Crocodiles fed on young dinosaurs

by phenomenica on March 2, 2013

in Palaeontology, Prehistory, Science

Crocodile-like beasts may have munched on young dinosaurs some 75 million years ago, scientists say.

Scientists who analysed bite marks on dinosaur bones suggested the rivalry between the reptiles started early in life.

Bites from living crocodylians such as alligators and crocodiles are often seen on the bones of their prey and scavenged bodies. Scientists can use these to identify bite marks on fossils from crocodyliforms, the reptiles to which modern crocodylians belong, LiveScience reported.

Now, scientists have unearthed fossils in the Grand Staircase-Escalante National Monument in southern Utah which provide direct evidence of a small crocodyliform biting juvenile dinosaurs.

“This area is very hot and arid in the summer and cold in the winter. Most of the area is dominated by massive, cliff-forming rock outcrops,” said researcher Clint Boyd, a vertebrate paleontologist at the South Dakota School of Mines and Technology.

Cretaceous-Crocodyliforms

Image credit: Todd Marshall/National Geographic

Back when the reptiles were alive, their environment was warm and wet, dominated by rivers and floodplains and lush with bushes and trees.

Dinosaurs in the area included duck-billed hadrosaurs, horned ceratopsians such as Triceratops and predatory relatives of T rex. The area also holds an especially diverse assembly of crocodyliforms, including the gigantic alligatoroid Deinosuchus riograndensis.

Scientists uncovered 75-million-year-old fossils of three members of a kind of small, two-legged herbivorous dinosaur known as a hypsilophodontid.

On the right thighbone of one, the researchers found a conical tooth embedded that was just 2.5 millimetres wide (a little less than one-tenth of an inch), and similarly tiny puncture marks were seen on a left shoulder bone.

“I was very surprised to find such clear feeding traces on such small bones,” Boyd told the website.

“It shows the importance of carefully evaluating all the fossils collected from an area, and not assuming that some fossils won’t be important just because they are very small or not completely preserved,” Boyd added.

Researchers could not determine how large the crocodyliform that made the marks was. However, the dinosaurs in question probably weighed about 13 to 21 kg; and living crocodylians 3 to 6 feet long are known to take down prey that big.

“Usually people tend to focus on the dangers that big, adult dinosaurs were having to deal with, but this study shows that even though dinosaurs were the dominant animals during the Cretaceous, they still had to worry about predators as soon as they were born,” Boyd said.

The study was published in the journal PLOS ONE.

PTI

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International scientists say they’ve discovered an 18-kilo meteorite in eastern Antarctica, the largest found in that area in 25 years.

The Brussels-based International Polar Foundation said today the meteorite is an “ordinary chondrite,” the most common meteorite. It was discovered January 28, and is undergoing a special thawing process in Japan so water won’t penetrate it before it’s studied.

During a 40-day expedition, scientists discovered 425 meteorites at an altitude of 2,900 meters, 140 kilometers south of Belgium’s Princess Elisabeth Antarctica research base.

antarctica

Image credit: International Polar Foundation

While this is the largest found in eastern Antarctica since 1988, a 21.5-kilo meteorite was found on the continent in 2005, according to the Meteoritical Bulletin Database. The largest in Antarctica was 407 kilograms, found in 1976 or 1977.

PTI

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Astronomers spot giant planet in formative stage

by phenomenica on March 1, 2013

in Space

Astronomers have spotted what could be a giant planet in the formative stage, still embedded in a thick disc of gas and dust, with the help of European Southern Observatory (ESO) very large telescope (VLT).

A team led by Sascha Quanz at the Swiss Federal Institute of Technology, (ETH-Zurich), has studied the disc of gas and dust that surrounds the young star HD 100546, a relatively nearby neighbour located 335 light-years from Earth.

The prospective planet could be a gas giant similar to Jupiter.

“So far, planet formation has mostly been a topic tackled by computer simulations,” said Quanz.

“If our discovery is indeed a forming planet, then for the first time scientists will be able to study the planet formation process and the interaction of a forming planet and its natal environment empirically at a very early stage.”

