WFS

Formation of sedimentary layers of white clay, Tamilnadu, India

Fossil site for wood fossils, Tamilnadu, India

Fossil site in Kerala, India

Fossil wood park maintained by geological survey of India at Tamilnadu

Cretaceous fossil sites india

Fossils in rack:-Cyad

Fossils in rack:-echiniderms

Fossils in rack:-Rastellum sp

Pre-historic seabed, Cretaceous period

More Intense North Atlantic Tropical Storms Likely in the Future

December 3rd, 2012

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Tropical storms that make their way into the North Atlantic, and possibly strike the East Coast of the United States, likely will become more intense during the rest of this century.

That’s the prediction of one University of Iowa researcher and his colleague as published in an early online release in the Journal of Climate, the official publication of the American Meteorological Society.

The study is a compilation of results from some of the best available computer models of climate, according to lead author Gabriele Villarini, assistant professor of civil and environmental engineering and assistant research engineer at IIHR-Hydroscience & Engineering, and his colleague Gabriel Vecchi of the National Oceanic and Atmospheric Administration, Princeton, N.J.

“We wanted to conduct the study because intense tropical cyclones can harm people and property,” Villarini says. “The adverse and long-lasting influence of such storms recently was demonstrated by the damage Hurricane Sandy created along the East Coast.”

The study itself examines projected changes in the North Atlantic Power Dissipation Index (PDI) using output from 17 state-of-the-art global climate models and three different potential scenarios. The PDI is an index that integrates storm intensity, duration, and frequency.

“We found that the PDI is projected to increase in the 21st century in response to both greenhouse gas increases and reductions in particulate pollution over the Atlantic over the current century. By relating these results to other findings in a paper we published May 13, 2012 in the journalNature Climate Change, we found that, while the number of storms is not projected to increase, their intensity is,” he says.

“Moreover, our results indicate that as more carbon dioxide is emitted, the stronger the storms get, while scenarios with the most aggressive carbon dioxide mitigation show the smallest increase in intensity,” he says

Presence of Magnesium oxide: From Earth to super-Earth

December 2nd, 2012

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The mantles of Earth and other rocky planets are rich in magnesium and oxygen. Due to its simplicity, the mineral magnesium oxide is a good model for studying the nature of planetary interiors. New work from a team led by Carnegie’s Stewart McWilliams studied how magnesium oxide behaves under the extreme conditions deep within planets and found evidence that alters our understanding of planetary evolution. It is published November 22 by Science Express.

Magnesium oxide is particularly resistant to changes when under intense pressures and temperatures. Theoretical predictions claim that it has just three unique states with different structures and properties present under planetary conditions: solid under ambient conditions (such as on the Earth’s surface), liquid at high temperatures, and another structure of the solid at high pressure. The latter structure has never been observed in nature or in experiments.

McWilliams and his team observed magnesium oxide between pressures of about 3 million times normal atmospheric pressure (0.3 terapascals) to 14 million times atmospheric pressure (1.4 terapascals) and at temperatures reaching as high as 90,000 degrees Fahrenheit (50,000 Kelvin), conditions that range from those at the center of our Earth to those of large exo-planet super-Earths. Their observations indicate substantial changes in molecular bonding as the magnesium oxide responds to these various conditions, including a transformation to a new high-pressure solid phase.

In fact, when melting, there are signs that magnesium oxide changes from an electrically insulating material like quartz (meaning that electrons do not flow easily) to a metal similar to iron (meaning that electrons do flow easily through the material).

Drawing from these and other recent observations, the team concluded that while magnesium oxide is solid and non-conductive under conditions found on Earth in the present day, the early Earth’s magma ocean might have been able to generate a magnetic field. Likewise, the metallic, liquid phase of magnesium oxide can exist today in the deep mantles of super-Earth planets, as can the newly observed solid phase.

“Our findings blur the line between traditional definitions of mantle and core material and provide a path for understanding how young or hot planets can generate and sustain magnetic fields,” McWilliams said.

