Formation of sedimentary layers of white clay, Tamilnadu, India

Fossil site for wood fossils, Tamilnadu, India

Fossil site in Kerala, 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

WFS News: First detailed 3-D images of a megathrust fault off Costa Rica

February 24th, 2018 Riffin

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Perspective view of the shallow megathrust looking seaward towards the trench; the frontal prism has been cut away. The color scales indicate depth below seafloor, and grey denotes the seafloor. Credit: Edwards et al., Nature Geoscience, Feb-2018

Perspective view of the shallow megathrust looking seaward towards the trench; the frontal prism has been cut away. The color scales indicate depth below seafloor, and grey denotes the seafloor. Credit: Edwards et al., Nature Geoscience, Feb-2018

Geophysicists have obtained detailed three-dimensional images of a dangerous megathrust fault west of Costa Rica where two plates of the Earth’s crust collide. The images reveal features of the fault surface, including long grooves or corrugations, that may determine how the fault will slip in an earthquake.

The study, published February 12 in Nature Geoscience, focused on the Costa Rica subduction zone where the Cocos plate slowly dives beneath the overriding Caribbean plate. Variations in texture seen in different portions of the fault surface may explain why Costa Rica has complex, patchy earthquakes that do not seem to slip to shallow depths, unlike some other megathrust faults, said first author Joel Edwards, a Ph.D. candidate in Earth and planetary sciences at UC Santa Cruz.

“Our new imagery shows large variability in the conditions along the megathrust, which may be linked to a number of earthquake phenomena we observe in the region,” Edwards said.

Megathrusts, the huge continuous faults found in subduction zones, are responsible for Earth’s largest earthquakes. Megathrust earthquakes can generate destructive tsunamis and are a serious hazard facing communities located near subduction zones. Understanding the mechanisms at work along these faults is vital for disaster management around the globe.

Edwards worked with a team of geophysicists at UC Santa Cruz, the U.S. Geological Survey, the University of Texas-Austin, and McGill University to obtain 3-dimensional imagery of the fault interface using cutting-edge acoustic imaging technology. The long grooves, or corrugations, they observed along the interface are similar in size to those found along the base of fast-flowing glaciers and along some ocean ridges. The images also showed varying amounts of smoothness and corrugations on different portions of the fault.

“This study produced an unprecedented view of the megathrust. Such 3-D information is critical to our ability to better understand megathrust faults and associated hazards worldwide,” said coauthor Jared Kluesner, a geophysicist at the USGS in Santa Cruz.

The acoustic dataset was collected in spring 2011 on the academic research vessel Marcus G. Langseth. The ship towed an array of underwater microphones and sound sources behind it as it made a series of overlapping loops over the area of the fault. The data were processed over the next 2 years and have since been used in a number of studies looking at different aspects of the subduction zone process. This particular study focused on the interface between the sliding plates, which serves as a record of slip and slip processes.

“The 3-D site selection was really good and the resulting acoustic dataset showed extraordinary detail,” said Edwards, noting that coauthor Emily Brodsky, professor of Earth and planetary sciences, was the first to recognize the corrugations. Such features had been observed in exposed faults on land, but never before in a fault deep beneath the surface.

“I had an early rendition of the interface that vaguely showed long grooves, and during my qualifying exam, Brodsky saw them and asked, ‘are those corrugations!?’ I didn’t know, but I knew they were real features. Slip-derived corrugations was a really neat hypothesis, and we dug into it after that,” he said.

The area in this study had long been a target for drilling into the megathrust by the Costa Rica Seismic Project (CRISP). Coauthor Eli Silver, professor emeritus of Earth and planetary sciences at UC Santa Cruz, and others in the CRISP program decided to pursue a 3-D seismic study, which must precede any deep drilling, and the project was funded by the National Science Foundation in 2009. “At present, two drilling expeditions have been accomplished with shallower targets, and, though not yet scheduled, we are hopeful that the deep drilling will occur,” Silver said.

Researchers hope to use similar imaging techniques on other subduction zones, such as the Cascadia margin along the northern U.S. west coast, where there is a long history of large megathrust earthquakes and related tsunamis. “Conducting this type of 3-D study along the Cascadia margin could provide us with key information along the megathrust, a plate boundary that poses a substantial hazard risk to the U.S. west coast,” Kluesner said.

  1. Joel H. Edwards, Jared W. Kluesner, Eli A. Silver, Emily E. Brodsky, Daniel S. Brothers, Nathan L. Bangs, James D. Kirkpatrick, Ruby Wood, Kristina Okamoto. Corrugated megathrust revealed offshore from Costa Rica. Nature Geoscience, 2018; DOI: 10.1038/s41561-018-0061-4
University of California – Santa Cruz. “Acoustic imaging reveals hidden features of megathrust fault off Costa Rica: First detailed 3-D images of a megathrust fault show long grooves and other features in the fault surface that are likely to control how it slips in an earthquake.” ScienceDaily. ScienceDaily, 12 February 2018. <www.sciencedaily.com/releases/2018/02/180212125801.htm>.

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WFS News: Forecasting the eruption of an open-vent volcano using resonant infrasound tones.

February 22nd, 2018 Riffin

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A new study has shown that monitoring inaudible low frequencies called infrasound produced by a type of active volcano could improve the forecasting of significant, potentially deadly eruptions.

Scientists from Stanford and Boise State University analyzed the infrasound detected by monitoring stations on the slopes of the Villarrica volcano in southern Chile, one of the most active volcanoes in the world. The distinctive sound emanates from the roiling of a lava lake inside a crater at the volcano’s peak and changes depending on the volcano’s activity.

