Earliest Baby Animals Preserved in Ancient Volcanic Ash

The ash from a Pompeii-style volcanic eruption more than a half-billion years ago smothered a nursery of what may be some of the earliest known animals, researchers say.

These well-preserved findings shed light on the evolution of early life on Earth, and reinforce evidence suggesting that life became more complex earlier than often suspected, investigators added.

Scientists hunted for evidence of life from the mysterious Ediacaran period, when the first complex multicellular organisms appeared about 540 million to 635 million years ago. The life-forms from the Ediacaran are typically bizarre, and very difficult to link with any modern animal groups. In fact, just this week researchers announced they'd discovered tiny tracks from the earliest complex life, bilaterally symmetrical animals that looked like slugs.

Continued:  http://www.livescience.com/21248-earliest-baby-animals-volcanic-ash.html

Ancient lakes show when eukaryotic life left the sea

18:00 13 April 2011 by Colin Barras

Pools of water on land were a lot livelier 1 billion years ago than previously thought.

It is generally assumed that life began in the ocean around 3.8 billion years ago, then moved onto land. Until now, there had been little evidence to suggest this landward migration happened before half a billion years ago. The discovery of eukaryote cells in 1-billion-year-old lake sediment looks set to change that.

Paul Strother at Boston College in Weston, Massachusetts, and colleagues discovered cyst-like bubbles made of organic matter in 1 to 1.2-billion-year-old lake deposits. The bubbles were packed full of fossilised cells, and found in a number of locations across the north-west of Scotland, UK.

Strother says the cells, which appear to be going through vegetative reproduction, show a level of structural complexity "beyond that seen in bacteria" but characteristic of eukaryotes – one of the three domains of life. This suggests the primitive relatives of all animals, plants and fungi had left the oceans and moved into terrestrial waters twice as long ago as thought.

Non-marine sediment

Palaeontologists contacted by New Scientist for comment agreed. "They most certainly appear to be eukaryotic, and the non-marine nature of the encompassing sediments seems well established," says Andrew Knoll at Harvard University. "Previous to this, the oldest clearly non-marine eukaryotes may have been [roughly 540-million-year-old] Cambrian spores."

Emmanuelle Javaux at the University of Liège, Belgium, calls it "a significant discovery". The age of the rocks puts them "near the beginning of diversification of eukaryotic supergroups, and is an important new element for improving our understanding of early terrestrialisation processes in general – and evolution of the eukaryotes in particular."

Eukaryotes may not have been the sole colonisers of land at the time. There is also evidence that cyanobacteria – some of the earliest known forms of life – evolved first in fresh water, before moving to the ocean.

Journal reference: Nature, DOI: 10.1038/nature09943

http://www.newscientist.com/article/dn20373-ancient-lakes-show-when-eukaryotic-life-left-the-sea.html

New Research Rejects 80-Year Theory of 'Primordial Soup' as the Origin of Life

ScienceDaily (Feb. 3, 2010) — For 80 years it has been accepted that early life began in a 'primordial soup' of organic molecules before evolving out of the oceans millions of years later. Today the 'soup' theory has been over turned in a pioneering paper in BioEssays which claims it was the Earth's chemical energy, from hydrothermal vents on the ocean floor, which kick-started early life.

"Textbooks have it that life arose from organic soup and that the first cells grew by fermenting these organics to generate energy in the form of ATP. We provide a new perspective on why that old and familiar view won't work at all," said team leader Dr Nick lane from University College London. "We present the alternative that life arose from gases (H₂, CO₂, N₂, and H₂S) and that the energy for first life came from harnessing geochemical gradients created by mother Earth at a special kind of deep-sea hydrothermal vent -- one that is riddled with tiny interconnected compartments or pores."

The soup theory was proposed in 1929 when J.B.S Haldane published his influential essay on the origin of life in which he argued that UV radiation provided the energy to convert methane, ammonia and water into the first organic compounds in the oceans of the early earth. However critics of the soup theory point out that there is no sustained driving force to make anything react; and without an energy source, life as we know it can't exist.

"Despite bioenergetic and thermodynamic failings the 80-year-old concept of primordial soup remains central to mainstream thinking on the origin of life," said senior author, William Martin, an evolutionary biologist from the Insitute of Botany III in Düsseldorf. "But soup has no capacity for producing the energy vital for life."

In rejecting the soup theory the team turned to the Earth's chemistry to identify the energy source which could power the first primitive predecessors of living organisms: geochemical gradients across a honeycomb of microscopic natural caverns at hydrothermal vents. These catalytic cells generated lipids, proteins and nucleotides which may have given rise to the first true cells.

The team focused on ideas pioneered by geochemist Michael J. Russell, on alkaline deep sea vents, which produce chemical gradients very similar to those used by almost all living organisms today -- a gradient of protons over a membrane. Early organisms likely exploited these gradients through a process called chemiosmosis, in which the proton gradient is used to drive synthesis of the universal energy currency, ATP, or simpler equivalents. Later on cells evolved to generate their own proton gradient by way of electron transfer from a donor to an acceptor. The team argue that the first donor was hydrogen and the first acceptor was CO₂.

"Modern living cells have inherited the same size of proton gradient, and, crucially, the same orientation -- positive outside and negative inside -- as the inorganic vesicles from which they arose" said co-author John Allen, a biochemist at Queen Mary, University of London.

"Thermodynamic constraints mean that chemiosmosis is strictly necessary for carbon and energy metabolism in all organisms that grow from simple chemical ingredients [autotrophy] today, and presumably the first free-living cells," said Lane. "Here we consider how the earliest cells might have harnessed a geochemically created force and then learned to make their own."

This was a vital transition, as chemiosmosis is the only mechanism by which organisms could escape from the vents. "The reason that all organisms are chemiosmotic today is simply that they inherited it from the very time and place that the first cells evolved -- and they could not have evolved without it," said Martin.

"Far from being too complex to have powered early life, it is nearly impossible to see how life could have begun without chemiosmosis," concluded Lane. "It is time to cast off the shackles of fermentation in some primordial soup as 'life without oxygen' -- an idea that dates back to a time before anybody in biology had any understanding of how ATP is made."

http://www.sciencedaily.com/releases/2010/02/100202101245.htm
(Submitted by Tim Chapman)

Earliest Four-Limbed Animals Left Mud Tracks

The finding of 395-million-year-old footprints in Poland turns back the clock on the evolution of four-legged creatures.

By Jennifer Viegas Wed Jan 6, 2010 07:57 AM ET

This is a sketch of a Devonian tetrapod making tracks. It is based on a species from the Late Devonian of Greenland but is a reasonable approximation to the track-maker of newly-found prints in Poland.
Per Ahlberg

The world's first four-limbed animals, called tetrapods, crawled on land much earlier than scientists thought, judging by tracks left behind by some of the animals in a prehistoric Polish lagoon.

The fossilized footprints from these animals are 18 million years older than the earliest tetrapod body fossils, pushing the emergence of four-limbed creatures back to at least the early Middle Devonian period, according to two papers published in the latest issue of the journal Nature.