“This pioneering study takes advantage of new laser techniques to explore the nature of the materials that comprise the wide array of planets being discovered outside of our Solar System,” said Russell Hemley, director of Carnegie’s Geophysical Laboratory. “These methods allow investigations of the behavior of these materials at pressures and temperatures never before explored experimentally

Note: This story has been adapted from a news release issued by the Carnegie Institution

Solving a magma mystery

December 1st, 2012

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Oceanic crust covers two-thirds of the Earth’s solid surface, but scientists still don’t entirely understand the process by which it is made. Analysis of more than 600 samples of oceanic crust by a team including Carnegie’s Frances Jenner reveals a systemic pattern that alters long-held beliefs about how this process works, explaining a crucial step in understanding Earth’s geological deep processes. Their work is published in Nature on November 29.

Magmas generated by melting of the Earth’s mantle rise up below the oceanic crust and erupt on the Earth’s surface at mid-ocean ridge systems, the longest mountain ranges in the world. When the magma cools it forms basalt, the planet’s most-common rock and the basis for oceanic crust.

It has long been assumed that the composition of magmas erupting out of mid-ocean ridges is altered when minerals that form during cooling sink out of the remaining liquid, a process called fractional crystallization. In theory, trace elements that are not included in the crystallizing minerals should be little affected by this process, and their ratios should be the same in the erupting magma as they were in the original magma before cooling.

If this is true, trace element ratios in magmas erupting at mid-ocean ridges should represent those of the original parental magma that formed deep in the Earth’s mantle. However, this process doesn’t account for the high abundance of trace elements found in samples of basalt from mid-ocean ridges around the world, so the reality of the situation is obviously more complicated than previous theories indicated.

Using the extensive array of samples and advanced modeling, Jenner and her research partner Hugh O’Neill of the Australian National University demonstrated that the concentration of trace elements is due to the process by which the magma is cycled through the oceanic crust prior to being erupted on the sea floor at the mid-ocean ridges.

oceanic crust

Magma collects under the Earth’s surface in a pool of liquid rock called a magma chamber. Each chamber is frequently flushed with new magma, which mixes with the old magma that was already there, and then this blended magma erupts out onto the ocean floor. Following the influx of new magma and eruption, the remaining magma undergoes fractional crystallization. This means that minerals are separated out from the magma as it cools. However, these minerals contain only minor amounts of the trace elements. As a result, trace elements build up in the magma over time, as the magma chamber is continually replenished by new magma coming in to the system.

“It’s a simple idea, but it fits remarkably well,” Jenner said. “These new findings will permit us to explore the conditions of mantle melting and production of the Earth’s most-common rock.”

Note: This story has been adapted from a news release issued by the Carnegie Institution

What happens when the modern evolutionary theory of punctuated equilibrium collides with the older theory of mosaic evolution?

November 30th, 2012

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What happens when the modern evolutionary theory of punctuated equilibrium collides with the older theory of mosaic evolution? Part of the answer comes from a new, wide-ranging study by paleobiologists Melanie J Hopkins at the Museum fuer Naturkunde Berlin and Scott Lidgard at the Field Museum in Chicago. Their results are published this week in the Proceedings of the National Academy of Sciences (PNAS).

While processes of evolution are largely studied by observation and experiment in the living world, evolutionary tempo and mode – rates and patterns of change, respectively – are mostly revealed by studying the fossil record. Paleontologists measure parts of the hard skeletal fossil remains of once-living organisms that they believe best represent the morphology, or form, of those organisms. They then analyze the variation in these traits through successive layers of rock that were laid down over longs spans of geologic time in order to determine the tempo and mode of species evolution. Punctuated equilibrium postulates that most evolutionary change takes place in relatively short periods of time during the origination of new species, while species themselves mostly undergo stasis, or little change, over longer periods. Several recent studies have indicated that stasis is much more common than gradual directional change in the fossil record. Mosaic evolution, on the other hand, is the tendency for different parts within species to evolve in different ways or at different rates.

The new study is based on data taken from hundreds of sequences of fossil samples previously reported in the scientific literature, but uses model selection methods available only in the last several years. The researchers compared models describing different modes of change, namely stasis, random change, and directional change, to each fossil series and found that different traits generally showed different, conflicting evolutionary modes within the same species. Many kinds of life were represented, including mammals, fish, mollusks, arthropods, and single-celled organisms. This large comparative study validates the ubiquity of mosaic evolution. However, it also raises questions about the evidence for different evolutionary modes, since the great majority of previous studies that quantify stasis, punctuated equilibrium, and gradual or “random” patterns in the fossil record are based on measurements of single traits, not on combined analyses of many traits. Further research will be required to establish the underlying processes driving the patterns of mosaic evolution and fossil species change. Nonetheless, the study is an excellent example of an emerging revolution in scientific inquiry as new techniques are used to breathe new life into old data.

