Wednesday 3 March 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

Dinosaurs Arose at Least 10 Million Years Earlier Than Thought

Posted: 03 Mar 2010 10:15 AM PST

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Scientists have discovered 243-million-year-old fossils of dinosaurs' closest relatives, pushing back the origin of dinosaurs by at least 10 million years.

The dinosaur-like creature, Asilisaurus kongwe, was about the size of a Labrador retriever and had teeth and jawbones ideally shaped for eating plants, indicating it ate a mostly vegetarian diet.

"This shows that the lineage leading to dinosaurs goes a lot further back in time than we thought. The second thing is that it shows that there's this real ecological diversity," said paleontologist Randy Irmis, co-author of the study appearing Mar. 3 in Nature. "No one thought that the closest relatives to dinosaurs were these four-legged, herbivorous animals. We thought they were small carnivores."

The earliest known dinosaur fossils are around 230 million years old. The new findings indicate that the dinosaurs and the silesaurs, the group that encompasses genus Asilisaurus, diverged more than 243 million years ago. That means dinosaurs must have originated sometime before then.

The team found more than a dozen partial skeletons of Asilisaurus in bare patches in the Tanzanian grasslands. During the Triassic period, the area was warm and lush, with a mixture of woodlands and lower plants like ferns.

"Back then it was a very large river system, maybe something like the Mississippi today," said lead author and University of Texas at Austin paleontologist Sterling Nesbitt. During that time, Africa, South America, Antarctica, Australia and India were all one giant continent called Gondwana.

Though silesaurs are very closely related to dinosaurs, they lack the open hip-sockets that are universal in dinosaurs. The Asilisaurus was a small, four-legged creatures with a long tail. Their beak-like jaws and leaf-shaped teeth helped the animals eat the soft, fibrous leaves of the primordial palms, ferns and conifers that were prevalent during the Triassic period. That suggests that, while the animal may not have been exclusively vegetarian, a good portion of its diet came from plants, he said.

"In a carnivorous animal, the teeth are pointed, or they are serrated, like a knife to cut meat. In order for this to be efficient, the serration has to be perpendicular to the edge of the tooth so that it functions like a knife," said paleontologist Gilles Cuny of the the Natural History Museum of Denmark, who was not involved in the study. "In these leaf-shaped teeth, you have some very vague serrations, but they are oriented towards the top of the teeth."

The findings overturn the previously held idea that the closest relatives to dinosaurs were two-legged, cat-sized predators, Irmis said.

The team also found that similar teeth and jaws evolved separately in the line of dinosaurs that includes apatosaurus, as well as in another line that included triceratops and stegosaurus. All these changes occurred within 10 million years of each other.

"We were really surprised," Irmis said. "These are three different groups that are really closely related to each other, so you'd expect that maybe their common ancestor had this tooth form. And no, it evolved independently in these three groups."

That suggests that each of these lineages evolved separately to take advantage of a large, untapped food source, he said.

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Images: 1) Left: A team member excavates a fossil in Tanzania. Right: Silesaur bone/L. Tsuji, Tibia, R. Smith
2) Skeletal reconstruction, with missing bones in gray./S. Nesbitt

Citation: "Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira," Sterling J. Nesbitt, Christian A. Sidor, Randall B. Irmis, Kenneth D. Angielczyk, Roger M. H. Smith and Linda A. Tsuji. Nature Vol. 464 (4) Mar. 2010.

See Also:

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10 Companies Reinventing Our Energy Infrastructure

Posted: 02 Mar 2010 05:05 PM PST

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When most people think about changing the way America uses energy, they imagine new ways of generating electricity like solar farms or new nuclear reactors.

But at an innovation summit organized by the Department of Energy's high-risk, high-reward research branch, ARPA-E (modeled after Darpa), it's not just power generation that's getting a makeover. The companies hawking their ideas there, which all received grant money from ARPA-E or were finalists, are trying to reinvent the entire energy system. Everything is getting a technological re-evaluation from the actual wires that power is transmitted on to the waste heat produced in industrial processes.

And of course there are also new ways of making electricity beyond just burning some rocks or oil to create steam to drive a turbine.

Here are 10 companies that caught our attention. Any one technology is unlikely to solve the looming climate change and peak oil problems, but working together within the larger system, they could tilt the globe away from catastrophe and towards a sustainable future.

Above:

Agrivida

Now, ethanol is made with corn cobs, which are just a small amount of the corn plant's total biomass. For years, people have been trying to come up with ways to use all the rest of the plant to make fuel. They call that stuff "cellulosic ethanol," because it doesn't just use the sugars in the cobs, but the cellulose in the rest of the plant. It turns out, though, that it's not so easy to do the chemistry that transforms a corn stalk into a liquid fuel that works.