_v-chili-ne-utihaet-vulkan-vilyarrika

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The study demonstrated how changes in this sound signaled a sudden rise in the lake level, along with rapid up-and-down motions of the surging lake near the crater’s rim just ahead of a major eruption in 2015. Tracking infrasound in real time and integrating it with other data, such as seismic readings and gas emission, might help alert nearby residents and tourists that a volcano is about to blow its stack, the researchers said.

“Our results point to how infrasound could aid in forecasting volcanic eruptions,” said study co-author Leighton Watson, a graduate student in the lab of Eric Dunham, an associate professor in the Department of Geophysics of the Stanford School of Earth, Energy & Environmental Sciences and also a co-author. “Infrasound is potentially a key piece of information available to volcanologists to gauge the likelihood of an eruption hours or days ahead.”

The study, published Feb. 14 in the journal Geophysical Research Letters, is led by Jeffrey Johnson, an Associate Professor of Geophysics at Boise State University in Idaho.

Sleeping giant roars awake

Villarrica is a picturesque mountain with an altitude of 9,300 feet. The snowcapped volcano looms over a lake and across from the city of Pucón, which swells to a quarter million people in the summer tourist season. At night, residents of Pucón can often see a scarlet glow from Villarrica’s lava lake, normally hidden well below the volcano’s rim.

The ominous serenity that had held at Villarrica since its last eruption in the mid-1980s ended in the early morning hours on March 3, 2015. An incandescent fountain of lava rocketed from the mountaintop nearly a mile into the sky, spewing ash and debris and triggering bolts of lightning from the thick heat-generated clouds enveloping the summit. Around 4,000 people evacuated the immediate area. The eruption proved short-lived, however, and with risks of mudslides and flooding from melted snow minimal, evacuees soon returned to their homes.

Infrasound monitoring stations established at Villarrica just two months before the 2015 event and maintained by co-author Jose Palma from the University of Concepcion in Chile captured its before-and-after sonic activity. Studying these data, the research team saw that in the build-up to the eruption, the pitch of the infrasound increased, while the duration of the signal decreased. Flyovers in aircraft documented the changes in Villarrica’s lava lake, allowing researchers to explore connections between its height and the sound generation.

Watson offered a music analogy to explain this relationship. Similar to a person blowing into a trombone, explosions from gas bubbles rising and then bursting at the surface of the lava lake create sound waves. Just as the shape of a trombone can change the pitch of the notes it produces, the geometry of the crater that holds the lava lake modulates its sounds. When the lava lake is deep down in the volcano’s crater, the sound registers at a lower pitch or frequency — “just like when a trombone is extended,” said Watson. When the lava lake rises up in the crater, potentially heralding an eruption, the pitch or frequency of the sound increases, “just like when the trombone is retracted,” said Watson.

Warning signs

Future research will seek to tie infrasound generation to other critical variables in volcano monitoring and eruption forecasting, such as seismicity. Ahead of an eruption, seismic activity in the form of small earthquakes and tremors almost always increases. This seismicity emanates from several miles underground as magma moves through the volcano’s “plumbing system” of fractures and conduits that connect the volcano’s opening to magma chambers in our planet’s crust. Volcanologists think that changes in lava lake levels — and their attendant infrasound — result from the injection of new magma through volcanic plumbing, increasing the odds of a violent outburst.

In this way, the collection of infrasound should prove beneficial for forecasting purposes at “open vent” volcanoes like Villarrica, where an exposed lake or channels of lava connect the volcano’s innards to the atmosphere. Closed vent volcanoes, however, where the pooling magma remains trapped under rock until an explosive eruption occurs, do not generate the same kind of infrasound and thus pose additional forecasting challenges. An example of a closed vent volcano is Mount St. Helens in southwestern Washington state, whose eruption in 1980 remains the most lethal and destructive eruption in the history of the United States.

“Volcanoes are complicated and there is currently no universally applicable means of predicting eruptions. In all likelihood, there never will be,” Dunham said. “Instead, we can look to the many indicators of increased volcanic activity, like seismicity, gas emissions, ground deformation, and — as we further demonstrated in this study — infrasound, in order to make robust forecasts of eruptions.”

  1. Jeffrey B. Johnson, Leighton M. Watson, Jose L. Palma, Eric M. Dunham, Jacob F. Anderson. Forecasting the eruption of an open-vent volcano using resonant infrasound tones. Geophysical Research Letters, 2018; DOI: 10.1002/2017GL076506
  2. Stanford’s School of Earth, Energy & Environmental Sciences. “Scientists eavesdrop on volcanic rumblings to forecast eruptions.” ScienceDaily. ScienceDaily, 16 February 2018. <www.sciencedaily.com/releases/2018/02/180216142649.htm>.

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WFS News: Osaka whale fossil believed to be first evidence of Eden’s whale

February 19th, 2018 Riffin

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This image of an Eden’s whale was based on this skull fossil (left) from Japan. | THE OSAKA MUSEUM OF NATURAL HISTORY / VIA KYODO

This image of an Eden’s whale was based on this skull fossil (left) from Japan. | THE OSAKA MUSEUM OF NATURAL HISTORY / VIA KYODO

OSAKA – A whale skull discovered just over 50 years ago in the city of Osaka is now thought to be the world’s first known trace of an Eden’s whale, dating from between 4,000 and 8,800 years ago.

The fossilized remains were reclassified in a study published recently in a paleontology journal by co-authors Yoshihiro Tanaka, curator of the Osaka Museum of Natural History, and Hiroyuki Taruno, a former curator of the same institution. The skull was originally thought to be of a Minke whale.

“The specimen adds a chronologically and geographically new record to the not well-known species,” the study says.

During the time frame in which the whale is thought to have lived, much of the location of modern-day Osaka was underwater.

