Science Tuesday - Fossils, Planets, and the Appendix

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Dinosaur Fossils Discovered in Utah
By THE ASSOCIATED PRESS, The New York Times, June 17, 2008

SALT LAKE CITY (AP) -- A newly discovered batch of well-preserved dinosaur bones, petrified trees and even freshwater clams in southeastern Utah could provide new clues about life in the region some 150 million years ago.

The Bureau of Land Management announced the find Monday, calling the quarry near Hanksville ''a major dinosaur fossil discovery.''

An excavation revealed at least four sauropods, which are long-necked, long-tailed plant-eating dinosaurs, and two carnivorous ones, according to the bureau. It may have also uncovered an herbivorous stegosaurus.

Animal burrows and petrified tree trunks 6 feet in diameter were found nearby. The site doesn't contain any new species but offers scientists the chance to learn more about the ecology of that time, said Scott Foss, a BLM paleontologist.

The fossilized dinosaurs are from the same late Jurassic period as those at Dinosaur National Monument, which straddles the Utah-Colorado state line, and the Cleveland-Lloyd quarry near Price.

It could be a decade or so before the full importance of the Hanksville quarry is known, Foss said. ''It does have the potential to match the other major quarries in Utah,'' he said.

The site, roughly 50 yards wide by 200 yards long, was excavated by a team from the Burpee Museum of Natural History in Rockford, Ill. Museum officials visited the site for about a week last summer and returned this year for a three-week excavation.

The area has long been known to locals and BLM officials as a dinosaur haven. But no one knew of the site's magnitude until excavation began.

The bones were found in a sandstone channel of an ancient river.

''The preservation of these dinosaurs is excellent,'' Foss said.

The mix of dinosaurs, trees and other species in the area may help scientists piece together what life was like 145 million years to 150 million years ago, including details about the ancient climate, Foss said.

BLM plans to close the site to conduct an environmental assessment for continued work in the area. The agency isn't disclosing the exact location of the find because of security concerns.





A Bounty of Midsize Planets Is Reported
By DENNIS OVERBYE, The New York Times, June 17, 2008

There is a lot of new territory out there in the cosmos, but nothing you would want to pitch camp on — yet.

About a third of all the Sun-like stars in our galaxy harbor modestly sized planets, according to a study announced Monday by a team of European astronomers.

At a meeting in Nantes, France, Michel Mayor of the Geneva Observatory and his group presented a list of 45 new planets, ranging in mass from slightly bigger than Earth to about twice as massive as Neptune, from a continuing survey of some 200 stars.

All of the planets orbit their stars in 50 days or less, well within the corresponding orbit of Mercury, which takes 88 days to go around the Sun, and well within frying distance of any lifelike creatures.

Among the bounty is a rare triple-planet system of “super-Earths” around the star HD 40307, about 42 light-years away in the constellation Pictor. The planets are roughly four, seven and nine times the mass of Earth and have orbital periods of 4, 10 and 20 days, respectively.

Dr. Mayor called the discoveries “only the tip of the iceberg” in a news release from the European Southern Observatory in Garching, Germany.

Theories of planet formation, Dr. Mayor said in an e-mail message from Nantes, hold that smaller planets like super-Earths and Neptunes should be numerous. “But evidently it was a nice surprise to see that with our instrument we have the sensitivity to detect that population,” he said.

Astronomers said the new results indicated that when their instruments got sensitive enough to detect even smaller planets, such planets would be there to be found.

Sara Seager, a planetary theorist at the Massachusetts Institute of Technology who was one of the organizers of the Nantes conference, said in an e-mail message, “We’ve always been hoping that low-mass planets are common — to increase the chance for an Earth analog to exist around a nearby star.”

In a terse statement, Dr. Mayor’s main rivals, a group of planet hunters led by Geoff Marcy of the University of California, Berkeley, and Paul Butler of the Carnegie Institution of Washington, said they were doing their own survey, to be completed within a year.

“Our survey will check the Swiss report that 30 percent of stars have super-Earths or Neptunes orbiting closer than Mercury does the Sun,” the group said in an e-mail message.

Dr. Mayor and his team discovered the first so-called exoplanet orbiting a regular star, known as Pegasi 51, in 1995. That planet, about half the mass of Jupiter, circles its star tightly in a four-day orbit. In the years since, some 270 exoplanets have been discovered, many of them like the original, so-called hot Jupiters in lethal scorching embraces of their stars.