Agrivida is working on plants that release enzymes to degrade the cellulose in their own cell walls — on command. They throw a molecular switch, and the plants start turning themselves into sugar, saving fuel processors a key and energy-intensive step.

Photo: Theophilos/Flickr

First Mirrors Polished for Next-Gen Space Telescope

Posted: 02 Mar 2010 03:20 PM PST

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The first mirror segment of the James Webb Space Telescope, the all-purpose instrument that will take the mantle of "most awesome" telescope from Hubble in 2014, is polished.

There are 18 mirror segments to go, but it still marked a milestone on the telescope's march towards flight-readiness.

The huge mirrors require incredible precision for collecting the tiny amounts of photons arriving at Earth from distant objects. Even the tiniest mistakes can kill the performance of a telescope.

Recall that an erroneously polished mirror fouled up Hubble's launch. The telescope got into orbit before researchers realized that things weren't working quite right.

It took a separate Shuttle mission — STS-61 — to get the telescope working properly.

Clearly, NASA doesn't want a repeat of that experience, so the agency and its contractors are taking special care polishing up its latest space observatory. This time around, everyone is taking their own measurements.

"For validation purposes, we're planning four sets of completely different cross checks and verification tests to authenticate the outcome of the mirror cryotests," said Scott Texter, Northrop Grumman Webb Optical Telescope Element Manager. "If any discrepancies surface, we can then investigate and re-verify."

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See Also:

WiSci 2.0: Alexis Madrigal's Twitter, Tumblr, and green tech history research site; Wired Science on Twitter and Facebook.

Sex-Changing Herbicide Makes Amphibians Sick, Too

Posted: 02 Mar 2010 01:15 PM PST

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Atrazine is receiving lots of attention for turning male frogs into girls, but that's not all the common herbicide does. It also weakens amphibian immune systems, leaving the fragile creatures vulnerable to disease.

Though less obvious than gender bending, immunosuppression could play just as large a part in the worldwide decline of amphibians, which have porous skin and easily absorb chemicals from rain, groundwater and even water vapor.

"Numerous studies have documented the effects of environmental pollutants on the amphibian immune system. Nearly all of these studies suggest that amphibians are particularly sensitive," wrote Tyrone Hayes, a University of California, Berkeley biologist, in a paper published in the March 15 Journal of Experimental Biology. "In particular, the widespread herbicide atrazine impairs immune function and increases disease rates."

Hayes is also an author of a March 1 Proceedings of the National Academy of Sciences study on the developmental changes wrought in male frogs by groundwater atrazine concentrations regularly found in the United States, where 80 million pounds of the herbicide are used every year. The frogs had low levels of sperm and testosterone; some even produced estrogen, developed female reproductive organs and were ultimately impregnated by their former gender mates.

The findings are disturbing, but atrazine's effects don't end there. As described in the JEB paper, a large body of scientific literature describes how atrazine drives down white cell counts and turns off immune system-regulating genes. Atrazine also suppresses immune function in snails, which often carry amphibian-infesting parasites, and feeds the algae on which snails live.

It's a perfect storm of infection: atrazine makes amphibians more vulnerable to disease, and carriers of disease more common.

The best-known amphibian killer, the chytrid fungus, has killed 95 percent of all frogs in Colombia and Panama, and driven 30 species in the Atelopus genus to extinction — and it was only identified in 1993. However, according to Hayes, chytrid is only the most apparent amphibian affliction. Others may go unnoticed because they don't kill the fragile creatures, but damage their health just enough to prevent populations from sustaining themselves. About 70 percent of amphibian populations around the world are now in decline.

Atrazine, which is scheduled for review by the Environmental Protection Agency after being declared safe by the Bush-era EPA, isn't the only chemical culprit. Many common pesticides and herbicides have also been linked to amphibian immune malfunction. But as bad as other chemicals may be, atrazine — which can travel up to 600 miles in groundwater — is considered the worst, said Hayes.

"It's so common, so mobile and persistent, and so active at low levels," he said. "But there may be chemicals out there just as bad, only we don't have data on them."

Image: Rainforest Harley/Flickr

See Also:

Citations: "The cause of global amphibian declines: a developmental endocrinologist's perspective." By T. B. Hayes, P. Falso, S. Gallipeau and M. Stice. Journal of Experimental Biology, Vol. 213 No. 5, March 15, 2010.

"Atrazine induces complete feminization and chemical castration in male African clawed frogs (Xenopus laevis)." By Tyrone B. Hayes, Vicky Khourya, Anne Narayana, Mariam Nazira, Andrew Parka, Travis Brown, Lillian Adame, Elton Chan, Daniel Buchholz, Theresa Stuevea, Sherrie Gallipeau. Proceedings of the National Academy of Sciences, Vol. 107 No. 9, March 1, 2010.

Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points.
Posted by johnald