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Whales in the desert: Fossil bonanza poses mystery

More than 2 million years ago, scores of whales congregating off the Pacific Coast of South America mysteriously met their end.

A paleontologist from the museum prepares a whale fossil at the site where many prehistoric whale fossils were discovered in the Atacama desert near Copiapo, Chile. The fossil is enclosed in a plaster jacket to protect it during transport back to the museum. More than 2 million years ago, scores of whales congregating off the Pacific Coast of South America mysteriously met their end. Maybe they became disoriented and beached themselves. Maybe they were trapped in a lagoon by a landslide or a ferocious storm. Maybe they died there over a period of a few millennia. But somehow, they ended up right next to one another, many just several yards (meters) apart, entombed over the ages as the shallow sea floor was driven upward by geologic forces and transformed into the driest place on the planet. Today, the whales have emerged again atop a desert hill more than half a mile (a kilometer) from the surf, where researchers have begun to unearth one of the world's best-preserved graveyards of prehistoric whales [Credit: AP Photo/Museo Paleontologico de Caldera]

Maybe they became disoriented and beached themselves. Maybe they were trapped in a lagoon by a landslide or a storm. Maybe they died there over a period of a few millennia. But somehow, they ended up right next to one another, many just meters (yards) apart, entombed as the shallow sea floor was driven upward by geological forces and transformed into the driest place on the planet.

Today, they have emerged again atop a desert hill more than a kilometer (half a mile) from the surf, where researchers have begun to unearth one of the world's best-preserved graveyards of prehistoric whales.

Chilean scientists together with researchers from the Smithsonian Institution are studying how these whales, many of the them the size of buses, wound up in the same corner of the Atacama Desert.

"That's the top question," said Mario Suarez, director of the Paleontological Museum in the nearby town of Caldera, about 700 kilometers (440 miles) north of Santiago, the Chilean capital.

Experts say other groups of prehistoric whales have been found together in Peru and Egypt, but the Chilean fossils stand out for their staggering number and beautifully preserved bones. More than 75 whales have been discovered so far — including more than 20 perfectly intact skeletons.

They provide a snapshot of sea life at the time, and even include what might have been a family group: two adult whales with a juvenile between them.

"I think they died more or less at the same time," said Nicholas Pyenson, curator of fossil marine mammals at the Smithsonian's National Museum of Natural History. Pyenson and Suarez are jointly leading the research.

As for why such a great number perished in the same place, Pyenson said: "There are many ways that whales could die, and we're still testing all those different hypotheses."

A prehistoric whale fossil lies in the Atacama desert near Copiapo, Chile. More than 2 million years ago, scores of whales congregating off the Pacific Coast of South America mysteriously met their end. Maybe they became disoriented and beached themselves. Maybe they were trapped in a lagoon by a landslide or a ferocious storm. Maybe they died there over a period of a few millennia. But somehow, they ended up right next to one another, many just several yards (meters) apart, entombed over the ages as the shallow sea floor was driven upward by geologic forces and transformed into the driest place on the planet. Today, the whales have emerged again atop a desert hill more than half a mile (a kilometer) from the surf, where researchers have begun to unearth one of the world's best-preserved graveyards of prehistoric whales [Credit: AP Photo/Museo Paleontologico de Caldera]

The scientists have yet to publish their findings about the fossil bed and the extensive remains, which began to emerge in June last year during a highway-widening project that is now on hold.

So far, the fossils have been found in a roadside strip the length of two football fields — about 240 meters (260 yards) long and 20 meters (yards) wide.

Pyenson said the spot was once a "lagoon-like environment" and that the whales probably died between 2 million and 7 million years ago.

Most of the fossils are baleen whales that measured about 8 meters (25 feet) long, Pyenson said.

The researchers also discovered a sperm whale skeleton and remains of a now-extinct dolphin that had two walrus-like tusks and previously had only turned up in Peru, he said.

"We're very excited about that," Pyenson said in a telephone interview. "It is a very bizarre animal."

Other unusual creatures found elsewhere in the fossil-rich Atacama Desert include an extinct aquatic sloth and a seabird with a 5-meter (17-foot) wingspan, bigger than a condor's.

Erich Fitzgerald, a vertebrate paleontologist at Museum Victoria in Melbourne, Australia, emailed that the latest find is very significant.

"The fossils are exceptionally well preserved and quite complete — a rare combination in paleontology and one that will likely shed light on many facets of the ... ecology and evolution of these extinct species," Fitzgerald said.

He said it's possible "these fossilized remains may have accumulated over a relatively long period of time."

Hans Thewissen, an expert on early whales, agreed. Another scenario, he said, is that the whales might have gathered in a lagoon and then an earthquake or storm could have closed off the outlet to the ocean.

Researchers from the museum work at the site where prehistoric whale fossils were discovered in the Atacama desert near Copiapo, Chile. More than 2 million years ago, scores of whales congregating off the Pacific Coast of South America mysteriously met their end. Maybe they became disoriented and beached themselves. Maybe they were trapped in a lagoon by a landslide or a ferocious storm. Maybe they died there over a period of a few millennia. But somehow, they ended up right next to one another, many just several yards (meters) apart, entombed over the ages as the shallow sea floor was driven upward by geologic forces and transformed into the driest place on the planet. Today, the whales have emerged again atop a desert hill more than half a mile (a kilometer) from the surf, where researchers have begun to unearth one of the world's best-preserved graveyards of prehistoric whales [Credit: AP Photo/Museo Paleontologico de Caldera]

"Subsequently the lagoon dries up and the whales die," said Thewissen, a professor of anatomy at Northeast Ohio Medical University. He said the accumulation of so many complete skeletons is "a very unusual situation."