HD 100546

Illustration of HD 100546. Image credit: ESO

HD 100546 is a well-studied object, and it has already been suggested that a giant planet orbits about six times further from the star than the Earth is from the Sun, the Astrophysical Journal Letters reports.

The planet candidate around HD 100546 was detected as a faint blob located in the circumstellar disc revealed thanks to the adaptive optics instrument on ESO’s VLT, combined with pioneering data analysis techniques, according to an ETH-Zurich statement.

According to current theory, giant planets grow by capturing some of the gas and dust that remains after the formation of a star.

Adam Amara, research team member, said: “Exoplanet research is one of the most exciting new frontiers in astronomy, and direct imaging of planets is still a new field, greatly benefiting from recent improvements in instruments and data analysis methods.”

IANS

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Tiny moons lurk in Saturn’s rings

by phenomenica on March 1, 2013

in Saturn, Solar System, Space

Tiny moons that can barely be seen hide inside Saturn’s majestic rings, according to researchers.

Like Jupiter, Saturn is orbited by a large number of moons – 62, at last count – ranging in size from the gigantic 3,200-mile-wide Titan, wrapped in thick clouds, to the barely 2-mile-wide Methone, smooth as a river rock.

But now scientists say there are even more moons in the ringed planet’s retinue – tiny worlds embedded inside the icy rings themselves – according to Discovery News.

Even with the Cassini spacecraft they are nearly impossible to see… until they give themselves away with their shining “propellers.”

A “propeller,” is a clumping of ring particles in front of and behind a tiny moonlet located between the two “blades,” according to the Cassini scientists.

saturn2The moonlet is too small to be resolved directly – it’s less than half a mile across – but its gravity is still strong enough to affect the tiny particles that comprise Saturn’s rings.

Made mostly of water ice, the more the particles gather together the more they tend to reflect sunlight – highlighting the moonlet’s location for Cassini.

Depending on the angle of sunlight, propellers can also appear darker than the surrounding rings.

In a new image released by the Discovery News, short, bright streaks of a propeller show the location of a mini-moon.

This particular propeller is nicknamed “Bleriot,” after the French aviator who made the first airplane flight across the English Channel in 1909.

First observed by Cassini in 2005 Bleriot has been repeatedly revisited, most recently in this observation from Nov. 11, 2012.

By observing propellers over time researchers hope to gain a better understanding of how they move and evolve, and what their effects are on the ring particles around them.

ANI

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New marine species discovered in Pacific Ocean

by phenomenica on March 1, 2013

in Nature, Science

Scientists have discovered new species of sea slugs, feather stars and amphipods in the Madang Lagoon on the north coast of Papua New Guinea.

An international team of researchers led by Jim Thomas discovered the new species of sea slugs (nudibranchs), feather stars (crinoids) and amphipods (genus Leucothoe).

There was more variety of these indicator species found than there is in the entire length of Australia’s 2,574-kilometres Great Barrier Reef, researchers said.

“In the Madang Lagoon, we went a half mile out off the leading edge of the active Australian Plate and were in 6,000 metres of water,” said Thomas, a researcher at Nova Southeastern University’s National Coral Reef Institute in Hollywood, Florida.

genus“It was once believed there were no reefs on the north coast of Papua New Guinea since there were no shallow bays and lagoons typical of most coral reef environments. But there was lots of biodiversity to be found,” Thomas said in a statement.

“This was an astonishing discovery. We returned to our labs and began to formally assess our collections. We had no idea this lagoon’s bounty was so profound,” Thomas said.

The international team Thomas led included researchers from and the Scripps Institute of Oceanography in San Diego, the California Academy of Sciences and the National Botanical Gardens of Ireland.

The three-week expedition ended late last year. While in Madang, they joined a large French contingent of scientists from the Paris Museum of Natural History.

PTI

Image credit: Nova Southeastern U.

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Origin of Russian meteor tracked down

by phenomenica on February 27, 2013

in Science, Space

A team of astronomers from Colombia has traced the origin of the meteor that struck central Russia earlier this month injuring about 1,000 people.

They used amateur video footage to plot the meteor’s trajectory through Earth’s atmosphere and then reconstruct its orbit around the Sun.

