Thursday, January 13, 2011

New Predator 'Dawn Runner' Discovered in Early Dinosaur Graveyard.

A team of paleontologists and geologists from Argentina and the United States on Jan. 13 announced the discovery of a lanky dinosaur that roamed South America in search of prey as the age of dinosaurs began, approximately 230 million years ago.

Sporting a long neck and tail and weighing only 10 to 15 pounds, the new dinosaur has been named Eodromaeus, the "dawn runner."
"It really is the earliest look we have at the long line of meat eaters that would ultimately culminate in Tyrannosaurus rex near the end of the dinosaur era," said Paul Sereno, University of Chicago paleontologist and National Geographic Explorer-in-Residence. "Who could foretell what evolution had in store for the descendants of this pint-sized, fleet-footed predator?"

Sereno and his colleagues describe a near-complete skeleton of the new species, based on the rare discovery of two individuals found side-by-side, in the Jan. 14, 2011 issue of the journal Science. The paper presents a new snapshot of the dawn of the dinosaur era -- a key period that has garnered less attention than the dinosaurs' demise. "It's more complex than some had supposed," Sereno said.

Set in picturesque foothills of the Andes, the site of discovery is known as the "Valley of the Moon," said the report's lead author, Ricardo Martinez of Argentina's National University of San Juan. For dinosaur paleontologists, it is like no other.

"Two generations of field work have generated the single best view we have of the birth of the dinosaurs," Martinez said. "With a hike across the valley, you literally walk over the graveyard of the earliest dinosaurs to a time when they ultimately dominate."

The area was once a rift valley in the southwest corner of the supercontinent Pangaea. Sediments covered skeletons over a period of five million years, eventually accumulating a thickness of more than 2,000 feet (700 meters).
Volcanoes associated with the nascent Andes Mountains occasionally spewed volcanic ash into the valley, allowing the team to use radioactive elements in the ash layers to determine the age of the sediments.

"Radioisotopes -- our clocks in the rocks -- not only placed the new species in time, about 230 million years ago, but also gave us perspective on the development of this key valley," said Paul Renne, director of the Berkeley Geochronology Center in California. "About five million years of time are represented in these layers, from one end to the other."

In the oldest rocks Eodromaeus lived alongside Eoraptor, a similar-sized, plant-eating dinosaur that Sereno and colleagues discovered in the valley in 1991. Eoraptor's descendants would eventually include the giant, long-necked sauropods. Eodromaeus, with stabbing canine teeth and sharp-clawed grasping hands, is the pint-sized precursor to later meat-eaters called theropods, and eventually to birds.

"We're looking at a snapshot of early dinosaur life. Their storied evolutionary careers are just unfolding, but at this point they're actually quite similar," Sereno said.

Eodromaeus at the root of the dinosaur family tree
Vexing scientific questions at the dawn of the dinosaur era include what gave them an edge over competitors, and how quickly did they rise to dominance? In Eodromaeus' day, other kinds of reptiles outnumbered dinosaurs, such as squat lizard-like rhynchosaurs and mammal-like reptiles. The authors logged thousands of fossils unearthed in the valley to find, as Martinez remarked, that "dinosaurs took their sweet time to dominate the scene."

Their competitors dropped out sequentially over several million years, not at a single horizon in the valley.

In the red cliffs on the far side of the valley, larger plant- and meat-eating dinosaurs had evolved many times the size of Eoraptor and Eodromaeus, but it would be even later when they dominated all land habitats in the succeeding Jurassic and Cretaceous periods.

"The story from this valley suggests that there was no single advantage or lucky break for dinosaurs but rather a long period of evolutionary experimentation in the shadow of other groups," Sereno said. Other researchers on the paper tracked climate change and other conditions across the layers of the valley. "The dawn of the age of dinosaurs," Martinez remarked, "is coming into focus."

Pint-sized Eodromaeus (“dawn runner”) weighed only 10 to 15 pounds and measured about 4 feet in length from snout to tail tip. It lies very close to the ancestor of all meat-eating dinosaurs, including Tyrannosaurus. (Credit: Illustration by Todd Marshall)

Tuesday, January 11, 2011

Mountain Glacier Melt to Contribute 12 Centimeters to World Sea-Level Increases by 2100.