"If this were a lagoon that dried up, you might see signs that ocean water evaporated," such as crystallized salt and gypsum in the rock, said Thewissen, who is not involved in the research. "On the other hand, if a giant wave or storm flung the whales onto shore, it would also have pushed the ocean floor around, and you would see scour marks in the rocks."

Dating fossils is complicated, experts said, and it will be very hard to distinguish dates precisely enough to determine whether the whales all died simultaneously.

The researchers have been told to finish their onsite studies so that fossils can be moved out of the path of the widened Pan American Highway, or Route 5, which is Chile's main north-south road.

Many of the fossils have been transported in plaster coverings to the museum in Caldera. Researchers from Chile's National Museum of Natural History are also studying the fossils.

Pyenson and his team are working quickly under tents to document the intact skeletons. With funding from the National Geographic Society, the Smithsonian team is using sophisticated photography and laser scanners to capture 3D images of the whales that can later be used to make life-sized models of them.

Suarez, the paleontologist, had long known about the whale bones just north of Caldera — they could be seen jutting out of the sandstone ridge alongside the highway at the spot known as Cerro Ballena, or Whale Hill. When the road work began last year, the construction company asked him to monitor the job to avoid destroying fossils.

"In the first week, about six or seven whales appeared," Suarez said. "We realized that it was a truly extraordinary site."

The Chilean government has declared the site a protected zone, and Pyenson said he hopes a museum will be built to showcase the intact skeletons where they lie, in the same way fossils are displayed at Dinosaur National Monument in Utah and Colorado.

Suarez thinks there are probably fossils of hundreds of whales waiting to be uncovered — enough to keep him working at this one spot for the rest of his life.

"We have a unique opportunity to develop a great scientific project and make a great contribution to science," he said.

Author: Eva Vergara | Source: Associated Press [November 19, 2011]

More on Prehistoric whales exposed in Chilean fossil bed

Scientists from Chile and the Smithsonian Institution have been working to protect a huge collection of whale fossils found in the Atacama desert.

A prehistoric whale fossil lays in the Atacama desert near Copiapo, Chile. More than 2 million years ago, scores of whales congregating off the Pacific Coast of South America mysteriously met their end. Maybe they became disoriented and beached themselves. Maybe they were trapped in a lagoon by a landslide or a ferocious storm. Maybe they died there over a period of a few millennia. But somehow, they ended up right next to one another, many just several yards (meters) apart, entombed over the ages as the shallow sea floor was driven upward by geologic forces and transformed into the driest place on the planet. Today, the whales have emerged again atop a desert hill more than half a mile (a kilometer) from the surf, where researchers have begun to unearth one of the world's best-preserved graveyards of prehistoric whales [Credit: AP/Museo Paleontologico de Caldera]

Those involved in the project say about 80 whales have been preserved in sedimentary rock, and that many of the fossils are completely preserved, including a family group that appears to be a mother, father and baby whale.

The area outside the town of Bahia Inglesa has long been called "Whale Hill" by locals, and was about to be paved over in a coastal highway expansion until paleontologist Mario Suarez persuaded his government to recover the bones first.

The government now plans to build a new museum to house what appears to be an amazing collection.

Source: Associated Press [November 17, 2011]

Antarctica's ghost mountains give up their secrets

The birth of the Gamburtsev Subglacial Mountains buried beneath the vast East Antarctic Ice Sheet – a puzzle mystifying scientists since their first discovery in 1958 – is finally solved. The remarkably long geological history explains the formation of the mountain range in the least explored frontier on Earth and where the Antarctic Ice Sheet first formed. The findings are published this week in the journal Nature.

While these ridges poke through Antarctica's frosty surface, the Gamburtsev mountains are completely hidden beneath three kilometres of ice [Credit: Mark Baker/Reuters]

A seven-nation team of scientists explored the Gamburtsev Subglacial Mountains - buried beneath up to 3km of ice – during the International Polar Year (2007- 09) by using two twin-engine aircraft equipped with ice penetrating radars, gravity meters and magnetometers.

By analyzing the new data, the researchers describe the extraordinary processes – which took place over the last billion years – that created and preserved a root beneath the mountains and the East Antarctic rift system – a 3,000km long fracture in the earth's surface that extends from East Antarctica across the ocean to India.

One billion years ago, before animals and plants evolved on Earth, several continents (or micro-continents) collided, crushing the oldest rocks of the mountain range together. This event formed a thick crustal root extending deep beneath the mountain range. Over time these ancient mountains were eroded but the cold dense root was left behind.

Three dimensional perspective of the Gamburtsev Subglacial Mountains, including a view of the deep root imaged beneath the range and of the thinner crust of the East Antarctic Rift System that surrounds the mountains [Credit: British Antarctic Survey]

Around 250-100 million years ago – when dinosaurs walked the Earth – rifting paved the way for the supercontinent Gondwana to break apart, which included Antarctica, causing the old crustal root to warm. This rejuvenated crustal root, together with the East Antarctic Rift forced the land upwards again reforming the mountains. Rivers and glaciers carved deep valleys and this helped uplift the peaks to create the spectacular landscape of the Gamburtsevs, which resemble the European Alps. The East Antarctic Ice Sheet, which formed 34 million years ago and covers 10 million km² of our planet (an area the size of Canada), protected the mountains from erosion.

Lead author, Dr Fausto Ferraccioli from British Antarctic Survey says:

"Understanding the origin of the Gamburtsevs was a primary goal of our International Polar Year expedition. It was fascinating to find that the East Antarctic rift system resembles one of the geological wonders of the world – the East African rift system – and that it provides the missing piece of the puzzle that helps explain the Gamburtsev Subglacial Mountains. The rift system was also found to contain the largest subglacial lakes in Antarctica."

Co-author, Dr Carol Finn from US Geological Survey says:

"Resolving the contradiction of the Gamburtsev high elevation and youthful Alpine topography but location on the East Antarctic craton by piecing together the billion year history of the region was exciting and challenging. We are accustomed to thinking that mountain building relates to a single tectonic event, rather than sequences of events. The lesson we learned about multiple events forming the Gamburtsevs may inform studies of the history of other mountain belts."