They suggest that the Chelyabinsk meteor (labelled ChM) appears to have been on an elliptical orbit around the Sun before it collided with Earth, according to the BBC.

As the space rock burned up over the city of Chelyabinsk, the shockwave blew out windows and rocked buildings.

Numerous videos of the fireball were taken with camera phones, CCTV and car-dashboard cameras and subsequently shared widely on the web. Furthermore, traffic camera footage of the fireball had precise time and date stamps.

russiaEarly estimates of the meteor’s mass put it at ten tones, but US space agency NASA later estimated it to be between 7,000 and 10,000 tonnes. The agency also estimated the size of the object was about 17m (55ft).

With the help of the footage and considering the location of an impact into Lake Chebarkul, Jorge Zuluaga and Ignacio Ferrin, from the University of Antioquia in Medellin were able to use simple trigonometry to calculate the height, speed and position of the rock as it fell to Earth.

To reconstruct the meteor’s original orbit around the Sun, they used six different properties of its trajectory through Earth’s atmosphere. Most of these are related to the point at which the meteor becomes bright enough to cast a noticeable shadow in the videos.

The researchers then plugged their figures into astronomy software developed by the US Naval Observatory.

The results suggest the meteor belongs to a well known family of space rocks – known as the Apollo asteroids – that cross Earth’s orbit.

Of about 9,700 near-Earth asteroids discovered so far, about 5,200 are thought to be Apollos.

“It certainly looks like it was a member of the Apollo class of asteroids. Its elliptical, low inclination orbit, indicates a solar system origin, most likely from the asteroid belt between Mars and Jupiter,” Dr Stephen Lowry, from the University of Kent, told BBC News.

“Perhaps with more data, we can determine roughly where in the asteroid belt it come from,” Dr Lowry added.

The team has published details of their finding on the Arxiv website.

ANI

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After the recent meteor strike in Russia, two Grants Pass residents have revealed that they witnessed an unidentified flying object hovering over the Southern Oregon night sky.

Heather Scherffius and Gregory Soldner recorded the UFO sighting on camera and claimed what they saw was not an asteroid or a meteor.

According to the two witnesses, they just happened to be outside of their home at about 10:30 pm when the UFO appeared, International Business Times reported.

“At first I was like what’s wrong with that star? I thought, whoa, that’s kind of trippy. So I went to get him and he’s like whoa! What is that? And it started moving,” Scherffius said.

Soldner said that it looked like a metal disk of some sort, but he wasn’t sure.

ufoHe added that the way it moved was weird.

The pair further added that the UFO remained in one spot for more than a few minutes even making a couple of irregular space movements.

“It moved up and down, back to one spot and then zigzaged a bit. It was there like 20-30 minutes and then it was just gone!” they said.

In the original video footage, it is difficult to determine what is being recorded. NBC 5 used a special filter to the video in order to make lighting more visible and the UFO clearly seen over the Grant Pass night sky last February 15, 2013.

NBC contacted the Federal Aviation Administration (FAA) upon hearing the UFO encounter to inquire if there were any other UFO sightings reported that day or if they were aircrafts flying over Grants Pass at that time.

An unnamed FAA staff confirmed that there are only few UFO reports in the area but they will conduct an investigation on the object spotted in Grants Pass and perhaps further determine if there is any relation to the Russia meteor blast that occurred.

ANI

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Apophis asteroid may strike Earth in 2068

by phenomenica on February 27, 2013

in Asteroids, Solar System, Space

The 325-metre asteroid 99942 Apophis that will safely fly by the Earth in 2029 and 2036, may strike the planet in 2068, says an article published on the NASA website.

The chances of it striking Earth are slim, however, with impact odds being about 2.3 in a million.

The asteroid has been the focus of considerable attention after it was discovered in December 2004 to have a significant probability of Earth impact in April 2029.

While the 2029 potential impact was ruled out through the measurement of archival telescope images, the possibility of a potential impact in the years after 2029 continues to prove difficult to rule out.

Based on optical and radar position measurements made in 2004-2012, the asteroid will pass the Earth in 2029 at an altitude of 31900, give or take 750 km.