Note: This story has been adapted from a news release issued by the Field Museum

Dinosaurs’ Role in Evolution of Bird Flight

November 26th, 2012

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A new study looking at the structure of feathers in bird-like dinosaurs has shed light on one of nature’s most remarkable inventions — how flight might have evolved.

Academics at the Universities of Bristol, Yale and Calgary have shown that prehistoric birds had a much more primitive version of the wings we see today, with rigid layers of feathers acting as simple airfoils for gliding.

An artist’s impression of what the Archaeopteryx lithographica would have looked like in flight. (Credit: Image by artist Carl Buel)

Close examination of the earliest theropod dinosaurs suggests that feathers were initially developed for insulation, arranged in multiple layers to preserve heat, before their shape evolved for display and camouflage.

As evolution changed the configuration of the feathers, their important role in the aerodynamics and mechanics of flight became more apparent. Natural selection over millions of years ultimately modified dinosaurs’ forelimbs into highly-efficient, feathered wings that could rapidly change its span, shape and area — a key innovation that allowed dinosaurs to rule the skies.

This basic wing configuration has remained more or less the same for the past 130 million years, with bird wings having a layer of long, asymmetrical flight feathers with short covert feathers on top. They are able to separate and rotate these flight feathers to gain height, change direction and even hover.

This formation allows birds to move in such a way as to produce both lift and thrust simultaneously — a capability that man, with the help of technology, is still trying to successfully imitate.

The research, published November 21 in Current Biology,looked at the dinosaur Anchiornis huxleyi and the Jurassic birdArchaeopteryx lithographica. The latter is 155 million years old and widely considered to be the earliest known bird, presenting a combination of dinosaur and bird characteristics.

Their wings differed from modern day birds in being composed of multiple layers of long feathers, appearing to represent early experiments in the evolution of the wing. Although individual feathers were relatively weak due to slender feather shafts, the layering of these wing feathers is likely to have produced a strong airfoil.

The inability to separate feathers suggests that taking off and flying at low speeds may have been limited, meaning that wings were primarily used in high-speed gliding or flapping flight.

Dr Jakob Vinther, from the University of Bristol’s Schools of Biological and Earth Sciences, said: “We are starting to get an intricate picture of how feathers and birds evolved from within the dinosaurs. We now seem to see that feathers evolved initially for insulation. Later in evolution, more complex vaned or pinnate feathers evolved for display.

“These display feathers turned out to be excellent membranes that could have been utilised for aerial locomotion, which only very late in bird evolution became what we consider flapping flight. This new research is shedding light not just on how birds came to fly, but more specifically on how feathers came to be the way they are today — one of the most amazing and highly specialised structures in nature.”

Dr Nicholas Longrich of Yale University added: “By studying fossils carefully, we are now able to start piecing together how the wing evolved. Before, it seemed that we had more or less modern wings from the Jurassic onwards. Now it’s clear that early birds were more primitive and represented transitional forms linking birds to dinosaurs. We can see the wing slowly becoming more advanced as we move from Anchiornis, toArchaeopteryx, to later birds.”

Dome-Headed Dinosaurs Did More than Just Butt Heads

November 25th, 2012

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We have all seen nature shows with footage of bighorn sheep rearing up and “butting heads” with each other using their heads and enlarged horns. People often assume other animals with horns and comparable head structures have similar behaviors. For a long time this was the case for the dome-headed dinosaurs, the pachycephalosaurids (pack-y-sef-a-lo-sore-ids), who were thought to use their thick, domed skulls in fights and mating displays. But new research presented at the recent Society of Vertebrate Paleontology meetings shows that, as is often the case with animal behaviors, the situation is more complex for both living horned animals and the extinct dinosaurs.