Co-author, Dr Robin Bell of Columbia University's Lamont-Doherty Earth Observatory says:

"The next steps will be to assemble a team to drill through the ice into the mountains to obtain the first rock samples from the Gamburtsevs. Amazingly, we have samples of the moon but none of the Gamburtsevs. With these rock samples we will be able to constrain when this ancient piece of crust was rejuvenated and grew to a magnificent mountain range."

"It is very fitting that the initial results of Antarctica's Gamburtsev Province (AGAP) project are coming out 100 years after the great explorers raced to the South Pole," said Alexandra Isern, Programme Director at the National Science Foundation. "The scientific explorers of the AGAP project worked in harsh conditions to collect the data and detailed images of this major mountain range under the East Antarctic Ice Sheet. The results of their work will guide research in this region for many years to come."

These discoveries in central East Antarctica have significant implications for understanding mountain building and ice sheet evolution within continental interiors.

Source: British Antarctic Survey [November 16, 2011]

Nest full of baby dinosaurs discovered

A 70-million-year-old nest of the dinosaur Protoceratops andrewsi has been found with evidence that 15 juveniles were once inside it, according to a paper in the latest Journal of Paleontology.

The dinosaur remains in the nest. Researchers believe sand entombed the dinosaur family while the members were still alive [Credit: Dr. Kh. Tsogtbaatar]

While large numbers of eggs have been associated with other dinosaurs, such as the meat-eating Oviraptor or certain duck-billed hadrosaurs, finding multiple juveniles in the same dino nest is quite rare.

"I, for one, cannot think of another dinosaur specimen that preserves 15 juveniles at its nest in this way," lead author David Fastovsky told Discovery News.

Fastovsky, who is chair of the University of Rhode Island’s Department of Geosciences, and his colleagues analyzed the dinosaur remains along with the nest, which measured about 2.3 feet in diameter and was round and bowl-shaped. All were found at Djadochta Formation, Tugrikinshire, Mongolia, where it's believed sand “rapidly overwhelmed and entombed” the youngsters while they were still alive.

The researchers conclude that the 15 dinosaurs all show juvenile characteristics. These include short snouts, proportionately large eyes, and an absence of adult characteristics, such as the prominent horns and large frills associated with adults of this species. At least 10 of the 15 fossil sets are complete.

The nest and its contents imply that Protoceratops juveniles remained and grew in their nest during at least the early stages of postnatal development. The nest further implies that parental care was provided.

The large number of offspring, however, also suggests that juvenile dinosaur mortality was high, not only from predation, but also from a potentially stressful environment.

"Large clutches may have been a way of ensuring survival of the animals in that setting -- even if there was extensive parental care," Fastovsky said. "Mongolia was, at the time, a place with a variety of theropod dinosaurs, some of whom likely ate babies such as these."

"The most obvious of these, found in the same deposits, is the (in)famous Velociraptor, a smallish nasty theropod with bad breath, for whom babies such as these would have made a nice bon bon," he continued.

Yet another discovery previously found at the same locality is the famous "fighting dinosaurs" specimen in which a Protoceratops and Velociraptor appear to have been preserved together "locked in what was evidently mortal combat," Fastovsky added. Parents and other adults of the sheep-sized herbivorous species may then have spent much of their time fighting off such hungry predators.

In a separate study, Lars Schmitz of the UC Davis Department of Evolution and Ecology, and colleagues studied bones surrounding what would have been the eyes of Protoceratops and other dinosaurs. The results allowed Schmitz and his team to conclude that this dinosaur and additional plant eaters were active both day and night. Velociraptor, on the other hand, was primarily a nocturnal carnivore, so night raids on Protoceratops nests must have taken place during the Late Cretaceous.

Even if the juvenile dinosaurs and their parents "had a good sensory system to notice a predator closing in, the success rate of a nocturnal attack may be higher than a diurnal attack," Schmitz told Discovery News.

Given the chances then of literally biting the (sand) dust or becoming dinner, it’s no wonder that some small dinosaurs had so many kids.

"This story certainly isn't your parents' dinosaurs-living-in-the-lush-Cretaceous-steaming-jungles that was in vogue a generation or two ago," Fastovsky said. "We now know that dinosaurs lived everywhere and did just about everything terrestrial."

The nest and its dinosaur family contents are currently housed at the Paleontological Center of the Mongolian Academy of Sciences, Ulan Baatar, Mongolia.

Author: ennifer Viegas | Source: Discovery News [November 16, 2011]

New fossils of oldest American primate found

Johns Hopkins researchers have identified the first ankle and toe bone fossils from the earliest North American true primate, which they say suggests that our earliest forerunners may have dwelled or moved primarily in trees, like modern day lemurs and similar mammals.

Magnified images reveal the fine tooth structure of Teilhardina magnoliana, a newly discovered species believed to be the oldest known primate in North America. The tiny, 55-million-year-old creature raises the controversial possibility that primates arrived in the Americas thousands of years before they reached Europe, according to the fossils' discoverer [Credit: PNAS/National Academy of Sciences (copyright 2008)]

Previous excavations have yielded pieces of the jaw and teeth of Teilhardina, primates that first appeared just after the beginning of the Eocene Epoch about 55.5 million years ago. In a report on their analysis of the fossils, published in the October issue of the American Journal of Physical Anthropology, the Johns Hopkins team said they identified the latest bones when they went prospecting for evidence of the earliest Eocene mammals in the badlands of the Bighorn Basin, Wyoming, an area rich in fossils. The primate fossils were discovered in strata—bands of stratified earth —dating to the beginning of the Eocene Epoch.