ApophisThe altitude is close enough for the Earth’s gravity to deflect the asteroid onto a trajectory that brings it back to an Earth impact during its next flyby.

Such impact trajectories require Apophis to pass the Earth at a precise altitude, known as a keyhole, in 2029 en route to a subsequent impact.

“The new report, which does not make use of the 2013 radar measurements, identifies over a dozen keyholes that fall within the range of possible 2029 encounter distances,” said the article prepared by a group of scientists led by Davide Farnocchia.

The uncertainty in predicting the asteroid’s position in 2029 is completely dominated by the so-called Yarkovsky effect, a subtle non-gravitational perturbation due to thermal re-radiation of solar energy absorbed by the asteroid.

“Only one of the potential impacts has a probability of impact greater than 1-in-a-million; there is a two-metre-wide keyhole that leads to an impact in 2068, with impact odds of about 2.3 in a million.”

IANS

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Hollow neck bones made it possible for the largest of all dinosaurs to evolve necks longer than any other creature that has ever lived, researchers have suggested.

They said sauropods, the plant-eating dinosaurs, had by far the longest necks of any known animal, Fox News reported.

Their necks reached up to 50 feet in length, six times longer than that of the current world-record holder, the giraffe, and at least five times longer than those of any other animal that has lived on land.

Sauropods were really stupidly, absurdly oversized. They were 10 times bigger than elephants. In fact they were the size of walking whales, said researcher Michael Taylor, a vertebrate paleontologist at the University of Bristol in England.

To find out how sauropod necks could get so long, scientists analyzed other long-necked creatures and compared sauropod anatomy with that of the dinosaurs’ nearest living relatives, the birds and crocodilians.

In their study, Taylor and his colleagues found that the neck bones of sauropods possessed a number of traits that supported such long necks.

dinosaurFor instance, air often made up 60 percent of these animals’ necks, with some as light as birds’ bones, making it easier to support long chains of the bones. The muscles, tendons and ligaments were also positioned around these vertebrae in a way that helped maximize leverage, making neck movements more efficient.

In addition, the dinosaurs’ giant torsos and four-legged stances helped provide a stable platform for their necks. In contrast, giraffes have relatively small torsos, while ostriches have two-legged stances.

Sauropods also had plenty of neck vertebrae, up to 19. In contrast, nearly all mammals have no more than seven, from mice to whales to giraffes, limiting how long their necks can get. (The only exceptions among mammals are sloths and aquatic mammals known as sirenians, such as manatees.)

Moreover, while pterosaur Arambourgiania had a relatively giant head with long, spear-like jaws that it likely used to help capture prey, sauropods had small, light heads that were easy to support.

Scientists have proposed three theories to explain why sauropods evolved such long necks.

They suggested that some of the dinosaurs might have used their long necks to feed on high leaves, like giraffes do. Others may have used their necks to graze on large swaths of vegetation by sweeping the ground side to side like geese do. This helped them make the most out of every step, which would be a big deal for such heavy creatures.

Scientists have also suggested that long necks may have been sexually attractive, therefore driving the evolution of ever-longer necks; however, Taylor and his colleagues have found no evidence this was the case.

In the future, Taylor and Wedel plan to delve even deeper into the mysteries of sauropod necks.

For instance, Apatosaurus, formerly known as Brontosaurus, had “really sensationally strange neck vertebrae,” Taylor said.

The scientists suspect the necks of Apatosaurus were used for “combat between males – fighting over women, of course.”

Their study results have been published in the journal PeerJ.

ANI

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‘Super-humans like X-Men will exist in 30 yrs’

by phenomenica on February 27, 2013

in Science

The iconic X-Men superheroes may soon spring out of comic books and become a reality!

Genetic experiments will create a superior race within 30 years, giving rise to super-humans like the X-Men by 2045, UK scientists claim.

Mutant humans like Wolverine, Storm and Rogue from the X-Men movies are possible, scientists told a Ministry of Defence (MOD) think-tank in UK.

“Advancements in gene technology could lead to a class of genetically superior humans by 2045,” a two-day summit to predict the future reported.

super“Human augmentation is likely to increase over the next 30 years. Discussions highlighted that it is possible that advances in biology, unequally shared across society, could generate genetic inequality,” it said.

