Sea Vents and Carbon
Fifty-five million years ago, a huge quantity of carbon -- almost certainly in the form of methane gas -- entered Earth's atmosphere. This occurred over just 10,000 to 20,000 years. On a geologic scale, it amounted to a day or two of serious flatulence.
Despite its brief duration, however, this event had stupendous and long-lasting effects. Temperatures rose about 10 degrees, many modern mammals (including primates) appeared, much of deep-ocean life died off, and there were large global migrations of living things.
"It was the most profound global environmental change over the last 65 million years," said Gerald R. Dickens, of Rice University. But what caused it? That got a bit closer to an answer last week.
In the journal Nature, a team of Norwegian geologists described their discovery of a virtual forest of sea-floor vents in two basins of the North Atlantic. The vents extend into the mantle and conducted melted rock up to Earth's surface.
Henrik Svensen and his University of Oslo colleagues believe the fiery material melted portions of the sea bottom -- rock made from decomposed life forms and loaded with carbon. That produced massive amounts of methane, which erupted through the overlying ocean.
The amount of carbon injected into the atmosphere was between 1,500 and 4,000 gigatons. A gigaton is a billion tons. Human activity is now releasing about 6.5 gigatons a year.
In light of the magnitude of carbon addition underway now, "environmental change during [this period] should become the subject of general investigation," Dickens wrote in a commentary.
-- David Brown
Fossil Ties Africa to Land
Paleontologists have discovered fossils of a meat-eating dinosaur whose presence in the Western Sahara suggests that Africa was linked to other land masses in a southern supercontinent far longer than previously thought.
The fossil skull of a new species named Rugops primus, or "first wrinkle face," was found in 95 million-year-old rocks in Niger. A second fossil, the spine of a species similar to the first, was about 135 million years old.
The skull, whose discovery was reported last week by the National Geographic Society and in the Proceedings of the Royal Society of London, is akin to fossils found in South America, Madagascar and India.
This suggests that Africa remained linked to the prehistoric "supercontinent" of Godwana until continental drift broke it apart (including Antarctica) between 90 million and 100 million years ago. The prevailing view held that Africa broke off much earlier, perhaps 120 million years ago.
"There wasn't a single voice, but 'Africa first' was the loudest," said University of Chicago paleontologist Paul Sereno, who led the excavations. "I felt that this was unlikely after we started to uncover a lot of things that had close counterparts on the other side [South America]. This was the last puzzle piece."
University of Chicago paleontologist Paul Sereno described R. primus as an upright, 30-foot-long predator with a powerful neck but small, delicate teeth, suggesting it was a scavenger rather than a hunter.
-- Guy Gugliotta
Doctors, Don't Tie One On
Doctors looking for an excuse to stop wearing neckties will be happy to learn they can back up that decision with scientific data. A new study suggests that doctors' ties often become contaminated with disease-causing microbes and may help spread patients' ailments around.
Steven Nurkin of New York Hospital Medical Center of Queens and his colleagues sampled 42 neckties worn by doctors, physician assistants and medical students over three days, including in intensive care units and surgical and medical wards. Twenty ties were found to harbor disease-causing bacteria, including Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae. By contrast, only one tie tested positive among 10 that had been worn by hospital security guards, who had minimal contact with patients.
"Our results suggest that neckties worn by clinicians may serve as a reservoir" of dangerous microbes, the group reported May 24 at the annual meeting of the American Society for Microbiology, held in New Orleans.
Ties may become infected when a clinician leans over a sick patient or when a patient coughs or sneezes -- or when the doctor, after caring for a patient, straightens his tie before washing his hands. Moreover, the team noted in a published abstract: "As most neckties are 'dry clean only,' they may be cleaned infrequently."
Bow ties are probably not a solution. A 1993 study of the neckwear worn by gynecologists and obstetricians found similarly high levels of bacterial contamination on straight ties and bowties.
"Although wearing a necktie may project a certain professionalism by the clinician that may increase patient confidence," Nurkin's team concluded, "it may also be accompanied by potential risks."
-- Rick Weiss