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Wednesday, June 29, 2016

Mammals Evolved Three Times Faster after Dinosaur Extinction

     Our ancestors evolved three times faster in the 10 million years after the extinction of the dinosaurs than in the previous 80 million years, according to University College of London researchers.

     The research team found the speed of evolution of placental mammals (a group that today includes about 5000 species including humans) was constant before the extinction event but exploded after, resulting in the varied groups of mammals we see today.

     Lead (not lead ;-)) researcher, Dr. Thomas Halliday said: "Our ancestors, the early placental mammals, benefitted from the extinction of non-avian dinosaurs and dwindling numbers of competing groups of mammals. Once the pressure was off, placental mammals suddenly evolved rapidly into new forms."

     "In particular, we found a group called Laurasiatheria quickly increased their body size and ecological diversity, setting them on a path that would result in a modern group containing mammals as diverse as bats, cats, rhinos, whales, cows, pangolins, shrews and hedgehogs."

        Laurasiatheria is a superorder of placental mammals believed to have originated on the northern supercontinent of Laurasia. Thus it was the northern landmasses that produced much of the mammal explosion.

     The team found that the last common ancestor for all placental mammals lived in the late Cretaceous period, about three million years before the non-avian dinosaurs became extinct 66 million years ago. This date is about 20 million years younger than suggestions from previous studies which used molecular data from living mammals and assumed a near-constant rate of evolution.

     In this study the researchers analysed fossils from the Cretaceous to the present day, and used the dates of their occurrence in the fossil record to estimate the timing of divergences based on an updated tree of life. The new tree was released in 2015 and has the largest representation of Paleocene mammals to date.

     The scientists measured all the small changes in the bones and teeth of 904 placental fossils and mapped the anatomical differences between species on the tree of life. From measuring the number of character changes over time for each branch, they found the average rate of evolution for early placental mammals both before and after the dinosaur extinction event. They compared the average rate of evolution over the geological stages before the extinction and the geological stages after to see what impact it had.

     Senior author, Professor Anjali Goswami said, "Our findings refute those of other studies which overlooked the fossils of placental mammals present around the last mass extinction. Using rigorous methods, we've successfully tracked the evolution of early placental mammals and reconstructed how it changed over time. While the rate differed between species, we see a clear and massive spike in the rates of evolution right after the dinosaurs become extinct, suggesting our ancestors greatly benefitted from the demise of the dinosaurs. The huge impact of the dinosaur extinction on the evolution of our ancestors really shows how important this event was in shaping the modern world."

      Professor Paul Upchurch, co-author of the study, added: "Our large and refined data set allows us to build a clearer picture of evolutionary history. We plan on using it to study other large-scale evolutionary patterns such as how early placental mammals dispersed across the continents via land bridges that no longer exist today."

       I'd like to take that land bridge from South America to Africa in the southern land masses of Gondwanaland. 

      How about you? Does "Reunite Gondwanaland!" ring true to you?


Friday, June 24, 2016

Kalgoorlieite: A new Mineral Discovered in Western Australia

     A new mineral has been discovered at Australia's Kalgoorlie’s Super Pit and is named ‘kalgoorlieite’ after the type locality of Kalgoorlie.

      The mineral, with chemical formula As^2Te^3, was discovered by Dr. Kirsten Rempel, from Australia's Curtin University’s Department of Applied Geology. She first identified the microscopic, silver colored particle in January, 2016, after examining ore samples at Curtin’s Kalgoorlie campus museum.

      “This mineral, while only seen in very small grains so far, can provide important information about the genesis of the giant Golden Mile gold deposit, which is widely contested,” she added.

     The sample was taken from the former Associated Gold Mines which was eventually consolidated into the Kalgoorlie Super Pit which is operated by Kalgoorlie Consolidated Gold Mines. For years it stayed in the museum, simply described as ‘gold ore showing tellurides’.

        Kalgoorlieite is the fourth oxygen-free As-Te mineral after benleonardite, debattistiite, and törnroosite. Its mineral class is monoclinic. [A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic system. They form a rectangular prism with a parallelogram as its base. Hence two vectors are perpendicular, while the third vector meets the other two at an angle other than 90°, seen below in orthoclase.] 

     Rempel told Australian Mining it took approximately three months to have the mineral approved by the International Mineralogical Association (IMA), with the measurements and tests conducted in London. She said the IMA receives over 100 mineral proposals each year, and that most of the newly discovered minerals are complex and have minor differences to existing ones.