The MoD’s obscure Development Concepts and Doctrine Centre met last summer, with experts from universities, industry and government and details from the meeting are awaited.

The X-Men first appeared in Marvel comics in the 1960s, fighting evil mutants. It led to the hit films, with Hugh Jackman, 44, playing Wolverine.

PTI

Image credit: NASA

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A lot of people mistakenly believe that Tyrannosaurus rex stood upright with its tail on the ground but in actuality they had a more bird-like posture, tail in the air and head pitched forward of its two massive legs.

According to the study authors, this discovery led major museums to update their T. rex displays and popular books have largely gotten the posture right since around 1990.

But when the researchers asked college students and kids to draw a Tyrannosaur rex, most of them gave it an upright posture instead, as they got the wrong idea from toys like Barney, games and other pop culture items, the New York Post reported.

Warren Allmon, a paleontology professor at Cornell University in Ithaca, New York, and an author of the study, struck him when he saw a box of dinosaur chicken nuggets at a grocery store.

“What they grew up with on their pajamas and their macaroni and wallpaper and everything else is the tail-dragging posture,” he said.

trexThe authors analysed 316 T. rex drawings made by pupils at Ithaca College and kids who visited an Ithaca museum.

Seventy-two percent of the Ithaca college students and 63 percent of the kids drew the animal as being too upright.

When the authors looked at other depictions of the dinosaur, they found the obsolete standing posture remains in pop culture items like toys, games, cookie cutters, clothing, comics and movies.

The study will be published in the Journal of Geoscience Education.

ANI

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Well-known tourist destinations, the Indian Ocean islands of Reunion and Mauritius, actually hide a micro-continent, say a team of researchers.

The continent fragment known as Mauritia detached about 60 million years ago while Madagascar and India drifted apart, and has been hidden under huge masses of lava, the researchers say.

A group of geoscientists from Norway, South Africa, Britain and Germany have suggested the existence of further fragments, based on the study of lava sand grains from the beach of Mauritius, the journal Nature Geoscience reports.

Bernhard Steinberger of the GFZ German Research Centre for Geosciences and Pavel Doubrovine of Oslo University calculated the hotspot trail: “On the one hand, it shows the position of the plates relative to the two hotspots at the time of the rupture, which points towards a causal relation.”

“On the other hand, we were able to show that the continent fragments continued to wander almost exactly over the Reunion plume, which explains how they were covered by volcanic rock,” adds Steinberger, according to a statement of the German Research Centre.

Mauritius

Image credit: experiencemauritius.com

Such micro-continents in the oceans seem to occur more frequently than previously thought. The break-up of continents is often associated with mantle plumes — these giant bubbles of hot rock rise from the deep mantle and soften the tectonic plates from below, until the plates break apart.

This is how Eastern Gondwana broke apart about 170 million years ago. At first, one part was separated, which in turn fragmented into Madagascar, India, Australia and Antarctica, which then migrated to their present position.

Plumes currently situated underneath the islands Marion and Reunion appear to have played a role in the emergence of the Indian Ocean.

IANS

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NASA’s Hubble Space Telescope peered deep into the vast stellar halo that envelops our Milky Way galaxy and uncovered tantalizing evidence for the possible existence of a shell of stars that are a relic of cannibalism by our Milky Way.

Hubble was used to precisely measure, for the first time ever, the sideways motions of a small sample of stars located far from the galaxy’s center. Their unusual lateral motion is circumstantial evidence that the stars may be the remnants of a shredded galaxy that was gravitationally ripped apart by the Milky Way billions of years ago.

These stars support the idea that the Milky Way grew, in part, through the accretion of smaller galaxies.

“Hubble’s unique capabilities are allowing astronomers to uncover clues to the galaxy’s remote past. The more distant regions of the galaxy have evolved more slowly than the inner sections. Objects in the outer regions still bear the signatures of events that happened long ago,” said Roeland van der Marel of the Space Telescope Science Institute (STScI) in Baltimore, Md.

