Dinosaurs might live on today as birds, but they hatched like reptiles. Developing dinos stayed in their eggs three to six months before emerging, far longer than previously suspected, researchers report online January 3 in the Proceedings of the National Academy of Sciences.

With few clues to dinosaurs’ embryonic lives, scientists assumed that young dinosaurs shared modern birds’ swift incubation period, which ranges from 45 to 80 days for eggs in the size range of dino eggs. A reptile egg generally takes about twice as long to hatch as a bird egg of similar size, says lead author Gregory Erickson, a paleobiologist at Florida State University in Tallahassee.
But counts of growth lines on the teeth of rare fossilized dinosaur embryos from two species, Protoceratops andrewsi and Hypacrosaurus stebingeri, suggest a longer trajectory like that of reptiles, say Erickson and colleagues at the University of Calgary in Canada and the American Museum of Natural History in New York City. These lines, laid down daily on teeth, can be used like tree rings.

The longer incubation time might have worked against dinosaurs, Erickson says. Guarding a brood of eggs for many months could put parents at risk of attack. And a species hit by environmental catastrophe would have a harder time bouncing back.

Before an immature Zika virus becomes infectious, it does some major remodeling.

In a fledgling virus particle, the inner protein and RNA core (shown in dark blue above, right) forms bridges to the membrane layer that surrounds it. As the virus matures, the core shuffles around and the bridges melt away (below, right).

It’s the first time scientists have seen such rearrangement in the core of a flavivirus, the group that also includes the viruses that cause dengue, West Nile and yellow fever, says virologist Richard Kuhn of Purdue University in West Lafayette, Ind.
Scientists don’t know why the immature Zika virus reshuffles its insides, Kuhn says — perhaps it helps the maturing virus become infectious. But that’s the next big question to answer, he says.

If blocking the reorganization somehow made mature viruses harmless, scientists would have a new clue about preventing Zika infection. Kuhn and colleagues’ map of the immature virus’s structure, published online January 9 in Nature Structural & Molecular Biology, could offer other hints for thwarting Zika.

With a technique called cryo-electron microscopy, the team could see three-headed protein spikes (shown in red) studding the surface like some kind of medieval weapon, and could even distinguish the separate layers of the membrane (aqua) that encloses the core. (The maps are radially colored; colors change as distance from the core increases.) Outside the membrane lie surface proteins called envelope, or E, proteins (green and yellow) that help the virus sneak into cells.

Last year, Kuhn’s team reported the structure of the mature Zika virus (SN: 4/30/16, p. 10). The new work offers another illuminating peek at Zika — a baby picture, of sorts.

Any exercise — even the weekend warrior approach, cramming it all into Saturday and Sunday — is better than none. Compared with inactive adults, those who got the recommended amount of weekly exercise, or even substantially less, had about a one-third lower risk of death during the study period, researchers report online January 9 in JAMA Internal Medicine.

Gary O’Donovan at the University of Leicester in England and colleagues analyzed data from 63,591 people ages 40 and older, surveyed between 1994 and 2012 as part of the Health Survey for England and the Scottish Health Survey. Adults should be getting 150 minutes of moderate activity (such as walking) or 75 minutes of vigorous activity (such as jogging) spread out across the week, according to the U.S. Centers for Disease Control and Prevention and the World Health Organization.
Measured against people who did absolutely nothing, active people who worked up a sweat three or more times per week, weekend warriors and even those who moved less (60 minutes per week on average) all reduced their risk of dying early. The observational study can’t say that exercise caused the reduced risk, just that there’s an association.

NASA’s Dawn spacecraft has detected organic compounds on Ceres — the first concrete proof of organics on an object in the asteroid belt between Mars and Jupiter.

This material probably originated on the dwarf planet itself, the researchers report in the Feb. 17 Science. The discovery of organic compounds adds to the growing body of evidence that Ceres may have once had a habitable environment.

“We’ve come to recognize that Ceres has a lot of characteristics that are intriguing for those looking at how life starts,” says Andy Rivkin, a planetary astronomer at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., who was not involved in the study.
The Dawn probe has previously detected salts, ammonia-rich clays and water ice on Ceres, which together indicate hydrothermal activity, says study coauthor Carol Raymond, a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

For life to begin, you need elements like carbon, hydrogen, nitrogen and oxygen, as well as a source of energy. Both the hydrothermal activity and the presence of organics point toward Ceres having once had a habitable environment, Raymond says.

“If you have an abundance of those elements and you have an energy source,” she says, “then you’ve created sort of the soup from which life could have formed.” But study coauthor Lucy McFadden, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., stresses that the team has not actually found any signs of life on Ceres.

Evidence of Ceres’ organic material comes from areas near Ernutet crater. Dawn picked up signs of a “fingerprint,” or spectra, consistent with organics. The pattern of wavelengths of light absorbed and reflected from these areas is similar to the pattern seen in hydrocarbons on Earth such as kerite and asphaltite. But without a sample from the surface, the team can’t say definitively what organic material is present or how it formed, says study coauthor Harry McSween, a geologist at the University of Tennessee.
The team suspects that the organics formed within Ceres’ interior and were brought to the surface by hydrothermal activity. An alternative idea — that a space rock that crashed into Ceres brought the material — is unlikely, the researchers say, because the concentration of organics is so high. An impact would have mixed organic compounds across the surface, diluting the concentration.

Detecting organics on Ceres also has implications for how life arose on Earth, McSween says. Some researchers think that life was jump-started by asteroids and other space rocks that delivered organic compounds to the planet. Finding such organic matter on Ceres “adds some credence to that idea,” he says.