     “It is rare to find a mineral with the simplicity of kalgoorlieite these days.” She added that kalgoorlieite was a telluride mineral that is chemically related to the silver and gold telluride ores in the super pit.

     “Kalgoorlieite contains only trace amounts of gold and silver, but it is closely associated with gold-silver telluride minerals such as sylvanite,” she said, adding that it may be possible to find other new minerals in the sample.

      “I think it’s actually possible because telluride is not very well studied and it is easily overlooked. But there are already quite a number of telluride found.” She added that telluride is important for gold recovery, with 20 % of gold from the mine coming from gold telluride (also known as calaverite).

Crystals have class...and so do PEOTS commenters. Are you happier knowing there's a new mineral in town?

Wednesday, June 15, 2016

Larger Super-Eruptions at Yellowstone National Park 8 to 12 Million Years Ago

    A smaller number of giant super-eruptions between 8 and 12 million years ago that could be larger than the colossal eruptions known to have taken place at Yellowstone have been identified in the United States through research led by the University of Leicester.

     The international research team suggests that while the number of volcanic eruptions thought to have originated from the central Snake River Plain in Idaho, USA, is less than previously believed, the 12 recorded giant eruptions were likely 'significantly larger' than research has previously suggested.

     Dr. Tom Knott, Professor Mike Branney and Dr. Marc Reichow, from the University of Leicester's Department of Geology's Volcanology Group, conducted the research with a team of international collaborators from the U. of California, Santa Cruz, the U. of Copenhagen, Denmark and Idaho State University.

     "Using a multi-technique approach, including whole-rock and mineral chemistries, palaeomagnetic data, and radio-isotopic dates, the team has been able to 'fingerprint' individual eruption deposits and correlate these over vast regions (thousands of square kilometers)."

    In establishing widespread correlations, the team drastically reduced the number of eruptions previously thought to have originated from the central Snake River Plain by more than half.

     "The researchers have reported that one of the super-eruptions from the Yellowstone hotspot-track, defined as the Castleford Crossing eruption, occurred about 8.1 million years ago and estimate the eruption volume to have exceeded 1,900 cubic kilometers. 

     "The single volcanic sheet covers an area over 14,000 square kilometers in southern Idaho, and is more than 1.3 kilometers thick in the caldera of the super-volcano."

     "This is just one of 12 giant eruptions reported from the area by the Leicester researchers who show that intense hotspot magmatism caused major crustal subsidence, forming the 100 kilometer-wide Snake River Basin. The team also demonstrates that these eruptions were in fact significantly larger than previously thought and may rival those better known at Yellowstone."

     Dr. Knott said "While it is well-known that Yellowstone has erupted catastrophically in recent times perhaps less widely appreciated is that these were just the latest in a protracted history of numerous catastrophic super-eruptions that have burned a track along the Snake River eastwards from Oregon to Yellowstone from 16 million years ago to present.

    "The size and magnitude of this newly defined eruption is as large, if not larger, than better known eruptions at Yellowstone, and it is just the first in an emerging record of newly discovered super-eruptions during a period of intense magmatic activity between 8 and 12 million years ago."

Ever been to the Snake River Plain or Yellowstone? Ash me no questions. . .

Tuesday, June 7, 2016

Finishing Blows: Not Muhammad Ali's but Antarctica's Larsen B Ice Shelf

     "The biggest ice shelf collapse on record was set in motion years earlier than previously thought, new research reveals."

     "Analyzing declassified images from spy satellites, researchers discovered that the downhill flow of ice on Antarctica’s Larsen B ice shelf was already accelerating as early as the 1960s and ’70s. By the late 1980s, the average ice velocity at the front of the shelf was around 20 percent faster than in the preceding decades, the researchers report in a paper to be published in Geophysical Research Letters."

     "Rising temperatures since the 1950s probably quickened the ice flow, which in turn put more strain on the ice and further weakened the shelf, says study coauthor Hongxing Liu, a geographer at the University of Cincinnati. Previous work had suggested that the ice shelf’s downward slide began only a few years before a Rhode Island-sized region of ice disintegrated into thousands of icebergs in 2002."

     "The new data will help scientists more confidently predict how Antarctic ice will fare in the coming decades, says Penn State glaciologist Richard Alley, who was not involved in the work. The early response of Larsen B to warming “is consistent with this ice shelf system being sensitive, and gives a target for future modeling studies to learn how sensitive, and for what reasons,” he says."

