Researchers confirm the existence of a 'lost continent' under Mauritius

This is Indian Ocean topography showing the location of Mauritius as part of a chain of progressively older volcanoes extending from the presently active hot-spot of Réunion toward the 65-million-year-old Deccan traps of northwest India.

Scientists have confirmed the existence of a "lost continent" under the Indian Ocean island of Mauritius that was left-over by the break-up of the supercontinent, Gondwana, which started about 200 million years ago. The piece of crust, which was subsequently covered by young lava during volcanic eruptions on the island, seems to be a tiny piece of ancient continent, which broke off from the island of Madagascar, when Africa, India, Australia and Antarctica split up and formed the Indian Ocean. "We are studying the break-up process of the continents, in order to understand the geological history of the planet," says Wits geologist, Professor Lewis Ashwal, lead author on the paper "Archaean zircons in Miocene oceanic hotspot rocks establish ancient continental crust beneath Mauritius," published in the journal Nature Communications.

By studying the mineral, zircon, found in rocks spewed up by lava during volcanic eruptions, Ashwal and his colleagues Michael Wiedenbeck from the German Research Centre for Geosciences (GFZ) and Trond Torsvik from the University of Oslo, guest scientist at GFZ, have found that remnants of this mineral were far too old to belong on the island of Mauritius.

"Earth is made up of two parts -- continents, which are old, and oceans, which are "young." On the continents you find rocks that are over four billion years old, but you find nothing like that in the oceans, as this is where new rocks are formed," explains Ashwal. "Mauritius is an island, and there is no rock older than 9 million years old on the island. However, by studying the rocks on the island, we have found zircons that are as old as 3 billion years."

Zircons are minerals that occur mainly in granites from the continents. They contain trace amounts of uranium, thorium and lead, and due to the fact that they survive geological process very well, they contain a rich record of geological processes and can be dated extremely accurately.

"The fact that we have found zircons of this age proves that there are much older crustal materials under Mauritius that could only have originated from a continent," says Ashwal.

This is not the first time that zircons that are billions of years old have been found on the island. A study done in 2013 has found traces of the mineral in beach sand. However, this study received some criticism, including that the mineral could have been either blown in by the wind, or carried in on vehicle tyres or scientists' shoes.

"The fact that we found the ancient zircons in rock (6-million-year-old trachyte), corroborates the previous study and refutes any suggestion of wind-blown, wave-transported or pumice-rafted zircons for explaining the earlier results," says Ashwal.

Ashwal suggests that there are many pieces of various sizes of "undiscovered continent," collectively called "Mauritia," spread over the Indian Ocean, left over by the breakup of Gondwanaland.

Read more at Science Daily

Deep-Sea Dragonfish Predators Have a Freakishly Wide Bite

Deep-sea dragonfishes, also known barbeled dragonfishes, open their mouths wider than any other fish, researchers now believe after studying the animal's very unique head joint.

The fish can open their mouths at least 120 degrees (a straight line measures 180 degrees) allowing them to eat extremely large prey relative to the size of these predators. Dragonfishes, described in the journal PLOS ONE, grow up to about one feet, six inches long.

"In the dark, deep sea food is very scarce," co-author G. David Johnson of the Smithsonian's National Museum of Natural History told Seeker.

"The barbeled dragonfishes are ambush lie-and-wait predators, advantageous because less energy is used searching for food. Because prey items are scarce, it is also advantageous to be able to swallow a wider size range of encountered prey and the head joint facilitates engulfing larger items," explained lead author Nalani Schnell of the French Muséum national d'Histoire naturelle.

The researchers, who have studied a myriad of fish anatomy over the years, have never seen anything like the head joint of the deep-sea dragonfishes.

The joint comprises the back of the head and a flexible rod running to the top of the fish's vertebral column. The researchers determined that, when the fish is in a resting position and not elevating its head, the rod has an additional sheath that embraces the back of the head like a socket. When the fish opens its mouth, the sheath gets stretched out and the bottom part of this rod is exposed.