The largest contributors to projected global sea-level increases are glaciers in Arctic Canada, Alaska and landmass bound glaciers in the Antarctic. Glaciers in the European Alps, New Zealand, the Caucasus, Western Canada and the Western United Sates--though small absolute contributors to global sea-level increases--are projected to lose more than 50 per cent of their current ice volume.

The study modelled volume loss and melt off from 120,000 mountain glaciers and ice caps, and is one of the first to provide detailed projections by region. Currently, melt from smaller mountain glaciers and ice caps is responsible for a disproportionally large portion of sea level increases, even though they contain less than one per cent of all water on Earth bound in glacier ice.

"There is a lot of focus on the large ice sheets but very few global scale studies quantifying how much melt to expect from these smaller glaciers that make up about 40 percent of the entire sea-level rise that we observe right now," says Valentina Radic, a postdoctoral researcher with the Department of Earth and Ocean Sciences and lead author of the study.

Increases in sea levels caused by the melting of the Greenland and Antarctic ice sheets, and the thermal expansion of water, are excluded from the results.
Radic and colleague Regine Hock at the University of Alaska, Fairbanks, modelled future glacier melt based on temperature and precipitation projections from 10 global climate models used by the Intergovernmental Panel on Climate Change.

"While the overall sea level increase projections in our study are on par with IPCC studies, our results are more detailed and regionally resolved," says Radic. "This allows us to get a better picture of projected regional ice volume change and potential impacts on local water supplies, and changes in glacier size distribution."

Global projections of sea level rises from mountain glacier and ice cap melt from the IPCC range between seven and 17 centimetres by the end of 2100. Radic's projections are only slightly higher, in the range of seven to 18 centimetres.

Radic's projections don't include glacier calving--the production of icebergs. Calving of tide-water glaciers may account for 30 per cent to 40 per cent of their total mass loss.

"Incorporating calving into the models of glacier mass changes on regional and global scale is still a challenge and a major task for future work," says Radic.
However, the new projections include detailed projection of melt off from small glaciers surrounding the Greenland and Antarctic ice sheets, which have so far been excluded from, or only estimated in, global assessments.

Aerial photo of Mount Garibaldi, Diamond Head with Howe Sound and Squamish British Columbia below. Melt off from small mountain glaciers and ice caps will contribute about 12 centimetres to world sea-level increases by 2100, according to University of British Columbia research. (Credit: iStockphoto/Douglas Burne)

Sunday, January 9, 2011

Dracula Orchids and Goblin Spiders.

Dracula orchids tempt flies by masquerading as mushrooms. Goblin spiders lurk unseen in the world's leaf litter. The natural world is often just as haunting as the macabre costumes worn on city streets, as highlighted by two studies published this year by curators in the Division of Invertebrate Zoology at the American Museum of Natural History, David Grimaldi and Norman Platnick.

Dracula Orchids
According to Grimaldi and colleagues, fruit flies (Drosophilidae) of the genus Zygothrica typically swarm on mushrooms and other rain forest fungi. But one group of orchids in the American tropics takes advantage of their preferences, duping the hapless flies into pollinating them with the scent and appearance of mushrooms. These orchids are from the genus Dracula, named so to keep the spirit of a former name, Masdevallia, when it was realized that there were separate orchid groups.

"Over 200 years ago, botanists on major Spanish expeditions to Peru named a new orchid Masdevallia because of the flower's similarity to monsterly creatures like dragons and bats," says Lorena Endara of the University of Florida in Gainesville. "Carlyle Luer, who later segregated Dracula from Masdevallia, sees these orchids as little bats flying in the forest since the flower faces down and the triangular sepals and the long sepaline tails display parallel to the ground."

"Some of the flies attracted to Dracula are new species, and I am presently working on descriptions of them," says Grimaldi. "I wanted to call this paper 'Dracula as Lord of the Flies,' but my co-authors convinced me to use the title 'Lord of the Flies: Pollination of Dracula orchids.'"

The paper, published in the orchid journal Lankesteriana, presents over 700 hours of observational data on flowers in Ecuadorian cloud forest where fruit flies were seen mating in (and hence pollinating) Dracula orchids. In addition to Endara and Grimaldi, Bitty Roy of the University of Oregon authored the paper; the research was funded by the National Science Foundation, the National Geographic Society, and other institutions.