Part of the reason that such unusual systems have been found first is that the detection method is biased toward finding large planets close to their stars. Both Dr. Mayor’s and Dr. Marcy’s groups use what is called the wobble method, deducing the presence of a planet by the to-and-fro gravitational tug it gives its star as it orbits. The more massive the planet and the closer it is, the bigger and more noticeable tug it will impart.

The tug perturbs the star’s velocity relative to Earth by as little as a few meters per second in the case of a super-Earth. That shows up as a periodic shift in the wavelength of light from the star.

In recent years, Dr. Mayor’s group has used a special spectrograph known as Harps, for High Accuracy Radial Velocity Planet Searcher, on a telescope at the European Southern Observatory’s site at La Silla, Chile, to detect such small wobbles in stars.

“Detection of planets with masses of about 2 Earth-masses (maybe less!) is possible,” Dr. Mayor said in an e-mail message.

To do much better, astronomers will have to go to space.

About one in 14 stars harbors a massive giant planet like Jupiter or Saturn, Dr. Mayor estimated. If in fact one in three harbors a Neptune or super-Earth, that is an appealing situation for astronomers and others who would like someday to find someplace livable or even someone living Out There.

Dr. Seager compared the quest to a giant Sudoku game. “Every time we fill in a key number,” she said in an e-mail message, “we take a big step towards finishing: finding the habitable planets and understanding how rare or common our solar system actually is.”





Helpful Bacteria May Hide in Appendix
By NICHOLAS BAKALAR, The New York Times, June 17, 2008

Everyone is born with one, but no one knows what it’s for. The human appendix is a small dead-end tube connected to the cecum, or ascending colon, one section of the large intestine. Everyone lives happily with it until it becomes painfully inflamed, when the only treatment is to remove it surgically.

Then everyone lives happily without it. So why is it there in the first place?

Some experts have guessed that it is a vestige of the evolutionary development of some other organ, but there is little evidence for an appendix in our evolutionary ancestors. Few mammals have any appendix at all, and the appendices of those that do bears little resemblance to the human one.

Last December, researchers published a novel explanation in The Journal of Theoretical Biology. The appendix, they suggest, is a “safe house” for commensal bacteria, the symbiotic germs that aid digestion and help protect against disease-causing germs.

Structurally, the appendix is isolated from the rest of the gut, with an opening smaller than a pencil lead, protected from the fecal stream that might be carrying pathogens. In times of trouble like a diarrheal infection that flushes the system, these commensal bacteria could hide out there, ready to repopulate the gut when the coast is clear.

William Parker, the senior author of the study and an assistant professor of surgery at Duke, emphasized that this was a hypothesis, not experimental proof. “At this point,” Dr. Parker said, “this is a deduction based on a lot of information that we’ve had for many years and some key pieces of information that have only been uncovered recently by our lab and others. It does make sense.

“But an experiment to prove this theory would be very expensive. And in any case, why would you want to spend money to find out something that is not likely to help cure a disease?”

Rebecca E. Fisher, an assistant professor of anatomy at the University of Arizona College of Medicine, said that although the appendix was “likely to be a derived feature, selected for a purpose, the enigma is that we didn’t know what that purpose might be.”

“I think Parker’s study offers an interesting solution,” Professor Fisher said.

Recent studies have found that biofilms, colonies of beneficial microbes that live outside cells, form in the large intestine, where they are dependent on the mucus that lines the bowel. There, they aid digestion and protect against infection, while enjoying the protection and nutrition of the human host.

The researchers, examining tissue from uninfected human appendices removed in kidney-pancreas transplants, found biofilms on the epithelial lining of the appendix, as well. Under their theory, it is in these biofilms in the appendix, well positioned to avoid pathogens in the rest of the gut, that commensal bacteria take refuge.

If that is true, why is it that removing the appendix apparently does not have negative side effects? The scientists contend that in industrialized countries with modern medical care and sanitation, maintaining a reserve of helpful bacteria has become unnecessary. Widespread outbreaks of intestinal disease are so rare that the commensal bacteria face little danger of extermination.

Dr. Parker wants to know whether biofilms function in the same way in other animals. “We already have an idea that the cecum in some animals works the same way,” he said. “But how, for example, do biofilms work in frogs and other species with no cecum and no appendix?”

Whether the human appendix has the function Dr. Parker thinks it has or whether it has no function at all, it is clear, he said, that “if your appendix gets inflamed, forget about the fact that it might have some function.”

“You have to get it out,” he added. “Appendicitis can be life threatening, and the earlier you treat it, the less likely it is that you will die from it.”