The process is illustrated in the below video:

While the fish clearly has many sharp teeth, they don't actually break food up into bits.

Barbeled dragonfish "swallow their prey whole," Schnell explained. "The teeth are not for chewing; they instead hold onto prey and pass it into the stomach. Some dagger-like teeth even act as a cage, so that swallowed prey won't be able to escape anymore."

Once the fish has swallowed prey, such as another fish, its stomach can expand, causing the predator to look somewhat like a snake that has just swallowed a big victim.

X-ray of a barbeled dragonfish that has eaten a whole lanternfish.

Barbeled dragonfishes inhabit depths between 1640 and about 5000 feet below the water's surface, so they pose no threat to humans. The researchers said that in nets, most of these fish "come up dead due to the difference in pressure, temperature and more."

Read more at Discovery News

Meteorite Reveals Mars Had Active Volcanoes Two Billion Years Ago

A new analysis of a half-pound meteorite from Mars shows that the Red Planet was volcanically active as far back as two billion years ago, making Mars home to not only the biggest volcanoes in the solar system, but the most long-lived ones as well.

The meteorite, known as Northwest Africa (NWA) 7635, was found in 2012 in Algeria (pictured above). A new isotopic analysis, headed by University of Houston geologist Tom Lapen, ties NWA 7635 with 10 other Martian meteorites that likely were blasted out from the same volcano or lava plain by an impacting asteroid or comet about 1.1 million years ago.

"We don't know exactly where these stones were launched from, but it is likely that they are from the volcanic plains and shield volcanoes of the Tharsis or Elysium regions on Mars," Lapen told Seeker.

The study also showed that NWA 7635's solidified lava dates back 2.4 billion years, far older than similar meteorites (known by their scientific designation as incompatible trace element (ITE) depleted shergottites.)

The previously analyzed meteorites range in age from 327 million years old to 600 million years old, the study shows.

"The discovery of a single Mars ejection site with over 2 billion years of stacked lava flows is critical for understanding the volcanic history of Mars," Lapen said. "These data are exciting because this is the first direct evidence for the absolute timing, mantle source characteristics, and spatial associations of volcanism on Mars."

The research also "sets a template for further testable hypotheses regarding the periodicity of magmatism, timing of volcanic gas fluxes into the atmosphere, and the nature of mantle dynamics over most of Mars' history," he added.

The analysis confirms that some of the oldest volcanoes in the solar system are located on Mars.

Mars already was known to host the largest known volcano in the solar system, Olympus Mons, which is as wide as the state of Arizona and about 16 miles high, according to NASA.

NWA 7635 is among about 124 meteorites from Mars that have been recovered on Earth, NASA's Mars Meteorite website shows.

Lapen's research appears in this week's Science Advances.

From Discovery News

Looking Into the 'Eye of the Storm' to Spy on a Brown Dwarf Hugging Its Star

When a hurricane rips across the ocean, a peculiar region of calm appears in its core — called the "eye of the storm." This surprising region of comparative calm is almost as dramatic as the powerful winds that whip around its perimeter. Now, astronomers have developed a method that is analogous to the eye of the storm to create their own region of calm, not within a violent weather system, but in astronomical observations of star systems.

The biggest difficulty facing astronomers looking for worlds orbiting distant stars is the obscuring glare of starlight that can completely hide the dimmer light bouncing off orbiting exoplanets. The glare can be millions of times brighter than the reflected light, requiring astronomers to devise ingenious techniques to reduce that glare. Oftentimes, "occulters" are used within instrumentation — basically tiny disks that physically block the intense starlight from view (a bit like holding your hand up to the sun to block the sun's glare), allowing features around the star to be detected.

Occulters, however, have their limitations. The biggest problem is that, though this method allows the detection of exoplanets orbiting far from their stars, too much glare still bleeds through, obscuring the signal of exoplanets orbiting near to their stars. Entire systems of planets can be blocked from view if their orbits are compact, particularly for more distant stars where planetary systems will appear smaller.

