built on Nanji island, buttressing existing radar installations on the island.
“It’s a strategically important location because of its proximity to the Diaoyu Islands, it can provide support to the East China Sea air defense zone, and it’s a major naval point on the Chinese coastal defense lines,” Li Jie, a senior researcher from the Chinese Naval Research Institute told Bloomberg.
“It’s unarguable that China would like to enhance the existing military presence there.”
link.
Russia's New Angara 5 Rocket Launches Successfully
link.Russian media are reporting that the first flight test of the new Angara 5 booster was successful on Wednesday from the Plesetsk Cosmodrome.
The rocket consisted of five Universal Rocket Modules (URM) powered by RD-191 engines clustered as the first stage. Upper stages used on other boosters were to put a dummy payload into geostationary orbit. It’s not clear whether that effort was successful.
Angara, which is produced by Khrunichev, is designed to replace a number of Soviet-era launch vehicles, including the Proton and Zenit systems. The booster will initially launch from the Plesetsk Cosmodrome, with eventual plans to operate from the new Vostochny facility under construction in the Russian Far East.
Marine Biota Response to the Middle Eocene Climatic Optimum
Benthic foraminiferal response to the Middle Eocene Climatic Optimum (MECO) in the South-Eastern Atlantic (ODP Site 1263)
Authors:
Galazzo et al
Abstract:
The response of marine biota to the Middle Eocene Climatic Optimum (MECO) is still poorly constrained. Specifically, changes in deep-sea benthic foraminiferal faunas have been documented at few locations only. We carried out a quantitative study of benthic foraminiferal assemblages at lower-bathyal ODP Site 1263 (Walvis Ridge, SE Atlantic), providing documentation of the response of benthic foraminiferal assemblage to the MECO in an open ocean setting. There was no major temporary or persistent assemblage turnover in benthic foraminiferal faunas in the SE Atlantic Ocean. The benthic foraminiferal accumulation rates (BFAR) and assemblage composition indicate that the delivery of food to the seafloor increased during the early stages of surface and deep-sea warming. During this period, the absolute and relative abundance of phytodetritus exploiters increased pronouncedly, indicating that the increase in the flux of organic matter to the sea floor was largely seasonal or otherwise pulsed. During later stages and peak warming of MECO, in contrast, the flux of organic matter to the seafloor declined markedly, as shown by a decrease in both infaunal and epifaunal benthic foraminiferal accumulation rates. The low flux of organic matter during the more extreme parts of the MECO thus did not favor one of these broad groups, but affected all common taxa. Paleoceanographic reconstructions combined with data on benthic foraminifera suggest that the MECO warming was the main cause of the reduction in the flux of organic matter to the sea floor, by increasing the metabolic rates of pelagic consumers, which thus used more food, preventing it from reaching the sea floor, as well as increasing remineralization of organic matter in the water column.
Evidence of Global Warming & Two Stage Glacial Retreat at Martian South Pole During Late Noachian/Early Hesperian
Late Noachian and early Hesperian ridge Systems in the South Circumpolar Dorsa Argentea Formation, Mars: Evidence for Two Stages of Melting of an Extensive Late Noachian Ice Sheet
Authors:
Kress et al
Abstract:
The Dorsa Argentea Formation (DAF), extending from 270°–100° E and 70°–90° S, is a huge circumpolar deposit surrounding and underlying the Late Amazonian South Polar Layered Deposits (SPLD) of Mars. Currently mapped as Early-Late Hesperian in age, the Dorsa Argentea Formation has been interpreted as volatile-rich, possibly representing the remnants of an ancient polar ice cap. Uncertain are its age (due to the possibility of poor crater retention in ice-related deposits), its mode of origin, the origin of the distinctive sinuous ridges and cavi that characterize the unit, and its significance in the climate history of Mars. In order to assess the age of activity associated with the DAF, we examined the ridge populations within the Dorsa Argentea Formation, mapping and characterizing seven different ridge systems (composed of nearly 4,000 ridges covering a total area of ~300,000 km2, with a cumulative length of ridges of ~51,000 km) and performing crater counts on them using the method of buffered crater counting to determine crater retention ages of the ridge populations. We examined the major characteristics of the ridge systems and found that the majority of them were consistent with an origin as eskers, sediment-filled subglacial drainage channels. Ridge morphologies reflect both distributed and channelized esker systems, and evidence is also seen that some ridges form looping moraine-like termini distal to some distributed systems. The ridge populations fall into two age groups: ridge systems between 270° and 0° E date to the Early Hesperian, but to the east, the Promethei Planum and the Chasmata ridge systems date to the Late Noachian. Thus, these ages, and esker and moraine-like morphologies, support the interpretation that the DAF is a remnant ice sheet deposit, and that the esker systems represent evidence of significant melting and drainage of meltwater from portions of this ice sheet, thus indicating at least some regions and/or periods of wet-based glaciation. The Late Noachian and Early Hesperian ages of the ridge systems closely correspond to the ages of valley network/open basin lake systems, representing runoff, drainage and storage of liquid water in non-polar regions of the surface of Mars. Potential causes of such wet-based conditions in the DAF include: 1) top-down melting due to atmospheric warming, 2) enhanced snow and ice accumulation and raising of the melting isotherm to the base of the ice sheet, or 3) basal melting associated with intrusive volcanism (volcano-ice interactions). The early phase of melting is closely correlated in time with valley network formation and thus may be due to global atmospheric warming, while the later phase of melting may be linked to Early Hesperian global volcanism and specific volcano-ice interactions (table mountains) in the DAF. Crater ages indicate that these wet-based conditions ceased by the Late Hesperian, and that further retreat of the DAF to its present configuration occurred largely through sublimation, not melting, thus preserving the extensive ridge systems. MARSIS radar data suggest that significant areas of layered, potentially ice-rich parts of the Dorsa Argentea Formation remain today.