“Living primates have nails on all or most of their toes and fingers, and they don’t occur in any other animal in exactly the same way,” says Ken Rose, Ph.D., professor of anatomy in the Center for Functional Anatomy and Evolution at the Johns Hopkins University School of Medicine. “The fossil toes we found have morphology [shape and form] indicating the presence of nails rather than claws, making our discovery the oldest evidence of nails found in primitive primates so far. “

The researchers noticed the ankle bone fossils were elongated, which is a characteristic of present-day prosimian (non-monkey or ape) primates that do a lot of jumping. The neck of the talus — one of the ankle bones — is relatively longer in Teilhardina than it is in present day lemurs, which move about by leaping from tree to tree, says Rose. Unfortunately the talus specimen was damaged and a total measurement can’t be taken for exact comparisons. However, another ankle bone, the navicular, is also elongated and the researchers were able to quantify its measurements.

Prior excavations in the same region revealed fossils of early relatives of horses, carnivores and rodents, as well as Teilhardina. The researchers screened through hundreds of pounds of sedimentary rock, reducing it to fine-grained concentrate, which was transported back to the lab for examination under the microscope. Some early primate teeth specimens are known to be many times smaller than a grain of rice and only appear as specks to the human eye. Under the microscope, the researchers discovered not only teeth and jawbones from Teilhardina as before, but also three fossilized toe bones and three ankle bones, which Rose says are the first found in North America. The bones were relatively free of attached sediment and appeared smooth and dark — due to the type of minerals accumulated during fossilization — against the gray, fine-grained sediment. Although toe bones are quite variable among species, Rose says, these particular primate specimens are highly distinctive to a trained anatomist.

Close examination of the tips of the toe bones revealed a widened, expanded arrow-shaped region characteristic of flat finger or toe nails, rather than claws. One of the toe bones was larger than the other two proportionally, and the research team proposed that this one was from the big toe or thumb.

Ancestors of Teilhardina originally had claws—hooked, narrow nail beds found on many land animals like cats or birds. One of the distinguishing factors of primates was that they evolved finger and toe nails, with wide nail beds, like those found in humans and apes.

Analysis of the intact navicular ankle bone involved a calculation known as the navicular index that takes into account the proportion of the length to the width of the bone. Teilhardina has a relatively elongated navicular bone with an index of 165 units, similar to those of lemurs which are less than 162 units. But the Teilhardina navicular bone is significantly shorter than those found in bush babies (between 300 to 500 units) and tarsiers (between 400 to 600 units). The modern lemurs are known leapers, while the bush babies and tarsiers are exceptional leapers that can jump up to six and a half feet. The numbers suggest that Teilhardina moved actively through the trees and was capable of some leaping, says Rose.

The leaping capabilities make Teilhardina most likely a tree-dweller too, says Rose, which is an incredibly different habitat than the badlands of Wyoming today, which are dry and rocky with little vegetation. These creatures lived during a period of global warming, when subtropical climates and vegetation stretched all the way to the Arctic Circle, explains Rose.

Rose says Teilhardina was most likely similar in appearance to modern-day bush babies — small primates with big eyes, strong back legs and long tails. But he estimates that the Teilhardina were smaller, only weighing about three or four ounces — about the size of the smallest living primates, mouse lemurs.

“Research on early primates gives us more evidence of our origins and our place in nature, with this particular study highlighting the oldest known member of our group from North America,” says Rose.

Source: Johns Hopkins University [November 16, 2011]

Sunken islands could cause tectonic shift in Gondwana story

In the remote waters of the Indian Ocean, west of Perth, scientists have just discovered two sunken islands, almost the size of Tasmania, which were once part of the supercontinent Gondwana.

The expedition collected rocks from more than 1.5km under the surface of the water [Credit: University of Sydney]

"The data collected on the voyage could significantly change our understanding of the way in which India, Australia and Antarctica broke off from Gondwana," said Dr Joanne Whittaker, a postdoctoral fellow at the University of Sydney's School of Geosciences.

Researchers from the University of Sydney, Macquarie University and the University of Tasmania led an international team of scientists on the voyage to map the seafloor of the Perth Abyssal Plain. The expedition returned to Perth last week after a three-week cruise.

Travelling on the CSIRO vessel Southern Surveyor the scientists discovered the islands through detailed seafloor mapping and by dredging rock samples from the steep slopes of the two islands, now in water depths of over 1.5km.

"The sunken islands charted during the expedition have flat tops, which indicates they were once at sea level before being gradually submerged," said Dr Whittaker.

Collecting rocks from the abyss more than 1.5km below the surface was not easy, but the geologists managed to retrieve hundreds of kilograms and unexpectedly found rocks that showed the islands had not always been underwater.

The University of Sydney's Dr Simon Williams, the chief scientist on the expedition said: "We expected to see common oceanic rocks such as basalt in the dredge, but were surprised to see continental rocks such as granite, gneiss and sandstone containing fossils."

In the Cretaceous period when dinosaurs roamed the Earth (more than 130 million years ago), India was adjacent to Western Australia. When India began to break away from Australia, the islands formed part of the last link between the two continents.

A sonar image of the underwater land masses [Credit: University of Sydney]

Eventually these islands, referred to as 'micro-continents' by scientists, were separated from both landmasses and stranded in the Indian Ocean, thousands of kilometres from the Australian and Indian coasts.

Dr Williams commented: "A detailed analysis of the rocks dredged up during the voyage will tell us about their age and how they fit into the Gondwana jigsaw."

Dr Whittaker - who applied for the successful grant that made the expedition possible, but was unable to take part in the voyage due to the recent birth of her baby - said the discovery is a significant development for her field. "Our preliminary analysis of the magnetic data that we collected could cause us to rethink the whole plate tectonic story for the whole of the eastern Indian Ocean," she said.