By manipulating the properties of light, however, a new device called a vortex coronagraph installed at the W.M. Keck Observatory in Hawaii has revealed the presence of a brown dwarf closely orbiting the star HIP 79124 (pictured top) and highlighted a planet-forming cloud of dust around the young star HD 141569. Neither objects would have been spotted if the astronomers used more conventional methods of direct imaging.

"The vortex coronagraph allows us to peer into the regions around stars where giant planets like Jupiter and Saturn supposedly form," said research scientist Dmitri Mawet, at NASA's Jet Propulsion Laboratory and Caltech in Pasadena. "Before now, we were only able to image gas giants that are born much farther out. With the vortex, we will be able to see planets orbiting as close to their stars as Jupiter is to our sun, or about two to three times closer than what was possible before."

The vortex coronagraph works by manipulating the starlight coming directly from the star. A filter with microscopic concentric rings act to direct the star's glare away from the instrument's optics. As light is electromagnetic waves, in the center of the coronagraph these waves are directed to cancel each other out (a physical mechanism known as destructive interference). This canceled light creates a dark region in the center, called an "optical singularity," effectively blocking the glare of the star. This method therefore allows the reflected light of worlds orbiting very close to their star to be resolved.

Appearing like a miniature CD, the vortex coronagraph mask is made out of synthetic diamond. A microscopic view of its concentric rings are shown to the right

"Hurricanes have a singularity at their centers where the wind speeds drop to zero — the eye of the storm," added Mawet. "Our vortex coronagraph is basically the eye of an optical storm where we send the starlight."

In the case of HIP 79124, a brown dwarf was discovered orbiting the star at a distance of 23 AU (astronomical units, where 1AU is the average distance at which the Earth orbits the sun). Brown dwarfs are commonly known as "failed stars" — they form a bridge between the most massive planets and the least massive stars and possess qualities of both.

In another vortex study, the innermost ring of planet-forming material around the star HD 141569 was studied. On combining the vortex data with infrared observations from NASA's Spitzer and WISE missions, plus the European Space Agency's Herschel mission, researchers were able to deduce that the material consists of silicate pebbles known as olivine, which is abundant in the Earth's mantle. The temperature of material was measured to be around 100 Kelvin (280 degrees Fahrenheit), a little warmer than the solar system's asteroid belt.

This image shows the dusty disk of planetary material surrounding the young star HD 141569, located 380 light-years away from Earth

"The three rings around this young star are nested like Russian dolls and undergoing dramatic changes reminiscent of planetary formation," said Mawet. "We have shown that silicate grains have agglomerated into pebbles, which are the building blocks of planet embryos."

Both studies were published in the January 2017 issue of The Astrophysical Journal.

Read more at Discovery News

Bursts of Methane May Have Prepped Ancient Mars for Life

Scientists have a new theory for how early Mars managed to stay warm enough for liquid surface water, a condition that is believed to be essential for life.

An armada of orbiters, landers and rovers studying Mars have returned overwhelming evidence that the dry, cold planet of today was far different three- to four billion years ago when rivers and lakes periodically flowed across its surface.

But at that time, Mars should have been too cold for water to remain liquid.

Newly published research shows Mars' atmosphere may have had periods of warming due to greenhouse gases spurred largely by the release of methane.

"The early Mars climate problem has been around for a long time," lead researcher Robin Wordsworth, with Harvard University's School of Engineering and Applied Science, told Seeker. "All the previously proposed explanations just didn't work. We couldn't get the climate warm enough or wet enough for long."

The new study, published in last week's Geophysical Research Letters, shows that interactions between methane, carbon dioxide and hydrogen in Mars' atmosphere could have absorbed enough solar radiation to spike surface temperatures high enough for water to stay liquid.

Blankets of greenhouse gases could have kept Mars warm for spans of time lasting tens of thousands of years, but not hundreds of millions of years, Wordsworth noted, a finding that matches the evidence of the periodic presence of water coming from NASA's Curiosity rover and other spacecraft at Mars.

