first new river dolphin found in a century

Scientists have made the first discovery in 100 years of a new river dolphin species in the waters of the Araguaia river in Brazil's vast Amazon rain forest.

The discovery of the "Inia araguaiaensis" was officially announced in a study posted online by the PLoS One scientific journal. The study's lead author, biologist Tomas Hrbek, of the Federal University of Amazonas in the city of Manaus, said the new species is the third ever found in the Amazon region. "It was an unexpected discovery that shows just how incipient our knowledge is of the region's biodiversity," Hrbek said.

"River dolphins are among the rarest and most endangered of all vertebrates, so discovering a new species is something that is very rare and exciting."

"The Araguaia dolphin is very similar to its Amazon river cousin although somewhat smaller and with fewer teeth," he said. He added that there were about 1,000 "Inia araguaiaensis" dolphins living in the 1,630-mile river.

birds don't actually sleep in their nests

Nests — for birds that even make nests — are for keeping eggs and chicks in place. So where do birds sleep?

Lots of places. When birds settle down to sleep, it's called "roosting," and the main things they're looking for are safety and warmth. Songbirds have to keep off the ground to avoid cats and things, and out of the open to avoid owls. Dense brush or foliage does fine. Bigger birds have more options and can sleep on the water, on a branch, or even just right on the ground.

Blue Jay eggs. Birds building nests.

Few roosts are completely safe so some birds have developed the ability to sleep with one eye open. The eyes of most birds (unlike in humans) send information to only one side of the brain. Unihemispheric slow-wave sleep (USWS) allows birds to slide one hemisphere of their brain into a deep sleep while leaving the other hemisphere awake and alert. Birds can turn USWS on and off depending on how safe their roost is. What's more, scientists suspect that some birds use USWS to sleep while in flight.

On mars, rock shows up out of the blue

Ten years ago, NASA's Opportunity rover bounded to the surface of Mars for what was planned to be a three-month exploration. Opportunity, shown below, is still going today — and still making discoveries.

The latest, scientists said, is a rock that seemingly appeared out of nowhere. The rock appears in an image taken Jan. 8. There had been no rock in a picture taken of the same spot less than two weeks earlier. "This is strange," said Steven Squyres, the principal investigator.

That prompted "Star Trek" actor William Shatner to chime in via Twitter, "Are you going to cover the alien rock throwers?"

But Squyres said the most likely explanation was that as the rover had pirouetted at an uphill location, its lame right front wheel, which has not turned for years, dragged across the rock and flicked it out of the ground. The rock is like nothing Opportunity has seen. Squyres said it appeared to have flipped upside down, possibly exposing its underside for the first time in several billion years. "It looks like a jelly doughnut," he continued: "White around the outside, red in the middle."

The composition is strange — high in sulfur, magnesium and manganese. "This is an ongoing story of discovery," Squyres said. "Mars keeps throwing new stuff at us."

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