Tracks left behind by the animals 397 million years ago show how they walked on their short, thick legs through the mud of what was once a coral reef lagoon. That type of location, with its regular tides and abundant food sources consisting of "washed-up dead animals," likely set the stage for the fish-to-land animal transition, according to the authors.

The crawlers have not yet been identified, but co-author Per Ahlberg told Discovery News that they were "basal tetrapods, the common ancestral stock of all the living tetrapod groups."

Dogs, cats, humans and any other animal with four limbs fall into that large overall group.

But there was something fishy about these early animals.

"There isn't anything living today with the strange combination of fish and tetrapod-like characteristics that we see in the earliest fossil tetrapods," said Ahlberg, an Uppsala University Professor of Evolutionary Organismal Biology.

Ahlberg and his colleagues found and studied the tracks at what is now the Zachelmie Quarry in southeastern Poland. Their analysis shows some of the animals appear to have moved in a straight line without dragging their bodies on the ground, while others had a less symmetrical gait.

The largest of the individual prints shows not just feet, but the animal's "whole limb as far as the knee," the researchers wrote. On one fossil track, "the tip of each triangular toe shows a small distinct cushion or pad," they added.

Before the discovery of these tracks, it was thought certain fish evolved into four-limbed animals during the Givetian Period, 391 to 385 million years ago. Fossils seemed to neatly support this timing for the fin-to-limb gradual change, since some fish, known as elpistostegids, appeared to belong to a mid-point stage where the fish had tetrapod-like heads and bodies, but retained fish characteristics, such as paired fins.

"In fact, tetrapods and elpistostegids coexisted for at least 10 million years," the researchers point out. "This implies that the elpistostegid morphology was not a brief transitional stage, but a stable adaptive position in its own right."

The scientists compare the coexistence of four-limbed animals and these fish with what happened to dinosaurs and birds. Dinosaurs didn't all just evolve into birds. Feathered and winged theropod dinosaurs were still around long after the first birds appeared about 150 million years ago.

Another revision to the animal history books concerns the habitat of the first tetrapods, according to Philippe Janvier and Gael Clement of the National Museum of Natural History in Paris.

In a separate commentary in Nature, they call the new finds a "stunning discovery." They write that the sea and lagoon location described by Ahlberg and his colleagues "is at odds with the long-held view that river deltas and lakes were the necessary environments for the transition from water to land during vertebrate evolution."

Given this difference, and the very early date of the tracks, Janvier and Clement believe the new findings "lob a grenade" into accepted theories of the fish-to-tetrapod transition.

http://news.discovery.com/animals/tetrapod-tracks-poland.html

Fossil tracks record 'oldest land-walkers'

Wednesday, 6 January 2010

By Jonathan Amos
Science correspondent, BBC News

The oldest evidence of four-legged animals walking on land has been discovered in southeast Poland.

Rocks from a disused quarry record the "footprints" of unknown creatures that lived about 397 million years ago.

Scientists tell the journal Nature that the fossil trackways even retain the impressions left by the "toes" on the animals' feet.

The team says the find means that land vertebrates appeared millions of years earlier than previously supposed.

"This place has yielded what I consider to be some of the most exciting fossils I've ever encountered in my career as a palaeontologist," said team member Per Ahlberg from Uppsala University, Sweden.

"[They are] fossil of footprints that give us the earliest record of how our very distant ancestors moved out of the water and moved on to the land and took their first steps."

Numerous trackways have been identified in the Zachelmie Quarry in the Holy Cross Mountains.

They represent the movements of many animals as they scurried around what would have been a tropical muddy shoreline in the Middle Devonian Period of Earth history.

Slabs of carbonate rock are dappled with prints that range in size and detail.

Some indentations are obscured where successive animals have trampled over the same patch of ground; but others retain exquisite features of the pads and digits that made them.

The animals were probably crocodile-like in appearance and lived an amphibian-like existence (although those specific animal forms did not appear until many millions of years later).

The dimensions of the prints suggest some individuals were more than two metres long.

The Polish and Swedish scientific team analysed the trackway patterns to reconstruct how the ancient creatures would have moved their "hips", "elbows" and "knees".

This confirms that only true four-legged animals, or tetrapods, could have left the marks.

Theory holds that the first land creatures evolved from fish that had pairs of lobed fins. The precise timing of this transition has been a dynamic field of study in recent years.

The assumption of palaeontologists had been that there was a swift but stepwise transition between water and land.

Perhaps the most notable fossil in this story is an organism called Tikaalik rosea, an animal that had features intermediate between fish and tetrapods.

But Tiktaalik lived about 375 million years ago; and although there are slightly older transition fossils, the Zachelmie Quarry tetrapods break the neat and simple timeline.

"The discovery of undoubted trackways from the earliest period of the Eifelian - that is 379 million years ago - pushes back the divergence between fishes and the four-legged vertebrates by about 18 million years, if not probably more," commented Dr Philippe Janvier from the National Museum of Natural History, Paris, France.

"I suspect that now we can push the divergence back to the Emsian stage, maybe 400 million years ago. That's surprising, but this is what the fossil evidence tells us," the independent researcher told BBC News.

Another key surprise from the research is the recognition that these tetrapods lived in a marine environment, perhaps a coral lagoon.

The favoured origin before now for the emergence of tetrapods had been marshy environments, such as deltas or lakes where freshwater dominated.

The team behind the latest research said the new explanation made sense because it would have allowed marine ancestors of tetrapods gradually to acquire terrestrial competence while accessing a new and essentially untouched resource of food washed up with the tides.

"In the intertidal setting, you've got a smorgasbord laid out twice a day," said Dr Ahlberg.

"Every time the tide goes out, it leaves behind this drift-line of dead and moribund animals. All this was just left there for vertebrates - our ancestors - to emerge on to land and pick them off."

http://news.bbc.co.uk/1/hi/sci/tech/8443879.stm

Fossil find reveals whales as suckers

BRIDIE SMITH
December 23, 2009

A WHALE fossil found near Torquay more than 70 years ago has provided scientists with clues about how the mammals evolved, backing up the theories of naturalist Charles Darwin.

Museum Victoria palaeobiologist Erich Fitzgerald spent five years studying the fossil of a primitive toothed whale known as a Mammalodon colliveri and found, as Darwin had suggested, that some whales evolved as suction feeders.

Dr Fitzgerald said the findings showed that south-east Australia was ''a cradle of evolution'' for a variety of unusual, tiny baleen whales.

A specialist in the evolution of marine mammals, Dr Fitzgerald's research on the 25 million-year-old fossil is published in the latest Zoological Journal of the Linnean Society.

The Mammalodon colliveri, a relatively small whale at just three metres long, was unique to south-east Australia, with fossils only found in Victoria.

The fossilised skull and lower jaw of the whale, found in 1932 by local collectors, is just 45 centimetres long and has unusual features, including a short, blunt snout.

Large holes in the upper and lower jaws indicate the mammal - a close cousin of the 30-metre-long blue whale, the largest animal to inhabit the planet - had huge blood and nerve supply to the lips and facial muscles.

''This is unusual and no other baleen whale has this … and it tells us that the Mammalodon was feeding in a really unusual way. It suggests that it was a bottom-feeding mud-sucker,'' Dr Fitzgerald said. He said the whale probably used its tongue and snout to suck small prey up from sand and mud on the sea floor.