The fossil of the Eden’s whale (Balaenoptera edeni) was found at a depth of roughly 14 meters during construction work in the eastern part of the city in 1966. Researchers had concluded in 1976 that it was an ancient Minke whale.

Minke and Eden’s whales are two types of baleen whale still in existence today, though the latter are less common. Japan has in only 12 previous instances been able to confirm a specimen as an Eden’s whale through DNA and other testing, and only half of these cases include bone samples stored by one of the country’s research institutions.

Tanaka and Taruno made the reassessment by analyzing the morphology of the skull, in particular the broad rostrum and the shape of rear cranial bones, and comparing their observations with the results of recent studies on baleen whale taxonomy. Tanaka noted that various other whale fossils have been unearthed in Osaka in past decades.

“We want to shed light on what kinds of whales were swimming in Osaka Bay in ancient times,” he said.

Source: Japan Times

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WFS News: Fossil footprints may put lizards on two feet 110 million years ago

February 16th, 2018 Riffin

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IMPRINTS Scientists think that these fossilized footprints may represent the earliest evidence of a lizard running on two legs. Here, a front print (left) and a back print (right) are shown. H. LEE ET AL/SCIENTIFIC REPORTS 2018

IMPRINTS Scientists think that these fossilized footprints may represent the earliest evidence of a lizard running on two legs. Here, a front print (left) and a back print (right) are shown.
H. LEE ET AL/SCIENTIFIC REPORTS 2018

Fossilized footprints from an iguana-like reptile provide what could be the earliest evidence of a lizard running on two legs.

The 29 exceptionally well-preserved lizard tracks, found in a slab of rock from an abandoned quarry in Hadong County, South Korea, include back feet with curved digits and front feet with a slightly longer third digit. The back footprints outnumber the front ones, and digit impressions are more pronounced than those of the balls of the feet. The lizard’s stride length also increases across the slab.

That’s what you’d expect to see in a transition from moseying along on four legs to scampering on two, says Yuong-Nam Lee, a paleontologist at Seoul National University who first came across the slab back in 2004. A closer examination two years ago revealed the telltale tracks.

Lee and his colleagues attribute the tracks to a previously unknown lizard ichnospecies, that is a species defined solely by trace evidence of its existence, rather than bones or tissue. Lee and his colleagues have dubbed the possible perpetrator Sauripes hadongensis and linked it to an order that includes today’s iguanas and chameleons in the Feb. 15 Scientific Reports.

CHASE SCENE Lizards may have run from the jaws of predatory pterosaurs in the swamp and lake environment where Sauripes hadongensis tracks were found, as in this illustration. CHUANG ZHAO

CHASE SCENE Lizards may have run from the jaws of predatory pterosaurs in the swamp and lake environment where Sauripes hadongensis tracks were found, as in this illustration.
Courtesy :CHUANG ZHAO

Bipedal running certainly would have come in handy when escaping predatory pterosaurssome 110 million to 128 million years ago, the age of the rock slab. Lizard tracks are pretty rare in the fossil record, due to the reptiles’ lightweight bodies and penchant for habitats that don’t make great fossils. Though tracks appear in older fossils from the Triassic Epoch, 200 million to 250 million years ago, those prints belong to more primitive lizardlike reptiles. The new find edges out another set from the same region as the oldest true lizard tracks in the world by a few million years, the researchers say.

Plenty of modern lizards use two legs to scurry around. Some studies have linked similarities in ancient lizard bone structure to bipedal locomotion, but it is unclear exactly when lizards developed bipedalism. Lee’s team argues that these tracks represent the earliest and only direct evidence of bipedal running in an ancient lizard.

Martin Lockley, a paleontologist at the University of Colorado Denver who studies ancient animal tracks, points to alternative explanations. S. hadongensis might have trampled over front prints with its back feet, obscuring them and giving the appearance of two-legged running. Preservation can vary between back and front footprints. And the stride lengths aren’t quite as long as what Lockley says he’d expect to see in running. “Running or ‘leaping’ lizards make for a good story, but I am skeptical based on the evidence,” he adds.

So it may take the discovery of more fossilized lizard prints to determine whether S. hadongensis’ tracks truly represent running on two legs rather than simply scurrying on four.

Source: Article by HELEN THOMPSON,sciencenews.org@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

WFS News: Did surface life evolve on Mars?

February 15th, 2018 Riffin

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Diverse mineralogy exhumed from the Martian subsurface: A false color image from the HiRISE instrument aboard NASA's Mars Reconnaissance Orbiter shows amazing diversity of rocks exhumed from the Martian subsurface a meteor impact in the Nili Fossae area. The image is 1 km across. This site and others like it contain rocks that were altered by fluids in the Martian crust billions of years ago, at the time when life first emerged on Earth. These rocks represent exploration targets that could teach us about the origin of life. Credit: NASA/JPL/University of Arizona

Diverse mineralogy exhumed from the Martian subsurface: A false color image from the HiRISE instrument aboard NASA’s Mars Reconnaissance Orbiter shows amazing diversity of rocks exhumed from the Martian subsurface a meteor impact in the Nili Fossae area. The image is 1 km across. This site and others like it contain rocks that were altered by fluids in the Martian crust billions of years ago, at the time when life first emerged on Earth. These rocks represent exploration targets that could teach us about the origin of life.Credit: NASA/JPL/University of Arizona

The planet Mars has long drawn interest from scientists and non-scientists as a possible place to search for evidence of life beyond Earth because the surface contains numerous familiar features such as dried river channels and dried lake beds that hint at a warmer, wetter, more earthlike climate in the past. However, Dr Joseph Michalski of the Department of Earth Sciences & Laboratory for Space Research at The University of Hong Kong (HKU) and his colleagues have published papers recently that cast increased doubt on the idea of surface life evolving on Mars. These paradigm changing publications have recently been published in Nature Geoscience (December 2017) and Nature Astronomy (February 2018).