The expedition took place aboard the Marine National Facility's Research Vessel Southern Surveyor, which is owned and managed by the Commonwealth Scientific and Industrial Research Organisation, with its operations funded by the Australian government and overseen by a government-appointed steering committee.

Source: University of Sydney [November 14, 2011]

Evidence of ancient lake in California's Eel River emerges

A catastrophic landslide 22,500 years ago dammed the upper reaches of northern California's Eel River, forming a 30-mile-long lake, which has since disappeared, and leaving a living legacy found today in the genes of the region's steelhead trout, report scientists at two West Coast universities.

This is how the ancient lake likely appeared after being formed by a landslide, based on LiDAR technology [Credit: Benjamin Mackey]

Using remote-sensing technology known as airborne Light Detection and Ranging (LiDAR) and hand-held global-positioning-systems (GPS) units, a three-member research team found evidence for a late Pleistocene, landslide-dammed lake along the river, about 60 miles southeast of Eureka.

The river today is 200 miles long, carved into the ground from high in the California Coast Ranges to its mouth in the Pacific Ocean in Humboldt County.

The evidence for the ancient landslide, which, scientists say, blocked the river with a 400-foot wall of loose rock and debris, is detailed this week in a paper appearing online ahead of print in the Proceedings of the National Academy of Sciences.

The National Science Foundation-funded study provides a rare glimpse into the geological history of this rapidly evolving mountainous region.

It helps to explain emerging evidence from other studies that show a dramatic decrease in the amount of sediment deposited from the river in the ocean just off shore at about the same time period, says lead author Benjamin H. Mackey, who began the research while pursuing a doctorate earned in 2009 from the University of Oregon. He is now a postdoctoral researcher at the California Institute of Technology.

This graphic shows the Eel River system in northern California, where researchers found evidence for an ancient lake [Credit: Benjamin Mackey]

"Perhaps of most interest, the presence of this landslide dam also provides an explanation for the results of previous research on the genetics of steelhead trout in the Eel River," Mackey said, referring to a 1999 study by U.S. Forest Service researchers J.L. Nielson and M.C. Fountain. In their study, published in the journal Ecology of Freshwater Fish, they found a striking relationship between two types of ocean-going steelhead in the river -- a genetic similarity not seen among summer-run and winter-run steelhead in other nearby rivers.

An interbreeding of the two fish, in a process known as genetic introgression, may have occurred among the fish brought together while the river was dammed, Mackey said. "The dam likely would have been impassable to the fish migrating upstream, meaning both ecotypes would have been forced to spawn and inadvertently breed downstream of the dam. This period of gene flow between the two types of steelhead can explain the genetic similarity observed today."

Once the dam burst, the fish would have reoccupied their preferred spawning grounds and resumed different genetic trajectories, he added.

"The damming of the river was a dramatic, punctuated affair that greatly altered the landscape," said co-author Joshua J. Roering, a professor of geological sciences at the University of Oregon. "Although current physical evidence for the landslide dam and paleo-lake is subtle, its effects are recorded in the Pacific Ocean and persist in the genetic make-up of today's Eel River steelhead. It's rare for scientists to be able to connect the dots between such diverse and widely-felt phenomena."

Sediment from ancient lakebed [Credit: Benjamin Mackey]

The lake's surface formed by the landslide, researchers theorize, covered about 12 square miles. After the damn was breached, the flow of water would have generated one of North America's largest landslide-dam outburst floods. Landslide activity and erosion have erased much of the evidence for the now-gone lake. Without the acquisition of LiDAR mapping, the lake's existence may have never been discovered, researchers say.

The area affected by the landslide-caused dam accounts for about 58 percent of the modern Eel River watershed. Based on today's general erosion rates, researchers theorize the lake could have been filled in with sediment within about 600 years.

"The presence of a dam of this size was highly unexpected in the Eel River environment given the abundance of easily eroded sandstone and mudstone, which are generally not considered strong enough to form long-lived dams," Mackey said.

He and his colleagues were drawn to the Eel River -- among the most-studied erosion systems in the world -- to study large, slow-moving landslides. "While analyzing the elevation of terraces along the river, we discovered they clustered at a common elevation rather than decrease in elevation downstream, paralleling the river profile, as would be expected for river terraces. This was the first sign of something unusual, and it clued us into the possibility of an ancient lake."

Source: University of Oregon [November 14, 2011]

Welsh mudstones reveal ancient sponge ecosystem

A remarkably complete record of a prehistoric seabed ecosystem of a kind never discovered before has been revealed with X-ray scanning.

Fossilised nautiloid with a curved shell [Credit: Planet Earth]

A paper in Geology gives the first account of the plentiful and exceptionally well-preserved organisms from the Ordovician period that have been found in the Llanfawr Mudstones near Llandrindod Wells in central Wales. More than 20 species have turned up so far, and it's almost certain that many more remain to be uncovered.

The fossils include sponges, priapulid worms and arthropods, and shed new light on how living things colonised the deep oceans. Among the most exciting are beautiful specimens of a type of animals known as solitary hydroids – the earliest known examples of the group.

The rocks, which are about 460 million years old, provide a unique new perspective on life in the Ordovician, which stretched between about 488 and 444 million years ago and saw an explosion in the variety of living things on Earth. By the end of the period, the planet's total count of species is thought to have quadrupled, and whole new kinds of ecosystem had appeared, including the first coral reefs.

This area of mid-Wales is known for its fossils. But this particular assemblage of living things was only found in 2004; since then, the researchers have returned repeatedly to gather more specimens, using hi-tech scanning equipment to find out what's in the rocks without physically having to delve inside them.

The three palaeontologists who made the find – Dr Joe Botting, Dr Lucy Muir and Talfan Barnie - are among the paper's authors. Recent finds of fossil sponges made them suspect the area might have more to offer to fossil-hunters. 'We were on a field trip to the area, and decided to spend a day in the quarry looking for more sponges,' says Muir. 'Talfan hammered a large fresh block, found something, and said, "Is this interesting?" It was.'