The fossil goes on public display for the first time at Museum Victoria until March. Since it was found in the 1930s, it was stored at Melbourne University's geology department before being transferred to Museum Victoria in the 1980s.

See video at: http://www.theage.com.au/national/fossil-find-reveals-whales-as-suckers-20091222-lbql.html

(Submitted by Peter Darben)

Mammoths Hung on Longer? Late-Surviving Megafauna Exposed by Ancient DNA in Frozen Soil

ScienceDaily (Dec. 15, 2009) — Extinct woolly mammoths and ancient American horses may have been grazing the North American steppe for several thousand years longer than previously thought. After plucking ancient DNA from frozen soil in central Alaska, a team of researchers used cutting-edge techniques to uncover "genetic fossils" of both species locked in permafrost samples dated to between 7,600 and 10,500 calendar years.

This new evidence suggests that at least one population of these now-extinct mammals endured longer in the continental interior, challenging the conventional view that these and other large species, or megafauna, disappeared from the Americas about 12,000 years ago.

"We don't know how long it takes to pinch out a species," says Ross MacPhee, Curator of Mammalogy at the American Museum of Natural History. "Extinctions often seem dramatic and sudden in fossil records, but our study provides an idea of what an extinction event might look like in real time, with imperiled species surviving in smaller and smaller numbers until eventually disappearing completely."

At the end of the Pleistocene, the geological epoch roughly spanning 12,000 to 2.5 million years ago, many of the world's megafauna, such as giant sloths, saber-toothed cats, dire wolves, stag-moose, and mammoths, vanish from the geological record. Some large species such as Equus caballus, the species from which the domestic horse derives, became extinct in North America but persisted in small populations elsewhere. Because of the apparent sudden disappearance of many megafaunal species in North America, some scientists have proposed cataclysmic explanations like human overhunting, an extraterrestrial impact, and the introduction of novel infectious diseases. The swiftness of the extinctions, however, is not suggested directly by the fossils themselves but is inferred from radiocarbon dating of bones and teeth discovered on the surface or buried in the ground. Current "macrofossil" evidence places the last-known mammoths and wild horses between 13,000 and 15,000 years ago.

But hard remains of animals are rarely preserved, difficult to find, and laborious to accurately date because of physical degradation. Because of this, MacPhee and co-authors Eske Willerslev of the University of Copenhagen in Denmark, Richard Roberts of the University of Wollongong in Australia, and Duane Froese of the University of Alberta in Canada decided to tackle the problem by dating the "last survivors" through dirt. Frozen sediments from the far north of Siberia and Canada can preserve small fragments of animal and plant DNA exceptionally well, even in the complete absence of any visible organic remains, such as bone or wood.

"In principle, you can take a pinch of dirt collected under favorable circumstances and uncover an amazing amount of forensic evidence regarding what species were on the landscape at the time," says Willerslev, director of the Centre for GeoGenetics at the University of Copenhagen. "The use of ancient DNA offers the possibility of being able to sample previous life within the last 400,000 years, freeing us from having to rely on skeletal and other macrofossil evidence as the only way to collect information about species that are no longer with us."

In order to prospect for genetic fossils, the team collected soil cores from undisturbed Alaskan permafrost. Wind-blown Stevens Village, situated on the bank of the Yukon River, fit the bill perfectly. Here, sediments were sealed in permafrost soon after deposition. Two independent methods (radiocarbon and optically stimulated luminescence) were used to date plant remains and individual mineral grains found in the same layers as the DNA.

"With these two techniques, we can be confident that the deposits from which the DNA was recovered haven't been contaminated since these lost giants last passed this way," said Roberts, director of the Centre for Archaeological Science at the University of Wollongong. "It's a genetic graveyard, frozen in time."

Cores collected at Stevens Village offer a clear picture of the local Alaskan fauna at the end of the last ice age. The oldest sediments, dated to about 11,000 years ago, contain remnant DNA of Arctic hare, bison, and moose; all three animals were also found in higher, more recent layers, as would be expected. But one core, deposited between 7,600 and 10,500 years ago, confirmed the presence of both mammoth and horse DNA. To make certain that the integrity of this sample had not been compromised by geologic processes (for example, that ancient DNA had not blown into the surface soils), the team did extensive surface sampling in the vicinity of Stevens Village. No DNA evidence of mammoth, horse, or other extinct species was found in modern samples, a result that supports previous studies which have shown that DNA degrades rapidly when exposed to sunlight and various chemical reactions.

"The fact that we scored with only one layer is not surprising," says MacPhee. "When you start going extinct, there will be fewer and fewer feet on the ground, and thus less and less source material for ancient DNA such as feces, shed dermal tissues, and decaying bodies."

The team also developed a statistical model to show that mammoth and horse populations would have dwindled to a few hundred individuals by 8,000 years ago.

"At this point, mammoths and horses were barely holding on. We may actually be working with the DNA of some of the last members of these species in North America," says permafrost expert Froese, associate professor in the Department of Earth and Atmospheric Sciences at the University of Alberta. "The Yukon Flats includes large shifting river bars with an abundance of high quality forage where large mammals can and could make a living. There may have been a handful of similar sites in Alaska, hosting small remnant populations," says Froese.

"Dirt DNA has lots of exciting potential to contribute to extinction debates in other parts of the world too, as well as a range of archaeological questions," said Willerslev, who also points out that the approach is not restricted to looking back at the past. "We can also use it to make a list of modern species living in any particular location," he said. "This kind of information is really valuable for studies of animals that are hard to detect, and there are some neat forensic applications too."

The new paper is published in the Proceedings of the National Academy of Sciences. In addition to Willerslev, MacPhee, Froese, and Roberts, authors include James Haile, Morten Rasmussen, and Thomas Gilbert of the University of Copenhagen in Denmark; Alberto Reyes, and Simon Robinson of the University of Alberta in Canada; Lee Arnold and Martina Demuro of the University of Wollongong in Australia; Rasmus Nielsen and Kasper Munch of the University of California at Berkeley; Barry Brook, Jeremy Austin, and Alan Cooper of the University of Adelaide in Australia; Ian Barnes of the Royal Holloway University of London in the United Kingdom; and Per Moller of Lund University in Sweden. The research was funded by the Danish National Research Foundation, the Natural Science and Engineering Research Council of Canada, the Alberta Ingenuity Foundation, the Australian Research Council; Discovery Communications, Inc.; the AHRB, and the Arts and Humanities Research Council.

http://www.sciencedaily.com/releases/2009/12/091214151946.htm

(Submitted by Terry Colvin)

Dinosaur-killing impact set Earth to broil, not burn

19:49 07 December 2009 by Jeff Hecht

The asteroid impact that ended the age of dinosaurs 65 million years ago didn't incinerate life on our planet's surface – it just broiled it, a new study suggests. The work resolves nagging questions about a theory that the impact triggered deadly wildfires around the world, but it also raises new questions about just what led to the mass extinction at the end of the Cretaceous period.