Joseph Peterson and Collin Dischler, both of the University of Wisconsin-Oshkosh, began by looking at living bovids, which are hoofed animals with horns that include goats and sheep. They noted that these animals all use their horns differently in displays and contests over mates. “They all have different horn shapes for different fighting styles,” said Peterson. Bighorn and Dall sheep “butt heads,” but American bison just “head shove” without big impacts. Domestic and mountain goats “flank butt,” hitting each other on the hips and sides.

Perhaps not surprisingly, these different fighting styles leave different injury patterns on skulls and skeletons. Peterson and Dischler reasoned that looking at injury patterns on the skulls of pachycepalosaurids would allow them to make better inferences about the behavior of these extinct animals.

The researchers discovered differences in the pattern of injuries on the skulls of different types of pachycephalosaurids. “Tall, high-peaked dome specimens that possess injuries typically show a high abundance of injuries to the back of the skull while lower, flat, or broad domes show a high abundance of injuries on the front of the skull.” These injuries imply that larger-domed pachycephalosaurids were probably “head-butters” or “head-shovers,” whereas smaller but higher-domed species were “flank-butters.”

“This is the first time that anyone has looked at a whole bunch of fossils from dome-headed dinosaurs to identify possible injuries from head-butting. Despite decades of work, many of the previous interpretations of behavior in dome-headed dinosaurs have been based on limited samples or single lines of evidence,” said Andrew Farke of the Raymond M. Alf Museum of Paleontology, who was not involved in the study but has studied the heads of dinosaurs.

Like many paleontological studies that try to understand the behavior of extinct organisms, this study used data from modern animals to make inferences about the past. “The present is the key to the past” is often the paleontologist’s credo, and this study used that practice to reveal a more complex, and interesting, picture about one of the more iconic dinosaur groups.

Source: Press release Prepared by members of the SVP Media Liaison Committee for use at the SVP 72nd Annual Meeting.

Echinoderms Display Morphological and Behavioural Phenotypic Plasticity in Response to Their Trophic Environment

November 24th, 2012

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Adam D. Hughes^*, Lars Brunner, Elizabeth J. Cook, Maeve S. Kelly, Ben Wilson

Department of Ecology, Scottish Association for Marine Science, Oban, Argyll, Scotland

The trophic interactions of sea urchins are known to be the agents of phase shifts in benthic marine habitats such as tropical and temperate reefs. In temperate reefs, the grazing activity of sea urchins has been responsible for the destruction of kelp forests and the formation of ‘urchin barrens’, a rocky habitat dominated by crustose algae and encrusting invertebrates. Once formed, these urchin barrens can persist for decades. Trophic plasticity in the sea urchin may contribute to the stability and resilience of this alternate stable state by increasing diet breadth in sea urchins. This plasticity promotes ecological connectivity and weakens species interactions and so increases ecosystem stability. We test the hypothesis that sea urchins exhibit trophic plasticity using an approach that controls for other typically confounding environmental and genetic factors. To do this, we exposed a genetically homogenous population of sea urchins to two very different trophic environments over a period of two years. The sea urchins exhibited a wide degree of phenotypic trophic plasticity when exposed to contrasting trophic environments. The two populations developed differences in their gross morphology and the test microstructure. In addition, when challenged with unfamiliar prey, the response of each group was different. We show that sea urchins exhibit significant morphological and behavioural phenotypic plasticity independent of their environment or their nutritional status.

Gross morphological (panel A&B) and microstructural differences (panel C&D) in the test of Psammechinus miliaris from the wild type diets (A&C) and the processed diet (B&D).
The sea urchins in panel A&B are approximately 40 mm test diameter. Scale bars on the SEM micrographs represent 200 µm.

Sea urchins are well known for their morphological and behavioural plasticity. It has long been observed that populations from different habitats were morphologically distinct . In addition, sea urchins have shown rapid morphological response to food availability , substrate morphology, the presence of predators and behavioural plasticity over environmental gradients. Sea urchin barrens themselves are one such driver of morphological change, with populations of sea urchins of the same species having different morphologies inside and outside of sea urchin barrens . In order to fully understand the role that phenotypic trophic plasticity in sea urchins plays in maintaining urchin barrens, it is first necessary to demonstrate that this plasticity is truly phenotypic. Secondly, we must show that the phenotypic plasticity is an adaption to the trophic environment unconfounded by other environmental factors, such as nutrient limitation or habitat differences. Thirdly, we need to understand if morphological adaption alters the way in which the sea urchins respond to their trophic environment in terms of prey handling and diet breadth. To do this we examined phenotypic plasticity in an echinoderm species: Psammechinus miliaris. This species is a small regular echinoid with a distribution along the north-eastern Atlantic from Scotland to North Africa. It is known to be strongly omnivorous and to exhibit a high degree of plasticity in the wild . Under controlled laboratory conditions we challenged P. miliaris with two nutritionally equivalent, but physically different trophic environments and examined the nature of their phenotypic response, in terms of any changes in gross and microstructural characteristics and behaviour to their trophic environment.