For the last 2.5 billion years, surface life on Earth has thrived largely due to the evolution of photosynthesis. Surface life is abundant and very successful because of the availability of sunlight, surface water, generally moderate climate conditions, and the protection of our magnetic field. But the planet Mars would have never experienced such habitable conditions at the surface. Michalski and colleagues published results in Nature Astronomyshowing that the climate of Mars has probably been extremely cold and dry most of the time. They argue that the familiar aqueous features on Mars included widespread, weathered soil horizons, could have formed in geologically short climate “excursions.” In other words, Mars was cold and dry throughout its history and only had abundant liquid water at its surface during short episodes of climate change.

However, all hope for life on Mars is not lost. In another paper led by Michalski and published recently, the scientists point out that the prospects for surface life on Mars might be dim, but the possibilities for subsurface life are promising. Life on Earth likely began in hydrothermal systems (environments where hot water reacts with rocks), and there is abundant evidence for many locations where hydrothermal environments exists on Mars at the time when life might have originated in similar environments on Earth. They argue that, in order to understand how life formed on Earth, we should ignore the surface environments on Mars and focus exploration on hydrothermal deposits.

Dr. Michalski and his team in the Department of Earth Sciences and Laboratory for Space Research at HKU explore Mars using remote sensing and infrared spectroscopy. Using infrared data collected at Mars by spacecraft, they can interpret which minerals are there and describe the geology of ancient hydrothermal systems. This type of work is based on laboratory measurements, which provide the required mineralogical background in which to interpret spectroscopic data from Mars. The HKU’ Faculty of Sciences new Infrared Spectroscopy Laboratory is a facility where scientists from around the world can come to measure geological samples in order to compare the measured spectra to data from returned from spacecraft. Michalski and his team use infrared measurements of hydrothermal minerals as a basis to interpret the detection of important minerals on Mars.

“This is an extraordinarily exciting time in Mars exploration” said Michalski. “We are getting very close to being able to detect evidence of ancient life on Mars or, perhaps more importantly, the chemical building blocks on which life forms.”

“This cutting edge and ground-breaking HKU based research is both exciting and thought provoking. It speaks to the very heart of trying to understand how life may have evolved not just on Earth but on other terrestrial bodies both in our own solar system and indeed around other stars that have planets that lie in the so-called “habitable zone” (where liquid water can exist on the surface). The discovery of bacteria two miles down in a Goldmine in South Africa a decade ago chimes perfectly with the thesis Dr. Michalski is proposing here,” said Professor Quentin Parker, Director of Laboratory for Space Research and Associate Dean (Global) of Faculty of Science, The University of Hong Kong.

  1. Joseph R. Michalski, Tullis C. Onstott, Stephen J. Mojzsis, John Mustard, Queenie H. S. Chan, Paul B. Niles, Sarah Stewart Johnson. The Martian subsurface as a potential window into the origin of life. Nature Geoscience, 2017; 11 (1): 21 DOI: 10.1038/s41561-017-0015-2
  2. Janice L. Bishop, Alberto G. Fairén, Joseph R. Michalski, Luis Gago-Duport, Leslie L. Baker, Michael A. Velbel, Christoph Gross, Elizabeth B. Rampe. Surface clay formation during short-term warmer and wetter conditions on a largely cold ancient Mars. Nature Astronomy, 2018; DOI: 10.1038/s41550-017-0377-9
The University of Hong Kong. “Did surface life evolve on Mars? Newly published research casts increased doubt: However, possibilities for subsurface life may be more promising.” ScienceDaily. ScienceDaily, 6 February 2018. <www.sciencedaily.com/releases/2018/02/180206100338.htm>.

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WFS News:Seafloor data point to global volcanism after Chicxulub meteor strike

February 12th, 2018 Riffin

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New University of Oregon research has identified gravity-related fluctuations dating to 66 million years ago along deep ocean ridges that point to a “one-two punch” from the big meteor that struck off Mexico’s Yucatan peninsula, possibly triggering a worldwide release of volcanic magma that could have helped seal the dinosaurs’ fate.

“We found evidence for a previously unknown period of globally heighted volcanic activity during the mass-extinction event,” said former UO doctoral student Joseph Byrnes.

Colored and black points mark the global distribution of mid-ocean ridges, with ages of 66 million years ago created at spreading rates above and below 35 millimeters a year, respectively. Colors indicate the maximum gravity anomaly within 2 degrees. Credit: Courtesy of Joseph Byrnes

Colored and black points mark the global distribution of mid-ocean ridges, with ages of 66 million years ago created at spreading rates above and below 35 millimeters a year, respectively. Colors indicate the maximum gravity anomaly within 2 degrees.
Credit: Courtesy of Joseph Byrnes

The study by Byrnes and Leif Karlstrom, a professor in the UO’s Department of Earth Sciences, was published Feb. 7 in Science Advances. It details a record of volcanism preserved along the mid-ocean ridges, which mark the oceanic boundaries of tectonic plates. The evidence comes from changes in the strength of gravity above the seafloor.

The findings of the UO’s National Science Foundation-supported study, Karlstrom said, point to a pulse of accelerated worldwide volcanic activity that includes enhanced eruptions at India’s Deccan Traps after the Chicxulub impact. The Deccan Traps, in west-central India, formed during a period of massive eruptions that poured out layers of molten rock thousands of feet deep, creating one of the largest volcanic features on Earth.