Goblin SpidersOver the past three years, Platnick and colleagues have named or redefined the taxonomy of hundreds of new species of goblin spiders -- an often overlooked group named for their unusual appearance and secretive habits. Goblin spiders (members of the family Oonopidae) are extremely small: the largest is 3 millimeters in size, and most are under 2 millimeters.
"Goblins are probably the most poorly known group of spiders," says Platnick.

"Their small size has made them difficult to study, but scanning electron microscopy and recent advances in digital imaging are allowing us to examine their structures in much more detail than was previously possible."

A recently published Bulletin of the American Museum of Natural History unravels the previous taxonomy of the genus Stenoonops, a group of spineless goblin spiders that have a soft abdomen and muddy-orange carapace. Fourteen of the 19 species moved to new genera (in fact, six different genera). But because 17 new species from the Caribbean were described as Stenoonops, the genus increased in numbers and now has 23 species. Two other genera are given new species as well: Longoonops and Australoonops gain five species combined.

"It isn't surprising that there are so many undescribed goblin spiders," says Platnick. "When we began the global inventory of the Oonopidae, there were only about 500 species known, a number we thought represented about 20 percent of the actual biodiversity in this group. There are a lot of species that have small ranges -- the perfect group for giving us hints about the biogeographic histories of the areas they occupy, as well as for conservation, by showing us what areas are most in need of protection against habitat destruction."

In addition to Platnick, Nadine Dupérré is an author of this paper. The research was funded by the National Science Foundation and the American Museum of Natural History.

This is a Goblin spider Australoonops granulatus from Africa. (Credit: AMNH)

Saturday, January 8, 2011

New Species of Carnivorous Plant Discovered in Cambodia

A new species of carnivorous pitcher plant has been found by Fauna & Flora International (FFI) in Cambodia's remote Cardamom Mountains. The discovery of Nepenthes holdenii is an indicator of both the stunning diversity and lack of research in the forests of the Cardamom Mountains.

The large red and green pitchers that characterize Nepenthes holdenii are actually modified leaves designed to capture and digest insects. The pitchers can reach up to 30 centimeters long. The carnivorous strategy allows the plants to gain additional nutrients and flourish in otherwise impoverished soils.

A further unusual adaptation seen in this new species is its ability to cope with fire and extended periods of drought. Cambodia's dry season causes forests to desiccate and forest fires are common. Nepenthes holdenii exploits the clearings caused by these regular blazes by producing a large underground tuber which sends up a new pitcher- bearing vine after the fires have passed.
British photographer Jeremy Holden, who first found the plant on the FFI survey and after whom it is named, said: "The Cardamom Mountains are a treasure chest of new species, but it was a surprise to find something as exciting and charismatic as an unknown pitcher plant."

This discovery is the latest in a series of new species described from the Cardamom Mountains, including a green-blooded frog and a number of new reptiles. Jenny Daltry, FFI Senior Conservation Biologist said: "The flora of Cambodia is still poorly known and potentially holds many new species for researchers to discover."

François Mey, the French botanist and Nepenthes expert who described the plant said: "This amazing species may be the most drought-tolerant of the genus. Thanks to a large underground tuber, it has the ability to endure extended periods of drought and fires."

Francois Mey and Jeremy Holden are currently working on a book devoted to the carnivorous plants of Cambodia.

Nepenthes holdenii with Francois Mey. (Credit: Jeremy Holden)

Lice DNA Study Shows Humans First Wore Clothes 170,000 Years Ago.

Principal investigator David Reed, associate curator of mammals at the Florida Museum of Natural History on the UF campus, studies lice in modern humans to better understand human evolution and migration patterns. His latest five-year study used DNA sequencing to calculate when clothing lice first began to diverge genetically from human head lice.

Funded by the National Science Foundation, the study is available online and appears in this month's print edition of Molecular Biology and Evolution.

"We wanted to find another method for pinpointing when humans might have first started wearing clothing," Reed said. "Because they are so well adapted to clothing, we know that body lice or clothing lice almost certainly didn't exist until clothing came about in humans."

The data shows modern humans started wearing clothes about 70,000 years before migrating into colder climates and higher latitudes, which began about 100,000 years ago. This date would be virtually impossible to determine using archaeological data because early clothing would not survive in archaeological sites.

The study also shows humans started wearing clothes well after they lost body hair, which genetic skin-coloration research pinpoints at about 1 million years ago, meaning humans spent a considerable amount of time without body hair and without clothing, Reed said.