Rhino Skull Preserved in Volcanic Ash

November 23rd, 2012

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Less than 2% of Earth’s fossils are preserved in volcanic rock, but researchers have identified a new one: the skull of a rhino that perished in a volcanic eruption 9.2 million years ago.

The find is described in a paper published Nov. 21 in the open access journal PLOS ONE by Pierre-Olivier Antoine and colleagues from the University of Montpellier, France.

The fossil, found in Turkey, is thought to be that of a large two-horned rhino common in the Eastern Mediterranean region during that period. According to the researchers, unusual features of the preserved skull suggest that the animal was ‘cooked to death’ at temperatures that may have approached 500° C, in a volcanic flow similar to that of the eruption of Mt. Vesuvius in Italy in 79 A.D.

The rhino’s grisly death was near-instantaneous, and followed by severe dehydration in the extreme heat of the eruption. As the researchers describe its end, “the body was baked under a temperature approximating 400°C, then dismembered within the pyroclastic flow, and the skull separated from body.” The flow of volcanic ash then moved the skull about 30 km north of the eruption site, where it was discovered by the four member research team.

Although other researchers have previously identified fossils of soft-bodied organisms preserved in volcanic ash, organic matter near an active volcanic eruption is usually quickly destroyed by the high temperatures, making a fossil such as this one extremely rare

November 22nd, 2012

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Less than 2% of Earth’s fossils are preserved in volcanic rock, but researchers have identified a new one: the skull of a rhino that perished in a volcanic eruption 9.2 million years ago.

The find is described in a paper published Nov. 21 in the open access journal PLOS ONE by Pierre-Olivier Antoine and colleagues from the University of Montpellier, France.

The fossil, found in Turkey, is thought to be that of a large two-horned rhino common in the Eastern Mediterranean region during that period. (Credit: Reconstruction by Maëva J. Orliac; Antoine et al. (2012) A Rhinocerotid Skull Cooked-to-Death in a 9.2 Ma-Old Ignimbrite Flow of Turkey. PLoS ONE doi:10.1371/journal.pone.0049997)

The fossil, found in Turkey, is thought to be that of a large two-horned rhino common in the Eastern Mediterranean region during that period. According to the researchers, unusual features of the preserved skull suggest that the animal was ‘cooked to death’ at temperatures that may have approached 500° C, in a volcanic flow similar to that of the eruption of Mt. Vesuvius in Italy in 79 A.D.

The rhino’s grisly death was near-instantaneous, and followed by severe dehydration in the extreme heat of the eruption. As the researchers describe its end, “the body was baked under a temperature approximating 400°C, then dismembered within the pyroclastic flow, and the skull separated from body.” The flow of volcanic ash then moved the skull about 30 km north of the eruption site, where it was discovered by the four member research team.

Although other researchers have previously identified fossils of soft-bodied organisms preserved in volcanic ash, organic matter near an active volcanic eruption is usually quickly destroyed by the high temperatures, making a fossil such as this one extremely rare.

Bacterial biofilms as fossil makers

November 21st, 2012

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Bacterial decay was once viewed as fossilization’s mortal enemy, but new research suggests bacterial biofilms may have actually helped preserve the fossil record’s most vulnerable stuff — animal embryos and soft tissues.

A team of 13 scientists led by Indiana University Bloomington biologists Rudolf and Elizabeth Raff found that the invasion of dying embryo cells by bacteria — and the subsequent formation of densely packed bacterial biofilms inside the embryo cells — can completely replace embryo cell structure, generating a faithful replica of the embryo. The scientists call this formation a “pseudomorph,” a model of the embryo made of bacteria. Their report will appear online via theProceedings of the National Academy of Sciences “Early Edition” as early as Nov. 24.