The Deccan Traps region has been in and out of the dinosaur debate. Rare volcanic events at such a scale are known to cause catastrophic disturbances to Earth’s climate, and, when they occur, they are often linked to mass extinctions. Huge volcanic events can eject so much ash and gas into the atmosphere that few plants survive, disrupting the food chain and causing animals to go extinct.

Since evidence of the meteor strike near present-day Chicxulub, Mexico, surfaced in the 1980s, scientists have debated whether the meteor or the Deccan Traps eruptions drove the extinction event that killed off all nonavian dinosaurs.

Progressively improving dating methods indicate that the Deccan Traps volcanoes already were active when the meteor struck. Resulting seismic waves moving through the planet from the meteor strike, Karlstrom said, probably fueled an acceleration of those eruptions.

“Our work suggests a connection between these exceedingly rare and catastrophic events, distributed over the entire planet,” Karlstrom said. “The meteorite’s impact may have influenced volcanic eruptions that were already going on, making for a one-two punch.”

That idea gained strength in 2015 when researchers at the University of California, Berkeley, proposed that the two events might be connected. That team, which included Karlstrom, suggested that the meteorite may have modulated distant volcanism by generating powerful seismic waves that produced shaking worldwide.

Similar to the impacts that normal tectonic earthquakes sometimes have on wells and streams, Karlstrom said, the study proposed that seismic shaking liberated magma stored in the mantle beneath the Deccan Traps and caused the largest eruptions there.

The new findings at the UO extend this eruption-triggering in India to ocean basins worldwide.

Byrnes, now a postdoctoral researcher at the University of Minnesota, analyzed publicly available global data sets on free-air gravity, ocean floor topography and tectonic spreading rates.

In his analyses, he divided the seafloor into 1-million-year-old groupings, constructing a record back to 100 million years ago. At about 66 million years, he found evidence for a “short-lived pulse of marine magmatism” along ancient ocean ridges. This pulse is suggested by a spike in the rate of the occurrence of free-air gravity anomalies seen in the data set.

Free-air gravity anomalies, measured in tiny increments call milligals, account for variations in gravitational acceleration, found from satellite measurements of additional seawater collecting where the Earth’s gravity is stronger. Byrnes found changes in free-air gravity anomalies of between five and 20 milligals associated with seafloor created in the first million years after the meteor.

  1. Joseph S. Byrnes, Leif Karlstrom. Anomalous K-Pg–aged seafloor attributed to impact-induced mid-ocean ridge magmatism. Science Advances, 2018; 4 (2): eaao2994 DOI: 10.1126/sciadv.aao2994
  2. University of Oregon. “A one-two punch may have helped deck the dinosaurs: Seafloor data point to global volcanism after Chicxulub meteor strike.” ScienceDaily. ScienceDaily, 7 February 2018. <www.sciencedaily.com/releases/2018/02/180207142713.htm>.

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WFS News: When did flowers originate?

February 11th, 2018 Riffin

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Flowering plants likely originated between 149 and 256 million years ago according to new UCL-led research.

The study, published today in New Phytologist by researchers from the UK and China, shows that flowering plants are neither as old as suggested by previous molecular studies, nor as young as a literal interpretation of their fossil record.

RAxML tree estimated from the 83 genes and 644 taxa of tracheophytes. The major angiosperm lineages and grades are highlighted: ANA grade (red), magnoliids (green), monocots (yellow), Ceratophyllales (pale blue), basal eudicots grade (pink), Dilleniales (orange), superasterids (purple) and superrosids (blue). Species names and bootstrap support values are indicated in Supporting Information Fig. S3

RAxML tree estimated from the 83 genes and 644 taxa of tracheophytes. The major angiosperm lineages and grades are highlighted: ANA grade (red), magnoliids (green), monocots (yellow), Ceratophyllales (pale blue), basal eudicots grade (pink), Dilleniales (orange), superasterids (purple) and superrosids (blue). Species names and bootstrap support values are indicated in Supporting Information Fig. S3

The findings underline the power of using complementary studies based on molecular data and the fossil record, along with different approaches to infer evolutionary timescales to establish a deeper understanding of evolutionary dynamics many millions of years ago.

“The discrepancy between estimates of flowering plant evolution from molecular data and fossil records has caused much debate. Even Darwin described the origin of this group as an ‘abominable mystery’,” explained lead author, Dr Jose Barba-Montoya (UCL Genetics, Evolution & Environment).

Summary tree of tracheophytes showing fossil calibrations. Calibrations are represented for 52 nodes, consisting of (>) soft minimum (closed red dots) or both ([min, max]) soft minimum and soft maximum (open red dots). Calibrated nodes are numbered as in Supporting Information Fig. S2. Justifications for these minima and maxima are provided in Notes S1 and an overview in Table S3. The dagger symbol shows a species that is extinct. The tree has been scaled to time on the basis of the minimum constraints.

Summary tree of tracheophytes showing fossil calibrations. Calibrations are represented for 52 nodes, consisting of (>) soft minimum (closed red dots) or both ([min, max]) soft minimum and soft maximum (open red dots). Calibrated nodes are numbered as in Supporting Information Fig. S2. Justifications for these minima and maxima are provided in Notes S1 and an overview in Table S3. The dagger symbol shows a species that is extinct. The tree has been scaled to time on the basis of the minimum constraints.

“To uncover the key to solving the mystery of when flowers originated, we carefully analysed the genetic make-up of flowering plants, and the rate at which mutations accumulate in their genomes.”Through the lens of the fossil record, flowering plants appear to have diversified suddenly, precipitating a Cretaceous Terrestrial Revolution in which pollinators, herbivores and predators underwent explosive co-evolution.

Molecular-clock dating studies, however, have suggested a much older origin for flowering plants, implying a cryptic evolution of flowers that is not documented in the fossil record.