The impact of a 10-kilometre asteroid is blamed for the extinction of the dinosaurs and most other species on the planet. Early computer models showed that more than half of the debris blasted into space by the impact would fall into the atmosphere within eight hours.

The models predicted the rain of shock-heated debris would radiate heat as intensely as an oven set to "broil" (260 °C) for at least 20 minutes, and perhaps a couple of hours. Intense heating for that long would heat wood to its ignition temperature, causing global wildfires.

Yet some species survived, and the global layer of impact debris doesn't contain as much soot as would be expected from burning the world's forests, raising questions about the extent of post-impact wildfires.

Read full article at: http://www.newscientist.com/article/dn18246-dinosaurkilling-impact-set-earth-to-broil-not-burn.html

(Submitted by Tim Chapman)

Antarctica Was Oasis for Life During "Great Dying" 250 Million Years Ago

Today it’s tempting to think of Antarctica as an icy wasteland, hospitable for penguins and seals but not much else. However, before the continent was covered by a permanent ice sheet, it may have been a refuge from a world in chaos, according to findings published in a journal called Naturwissenschaften.

Jörg Fröbisch of Chicago’s Field Museum says that a distant relative of mammals, a cat-sized herbivore called Kombuisia antarctica survived the Permian-Triassic Extinction 250 million years ago by migrating from southern Africa to Antarctica. At the time of the end-Permian extinction, Antarctica was some distance north of its present location, warmer than it is today, and not covered with permanent glaciers [The Telegraph].

Scientists actually possessed the K. antarctica fossils for three decades before this paper was published, but didn’t bother with this question because identifying the animals wasn’t the reason for collecting the fossils. The fossil hoard had been assembled for the American Museum of Natural History as evidence of the existence of the ancient supercontinent Pangaea, in which all today’s continents were locked together in one land mass [New Scientist].

Because scientists have turned up no vertebrate fossils in Antarctica from before the “Great Dying” 250 million years ago, Fröbisch’s team is confident that K. antarctica migrated there across Pangaea in response to the changing world, rather than having lived there all along. That jibes with what scientists are seeing now—species on the move in response to the changing climate.

http://blogs.discovermagazine.com/80beats/2009/12/03/antarctica-was-oasis-for-life-during-great-dying-250-million-years-ago/

(Submitted by Phyllis K. Ray)

Comets 'not cause of extinctions'

Sunday, 2 August 2009 13:04 UK

By Griet Scheldeman
Science reporter, BBC News

Comet strikes are an unlikely cause of past mass extinctions on Earth, according to computer simulations.

Scientists used the simulations to model the paths of long-period comets, to determine the likelihood of these "dirty snowballs" striking our planet.

The University of Washington, Seattle, research appears in Science journal.

How many mass extinctions in Earth's history were caused by these icy bodies crashing into our planet has been a subject of considerable debate.

Many scientists agree that an asteroid strike 65 million years ago wiped out the dinosaurs. But there is uncertainty about how many other such events were triggered by asteroid or comet colliding with Earth.

Comets are composed of dust, rock, water ice and frozen gases. When their orbits bring them into close proximity with the Sun, parts of them warm up, causing material to sublimate (turn directly from a solid to a gas state) and form a "fuzzy" envelope around the comet nucleus.

Asteroids are distinguished from comets precisely because they lack this envelope, or "coma".

Comets 'acquitted'

Halley's comet - which reappears in our sky every 75 years - is described as "short period". This type of comet originates in a region of our Solar System called the Kuiper Belt.

So-called "long period" comets are thought to come from the more distant Oort Cloud. This is a large area of debris left over from the formation of the Solar System some 4.5 billion years ago.

The outer part of this Oort Cloud region was previously thought to be a source of long-period comets that pass close to Earth.

Their orbits are thought to change when they are nudged by the gravity of a nearby star. These events are thought to trigger an increase in the frequency of comets entering the inner Solar System - a phenomenon called "comet showers".

But simulations carried out by Nathan Kaib and co-author Thomas Quinn at the University of Washington in Seattle suggest the inner Oort Cloud could instead be a major source of the long-period comets crossing Earth's path.

This suggests many observable comets come from a different source than previously thought. But the findings also have implications for investigating the causes of mass extinctions.

The exact number of objects in the inner Oort Cloud is unknown. But by assuming the maximum possible number, the researchers showed that only two or three objects from this region should have struck our planet over the last 500 million years.

The gas giants Jupiter and Saturn act as a barrier, preventing most of them from hitting us. That point was reinforced recently when a huge scar appeared on Jupiter's surface, likely evidence of an impact.

A minor extinction event on Earth about 40 million years ago has been attributed to one of these comet showers. The University of Washington research suggests this was probably the most intense shower on record.

"That tells you that the most powerful comet showers caused minor extinctions and other showers should have been less severe, so comet showers are probably not likely causes of mass extinction events," said Mr Kaib.

http://news.bbc.co.uk/1/hi/sci/tech/8179895.stm

The common ancestor of humans, monkeys and apes may have originated in Asia

July 15th, 2009

(PhysOrg.com) -- The discovery of a new primate fossil in Myanmar (formerly Burma) lends weight to the hypothesis that the common ancestor of humans, monkeys and apes (anthropoid primates) originated in Asia, and not in Africa. To support the hypothesis, an international team of paleontologists, including two French researchers, has shown that these primates, which are 37 million years old and named Ganlea megacanina, had an ability observed today in modern monkeys, but not in lemurs: they pried open and ate seeds in a specific way by using their greatly enlarged canine teeth, like certain South American monkeys today. This ability is one of the reasons that justifies them being placed in the family of anthropoid primates.

This research is published in the journal Proceedings of the Royal Society B.

In primates, there exist two major lineages: anthropoid primates (monkeys, apes and humans) and prosimians, considered to be more primitive and whose best-known representatives today are lemurs. Until now, scientists assumed that anthropoid primates originated in Africa However, this hypothesis is now questioned.

Working together with several foreign colleagues, Laurent Marivaux, CNRS researcher at ISEM and Jean-Jacques Jaeger, professor at IPHEP, have for the past 20 years been carrying out paleontological excavations in Asia, specifically in China, Thailand, Pakistan and Myanmar (formerly Burma), where they started exploring in 1999, in close cooperation with Burmese academics. In November 2005, the researchers discovered several fossils in central Myanmar dating from 37 million years ago and belonging to a new species of primate named Ganlea megacanina. In November 2008, part of the lower jaw of one member of this species was discovered. This find provides the paleontologists with powerful evidence supporting an Asian origin for anthropoid primates.

The new primate has greatly enlarged canine teeth which show heavy abrasion, indicating that Ganlea megacanina used them to pry open the tough exteriors of tropical fruit in order to extract the nutritious seeds contained inside. This is an unusual form of feeding adaptation that has never been observed in prosimian primates such as lemurs. It is, however, characteristic of South American saki monkeys, which are members of the large family of anthropoid primates. "Ganlea megacanina shows that the first anthropoids originated in Asia rather than in Africa," Marivaux and Jaeger explain.