The invasion of dying Heliocidaris erythrogramma cells by bacteria can create a faithful replica. Scientists believe embryo fossils are actually a bacterial ‘sculpture’ — a vestige of the embryos’ destruction – F.R. Turner, E.C. Raff, and R.A. Raff

“The bacteria consume and replace all the cytoplasm in the cells, generating a little sculpture of the embryo,” said Elizabeth Raff, the report’s lead author. “We did find, however, that certain conditions must be met if the bacteria are going to aid the preservation process.”

Among those conditions, Raff said that at the time of its death, the embryo must exist in a low-oxygen or reducing environment, such as the bottom of a deep ocean or buried in anoxic lakeside mud. If significant oxygen is available, the embryo will undergo “autolysis,” or self-destruction, as digestive enzymes get free and wreak havoc. Without oxygen, autolytic enzymes remain stuck inside their organelle prisons.

“The next step, we believe, is that bacteria able to survive in low-oxygen conditions must then infest the cells of the dying embryo,” Raff said.

The bacteria form biofilms, crowded assemblies of bacterial cells held together by sticky fibers made of proteins and sugars. As the biofilms fill the embryo cells, the tiny bacteria insinuate themselves between and among the organelles, forming a faithful representation of the cell’s innards.

Lastly, the bacteria must leave a permanent record. In the case of finely preserved fossil embryos, the bacteria likely excrete tiny crystals of calcium phosphate (CaPO₄), which eventually replace the bacterial sculptures. It is these crystals, Raff says, that provide the support for embryo and soft tissue fossilization.

“That’s a crucial step,” said Rudolf Raff. “Calcium deposits can show us even minute details of structure and shape, not only of the bacteria laying down the minerals, but also of the embryo cell structures all around them. In our experiments, we observed bacteria depositing calcium carbonate (CaCO₃), but not calcium phosphate. We’ll need to simulate different conditions to fully replicate this step.”

High resolution imaging of a trove of half-a-billion-year-old animal embryo fossils from Doushantuo, China, provided scientists with tantalizing evidence that bacteria may have been involved in the preservation of the delicate cells. Scanning electron microscopy shows oblong concavities on the surface of the embryo fossils, suggesting the cells had been infested with bacteria or bacterial biofilms.

The research presented in the PNAS paper reveals how bacteria-aided fossilization could happen.

The Raffs studied early-stage embryos of two Australian sea urchin species, Heliocidaris erythrogramma and Heliocidaris tuberculata. The experimental results with modern embryos were compared to the high resolution images of fossil embryos prepared by colleagues from China, England, Sweden, and Switzerland.

The scientists examined embryos in the presence of high and low oxygen, with or without inoculums of oxygen-poor marine mud, and in the presence or absence of bacteria-killing antibiotics. In the experiments that produced embryo-infesting biofilms, the scientists used DNA sequence comparisons to identify the bacterial species present.

The researchers learned low-oxygen conditions block autolysis, and that embryos prevented from autolyzing are quickly colonized by marine bacteria. Once inside, the bacteria form biofilms that fill the embryo cells. Sturdy cell membranes and the embryo’s fertilization envelope provide the exterior cast. These biofilms formed detailed replicas of the embryos they had replaced.

Species of the common marine bacterium Pseudoalteromonas provided the majority of the bacterial flora present inside the embryo cells under aerobic conditions. Under oxygen-poor conditions, a much greater diversity of bacterial species was present, not detectable under aerobic conditions.

The scientists also examined oxygen-starved embryos exposed to inoculums of oxygen-poor marine mud, and again found a high diversity of bacterial flora present in embryo replica biofilms, with species of the Bacteroidetes phylum being most common.

Although it is impossible to know whether bacteria aided the preservation of 550-million-year-old embryo fossils from Doushantuo and elsewhere, the Raffs argue the evidence they gathered strongly favors the view that bacteria are a fundamental force in fossil formation, as rapid biological processes must be available to convert highly delicate cells into a stable form and catalyse mineralization.

“This work is important because it helps us understand fossilization as a biological as well as geological process,” Elizabeth Raff said. “It gives us a window onto the evolution of the embryos of the earth’s first animals.”

Note: This story has been adapted from a news release issued by the Indiana University