“In large part, the discrepancy between these two approaches is an artefact of false precision on both palaeontological and molecular evolutionary timescales,” said Professor Philip Donoghue from the University of Bristol’s School of Earth Science, and a senior author of the study.

Palaeontological timescales calibrate the family tree of plants to geological time based on the oldest fossil evidence for its component branches. Molecular timescales build on this approach, using additional evidence from genomes for the genetic distances between species, aiming to overcome gaps in the fossil record.

The effect of calibrations on posterior divergence time estimates of major groups of tracheophytes and angiosperms. (a) Summary chronogram for tracheophytes (including two lycophytes, two ferns, eight gymnosperms and 64 orders of angiosperms) with terminals collapsed to represent angiosperm orders showing divergence time estimates. Nodes are drawn at the posterior means obtained and horizontal bars represent 95% high posterior density (HPD) credibility intervals (CIs). Estimates were obtained using the HKY85 + Γ5 substitution model, independent rates model (IR), with the 83 genes subdivided into three partitions: 1st and 2nd codon positions for plastid genes; 1st and 2nd codon positions for mitochondrial genes; and nuclear RNA genes. Five nodes are connected (purple open dots) across the analyses to facilitate comparison: tracheophytes (n = 645), seed plants (n = 647), angiosperms (n = 648), eudicots (n = 655) and monocots (n = 1193). (b–d) Calibration, prior and posterior densities for three angiosperm nodes in the tracheophyte phylogeny. Colouring relates to the calibration strategy as in (a). The phylogeny with clade names is provided in Fig. 6. Nodes in parentheses are numbered as in Supporting Information Fig. S2.

The effect of calibrations on posterior divergence time estimates of major groups of tracheophytes and angiosperms. (a) Summary chronogram for tracheophytes (including two lycophytes, two ferns, eight gymnosperms and 64 orders of angiosperms) with terminals collapsed to represent angiosperm orders showing divergence time estimates. Nodes are drawn at the posterior means obtained and horizontal bars represent 95% high posterior density (HPD) credibility intervals (CIs). Estimates were obtained using the HKY85 + Γ5 substitution model, independent rates model (IR), with the 83 genes subdivided into three partitions: 1st and 2nd codon positions for plastid genes; 1st and 2nd codon positions for mitochondrial genes; and nuclear RNA genes. Five nodes are connected (purple open dots) across the analyses to facilitate comparison: tracheophytes (n = 645), seed plants (n = 647), angiosperms (n = 648), eudicots (n = 655) and monocots (n = 1193). (b–d) Calibration, prior and posterior densities for three angiosperm nodes in the tracheophyte phylogeny. Colouring relates to the calibration strategy as in (a). The phylogeny with clade names is provided in Fig. 6. Nodes in parentheses are numbered as in Supporting Information Fig. S2.

“Previous studies into molecular timescales failed to explore the implications of experimental variables and so they inaccurately estimate the probable age of flowering plants with undue precision,” said Professor Ziheng Yang (UCL Genetics, Evolution & Environment) and senior author of the study.

“Similarly, interpretations of the fossil record have not fully recognised its shortcomings as an archive of evolutionary history, that is, that the oldest fossil evidence of flowering plants comes from very advanced, not primitive flowering plant lineages,” Professor Donoghue added.

The researchers compiled a large collection of genetic data for many flowering plant groups including a dataset of 83 genes from 644 taxa, together with a comprehensive set of fossil evidence to address the timescale of flowering plant diversification.

“By using Bayesian statistical methods that borrow tools from physics and mathematics to model how the evolutionary rate changes with time, we showed that there are broad uncertainties in the estimates of flowering plant age, all compatible with early to mid-Cretaceous origin for the group,” said Dr Mario dos Reis (School of Biological and Chemical Sciences at Queen Mary University of London), a co-author of the study.

  1. Jose Barba-Montoya, Mario dos Reis, Harald Schneider, Philip C. J. Donoghue, Ziheng Yang. Constraining uncertainty in the timescale of angiosperm evolution and the veracity of a Cretaceous Terrestrial Revolution. New Phytologist, 2018; DOI: 10.1111/nph.15011
University College London. “When did flowers originate?.” ScienceDaily. ScienceDaily, 5 February 2018. <www.sciencedaily.com/releases/2018/02/180205092926.htm>.
@ WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

WFS News: Part spider, part scorpion creature captured in amber

February 9th, 2018 Riffin

By Elizabeth Pennisi

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

This reconstruction shows how this amber fossil looks like it’s part scorpion and part spider. BO WANG


This reconstruction shows how this amber fossil looks like it’s part scorpion and part spider.BO WANG

Amber mined for centuries in Myanmar for jewelry is a treasure trove for understanding the evolution of spiders and their other arachnid relatives. This week, two independent teams describe four 100-million-year-old specimens encased in amber that look like a cross between a spider and a scorpion. The discovery, “could help close major gaps in our understanding of spider evolution,” says Prashant Sharma, an evolutionary developmental biologist at the University of Wisconsin in Madison who was not involved in the work.

Arachnids are a group of eight-legged invertebrates that includes scorpions, ticks, and spiders. Spiders, which crawled into existence some 300 million years ago, are known for their spinnerets—modified “legs” that produce silk and control its extrusion from tiny pores called spigots. Male spiders have also evolved another modified “leg” between their fangs and the back four pairs of legs that inserts sperm into the female. All but the most primitive spiders have smooth backs, unlike the segmented abdomens of scorpions, which are believed to have diverged from an ancestral arachnid more than 430 million years ago.