Why Did the Chicken Cross the World?
For most of us, the word "chicken" spells a cold, clammy slab of plastic-wrapped white meat plucked out of the refrigerated section of our local supermarket. But in the ancient world, and in many cultures today, chickens had deep religious and social significance.
Speaking from his home in Nashville, Tennessee, Andrew Lawler, author of Why Did the Chicken Cross the World: The Epic Saga of the Bird That Powers Civilization describes how fried chicken has its origins in West Africa, why the Puritans tried to ban the word "cock," and how the backyard chicken movement is bringing roosters to towns and cities all over America.
link.
Fosterovenator churei & the Cryptic Theropod PaleoDiversity of the Tithonian Jurassic Morrison Formation
New data on small theropod dinosaurs from the Upper Jurassic Morrison Formation of Como Bluff, Wyoming, USA
Author:
Dalman
Abstract:
In 1879, Othniel C. Marsh and Arthur Lakes collected in the Upper Jurassic Morrison Formation Quarry 12 at Como Bluff, Wyoming, USA, several isolated axial and appendicular skeletal elements of small theropod dinosaurs. Since the discovery the specimens remained unnoticed for over a century. The skeletal remains of small theropods are rare at Como Bluff and throughout the Morrison Formation. Their bones are delicately constructed, so they are not as well-preserved as the bones of large-bodied theropods. The bones of small theropods described here were found mixed with isolated crocodile teeth and turtle shells. Comparison of the skeletal materials with other known theropods from the Morrison Formation reveals that some of the bones belong to a very small juvenile Allosaurus fragilis and Torvosaurus tanneri and also to a new ceratosaur taxon, here named Fosterovenator churei, whereas the other bones represent previously unidentified juvenile taxa of basal tetanuran and coelurid theropods. The discovery and description of these fossil materials is significant because they provide important information about the Upper Jurassic terrestrial fauna of Quarry 12, Como Bluff, Wyoming. The presence of previously unidentified theropod taxa in the Morrison Formation indicates that the diversity of basal tetanuran and coelurid theropods may have been much greater than previously expected. Although the fossil material here described is largely fragmentary, it is tenable that theropods of different clades co-existed in the same ecosystems at the same time and most likely competed for the same food sources.
Microphon exiguus: an Aquatic Neotonic Kotlassiid Seymouriamorph (Reptiliomorph) From Permian Russia
Bulanov
Abstract:New data on the morphology and ontogeny of the Permian kotlassiid Microphon exiguus Ivachnenko, 1983 (Tetrapoda, Seymouriamorpha), based on the collection from the Ust’e Strelny locality (Russia, Vologda Region; Severodvinian Regional Stage), are reported. At the definitive stage, M. exiguus retains the larval skull habitus (short preorbital region, a few marginal teeth, widely open posttemporal fenestra) and seismosensory grooves. These features, along with the reduced nasolacrimal duct, are indicative of an important role of pedomorphosis in the evolution of Severodvinian kotlassiids and, in particular, the genus Microphon, which should be regarded as a neotenic, permanently aquatic Permian amphibian.
The Paleoecology of the Avalonian Ediacaran NeoProterozoic Biota
Remarkable insights into the paleoecology of the Avalonian Ediacaran macrobiota
Authors:
Liu et al
Abstract:
Ediacaran macrofossils from the Avalon Terrane (primarily eastern Newfoundland and the central U.K.) record some of the earliest large and complex multicellular organisms on Earth. Perhaps the greatest unknown regarding these fossils is their relevance to the early evolutionary history of the Kingdom Animalia. In recent years, new data and discoveries have revealed insights into Ediacaran paleobiology, taxonomic relationships, paleoecology and taphonomy, significantly refining our understanding of Avalonian ecosystems. Here, we summarise recent observational and quantitative studies, and their bearing on the current understanding of Avalonian benthic marine ecosystems. A review of existing knowledge of the biological composition of Avalonian marine assemblages demonstrates that they record densely-populated ecosystems inhabited by a diverse range of organisms, likely representing multiple biological Kingdoms. Appreciation of this diversity, and of the complexities it introduces to paleoecological studies, is vital when considering the relationship between macroevolution and contemporaneous climatic, tectonic and geochemical events. We then summarise current understanding of Avalonian paleoecology. Studies into locomotion, reproduction, feeding strategies, and community structure and succession reveal that these ecosystems were considerably different to Phanerozoic settings. Furthermore, we suggest that Avalonian ecosystems witnessed the appearance of novel nutrient sources, offering new opportunities and niches for benthic organisms. The suggestion that the numerically dominant rangeomorphs were osmotrophic is reviewed and appraised in light of geochemical, morphological, and biological information. Finally, the use of modern ecological metrics in the study of Ediacaran fossil assemblages is assessed. Concerns regarding the interpretation of paleoecological data are outlined in light of current taphonomic and sedimentological understanding, and these cast doubt on previous suggestions that the Avalonian assemblages were largely composed of metazoans. Nevertheless, we emphasise that if treated with necessary caution, paleoecological data can play a significant role in assisting efforts to determine the biological affinities of late Ediacaran macroscopic organisms.
Subscribe to:
Posts (Atom)