Wordsworth said he got the idea about methane bursts from looking at Titan, the largest moon of Saturn and the only body in the solar system besides Earth that has a substantial atmosphere. Titan is loaded with methane, as well as other hydrocarbons.

"It's an analog for how Mars might have been," Wordsworth said.

The scientists expect data from NASA's ongoing MAVEN mission, which is monitoring how Mars' atmosphere is bleeding away into space, will flesh out their models of the planet's past climate.

Read more at Discovery News

Hybrid Lion-Tiger Born in Russia

An extremely rare cross between a tiger and a lion has been born in a travelling zoo in southern Russia, one of only a few dozen of the animals believed to exist.

Named Tsar, the two-month-old "liger" cub is the offspring of a tigress Princess and lion Caesar, zoo director Erik Airapetyan told AFP.

"They have lived together for a long time and know each other well. When the tigress was on heat, she didn't have any other choice," he said.

The cub has the beige fur of a lion and the stripes of a tiger and is currently being fed on milk from one of the zoo's goats.

Ligers can grow to be the biggest cat in the animal kingdom, weighing more than 400 kilograms (882 pounds).

A liger called Hercules in the United States is currently listed in the Guinness Book of World Records as the biggest feline in the world, at a weight of 418 kilograms (922 pounds) and length of 3.33 meters (11 feet).

U.S. zoos do not generally cross-breed big cats, as there is thought to be no purpose to breeding an animal that does not exist in the wild. Instead, they put their energies toward conservation of existing species.

"In terms of conservation," a U.S. lion expert told National Geographic in 2012, "it's so far away from anything, it's kind of pointless to even say it's irrelevant."

In the case with Tsar: "The mother [tiger] was in heat but there were no tigers, and we saw that she was suffering [without a male tiger] so we decided to put her together with a lion. Because they lived next to each other for a long time before, it worked," Airapetyan told Deutsche Welle.

Earlier notions that all ligers are sterile have not proved accurate, as shown by the birth in 2012 of "liliger" Kiara - born to a liger mother and a lion father.

AFP contributed to this report.

From Discovery News

This Bag-Like Sea Creature Was Our Earliest Ancestor

A microscopic bag-like sea creature dating to 540 million years ago is the earliest known ancestor of humans, research on the newly discovered species finds.

The ultra-tiny animal, named Saccorhytus coronarius, is now thought to be the first known "deuterostome" and is described in the journal Nature. Deuterostome refers to a broad biological group of animals that encompasses a number of sub-groups, including vertebrates, which are all animals with a backbone or spinal column.

"Humans are deuterostomes and so too are other vertebrates, as well as animals like sea-squirts and starfish," co-author Simon Conway Morris of the University of Cambridge told Seeker. "What we want to know is what the common ancestor of all these animals looked like. In our opinion, Saccorhytus is the best candidate."

To the naked eye, the creature resembles a black speck of dust. When magnified, however, "the preservation of detail in this (and the other) microscopic fossils is extraordinary," he said.

Conway Morris, lead author Jian Han and their international team of researchers analyzed the remains of Saccorhytus. They believe it lived in a shallow sea ecosystem with primitive mollusks, early representatives of arrow worms (nearly transparent worm-like marine predators) and other water-dwelling species.

There was not much to the animal, by the looks of it. The body was a rounded sack covered with a thin and flexible skin. A relatively large mouth was at the top, with small openings called "body cones" around the primary orifice.

"It could have slithered between the sediment grains, and the mouth seems to have been capable of considerable dilation and so, for its size, (it could) have swallowed relatively large prey with the excess water being discharged via the openings," Conway Morris said.

"We have not observed an anus," he added, explaining that waste material could have left through the mouth.

The openings that are on the body were likely the precursors of gill slits that later evolved in fish and other marine life, the researchers believe. Gills were lost once the ancestors of humans and other related animals became terrestrial.

Read more at Discovery News

On Mars, Life Could Be Hiding Under the Rocks

Living on Mars would be tough by any measure — so tough, that there's considerable debate about whether even the hardiest of microbes could survive. The atmosphere is thin, the surface is baked with radiation and the planet itself is mostly arid, dusty and wind-swept.