But in 1989, researchers discovered a suspicious, spigot-bearing fossil that was 100 million years older than the earliest known spider. By 2008, paleobiologists realized that this ancient silk producer was just a spider relative, perhaps a stepping stone to true spiders. Researchers put it into the group Uraraneida, which was thought to have thrived between 400 million and 250 million years ago. That left unanswered many questions about when spinnerets and other spider traits first evolved.

Then, several years ago, amber fossil dealers independently approached two paleobiologists at the Nanjing Institute of Geology and Paleontology in China with what looked like 5-millimeter-long Uraraneida encased in amber. One of them, Wang Bo, pulled together a team to look at his two specimens, which they eventually named Chimerachne yingi (“chimera spider” in Latin). The other paleobiologist, Huang Diying, assembled a second team that examined a different pair of these fossils. The two groups say they didn’t know about each other until after they submitted their results to the same journal. But, despite some differences, “they draw the same conclusion—that fossil uraraneids, as this group is called, are the closest extinct relatives of spiders,” says Greg Edgecombe, a paleobiologist at the Natural History Museum in London, who was not involved with the work.

Amber preserved in exquisite detail these 100-million-year-old close relatives to spiders.Bo WANG

One group’s specimens give a really clear view of the top of this organism and the other, a great look at the underside, spinnerets and all, Huang and his colleagues report today in Nature Ecology and Evolution. “The degree of preservation is exquisite, and the fossils’ anatomy is easy to interpret,” Sharma says. The presence of the spinnerets, he adds, means they must have originated “very early” in arachnid evolution. The male specimens also have the special appendages for inserting sperm into the female.

Yet they also have a segmented abdomen and a long tail, like a whip scorpion’s whip, Wang and his colleagues report today in the same journal. “These things appear to be essentially spiders with tails!” says Jason Bond, an evolutionary biologist at Auburn University in Alabama who was not involved with the work. This means that early arachnids had a mix of all these traits, which were selectively lost in their descendants, giving rise to the array of arachnids seen today.

And what is even more amazing, says Bond, is that the amber is only 100 million years old. So these spider relatives hunted side by side with spiders for 200 million years.

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WFS News: Earth’s core and mantle separated in a disorderly fashion

February 5th, 2018 Riffin

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Plumes of hot rock surging upward from the Earth’s mantle at volcanic hotspots contain evidence that the Earth’s formative years may have been even more chaotic than previously thought, according to new work from a team of Carnegie and Smithsonian scientists published in Nature.

It is well understood that Earth formed from the accretion of matter surrounding the young Sun. Eventually the planet grew to such a size that denser iron metal sank inward, to form the beginnings of the Earth’s core, leaving the silicate-rich mantle floating above.

Earth experienced multiple large impacts; the high-pressure and -temperature conditions caused pockets of core and mantle partitioning that persist as chemically distinct today. Credit: Neil Bennett

Earth experienced multiple large impacts; the high-pressure and -temperature conditions caused pockets of core and mantle partitioning that persist as chemically distinct today.
Credit: Neil Bennett

But new work from a team led by Carnegie’s Yingwei Fei and Carnegie and the Smithsonian’s Colin Jackson argues that this mantle and core separation was not such an orderly process.

“Our findings suggest that as the core was extracted from the mantle, the mantle never fully mixed,” Jackson explained. “This is surprising because core formation happened in the immediate wake of large impacts from other early Solar System objects that Earth experienced during its growth, similar to the giant impact event that later formed the Moon. Before now, it was widely thought that these very energetic impacts would have completely stirred the mantle, mixing all of its components into a uniform state.

“The smoking gun that led the team to their hypothesis comes from unique and ancient tungsten and xenon isotopic signatures found at volcanic hotspots, such as Hawaii. Although it was believed that these plumes originated from the mantle’s deepest regions, the origin of these unique isotopic signatures has been debated. The team believes that the answer lies in the chemical behavior of iodine, the parent element of xenon, at very high pressure.

Isotopes are versions of elements with the same number of protons, but different numbers of neutrons. Radioactive isotope of elements, such as iodine-129, are unstable. To gain stability, iodine-129 decays into xenon-129. Therefore, the xenon isotopic signatures in plume mantle samples are directly related to iodine’s behavior during the period of core-mantle separation.

Using diamond anvil cells to recreate the extreme conditions under which Earth’s core separated from its mantle, Jackson, Fei, and their colleagues — Carnegie’s Neil Bennett and Zhixue Du and Smithsonian’s Elizabeth Cottrell — determined how iodine was partitioning between metallic core and silicate mantle. They also demonstrated that if the nascent core separated from the deepest regions of the mantle while it was still growing, then these pockets of the mantle would possess the chemistry needed to explain the unique tungsten and xenon isotopic signatures, provided these pockets remained unmixed with the rest of the mantle all the way up through the present day.

According to Bennett: “The key behavior we identified was that iodine starts to dissolve into the core under very high pressures and temperatures. At these extreme conditions, iodine and hafnium, which decay radioactively to xenon and tungsten, display opposing preferences for core-forming metal. This behavior would lead to the same unique isotopic signatures now associated with hotspots.”

Calculations from the team also predict that the tungsten and xenon isotopic signatures should be associated with dense pockets of the mantle.

“Like chocolate chips in cookie batter, these dense pockets of the mantle would be very difficult stir back in, and this may be a crucial aspect to the retention of their ancient tungsten and xenon isotopic signatures to the modern day,” Jackson explained.

“Even more exciting is that there is increasing geophysical evidence that there actually are dense regions of mantle, resting just above the core — called ultralow velocity zones and large low shear velocity provinces. This work ties together these observations,” Fei added. “The methodology developed here also opens new opportunities for directly studying the deep Earth processes.”

This work was supported by the National Science Foundation, the Carnegie Institution for Science, and the Smithsonian Institution.