Ganlea and its closest relatives inhabited Myanmar 37 million years ago during the Eocene, in a tropical flood plain that was certainly very similar to the modern Amazon Basin. They belonged to an extinct family of Asian anthropoid primates, the Amphipithecidae. Four other amphipithecids had previously been discovered in Asia: two in Myanmar, one in Thailand and one in Pakistan. A detailed analysis of their evolutionary relationships shows that they are closely related to today's anthropoid primates, and that the Myanmar forms evolved from a single common ancestor.

These Asian anthropoid primates differ radically from adapiform primates such as 'Ida', the complete fossilized skeleton of a primate recently discovered in Germany. "'Ida' is closer to modern lemurs than to anthropoid primates. It hasn't developed the characteristics needed to become a highly specialized seed-eater," Marivaux points out.

More information: A new primate from the Eocene Pondaung Formation of Myanmar and the monophyly of Burmese amphipithecids. K. Christopher Beard, Laurent Marivaux, Yaowalak Chaimanee, Jean-Jacques Jaeger, Bernard Marandat, Paul Tafforeau, Aung Naing Soe, Soe Thura Tun and Aung Aung Kyaw. Proceedings of the Royal Society B. July 2009.

Provided by CNRS

http://www.physorg.com/news166891773.html

'Alien' lifeform wakened from 120,000 year Arctic slumber

[Why am I reminded of the Doctor Who story "The Seeds of Doom"? - Ed]

Meddling boffins refuse to heed sci-fi common sense

By Lewis Page • Get more from this author
Posted in Biology, 15th June 2009 09:52 GMT

American scientists, showing the reckless disregard for the warnings implicit in quality science fiction that is so regrettably common in the boffinry community, have revived an ancient lifeform which has been slumbering beneath the Arctic ice pack for 120,000 years. To add insult to injury, the scientists believe that their laboratory revenant may be related to indestructible super-aliens yet to be discovered on extraterrestrial iceworlds.

The creature in question is named Herminiimonas glaciei, and was revived from its aeons-long sleep by Dr Jennifer Loveland-Curtze and her colleagues from Pennsylvania State University. The purplish-brown, blobby entity was "coaxed back to life with great patience", according to Penn Uni.

The thinking is that if life can survive millennia of terrible cold beneath a glacier here on Earth, it might do so on other planets - perhaps here in the solar system, under the Martian or possible lunar icecaps.

"These extremely cold environments are the best analogues of possible extraterrestrial habitats", says Loveland-Curtze.

"The exceptionally low temperatures can preserve cells and nucleic acids for even millions of years... studying these bacteria can provide insights into how cells can survive and even grow under extremely harsh conditions, such as temperatures down to -56˚C, little oxygen, low nutrients, high pressure and limited space."

Loveland-Curtze believes that study of H Glacei in the lab can be done safely, as it is a micro-organism, rather than a huge, ravening blobomination type of affair. In fact, it's uncommonly small and puny even for a bacterium - 10 to 50 times smaller even than the well-known E Coli, and correspondingly more capable of worming its way in where it isn't wanted.

Loveland-Curtze assures us that H Glacei isn't a deadly pathogen like E Coli, however. Though she does sound a note of caution:

"It can pass through a 0.2 micron filter, which is the filter pore size commonly used in sterilization of fluids in laboratories and hospitals," she warns.

"If there are other ultra-small bacteria that are pathogens, then they could be present in solutions presumed to be sterile. In a clear solution very tiny cells might grow but not create the density sufficient to make the solution cloudy".

In summary, then, we're looking at an ancient lifeform - albeit tiny - recently wakened by meddling scientists from its hundred-thousand-year sleep beneath the polar icecap. It's capable of surviving, perhaps, in the most hostile alien interplanetary environments known to man. It can evade mankind's toughest lab sterilisation precautions.

Meanwhile humanity may be nearing its first attempt at a manned mission to Mars.

Coincidence? Or have the glacial supermicrobes, having long ago seeded Earth, merely been waiting for a vector species to arise and carry them onward to Mars for the next stage in their campaign of interplanetary conquest?

http://www.theregister.co.uk/2009/06/15/slumbering_arctic_alien/

Meteorites may have brought building blocks of life to Earth

A British research team suggests that a massive bombardment billions of years ago delivered enough water and carbon dioxide to create the conditions for life to form.

By John Johnson Jr.
June 7, 2009

A massive bombardment of meteorites billions of years ago could have brought in enough water and carbon dioxide to jump-start the chemistry that let the Earth develop into the garden spot of our solar system.

By studying meteorites and other evidence from this bombardment, a team of researchers at Imperial College in England has calculated that the meteorites could have carried in as much as 10 billion tons of water vapor and carbon dioxide to the young Earth every year for millions of years.

That amount of water and carbon dioxide would have been enough to set off a greenhouse effect that eventually made the Earth warm and wet enough to harbor plants and creatures.

This isn't the first time scientists have theorized that the ingredients for life on Earth could have been delivered. Comets and asteroids both have been proposed as carriers of water as well as organic compounds to Earth.

What distinguishes the new research, published in the earth and planetary science journal Geochimica et Cosmochimica Acta, is its suggestion of when and how the Earth received its shipment of life-giving material.


"The amount delivered in this bombardment alone was enough to kick-start the Earth on its way to habitability," study co-author Richard Court, an Imperial College London professor of Earth science and engineering, said in an e-mail message.

The incident at the heart of the study is known as the Late Heavy Bombardment, a time about 4 billion years ago, not long after the Earth was formed from the dust and debris swirling around the young sun. According to the scientists, the Late Heavy Bombardment lasted 20 million years and rained millions of space rocks onto the Earth, moon and Mars.

Because of the Earth's rapidly changing geology, evidence of this event was mostly lost, except for the leftover meteorites themselves. But the moon, with no atmosphere, has little erosion, allowing closer study of the bombardment period's effects on the lunar surface. Court said that at least 6,000 craters greater than 14 miles across remain from this period. On Earth, the bombardment might have produced 22,000 of these huge craters, he said.

According to the scientists' theory, the frictional heat of passing through the thin atmosphere that surrounded the Earth at that time would have been enough to strip the oxygen- and water-rich outer layers from the meteorites as they plunged toward the planet. That process would slowly have caused a buildup of oxygen and water in the atmosphere.

To find out how much of those critical compounds could be carried by each meteorite, the team used samples of ancient rocks left over from the bombardment, flash-heating them in the absence of oxygen to prevent combustion. The gases given off during the heating process were then measured.

The team found that, on average, the meteorites gave off as much as 12% of their masses as water and 6% as carbon dioxide, a potent greenhouse gas whose greater concentration in the atmosphere today is causing world temperatures to rise.

The atmosphere of the early Earth was so thin that it needed a lot of greenhouse gas to reach the point that it was thick enough to trap the sun's heat, allowing the Earth's surface to warm up and water to remain in liquid form over much of the planet.

Paul Warren, a planetary scientist at UCLA, said he was impressed by the British team's efforts to try to quantify the amount of water that could have been delivered by the Late Heavy Bombardment. But he said he's not convinced this one event could account for all the water on Earth.

He also said that far from giving life a running start, the bombardment could just as easily have caused "catastrophic heating" of the young planet's atmosphere.

"It actually could be an impediment to life," Warren said.