They also offer a new opportunity for measuring the “hidden” mass of our galaxy, which is in the form of dark matter (an invisible form of matter that does not emit or reflect radiation). In a universe full of 100 billion galaxies, our Milky Way “home” offers the closest and therefore best site for detailed study of the history and architecture of a galaxy.

Milky_WayA team of astronomers led by Alis Deason of the University of California, Santa Cruz, and van der Marel identified 13 stars located roughly 80,000 light-years from the galaxy’s center.

They lie in the Milky Way’s outer halo of ancient stars that date back to the formation of our galaxy. The team was surprised to find that the stars showed more of a sideways, or tangential, amount of motion than they expected. This movement is different from what astronomers know about the halo stars near the Sun, which move predominantly in radial orbits.

Deason and her team plucked the outer halo stars out of seven years’ worth of archival Hubble telescope observations of our neighboring Andromeda galaxy. In those observations, Hubble peered through the Milky Way’s halo to study the Andromeda stars, which are more than 20 times farther away.

The astronomers identified the stars based on their colors, brightnesses, and sideways motions. The halo stars appear to move faster than the Andromeda stars because they are so much closer.

Team member Sangmo Tony Sohn of STScI identified the halo stars and measured both the amount and direction of their slight sideways motion. The stars move on the sky only about one milliarcsecond a year, which would be like watching a golf ball on the Moon moving one foot per month. Nonetheless, this was measured with 5 percent precision, made possible in visible-light observations because of Hubble’s razor-sharp view and instrument consistency.

Stars in the inner halo have highly radial orbits. When the team compared the tangential motion of the outer halo stars with their radial motion, they were very surprised to find that the two were equal. Computer simulations of galaxy formation normally show an increasing tendency towards radial motion if one moves further out in the halo. These observations imply the opposite trend.

The existence of a shell structure in the Milky Way halo is one plausible explanation of the researchers’ findings. Such a shell can form by accretion of a satellite galaxy. This is consistent with a picture in which the Milky Way has undergone continuing evolution over its lifetime due to the accretion of satellite galaxies.

The team compared their results with data of halo stars recorded in the Sloan Digital Sky Survey. Those observations uncovered a higher density of stars at about the same distance as the 13 outer halo stars in their Hubble study. A similar excess of halo stars exists across the Triangulum and Andromeda constellations. Beyond that radius, the number of stars plummets.

Deason immediately thought the two results were more than just coincidence.

“What may be happening is that the stars are moving quite slowly because they are at the apocenter, the farthest point in their orbit about the hub of our Milky Way. The slowdown creates a pileup of stars as they loop around in their path and travel back towards the galaxy. So their in and out or radial motion decreases compared with their sideways or tangential motion,” Deason explained.

Shells of stars have been seen in the halos of some galaxies, and astronomers predicted that the Milky Way may contain them, too. But until now there was limited evidence for their existence. The halo stars in our galaxy are hard to see because they are dim and spread across the sky.

Encouraged by this study, the team hopes to search for more distant halo stars in the Hubble archive.

The Hubble study will appear in an upcoming issue of the Astrophysical Journal.

ANI

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A recent newspaper poll found that nearly half of its readers believe that the meteor strike in Russia could be anything from a divine message to UFOs to a US weapons test.

A survey published by the fairly staid Moscow daily Noviye Izvestia found that barely half its readers believe the official report that the blast was caused by a meteor.

According to the newspaper, the other half prefer to believe in an assortment of bizarre explanations, including that the blast was a secret US weapon test, an off-course ballistic missile, a message from God, a crashing alien spaceship, or even an extraterrestrial trojan horse carrying a deadly space virus to wipe out the Earth, C S Monitor reported.

“Our people remember the Soviet past, when news of disasters was concealed or lied about,” Alexei Grazhdankin, deputy director of the Levada Center, an independent Moscow polling agency said.

“We have no scientific polls on what people think about the Chelyabinsk event last week, but it’s safe to assume the majority of Russians accept that it was a meteorite. However, our past surveys show that up to 25 percent of Russians do believe in UFOs. A lot of our people just prefer not to accept the safe explanations they were taught at school. Even when all necessary information is available, they don’t want to believe it,” he said.

russia

Image credit: Julia Airikh/Itar-Tass/Abaca Press/MCT Photo

Scientists insist that they already know most key facts about 10,000-ton iron and stone meteorite – now named Chebarkul, after a city nearest to where the largest fragments landed – that exploded over the Urals city of Chelyabinsk a week ago in a dazzling fireball that released 500 kilotons, the power of 30 Hiroshima A-bombs, about 15 miles above the city.