But there could be niches where life thrived in the distant past, when Mars had a thicker atmosphere and a wetter surface. So when Red Planet scientist Janice Bishop was invited to look at carbonate rocks in the Mojave Desert a few years ago, she immediately saw implications for Mars.

Bishop had already published a 2006 International Journal of Astrobiology paper calling iron oxides an "ultraviolet sunscreen" for ancient photosynthesis on Earth. The result of the newer study, published in 2011 in the same journal showed that the Mojave rocks collected also had iron oxide coatings, under which carbonates were hiding.

"They were all hiding under this red mineral at the top, called hematite," Bishop told Seeker in an interview. Hematite is also a common element on Mars.

Besides being senior research scientist and chair of the astrobiology group at the SETI Institute, Bishop is known for her work creating an instrument on the Mars Reconnaissance Orbiter called CRISM (Compact Reconnaissance Imaging Spectrometer). The spacecraft has been taking high-resolution pictures and spectroscopic images of Mars for more than a decade, providing reams of information on how the surface looks like today and how it may have evolved.

And Bishop is one of several scientists working on the "sunscreen" idea. The University of Maryland's Gozen Ertem, for example, is looking at how well biomolecules can hide from ultraviolet radiation in different mixtures. She will present on her research at the American Association for the Advancement of Science Conference next month. (Ertem did not respond to requests for an interview.)

It's unclear how well Martian microbes (if they existed) would have fared in their environment, but at the least the studies on iron oxides are yielding valuable information about how life evolved on Earth. This could help scientists better understand the possibility of life in other environments across the solar system, or even exoplanetary systems.

Banded iron formations (such as the one pictured at ceter at Karijini National Park, Western Australia) may come in part from iron metabolized by microorganisms

Some people in this field are trying to figure out how microbes could have evolved when the Earth had no protective ozone layer, similar to what is on Mars today. A 2015 Geology paper led by Tina Gauger at the University of Tubingen suggests that some strains of bacteria could have created iron oxide layers in their environment for protection.

Read more at Discovery News

Climate change helped kill off super-sized Ice Age animals in Australia

Kangaroo silhouette against sky

During the last Ice Age, Australia, Tasmania and New Guinea formed a single landmass, called Sahul. It was a strange and often hostile place populated by a bizarre cast of giant animals.

There were 500-pound kangaroos, marsupial tapirs the size of horses and wombat-like creatures the size of hippos. There were flightless birds that weighed twice as much as modern emu, 33-foot snakes, 20-foot crocodiles, 8-foot turtles with horned heads and spiked tails, and giant monitor lizards that measured greater than 6 feet from tip to tail and were likely venomous.

By about 30,000 years ago, however, most of these 'megafauna' had disappeared from the Sahul as part of a global mass extinction that saw the end of nearly all of the super-sized animals that had evolved to survive in extreme Ice Age climates. The factors that forced the Australian megafauna into extinction remain a matter of considerable controversy. Many experts argue that the ancestors of the Australian aborigines, who made an appearance approximately 50,000 years ago, either hunted them into extinction or gradually destroyed the habitat they required by practices such as fire-stick burning. Others argue that the gradual drying out of Australia and weakening of the Australian monsoon played a major role in their demise.

A new study has compared the diet of a variety of Australian megafaunal herbivores from the period when they were widespread (350,000 to 570,000 years ago) to a period when they were in decline (30,000 to 40,000 years ago) by studying their fossil teeth. The analysis suggests that climate change had a significant impact on their diets and may well have been a primary factor in their extinction.

"We have found evidence that, as the climate was changing and getting drier, animal diets were shifting dramatically," said Larisa DeSantis, assistant professor of earth and environmental studies at Vanderbilt University, who directed the study. "If climate change was a primary or contributing factor in their demise, as it appears, we need to pay more attention to how current levels of climate change are affecting animals today."