The British researchers believe Mars experienced the same unrelenting bombardment as the Earth. The Martian rovers Spirit and Opportunity have uncovered evidence that the Red Planet once featured standing seas and relatively mild weather. That ended billions of years ago. The Imperial College team believes the key difference between the planets' fates is the Earth's molten iron core, which allowed our planet to develop a magnetic field. That magnetic field prevents most harmful solar radiation from damaging the atmosphere.

Mars lost its magnetic shield long ago, allowing the atmosphere to be worn away by the sun's relentless radiation. Slowing of volcanic activity also cooled the planet, causing the water to retreat underground at the poles.

http://www.latimes.com/news/nationworld/nation/la-sci-meteor7-2009jun07,0,1408663.story

'Stunning' fossil goes on display

13:00 GMT, Tuesday, 26 May 2009 14:00 UK

A 47-million-year-old fossil is on display for one day only at London's Natural History Museum.

The lemur-like creature, nicknamed Ida, is claimed to be a "missing link" between today's higher primates - monkeys, apes and humans - and more distant relatives.

But some independent experts are sceptical of the claim.

http://news.bbc.co.uk/1/hi/sci/tech/8068503.stm

A new Twist in Megafauna History

Cave explorers recently discovered bones of large prehistoric creatures previously unknown to Minnesota.

By David Mather

The ladder quickly disappears into the darkness as I peer down the steel tube. This is the recently established safe entrance to Tyson Spring Cave, in the so-called driftless area of southeastern Minnesota. Cave explorer John Ackerman has purchased this patch of land, as well as a larger area of underground rights, to include the cave in his privately owned Minnesota Karst Preserve.

Despite a cool day, I'm starting to sweat as the sun hits my coveralls, wetsuit, and helmet. Ackerman tells me that it's 124 feet down to the cave floor. "You go first," he says, and I do.

My back bumps against the tube as I descend. My vision shrinks to the headlamp beam shining on my hands and the ladder rungs. My breathing echoes in my ears, but before long I can hear a trickle of water below. I pause to look up: The world I know is a tiny, white circle far above. A dozen rungs later, I step off the ladder and call up that I'm clear.

I stand on a gravel bar at the edge of an underground stream. The stream bends and falls, rushing over ledges and flowing through pools.

Ackerman soon joins me, followed by cave explorer Clay Kraus. We set off through the water, heading downstream. I stumble at times, uncertain of my footing. I wonder what I'm doing down here and then tell myself to shut up. I know the answer. I've come to see where the antler was found.

I first learned of Tyson Spring Cave several weeks before this visit. The explorers had found a large bone deep in the cave. Ackerman heard that I study animal bones and brought the specimen to my office at the Minnesota History Center. It was a thick section of antler, about 1.5 feet long, encrusted with mineralized sediment. A fragment of the skull was attached on one end. It definitely looked old, and I guessed it to be from an elk. But it was missing the classic lower tines of an elk antler.

As I wrote a brief report of the find, I had some incredible Internet-age luck. Searching the Illinois State Museum Web site for elk finds across North America, I found an online exhibit about ice age animals, including the extinct stag-moose (Cervalces scotti). I clicked on the link and nearly fell off my chair when I saw a picture of a stag-moose skull: It looked like a good possibility for the fragment from Tyson Spring Cave. Later, paleontologists at the Illinois State Museum examined the fragment and confirmed that it came from an ancient animal, probably Cervalces or another extinct moose species.

Minnesota is not known for discoveries of Pleistocene megafauna because most of this land was then covered by glacial ice. But the driftless area was untouched by the most recent Wisconsin glaciation, which ended about 12,000 years ago. The region's deeply dissected karst topography is a truly ancient landscape.

Ice age Minnesota was a different world that slowly grew into the one we know today. A vast array of creatures disappeared shortly after the last glaciers melted. They once ruled the land, and the karst's limestone caverns and underground riverbeds might now hold a scientific treasure trove of their bones.

First of Its Kind
The possible stag-moose antler isn't the only find from Tyson Spring Cave. Chris Widga, a paleontologist from the Illinois State Museum, visited the cave with Ackerman and Kraus after he received the antler for examination. Gently digging in the gravel near the underground streambed, they uncovered part of a large skull. The teeth and jaws were missing, but Widga knew immediately it was a big cat.

Widga suspected the bone could have been from an American lion, due to its large size. Being a cautious scientist, he took it to the University of Kansas to confer with fossil cat expert Larry Martin. The greater range of comparative specimens there allowed a secure identification but, to Widga's surprise, not as a lion. Tyson Spring Cave had yielded the state's first saber-tooth cat (Smilodon fatalis -- now that's a name with chilling poetry), an incredible scientific contribution to Minnesota's natural heritage.

And the story got better: Widga arranged for radiocarbon dating of a bone fragment from the saber-tooth skull. Astonishingly, the results indicated the cat died about 22,250 years ago. Widga said this was a time of a cold, dry climate, and the landscape would have been a steppe tundra with few trees. Herbivores included musk oxen, caribou, mammoths, and bison (larger than the modern species). Other predators might have included dire wolves and short-faced bears.

Skeletons of ice age animals are much better known from Kansas, Nebraska, and other states that were not covered by the most recent glacial advance. Rancho La Brea in Los Angeles is probably the most famous megafauna site in North America, and it holds the best samples of Smilodon. Closer to Minnesota, Pleistocene animal skeletons were found in an ancient sinkhole in Hot Springs, South Dakota. Both of those sites were natural traps. If the Tyson Spring bones came from a sinkhole as the explorers suspect, this cave could contain concentrations of ancient bones as well.

Pleistocene Boneyard
Despite the Pleistocene disadvantage of ice cover across most of Minnesota, a number of megafauna finds had occurred in other places prior to the ones at Tyson Spring Cave. A century ago the first director of the Geological and Natural History Survey of Minnesota, Newton Winchell, published a summary of discoveries known at that time. He described a mammoth tooth found in glacial gravels along the Mississippi River at Wabasha. Surprisingly, he also noted remains of ancient elephants found during early construction work around Minnesota's towns and cities: Stillwater, Northfield, Minneapolis, Minnetonka, Hastings, Mankato, and elsewhere. Bones of the extinct giant beaver (Castoroides ohioensis) were unearthed in Minneapolis in 1879, while a cistern was being dug at the corner of 15th and Washington avenues. Winchell also described bones of musk oxen. These are not an extinct species, but today they live in the arctic, far from Minnesota.

University of Minnesota geologist Clinton Stauffer presented the next summary of Minnesota megafauna in 1945, in the Proceedings of the Minnesota Academy of Science. He elaborated on some of the finds mentioned by Winchell, but the species list didn't change much. One addition was an ancient horse bone discovered 31 feet underground by a well driller in Marshall. Interestingly, Stauffer also mentioned a few discoveries of mammoth and mastodon from northern Minnesota -- near Brainerd, Chisholm, Deer River, Ball Club, and Grand Rapids. This was unexpected, because the north was covered by glaciers until around the time that most megafauna became extinct.