It was the largest meteorite to make contact with Earth since the vastly more destructive 1908 Tunguskaya event, which involved an estimated 50 megaton blast that leveled an area of almost 800 square miles, and flattened 80-million trees, in a remote part of central Siberia.

For those Russians not prepared to believe in UFOs, a wide variety of other offbeat explanations are available for the Chelyabinsk event.

Russian ultranationalist parliamentarian Vladimir Zhirinovsky, with a nod to the currently strained relations between Russia and the US, has suggested that anti-Russian hardliners in the US staged a secret weapons test over Russia.

About a third of Noviye Izvestia’s readers said they thought the meteor was actually a Russian missile test gone awry, or perhaps a falling satellite, which was covered up with the official story of a meteorite.

Inevitably perhaps, at least one leading Russian cleric has insisted that the meteor was a message from God, to remind us all of the fragility of life on this world.

And from the trade union newspaper, Trud, the cheery suggestion that the meteorite could be carrying deadly viruses from outer space, possibly the work of malevolent extraterrestrial forces.

ANI

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How whales got their teeth

by phenomenica on February 21, 2013

in Nature, Science

A multidisciplinary team of researchers has married together the fossil record and the embryonic development process to investigate how the whale got its teeth.

Not all whales have teeth, but those that do, such as killer whales, have rows of simple peg like teeth, each one looking the same as the next.

Whales use this spiked row of teeth to grab prey, but unlike other mammals, whales do not chew.

In a new study, Brooke Armfield and colleagues investigated the developmental processes that cause the teeth of dolphins, whales’ smaller cousins, to be different, and tracked the evolutionary progression of their unique dentition across the fossil record.

Whales evolved from land mammals and so Armfield and co-workers first went to the fossil record to trace when and how whales evolved their simple teeth. The fossil record shows that, 48 million years ago, whales had the same four kinds of teeth just like most other mammals.

species_grey_whaleMost mammals have four kinds of teeth, each shaped for specific tasks. In most mammals there are wedge-shaped incisors, a pointy canine, and premolars and molars with bumps and valleys that fit together like a mortar and pestle when you chew.

Gradually, the teeth of whales became simpler and acquired their characteristic peg-like appearance around 30 million years ago, well after the time that they had acquired an array of adaptations for living in the water.

Next, Armfield and her colleagues explored just how teeth are shaped during development. Specific proteins in the embryo cause developing teeth to grow into certain shapes.

Armfield and colleagues zeroed in on two proteins, BMP4 (Bone Morphogenetic Protein 4) and FGF8 (Fibroblast Growth Factor 8). BMP4 expression leads to teeth developing into simple prongs, and this occurs near the tip of the jaws, where the incisors form. Prior to teeth forming in the embryo, FGF8 expression in the back of the jaw leads to development of molar teeth with their complex hills and valleys in mice and other mammals.

Armfield and her co-workers studied FGF8 and BMP4 in pig embryos, relatives of whales and dolphins. Pigs have the four typical types of teeth, and, sure enough, the two proteins are distributed in the same way as they are in other mammals, showing that whales’ ancestors likely had this distribution of gene expression too.

Next, the authors moved on to examine dolphin embryos. Here, the pattern was different: FGF8 is present in the back part of the jaw, but BMP4 is present along the entire length of the jaw, including where FGF8 is found.

The researchers hypothesize that the overlapping presence of BMP4 in these new areas causes the teeth all along the jaw to be simple in shape, like incisors, and to be similar to each other. Interestingly, other researchers had shown that in mouse embryos in which BMP4 is experimentally introduced in the back of the jaw, the back teeth also take on this simplified appearance.

“The simple shift in the location of proteins that influence tooth shape found in whales may help us to better understand how mammals evolved their complex tooth in the first place,” said Armfield.

The research has been published in the open access journal PeerJ.

ANI

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