X-ray scan of a nautiloid [Credit: Planet Earth]

The team took rock samples back to the Natural History Museum, where a colleague suggested X-raying them to find out what was inside. 'We tried one or two slabs, just to see if the technique worked, and this spectacular hydroid turned up in the very first slab,' Muir explains. 'It's not visible on the surface of the rock, so we had no idea that it was there.'

Unlike the few other exceptionally preserved Ordovician faunas we know of, this habitat was dominated by sponges, which account for three quarters of the inhabitants. There were few mobile animals – not unlike the sponge-based communities still common on modern deep ocean seabeds. Most of these animals had delicate skeletons or were completely soft-bodied, so it's very rare to find them preserved – creatures with hard skeletons are far more likely to become fossilised.
Ordovician ecologies

This means our knowledge of the Ordovician is skewed towards hard-bodied animals. 'We just don't know what the less well-preservable animals were doing,' says Muir. 'They may have been diversifying in the same way as the ones we know about, but they might have been doing something completely different. The significance of this particular community is that it's rather different from the others described from this age, even the ones that do preserve soft-bodied animals. The fact that all the sites with soft-bodied preservation have different communities from each other indicates that the Ordovician diversification of species and communities applied to soft-bodied animals as well as those that fossilised easily.'

This community is very unusual from an ecological perspective,' adds Dr Mark Sutton of Imperial College London, another of the paper's authors. 'It's dominated by fixed filter-feeders, with relatively few arthropods and other mobile organisms. If you found this in the modern world you'd certainly assume it came from the deep ocean beds, but we know that this was found in relatively shallow shelf-sea waters.'

X-ray scan of a hydroid - an animal with a mass of flexible tentacles, a small body, and a long stalk, which has split in two [Credit: Planet Earth]

These organisms' traces survive in the Welsh mudstones largely because of the unusual way they've been fossilised. Their shapes are preserved as patterns of iron pyrite, also known as fool's gold. The pyrite blocks X-rays much better than the rock around it does, so the fossil shapes show up well under scanning. But since they aren't usually visible from outside, it's a hit-and-miss process - the team brings blocks back for scanning; sometimes they contain a hitherto-undiscovered species, while at other times there's nothing at all.

It wouldn't be practical to investigate these fossils using more traditional methods – they're so small – often only a few millimetres long - and so delicate that trying to dig them out of the mudstone using even very precise tools would be time-consuming and would probably still end up destroying many of the fossils' finer details.

So as well using X-ray imaging to find and categorise fossils within the stone, the researchers used a CT scanner to see them in partial 3D, rather than simply as flattened smears. This makes it far easier to reconstruct a living, functioning organism from its fossilised form.

The findings shed light on how living things colonised the deep oceans. 'There's been a school of thought for a long time that the ecosystems that are now found on the deep seabed were once found in shallower waters and moved out, perhaps because they were displaced by new organisms that evolved to live in the shelf seas,' Sutton explains. 'We have a good idea this happened with hard-bodied organisms, but our findings are some of the first evidence that it's true of soft-bodied organisms too.'

The finds suggest that even areas that have been extensively explored by fossil hunters may have much more to tell us, particularly now that affordable X-ray and CT scanning means that exciting new fossils can be found even in seemingly dull blocks of stone. The team are now preparing formal descriptions of some of the new organisms they've identified, while continuing to visit the site in search of more specimens.

The researchers also believe that collections of organisms like this may be much more common than previously thought. The reason the fossils were overlooked for so long is probably that the pyrite quickly decays to almost nothing in the Welsh weather. The fossils are only visible when you examine fresh rock surfaces – so other black mudstones may be hiding unexpected surprises as well.

Author: Tom Marshall | Source: Planet Earth [November 14, 2011]

Insects offer clues to climate variability 10,000 years ago

An analysis of the remains of ancient midges – tiny non-biting insects closely related to mosquitoes – opens a new window on the past with a detailed view of the surprising regional variability that accompanied climate warming during the early Holocene epoch, 10,000 to 5,500 years ago.

University of Illinois plant biology and geology professor Feng Sheng Hu collected core samples from Alaskan lakes. The abundance and diversity of midges buried in sediments offers a reliable record of temperature fluctuations over time [Credit: Feng Sheng Hu]

Researchers at the University of Illinois and the University of British Columbia looked at the abundance and variety of midge larvae buried in lake sediments in Alaska. Midges are highly sensitive to summer temperatures, so changes in the abundance of different species over time gave the scientists a reliable marker of temperature fluctuations over the last 10,000 years.

Northern high latitudes are thought to have been warmer than today during the early Holocene, a time of heightened solar irradiation as a result of Earth's axial tilt and orbit around the sun. The period is often referred to as the Holocene Thermal Maximum. Scientists hope to understand the ecological impacts of climate warming during that time to make better predictions about the effects of future warming. But several decades of research have yielded only ambiguous evidence of climate conditions in Alaska at that time.

The new analysis, conducted by University of Illinois doctoral student Benjamin Clegg with U. of I. plant biology and geology professor Feng Sheng Hu, who led the study, offers the first detailed record of temperature variation over the last 10,000 years in Alaska. The analysis reveals that the region was significantly cooler than expected during the early Holocene.

"This study shows that early Holocene warming did not occur everywhere in high latitudes, and exhibited important regional exceptions, even though the driving force behind it – solar input, in this case – was geographically uniform," said Clegg, who is now a postdoctoral researcher in Hu's lab.

The drivers of climate change during the early Holocene "were different than the greenhouse gases responsible for global warming today," Clegg said. "So we should not expect to see exactly the same spatial patterns of temperature anomalies in the next few decades as during the early Holocene."

