Scientific American magazine Editor in Chief Mariette DiChristina and editor Michael Moyer talk about the "World Changing Ideas" feature as well as other contents of the December issue.

Only two kinds of egg-laying mammals are left on the planet today--the duck-billed platypus and the echidna, or spiny anteater. These odd “monotremes” once dominated Australia, until their pouch-bearing cousins, the marsupials, invaded the land down under 71 million to 54 million years ago and swept them away. New research suggests these two kinds of creatures managed to survive because their ancestors took to the water.

Before making their way to Australia, the marsupials had migrated from Asia to the Americas to Antarctica. Forced to contend with all the animals along the way, marsupials may have been primed for competition, hence accounting for their overwhelming success in Australia, says evolutionary biologist Matthew Phillips of the Australian National University in Canberra: “The question then becomes, ‘Why did the monotremes survive?’”

Looming larger than a double-decker bus and baring teeth that have been likened to serrated bananas, Tyrannosaurus rex has long been considered one of the most fearsome creatures ever to have walked the earth. Other familiar tyrannosaurs, such as Albertosaurus and Tarbosaurus , were likewise terrifying in their size and bite--despite those absurd-looking but characteristic arms. But it turns out that not all tyrannosaurs have these hallmark features.

This past fall paleontologists unveiled two tyrannosaurs new to science that are shaking up long-standing ideas about everyone’s favorite mega-predator. The finds are forcing researchers to reevaluate the origin of the tyrannosaur body plan and reconsider what they thought they knew about the diversity of this well-studied group. “Our view of tyrannosaur evolution has changed dramatically,” says doctoral student Stephen L. Brusatte of the American Museum of Natural History in New York City.

Almost three centuries after his death, Antonio Stradivari is still a legend for the sound of his instruments, from the rich depths of his cellos [cello sound] to the soaring clarity of his violins [violin sound]. Theories are often been put forth that Stradivari must have used a secret ingredient that made his instruments special, perhaps in the varnish. 

Now researchers have performed spectroscopic and microscopic examinations on the wood and varnish of five Stradivarius violins and think they have uncovered Stradivari’s secret. The study appears in the German chemistry journal Angewandte Chemie . The first layer of varnish is an oil comparable to that used by painters of the era. The next layer is a tinted oil and common resin mix. The researchers found no unusual proteins or gums. And they found no mineral-rich layer, which some earlier examiners thought might be there. So Stradivari employed common materials in broad use in his time. Which leads the researchers to conclude that Stradivari’s true secret?: his incredible artistry as an instrument builder.

Thanks to a new, wired undersea observatory, when it comes to exploring the deep blue sea, there will be no more of this tethered buoy business or taking ships out to upload data from brief time snapshots taken by instruments. The NEPTUNE network set to go online Tuesday will stream data from hundreds of undersea instruments and sensors direct from the Pacific Ocean floor to the Internet 24/7, year-round.