     "Ice shelves such as Larsen B line Antarctica’s coast and slow the flow of the continent’s glaciers and ice sheets into the sea. Rising temperatures are shrinking Antarctica’s ice, with several ice shelves on track to disappear completely within 100 years.Tracking the long-term decline of ice shelves is tricky, though. Scientific satellite images are sparse prior to the 1990s and next to nonexistent before the 1980s."

     Liu and others turned to another group that peered at Antarctica, a U.S. intelligence agency called the National Reconnaissance Office. In 1963, the agency photographed the continent as part of an intelligence-gathering mission. While these images were declassified in 1995, the photos were too distorted by effects such as the camera used and Earth’s curvature to use for ice flow measurements.  

     "Making the photographs usable required identifying stationary landmarks for reference, a difficult task on a continent covered with shifting white ice. Comparing the spy photos with later scientific images, Liu and colleagues identified 44 potential landmarks. Then, using the locations as anchor points, the researchers unwarped the images. Along with additional satellite images taken in 1979 and the 1980s, the modified images allowed the researchers to track Larsen B’s ice flow over time."

     "The ice on Larsen B’s front flowed at around 400 meters per year on average between 1963 and 1986, calculations using images from those years indicate. From 1986 to 1988, the average was 490 meters per year. That speed boost suggests that the ice flow accelerated between the 1963 to 1986 satellite images. Several glaciers that feed into Larsen B underwent similar accelerations, the researchers found."

     Larsen B’s early acceleration hints that the ice shelf was already weakening well before the 1990s, says Ted Scambos, a polar scientist at the National Snow and Ice Data Center in Boulder, Colorado, USA, who was not involved in the study. 

     Previous studies suggested that balmy surface temperatures caused Larsen B’s demise by forming meltwater pools 

on top of the ice shelf that forced open cracks in the ice. The new satellite data suggest that this fracturing was a finishing blow*

 following long-term weakening by forces such as relatively warm seawater eroding the ice shelf’s underside, Scambos said.

      I wonder what else is to be revealed in older aerial photographs and Landsat images of Antarctica and other areas. . .

Unwarpedly, ;-)

*My dad was such a Muhammad Ali fan and I wanted to pay homage to the man; Dad and Mom were in Atlanta in 1996 for the Olympics. It was a very special opening ceremony. . .

Wednesday, June 1, 2016

Check out that Jabot: Praying Mantis Named After Ruth Bader Ginsburg

     "For the first time, scientists have used the genitals of female praying mantises to formally distinguish one species from another. And using this novel technique, they've identified a previously unknown creature: Ilomantis ginsburgae

     The new mantis is named in honor of Ruth Bader Ginsburg, associate justice of the Supreme Court of the United States, for her efforts toward achieving gender equality and her love of the jabot – otherwise known as 'that neck thingy.'"

     "The researchers behind the new species say that its neck plate resembles Ginsburg's favorite neckwear, but bear in mind that scientists have compared the golden butt hairs of a fly to BeyoncĂ©'s rear end and the mouth of a fossilized ancient swamp pig to Mick Jagger's luscious lips. Point being: If you want to honor your favorite celebrity by naming a new species after them (which, by the way, is totally allowed, scientifically speaking) you can probably come up with some physical "similarity" between the two to strengthen your case and keep your co-authors from arguing with you. Ergo, jabot."

     "Ilomantis ginsburgae isn't particularly noteworthy, in the realm of praying mantises. The species was identified using a specimen collected in 1967 in Madagascar. Like other leaf-dwelling praying mantises, the species is green, with a flattened body, conical eyes and broad wings that look like veiny leaves."

      "But its identification was a little more special – because the researchers relied on its genitals."

       “As a feminist biologist, I often questioned why female specimens weren’t used to diagnose most species," Sydney Brannoch, a Case Western Reserve University PhD candidate, said in a statement. Along with Gavin Svenson, who oversees her research at the Cleveland Museum of Natural History, Brannoch recently published research on this technique in Insect Systematics & Evolution. They studied 30 female specimens from different museum collections, noting distinguishing genital characteristics and using them to distinguish species, then compared the results of their technique to more traditional methods."

     "This research establishes the validity of using female specimens in the classification of praying mantises. It is my hope that our work not only sets a precedent in taxonomy but also underscores the need for scientists to investigate and equally consider both sexes in other scientific investigations," Brannoch added."

     "This adds to the working toolkit that researchers can use to identify the insects, which will allow them to more accurately distinguish one species from another. And it makes it easier for species to be identified and categorized into families based on female insects alone."

What would you name a new insect you just discovered?