The researchers hypothesize that solar warming during the early Holocene spurred atmospheric circulation patterns that contributed to extensive sea-ice off the Alaskan coast. That, and a treeless tundra over more of the land area than at present would have increased surface reflectivity, potentially contributing to the observed cooling, Clegg said.

"This study has important ecological and societal implications," Hu said. "Nonlinear responses such as those identified here constitute a major source of potential climate 'surprises' that make it more difficult to anticipate and prepare for future regional climate scenarios."

The findings appear in the Proceedings of the National Academy of Sciences.

Source: University of Illinois at Urbana-Champaign [November 14, 2011]

Study determines diet of giant extinct hominoid

The extinct giant ape, Gigantopithecus blacki, is a species of large hominoids that dominated the Pleistocene of South China. Its massive mandible, large postcanine teeth and extremely thick enamel always spark people's curiosity about what a diet for this giant ape was. The precise diet and habitat of Gigantopithecus remains unknown so far.

Gigantopithecus is an extinct genus of ape, known to lived in what is now China and Southeast Asia [Credit: Craig Newsom/Flickr]

Drs. Zhao LingXia, Zhang LiZhao and Wu XinZhi, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, and Zhang Fusong from Institute of Geology and Geophysics, Chinese Academy of Sciences, analyze enamel stable carbon isotope values of G. blacki and the associated mammalian megafauna from two sites in South China, and find that this giant ape and other large mammals solely fed on C3 biomass, and lived in forest habitats, as reported in the journal of Chinese Science Bulletin, 2011(56), No.33:3590-3595.

Zhao and her collaborators prepared and analyzed a total of 32 tooth samples for their study. Four teeth of G. blacki and 24 teeth of associated large mammals were from Longgudong Cave, Jianshi, Hubei province, and the other 4 teeth of G. blacki were taken from Juyuandong Cave of Liucheng, Guangxi province.

The most enriched δ13C value was -14.1‰, and the most depleted was -18.8‰. Concerning an enrichment of about 14‰ for δ13C between food and enamel, the δ13C values of food sources would be from -32.8‰ to -28.1‰, which is within the δ13C range of C3 biomass and far too negative for that of C4 biomass.

The mandibles of Gigantopithecus blacki from Juyuandong Cave of Liucheng, Guangxi Province, China [Credit: CAS]

It is clear that Gigantopithecus and the affiliated megafauna, such as browsers (Cervus sp. and Tapirus sinensis), grazers (Equus sp. and Leptobos sp.) and carnivores (Pachycrocuta licenti and Ursus sp.), all derived their carbon from solely C3 biomass sources. Zhao and her collaborators suggested that Gigantopithecus should live in closed forest habitat and not an open habitat, which is consistent with the associated faunal and floral analyses.

"Analysis of stable carbon isotopes is a powerful method for exploring the diet and habitat use of extinct herbivorous mammals, and it has been used in paleoanthropology in analysis on early hominins fossils. This method is based on the fact that the carbon isotope composition is significantly different between plants that use different photosynthetic pathways, such as C3 plants (δ13C from -22‰ to -35‰) and C4 plants (δ13C from -8‰ to -16‰), and the stable carbon isotope composition of enamel is dependent on the diet components throughout the food chain”, said Dr. ZHAO LingXia, the lead author and research designer.

“The diet and habitat of Gigantopithecus blacki was significantly different from that of early hominins in Africa, such as Australopithecus and Paranthropus, which could consume both C3 and C4 resources and live in open habitats, although they all somehow show similar powerful mastication morphology. Dependence on forest habitat might be an important factor that made Gigantopithecus extinct when the climate and environment changed dramatically during the Pleistocene.”

Source: Chinese Academy of Sciences [November 10, 2011]

Prehistoric whales exposed in Chilean fossil bed

Scientists from Chile and the Smithsonian Institution have been working to protect a huge collection of whale fossils found in the Atacama desert.

The whales are ancient relatives of the whales of today [Credit: Reuters]

Baby Mammoth innards revealed in X-Ray images

High-tech scans of two baby mammoths pulled from the Siberian permafrost reveal that one, originally identified as male, was in fact a female.

Lyuba, a baby mammoth that suffocated in thick mud 42,000 years ago, gets the high-tech treatment with this computed tomography (CT) scan [Credit: International Mammoth Committee; CT scans by Ford Motor Company, USA, and Centre hospitalier Emile Roux, Le Puy-en-Velay, France]

In addition, the scans showed major skeletal differences between the two mammoths, perhaps representing evolutionary change in the mammoth lineage.

"A lot of what we've done with mammoths in the past has been done based on dental anatomy, based on what we can see from teeth," study researcher Ethan Shirley of the University of Michigan Museum of Paleontology told LiveScience here in Las Vegas at the annual meeting of the Society of Vertebrate Paleontology.

"Now, we have teeth … but we also have the whole rest of the baby mammoth: skin, fat, muscle, bone, everything in between," Shirley added.

Even the contents of the animals' stomachs are preserved, Shirley said, a clue as to the diet of the Ice-Age beasts.

Two little mammoths

The two mammoths, dubbed "Lyuba" and "Khroma" were found in 2007 and 2009, respectively. Lyuba is 42,000 years old, while Khroma was found in geologically older sediments.

Lyuba is female and is believed to have suffocated in thick mud after getting stuck. Khroma was originally pegged as male. Khroma was originally thought to have died of an anthrax infection, prompting scientists to irradiate the mummy for fear of infection, but further research suggests the mammoth died of some other cause, said study researcher Daniel Fisher, also of the University of Michigan museum.

The scans revealed not only bones, but muscle, organs and even stomach contents. Researchers hope to learn more about these animal's lives and adaptations to their frigid Siberian homes [Credit: International Mammoth Committee; CT scans by Ford Motor Company, USA, and Centre hospitalier Emile Roux, Le Puy-en-Velay, France]

The new computed tomography (CT) scans, however, allow an inside look at Khroma's reproductive tract, revealing he is a she. It turns out that the surface anatomy of baby mammoth genitals is not very different between males and females, Fisher said.