Across the Great Plains and Midwest, bison were the only species of ice age megafauna to survive the Pleistocene extinctions. The size of these ancient animals decreased throughout the past 12,000 years, culminating in much smaller modern bison. Ancient bison bones are not uncommon in Minnesota, often preserved in peat. A few of these finds are archaeological sites, where the animals were killed and butchered by people. The bison kill site in Itasca State Park is a scientific treasure itself, dating to about 8,000 years ago. The bog where the animals were trapped can be seen along Wilderness Drive. DNR archaeologist Dave Radford says that this is the only documented case of megafauna bones being found in Minnesota state parks.

Still Uncovering Mysteries
Bruce Erickson, chair of Paleontology at the Science Museum of Minnesota, has firsthand knowledge of the megafauna relics in the museum's exhibits and collection vaults. There are skulls of giant beavers and musk oxen. A single claw from a giant ground sloth (Megalonyx jeffersoni) is incredibly well-preserved, with its fragile outer sheath intact. Found in a peat bog in the Twin Cities, the 9-inch-long claw belonged to a huge, lumbering animal. It is Minnesota's only known sloth specimen.

One of the most complete skeletons of giant beaver known anywhere was found in St. Paul in 1938. A work crew was clearing away a collapsed shelf of Platteville limestone at Hidden Falls along the Mississippi and discovered the Castoroides skeleton along with bones from the modern species of beaver.

Erickson undertook a new analysis of this skeleton in the early 1960s, because the rare bones of the feet had not been properly described in earlier reports. Radiocarbon dating revealed that the beaver died about 10,300 years ago. The circumstances of the find indicate that Castoroides coexisted with modern beavers at that time. Erickson estimated that the animal might have weighed 250 pounds. It was not fully grown, as the ends of the longbones had not completely fused. Paleontologists suggest that an adult giant beaver would have been similar in size to a present-day black bear.

The Hidden Falls giant beaver is on display in the Mississippi River gallery at the Science Museum. It looks across at the Hollandale mammoth, the most complete woolly mammoth skeleton known from Minnesota. Downstairs in the paleontology laboratory, volunteers are removing the plaster field jackets from bones of the Lyle mammoth, a major discovery that is yet to be fully examined. These two mammoths were found relatively close to one another, in the vicinity of Albert Lea and Austin.

Back to the Cave
My headlamp goes out as I follow Ackerman and Kraus on our exit hike from Tyson Spring Cave. Ackerman notices and trades helmets with me. The trip back upstream doesn't seem nearly as long. I'm second up the ladder.

Wrestling my way out of the loaned caving gear in the sunlight, I laugh when Kraus emerges saying that he found another bone near the bottom of the ladder. But he's not kidding. The bone is small and stained black. It looks old. Its ends are rough, suggesting that the animal was young when it died. The shape is similar to a radius (forearm bone) from a large mammal, but it is tiny.

Small bones like this one hint at further possibilities that could fill out the picture of this ancient world. Widga has wondered if small bones found near the saber-tooth skull could be from saber-tooth kittens, although he stresses that more study is needed to determine if that's the case.

Tyson Spring Cave has produced two major discoveries -- two Minnesota firsts -- before an organized search has even begun. Just imagine what other discoveries might await.

New discoveries
Fillmore County's Tyson Spring Cave is one of several located within the privately owned Minnesota Karst Preserve. Nearly 100 bones have been unearthed at the preserve since the initial finds discussed in this story. Southeastern Minnesota's caves may hold a new chapter in what scientists know about Minnesota's natural history during the ice age. Though the region's caves are a promising area for future paleontological research, scientists must brave wet, dark conditions and take care not to damage the fragile geology.

http://www.dnr.state.mn.us/volunteer/marapr09/megafauna_history.html

Scientists hail stunning fossil

14:35 GMT, Tuesday, 19 May 2009 15:35 UK

By Christine McGourty
Science correspondent, BBC News

The beautifully preserved remains of a 47-million-year-old, lemur-like creature have been unveiled in the US.

The preservation is so good, it is possible to see the outline of its fur and even traces of its last meal.

The fossil, nicknamed Ida, is claimed to be a "missing link" between today's higher primates - monkeys, apes and humans - and more distant relatives.

But some independent experts, awaiting an opportunity to see the new fossil, are sceptical of the claim.

And they have been critical of the hype surrounding the presentation of Ida.

The fossil was launched amid great fanfare at the American Museum of Natural History in New York, by the city's mayor.

Although details of the fossil have only just been published in a scientific journal - PLoS One - there is already a TV documentary and book tie-in.

Ida was discovered in the 1980s in a fossil treasure-trove called Messel Pit, near Darmstadt in Germany. For much of the intervening period, it has been in a private collection.

The investigation of the fossil's significance was led by Jorn Hurum of the Natural History Museum in Oslo, Norway.

He said the fossil creature was "the closest thing we can get to a direct ancestor" and described the discovery as "a dream come true".

The female animal lived during an epoch in Earth history known as the Eocene, which was crucial for the development of early primates - and at first glance, Ida resembles a lemur.

But the creature lacks primitive features such as a so-called "toothcomb", a specialised feature in which the lower incisor and canine teeth are elongated, crowded together and projecting forward. She also lacks a special claw used for grooming.

The team concluded that she was not simply another lemur, but a new species. They have called her Darwinius masillae, to celebrate her place of origin and the bicentenary of the birth of Charles Darwin.

Dr Jens Franzen, an expert on the Messel Pit and a member of the team, described Ida as "like the Eighth Wonder of the World", because of the extraordinary completeness of the skeleton.

It was information "palaeontologists can normally only dream of", he said.

In addition, Ida bears "a close resemblance to ourselves" he said, with nails instead of claws, a grasping hand and an opposable thumb - like humans and some other primates. But he said some aspects of the teeth indicate she is not a direct ancestor - more of an "aunt" than a "grandmother".

"She belongs to the group from which higher primates and human beings developed but my impression is she is not on the direct line."

Independent experts are keen to see the new fossil but somewhat sceptical of any claim that it could be "a missing link".

Dr Henry Gee, a senior editor at the journal Nature, said the term itself was misleading and that the scientific community would need to evaluate its significance.

"It's extremely nice to have a new find and it will be well-studied," he said. But he added that it was not likely to be in the same league as major discoveries such as "Flores man" or feathered dinosaurs.

Dr Chris Beard, curator of the Carnegie Museum of Natural History and author of The Hunt for the Dawn Monkey, said he was "awestruck" by the publicity machine surrounding the new fossil.

He argued that it could damage the popularisation of science if the creature was not all that it was hyped up to be.

Dr Beard has not yet seen scientific details of the find but said that it would be very nice to have a beautiful new fossil from the Eocene and that Ida would be "a welcome new addition" to the world of early primates.

But he added: "I would be absolutely dumbfounded if it turns out to be a potential ancestor to humans."

In the PLoS paper itself, the scientists do not actually claim the specimen represents a direct ancestor to us. But Dr Hurum believes that is exactly what Ida is.

He told BBC News that the key to proving this lay in the detail of the foot. The shape of a bone in the foot called the talus looks "almost anthropoid".

He said the team was now planning a 3D reconstruction of the foot which would prove this.

"We're not finished with this specimen yet," said Dr Hurum. "There will be plenty more papers coming out."