  1. Colin R. M. Jackson, Neil R. Bennett, Zhixue Du, Elizabeth Cottrell & Yingwei Fei. Early episodes of high-pressure core formation preserved in plume mantle. Nature, 2018 DOI: 10.1038/nature25446
  • Carnegie Institution for Science. “Earth’s core and mantle separated in a disorderly fashion: How is the Earth’s mantle like chocolate chip cookie dough?.” ScienceDaily. ScienceDaily, 24 January 2018. <www.sciencedaily.com/releases/2018/01/180124131721.htm>.

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

WFS News: Dinosaur-Era Bird Found Trapped in Amber

February 4th, 2018 Riffin

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

The amber containing the dinosaur-era bird had been polished partway through the body, allowing researchers to peer inside the skull and chest cavity and chemically map its exposed soft tissues. Photograph by R.C. McKellar, Royal Saskatchewan Museum

The amber containing the dinosaur-era bird had been polished partway through the body, allowing researchers to peer inside the skull and chest cavity and chemically map its exposed soft tissues.Photograph by R.C. McKellar, Royal Saskatchewan Museum

The squashed remains of a small bird that lived 99 million years ago have been found encased in a cloudy slab of amber from Myanmar (Burma). While previous birds found in Burmese amber have been more visually spectacular, none of them have contained as much of the skeleton as this juvenile, which features the back of the skull, most of the spine, the hips, and parts of one wing and leg. (Help us celebrate 2018 as the Year of the Bird.)

The newfound bird is also special because researchers can more clearly see the insides of the young prehistoric creature, says study co-author Ryan McKellar of the Royal Saskatchewan Museum in Regina, Canada.

“The amber is turbid, with lots of little wood particulates. It looks like it was produced on or near the forest floor,” McKellar says. This means the external view of the bird isn’t great, but the interior is much more exciting.

“When it was being prepared in Myanmar, they polished through the front half of the specimen, which gave us an exposed view into the chest cavity and the skull,” McKellar says.

The discovery adds to a remarkable collection of Cretaceous-period fossils from the amber deposits in northern Myanmar’s Hukawng Valley. In the past few years, the region has also yielded several beautiful bird wings, the spectacular feathered tail of a small carnivorous dinosaur, and the outline of an entire hatchling bird. In December, researchers even revealed ticks in amber that may have feasted on dinosaurs.

“This Myanmar fossil deposit is clearly game-changing. It’s arguably the more important breakthrough for understanding bird evolution right now,” says Julia Clarke, an expert on the evolution of birds and flight at the University of Texas at Austin.

“We used to think we’d never have a whole bird in Cretaceous amber, but now we have multiple examples.”

Foamy and Squashed

Lida Xing, lead author of the paper detailing the specimen in the journal Science Bulletin, says that when he first saw the newfound bird being sold for jewelry in Myanmar in 2015, his heart began to beat very fast.

The team was lucky to acquire the bird for the Dexu Institute of Paleontology in Chaozhou, China. Birds in amber can sometimes sell for up to $500,000, putting them beyond the reach of scientists, says Xing, a paleontologist at the China University of Geosciences in Beijing.

He estimates that this is only the second bird in Burmese amber that’s been described by scientists and published in a journal. But he thinks as many as six have been discovered so far, around half of which have disappeared into the hands of private collectors.

Based on their analysis, supported in part by National Geographic, the team says that the young bird fell into the Cretaceous tree resin either dead or alive, and moisture caused the resin to foam slightly, later creating the cloudy amber. Some of the bones and soft tissues were weathered away, and sediment got trapped inside the spaces.

An illustration shows the young Cretaceous bird trapped in tree resin, which would eventually fossilize into amber. Illustration by Cheung Chung Tat

An illustration shows the young Cretaceous bird trapped in tree resin, which would eventually fossilize into amber.Illustration by Cheung Chung Tat

“A subsequent resin flow sealed the remains to protect them from further weathering or dissolution, but the amber was later squished, shattering many of the bones,” says McKellar. “All of this is now trapped in a wafer of amber about as large as a belt buckle.”

The bird itself is around 2.4 inches long and is perhaps slightly older than the 1.8-inch hatchling bird described last year. The structure of its feathers and skeleton suggests it was an enantiornithine, a type of primitive bird that went extinct with the non-avian dinosaurs 66 million years ago. (Here’s what happened on the day the dinosaurs died.)

“Even though they are hatchlings, they already have a full set of flight feathers,” McKellar says. “They have a weakly developed rachis, or central shaft, so they may not have been excellent flyers.”

In life, the bird would have had teeth in its beak and would have been dark chestnut or walnut in color, with fuzzy feathers on its head and neck.

Nest Mates

“It’s always exciting when a vertebrate fossil is found in amber, especially Cretaceous amber,” says George Poinar, a paleobiologist at Oregon State University in Corvallis, whose research on fossilized insects in amber inspired the plot of Jurassic Park.

Assigning it to the enantiornithine birds makes sense, he adds, as they were common at that time. But it’s a pity “that the two diagnostic features of that family are missing: the toothed beak and clawed fingers on the wings.”

Poinar speculates that the fledgling may have been attacked by a predator and knocked out of the nest into resin oozing from the same tree, and that some of the plant fragments and a cockroach also found trapped in the amber piece may have originated in the nest.

“Cockroaches are general scavengers, and finding them in nesting material would not be a surprise,” he says.

With time and luck, McKellar says, the team hopes to have a whole growth series of enantiornithine birds in Burmese amber. There’s certainly no shortage of raw material to comb through—in 2015 alone, an estimated 10 tons of amber were extracted from the Hukawng Valley.

Source: Article  By John Pickrell,news.nationalgeographic.com

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