The results of the study are described in a paper titled "Dietary responses of Sahul (Pleistocene Australia-New Guinea) megafauna to climate and environmental change" published on Jan. 25 by the journal Paleobiology. Co-authors on the paper are Judith Field and John Dodson from the University of New South Wales and Stephen Wroe from the University of New England.

Michael Archer, a leading Australian paleontologist at the University of New South Wales who was not involved in the study, commented, "This new study, based on hard evidence, makes it clear that changes in late Pleistocene climate had a major impact on the late Pleistocene megafauna of Australia, adding even more evidence to challenge the imaginative a priori assumption that 'blitzkrieg' by early humans caused the extinction of this continent's lost megafauna.Climate change clearly has been in the past and will continue to be a major cause of extinction into the future."

The teeth that were analyzed came from the Cuddie Springs site in southeastern Australia. It is located on a prehistoric ephemeral lake and it is the only site on mainland Australia that has produced fossil evidence of the co-existence of humans and megafauna. "Unfortunately, many of the advocates of the human predation hypothesis have discounted Cuddie Springs because it does not support the popular 'blitzkrieg' theory that maintains the megafauna went extinct in the 1,000-year period after humans arrived on the scene," said DeSantis.

It's amazing how much information about the prehistoric environment paleontologists can extract from fossil teeth using a dental drill, dental impression material and some sophisticated instruments. The ratios of oxygen and carbon isotopes locked in the enamel provide clues about the animals' diet and the average temperature and humidity of the environment at the time the teeth formed. Differences within individual teeth mirror climate variability. Analysis of the microscopic scratches on the surface of the teeth provides evidence of what the animal was eating in the last few weeks of its life. Differences in wear-patterns can differentiate between animals that were grazing on grass and browsing on bushes.

"For example, we know from the analysis of modern day kangaroos that oxygen isotope ratios in their teeth are highly correlated with the relative humidity and amount of precipitation in their environment," DeSantis said. "This makes them ideally suited for tracking changes in aridity over time."

During the megafaunal heyday around 500,000 years ago, the dental analysis revealed that the climate was semi-arid. In addition, the animals' diets were highly variable, implying that there were a number of ecological niches available to them.

That contrasts markedly with the period from 30,000 to 40,000 years ago. Here, the analysis indicates that the climate was substantially drier and the diet of the giant herbivores was considerably more restricted.

Read more at Science Daily

Anthropologists uncover art by (really) old masters

An international team of anthropologists has uncovered a 38,000-year-old engraved image in a southwestern French rockshelter -- a finding that marks some of the earliest known graphic imagery found in Western Eurasia and offers insights into the nature of modern humans during this period.

"The discovery sheds new light on regional patterning of art and ornamentation across Europe at a time when the first modern humans to enter Europe dispersed westward and northward across the continent," explains NYU anthropologist Randall White, who led the excavation in France's Vézère Valley.

The findings, which appear in the journal Quaternary International, center on the early modern humans' Aurignacian culture, which existed from approximately 43,000 to 33,000 years ago.

Abri Blanchard, the French site of the recently uncovered engraving, a slab bearing a complex image of an aurochs, or wild cow, surrounded by rows of dots, was previously excavated in the early 20th century. White and his team members began their methodical exploration of remaining deposits at the site in 2011, with the discovery occurring in 2012.

White contends that Aurignacian art offers a window into the lives and minds of its makers -- and into the societies they created.

"Following their arrival from Africa, groups of modern humans settled into western and Central Europe, showing a broad commonality in graphic expression against which more regionalized characteristics stand out," he explains. "This pattern fits well with social geography models that see art and personal ornamentation as markers of social identity at regional, group, and individual levels."

Abri Blanchard and its sister site, Abri Castanet, previously excavated by White's team, have long been recognized as being among the oldest sites in Eurasia bearing artifacts of human symbolism. Over time, hundreds of personal ornaments have been discovered, including pierced animal teeth, pierced shells, ivory and soapstone beads, engravings, and paintings on limestone slabs.

From Science Daily