More videos at: http://news.bbc.co.uk/1/hi/sci/tech/8057465.stm

Earliest animal traces solve time-gap mystery

17:07 11 May 2009 by Jeff Hecht

Meet the ancestors: blobs of gelatinous goo that were some of the first animals on Earth.

The fossil traces have been discovered in Canadian rocks some 850 million years old – potentially solving a major problem for the origin of animal life.

And going back in time another two billion years, evidence of the earliest known cave-dwelling organisms are offering a glimpse of how life left the seas and conquered the continents.

Ancient traces

The previous oldest animal fossils date from "only" 650 million years ago, although "molecular clocks" based on rates of genetic divergence indicate that animals should have originated about 850 million years ago. The new findings may therefore help solve the problem of the 200 million-year-gap.

Palaeontologists have looked long and hard for traces left by the first multi-celled organisms, fully aware that the soft-bodies might have left very few fossils.

The breakthrough came when Elizabeth Turner, of Laurentian University in Sudbury, Ontario, spotted odd patterns in the rocks of 850-million-year-old limestone reefs in the Mackenzie Mountains of Canada's Northwestern territory, and has spent the last 15 years, with Fritz Neuweiler of University Laval in Quebec, trying to deduce their origin.

Now Turner and Neuweiler, along with David Burdige of Old Dominion University in Virginia, have shown that the patterns match the distinctive textures found in reefs built by sponges.

Read full article at: http://www.newscientist.com/article/dn17105-earliest-animal-traces-solve-timegap-mystery.html

New theory on largest known mass extinction in the history of the earth

Did volatile halogenated gases from giant salt lakes at the end of the Permian Age lead to a mass extinction of species?

Leipzig/Heidelberg. The largest mass extinction in the history of the earth could have been triggered off by giant salt lakes, whose emissions of halogenated gases changed the atmospheric composition so dramatically that vegetation was irretrievably damaged. At least that is what an international team of scientists have reported in the most recent edition of the "Proceedings of the Russian Academy of Sciences". At the Permian/Triassic boundary, 250 million years ago about 90 percent of the animal and plant species ashore became extinct. Previously it was thought that volcanic eruptions, the impacts of asteroids, or methane hydrate were instigating causes. The new theory is based on a comparison with today’s biochemical and atmospheric chemical processes. "Our calculations show that airborne pollutants from giant salt lakes like the Zechstein Sea must have had catastrophic effects at that time", states co-author Dr. Ludwig Weißflog from the Helmholtz-Center for Environmental Research (UFZ). Forecasts predict an increase in the surface areas of deserts and salt lakes due to climate change. That is why the researchers expect that the effects of these halogenated gases will equally increase.

The team of researchers from Russia, Austria, South Africa and Germany investigated whether a process that has been taking place since primordial times on earth could have led to global mass extinctions, particularly at the end of the Permian. The starting point for this theory was their discovery in the south of Russia and South Africa that microbial processes in present-day salt lakes naturally produce and emit highly volatile halocarbons such as chloroform, trichloroethene, and tetrachloroethene. They transcribed these findings to the Zechstein Sea, which about 250 million years ago in the Permian Age, was situated about where present day Central Europe is. The Zechstein Sea with a total surface area of around 600.000 km2 was almost as large as France is today. The hyper saline flat sea at that time was exposed to a predominantly dry continental desert climate and intensive solar radiation - like today’s salt seas. "Consequently, we assume that the climatic, geo-chemical and microbial conditions in the area of the Zechstein Sea were comparable with those of the present day salt seas that we investigated," Weißflog said.

In their current publication the authors explain the similarities between the complex processes of the CO2-cycle in the Permian Age as well as between global warming from that time and at present. Based on comparable calculations from halogenated gas emissions in the atmosphere from present-day salt seas in the south of Russia, the scientists calculated that from the Zechstein Sea alone an annual VHC emissions rate of at least 1.3 million tonnes of trichloroethene, 1.3 million tonnes of tetrachloroethene, 1.1 million tonnes of chloroform as well as 0.050 million tonnes of methyl chloroform can be assumed. By comparison, the annual global industrial emissions of trichloroethene and tetrachloroethene amount to only about 20 percent of that respectively, and only about 5 percent of the chloroform from the emissions calculated for the Zechstein Sea by the scientists. Incidentally, the industrial production of methyl chloroform, which depletes the ozone layer, has been banned since 1987 by regulation of the Montreal Protocol.

"Using steppe plant species we were able to prove that halogenated gases contribute to speeding up desertification: The combination of stress induced by dryness and the simultaneous chemical stressor `halogenated hydrocarbons´ disproportionately damages and destabilize the plants and speeds up the process of erosion," Dr. Karsten Kotte from the University of Heidelberg explained.

Based on both of these findings the researchers were able to form their new hypothesis: At the end of the Permian Age the emissions of halogenated gases from the Zechstein Sea and other salt seas were responsible in a complex chain of events for the world’s largest mass extinction in the history of the earth, in which about 90 percent of the animal and plant species of that time became extinct.

According to the forecast from the International Panel on Climate Change (IPCC), increasing temperatures and aridity due to climate change will also speed up desertification, increasing with it the number and surface area of salt seas, salt lagoons and salt marshlands. Moreover, this will then lead to an increase in naturally formed halogenated gases. The phytotoxic effects of these substances become intensified in conjunction with other atmospheric pollutants and at the same time increasing dryness and exponentiate the eco-toxicological consequences of climate change.

The new theory could be like a jigsaw piece that contributes to solving the puzzle of the largest mass extinction in the history of the earth. "The question as to whether the halogenated gases from the giant salt lakes alone were responsible for it or whether it was a combination of various factors with volcanic eruptions, the impact of asteroids, or methane hydrate equally playing their role still remains unanswered," Ludwig Weißflog said. What is fact however is that the effects of salt seas were previously underestimated. In their publication the researchers working with Dr. Ludwig Weißflog from the UFZ and Dr. Karsten Kotte from the University of Heidelberg want to prove that recent salt lakes and salt deserts of south-east Europe, Middle Asia, Australia, Africa, America can not only influence the regional but also the global climate. The new findings on the effects of these halogenated gases are important for revising climate models, which form the basis for climate forecasts.

Tilo Arnhold

http://www.ufz.de/index.php?en=17896

Life could have survived Earth's early pounding

10 March 2009 by Jeff Hecht

Microbes living deep underground could have survived the massive barrage of impacts that blasted the Earth 3.9 billion years ago, according to a new analysis. That means that today's life might be descended from microbes that arose as far back as 4.4 billion years ago, when the oceans formed.

Around 3.9 billion years ago, shifts in the orbits of the gas giant planets are thought to have disrupted other objects in the solar system, sending many hurtling into the inner planets. Geologists call that time the Hadean Eon, and thought its fiery hell of impacts would have sterilised the Earth.

But a new study by Oleg Abramov and Steve Mojzsis of the University of Colorado in Boulder suggests hardy life-forms could have survived if they were buried underground. They will report the results on 23 March at the Lunar and Planetary Science Conference in Texas.

Full story at: http://www.newscientist.com/article/dn16733-life-could-have-survived-earths-early-pounding.html