"It's interesting to think humans were able to survive in Africa for hundreds of thousands of years without clothing and without body hair, and that it wasn't until they had clothing that modern humans were then moving out of Africa into other parts of the world," Reed said.

Lice are studied because unlike most other parasites, they are stranded on lineages of hosts over long periods of evolutionary time. The relationship allows scientists to learn about evolutionary changes in the host based on changes in the parasite.

Applying unique data sets from lice to human evolution has only developed within the last 20 years, and provides information that could be used in medicine, evolutionary biology, ecology or any number of fields, Reed said.
"It gives the opportunity to study host-switching and invading new hosts -- behaviors seen in emerging infectious diseases that affect humans," Reed said.
A study of clothing lice in 2003 led by Mark Stoneking, a geneticist at the Max Planck Institute in Leipzig, Germany, estimated humans first began wearing clothes about 107,000 years ago. But the UF research includes new data and calculation methods better suited for the question.

"The new result from this lice study is an unexpectedly early date for clothing, much older than the earliest solid archaeological evidence, but it makes sense," said Ian Gilligan, lecturer in the School of Archaeology and Anthropology at The Australian National University. "It means modern humans probably started wearing clothes on a regular basis to keep warm when they were first exposed to Ice Age conditions."

The last Ice Age occurred about 120,000 years ago, but the study's date suggests humans started wearing clothes in the preceding Ice Age 180,000 years ago, according to temperature estimates from ice core studies, Gilligan said. Modern humans first appeared about 200,000 years ago.

Because archaic hominins did not leave descendants of clothing lice for sampling, the study does not explore the possibility archaic hominins outside of Africa were clothed in some fashion 800,000 years ago. But while archaic humans were able to survive for many generations outside Africa, only modern humans persisted there until the present.

"The things that may have made us much more successful in that endeavor hundreds of thousands of years later were technologies like the controlled use of fire, the ability to use clothing, new hunting strategies and new stone tools," Reed said.

Study co-authors were Melissa Toups of Indiana University and Andrew
Kitchen of The Pennsylvania State University, both previously with UF. Co-author Jessica Light of Texas A&M University was formerly a post-doctoral fellow at the Florida Museum. The researchers completed the project with the help of Reed's NSF Faculty Early Career Development Award, which is granted to researchers who exemplify the teacher-researcher .

In this photo taken Nov. 4, 2010, University of Florida researcher David Reed is lead investigator on a five-year study following the evolution of lice that found modern humans first began wearing clothes about 170,000 years ago, a technology which enabled them to successfully migrate out of Africa. Reed, assistant curator of mammals at the Florida Museum of Natural History on the UF campus, is pictured in front of the museum's "Northwest Florida: Waterways and Wildlife" exhibit. The loose-fitting clothing worn by Native Americans depicted in the exhibit is similar to garments lice would have first inhabited about 170,000 years ago. (Credit: Photo by Jeff Gage, Florida Museum of Natural History)

Friday, January 7, 2011

Longstanding Mystery of Sun's Hot Outer Atmosphere Solved

 One of the most enduring mysteries in solar physics is why the Sun's outer atmosphere, or corona, is millions of degrees hotter than its surface.

Now scientists believe they have discovered a major source of hot gas that replenishes the corona: jets of plasma shooting up from just above the Sun's surface.

The finding addresses a fundamental question in astrophysics: how energy is moved from the Sun's interior to create its hot outer atmosphere.

"It's always been quite a puzzle to figure out why the Sun's atmosphere is hotter than its surface," says Scott McIntosh, a solar physicist at the High Altitude Observatory of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., who was involved in the study.

"By identifying that these jets insert heated plasma into the Sun's outer atmosphere, we can gain a much greater understanding of that region and possibly improve our knowledge of the Sun's subtle influence on the Earth's upper atmosphere."

The research, results of which are published in the journal Science, was conducted by scientists from Lockheed Martin's Solar and Astrophysics Laboratory (LMSAL), NCAR, and the University of Oslo. It was supported by NASA and the National Science Foundation (NSF), NCAR's sponsor.
"These observations are a significant step in understanding observed temperatures in the solar corona," says Rich Behnke of NSF's Division of Atmospheric and Geospace Sciences, which funded the research.

"They provide new insight about the energy output of the Sun and other stars. The results are also a great example of the power of collaboration among university, private industry and government scientists and organizations."
The research team focused on jets of plasma known as spicules, which are fountains of plasma propelled upward from near the surface of the Sun into the outer atmosphere.