"It's when you follow it inwards, which we were not able to do visually or tactilely, that the differences become manifest," Fisher told LiveScience, explaining that the tissue believed to be Khroma's penis was in fact a clitoris.

The scans also exposed Lyuba and Khroma's skeletons for the first time. Although both are the same species, there were major differences in their bones, Shirley said. Lyuba's front legs are proportionally longer than Khroma's, and Khroma has bony ridges where her tusks would have erupted that Lyuba lacks, he said.

"That was all really a surprise," Shirley said.

Mammoths adapting

It's too early to say what those anatomical differences mean, Fisher said. It could be that mammoth populations varied slightly over the vast geography of Siberia. Or perhaps evolution refined the mammoth line over the time between Khroma's death and Lyuba's life.

A view of Khroma's skull, showing her teeth. The mammoth had unusual thick bony structures on her skull, which researchers compared to mustache-like structures [Credit: International Mammoth Committee; CT scans by Ford Motor Company, USA, and Centre hospitalier Emile Roux, Le Puy-en-Velay, France]

"In any case, it gives us a clearer picture of the sort of variation that exists within lineages of organisms like mammoths," Fisher said. "It is variation like this that natural selection operates on to produce evolutionary change."

The scans are also turning up smaller revelations about mammoth life. For example, Fisher said, Lyuba has much larger kidneys than researchers would have expected. It's possible these massive organs allowed mammoths to process urine more effectively, excluding waste while holding on to water.

"They're living in a cold, cold environment where essentially all available water is frozen, and having to pee a lot would get rid of a lot of body water that would have to be replaced by eating snow or ice, which is cold," Fisher said. "So it's much better just to recycle the urine. Nobody's ever had an idea that that aspect of physiology was part of mammoth adaptation to the cold."

Author: Stephanie Pappas | Source: LiveScience [November 09, 2011]

Palaeontologists develop new way to find new dig sites

National science journals are putting the spotlight on two Western Michigan University professors for discovering a new way to predict where fossils are hidden.

University of Michigan graduate student in Anthropology Craig Wuthrich at the 2009 fossil site in the Great Divide Basin in Wyoming [Credit: Robert Anemone]

Traditionally, finding fossils is a "serendipitous and intuitive" event that comes with lots of reading and luck.

Paleontologist and WMU anthropology professor Robert Anemone and WMU geography associate professor Charles Emerson said technologies are available and should be used to develop clues about where fossil sites are located.

Their researched method - using a neural network, infrared electromagnetic radiation and satellite imagery - is being recognized as a possible option to help paleontologists prioritize where to spend time and resources out in the field with better results.

Glenn Conroy, an anatomy and anthropology professor at Washington University, was a partner in developing this method.

The professors were invited to present the neural network approach at the Society for Vertebrate Paleontology meeting in Las Vegas last week and were featured in national scientific journals Nature and New Scientist.

Finding fossils

During a field excursion, paleontologists camp out in a region and use their eyeballs and other tools to hunt for fossil treasure.

"We understand the geology of the region and we don't just wander around but in the field it's a lot of intuition," Anemone said. "We want to add a more rigorous, predictive tool and we're trying to pioneer the use of new tools from geographic sciences in the search for fossils."

Anemone has been leading field crews of students and other professionals to the Great Divide Basin in southwestern Wyoming since 1993 to collect mammal bones and fossils from the Paleocene and Eocene eras, 55 to 48 million years ago.

In 2009, Anemone's team took a wrong turn and found themselves in an area of land with recognizable traits or hints of holding fossils. They "crawled around" for an hour and there it was: at least 100 partial mammal jaws with teeth.

It was the greatest find he ever "stumbled upon," he said, with the discovery of one new rodent species and two new species of early primates that roamed the earth 50 million years ago.

He said if the rodent were around today, it'd be some sort of "desert squirrel."

"It's not just history, it's pre-history," he said. "It's the deep past. Fifty million years ago the only way we know what the earth was like and the living inhabitants that existed is by people going out and collecting fossils and studying the geology of the things that were alive."

A better way

After the big find, Anemone said he knew there had to be a better way.

He asked Emerson, who has an extensive knowledge of satellite imagery, to get involved in 2010. They partnered to develop the neural network approach and have been conducting research for the past year.

"We suggest that the geospatial sciences have earned a place in the paleoanthropological tool kit, and that 21st century research must increasingly rely on the kinds of sophisticated spatial analyses that can only come from collaborations with our colleagues in the geographical and geospatial sciences," it says in their study.

While the use of GPS and satellite imagery is not entirely new in the profession, this method goes further by training a neural network - or the software brain - to recognize the characteristics and electromagnetic radiation data of a landscape to project the probability of finding fossils.

By training the network to recognize "the fingerprint" of fruitful fossil sites, they hope it can find more.

New approach

The results are promising, with 85 percent accuracy in the testing stage. Next summer their model will be used to identify where to conduct field research. The results will show if the approach actually increases the number of fossil finds.

Gerald Smith, the curator emeritus in the University of Michigan Museum of Paleontology, attended the Las Vegas meeting and said the neural network approach has the potential to change the field.

"Some of us spent the day after the meetings looking for new fossil sites without any success, so in the future it's possible that their approach will be an important tool," he said.

For Anemone, more fossils means more research.

"In the time we are working with - 50 million years ago - there was a major event of global warming," he said. "The earth's climate was warmer than what it had ever been, so we are interested in the effects of climate change in the past on living things so we better prepare for climate change today by seeing the past events."

But, they have to find the fossils first.

Author: Ursula Zerilli | Source: The Kalamazoo Gazette [November 12, 2011]