For decades scientists believed spicules could send heat into the corona. However, following observational research in the 1980s, it was found that spicule plasma did not reach coronal temperatures, and so the theory largely fell out of vogue.

"Heating of spicules to millions of degrees has never been directly observed, so their role in coronal heating had been dismissed as unlikely," says Bart De Pontieu, the lead researcher and a solar physicist at LMSAL.
In 2007, De Pontieu, McIntosh, and their colleagues identified a new class of spicules that moved much faster and were shorter-lived than the traditional spicules.

These "Type II" spicules shoot upward at high speeds, often in excess of 100 kilometers per second, before disappearing.

The rapid disappearance of these jets suggested that the plasma they carried
might get very hot, but direct observational evidence of this process was missing.

The researchers used new observations from the Atmospheric Imaging Assembly on NASA's recently launched Solar Dynamics Observatory and NASA's Focal Plane Package for the Solar Optical Telescope (SOT) on the Japanese Hinode satellite to test their hypothesis.

"The high spatial and temporal resolution of the newer instruments was crucial in revealing this previously hidden coronal mass supply," says McIntosh.

"Our observations reveal, for the first time, the one-to-one connection between plasma that is heated to millions of degrees and the spicules that insert this plasma into the corona."

The findings provide an observational challenge to the existing theories of coronal heating.

During the past few decades, scientists proposed a wide variety of theoretical models, but the lack of detailed observation significantly hampered progress.
"One of our biggest challenges is to understand what drives and heats the material in the spicules," says De Pontieu.

A key step, according to De Pontieu, will be to better understand the interface region between the Sun's visible surface, or photosphere, and its corona.

Another NASA mission, the Interface Region Imaging Spectrograph (IRIS), is scheduled for launch in 2012 to provide high-fidelity data on the complex processes and enormous contrasts of density, temperature and magnetic field between the photosphere and corona. Researchers hope this will reveal more about the spicule heating and launch mechanism.

The LMSAL is part of the Lockheed Martin Space Systems Company, which designs and develops, tests, manufactures and operates a full spectrum of advanced-technology systems for national security and military, civil government and commercial customers.

Narrow jets of material, called spicules, streak upward from the Sun's surface at high speeds. (Credit: NASA)

Thursday, January 6, 2011

Prehistoric Bird Used Club-Like Wings as Weapon.

Paleontologists at Yale University and the Smithsonian Institution have discovered that Xenicibis, a member of the ibis family that lived about ten thousand years ago and was found only in Jamaica, most likely used its specialized wings like a flail, swinging its upper arm and striking its enemies with its thick hand bones.

"No animal has ever evolved anything quite like this," said Nicholas Longrich of Yale, who led the research. "We don't know of any other species that uses its body like a flail. It's the most specialized weaponry of any bird I've ever seen."
As part of the new study, the researchers analyzed a number of recently discovered partial skeletons of Xenicibis and found that the wings were drastically different from anything they'd seen before. "When I first saw it, I assumed it was some sort of deformity," Longrich said. "No one could believe it was actually that bizarre."

The bird, which was the size of a large chicken, is anatomically similar to other members of the ibis family except for its wings, which include thick, curved hand bones unlike those of any other known bird. Xenicibis also had a much larger breastbone and longer wings than most flightless birds. "That was our first clue that the wings were still being used for something," Longrich said.
While other birds are known to punch or hammer one another with their wings, Xenicibis is the only known animal to have used its hands, hinged at the wrist joint, like two baseball bats to swing at and strike its opponents. Although modern day ibises do not strike one another in this fashion, they are very territorial, with mates often fighting other pairs over nesting and feeding rights.
It's also possible that the birds used their club-like wings to defend themselves against other species that might have preyed on the birds' eggs or young. Xenicibis is unusual in that it became flightless even in the midst of a number of predators, including the Jamaican yellow boa, a small extinct monkey and over a dozen birds of prey.

The team found that two of the wing bones in the collection showed evidence of combat, including a fractured hand bone and a centimeter-thick upper arm bone that was broken in half. The damage is proof of the extreme force the birds were able to wield with their specialized wings, Longrich said.

The prehistoric Xenicibis used its wings like two clubs hinged at the wrist joint in order to swing at and attack one another. (Credit: Nicholas Longrich/Yale University)