Some 66 million years ago, about 75 percent of species on Earth disappeared. It wasn't just dinosaurs but most large mammals, fish, birds and plankton. Scientists have known this for a long time just from looking at the fossil record. If you dig deep enough, you find lots of dinosaur bones. And then a few layers up, they're gone.
But scientists couldn't figure out exactly what had caused this phenomenon. Of course, there were lots of theories.
The faces of American Kim Lee and her Chinese husband, Li Yang, both in their 40s, once graced the covers of books that sold in the millions. He was China's most famous English teacher, the "Crazy English" guru of China, who pioneered his own style of English teaching: pedagogy through shouted language, yelling to halls of thousands of students.
His methods were given official recognition after he was employed by the Beijing Olympic Organizing Committee to teach Olympic volunteers.
Just a stone's throw from two of Los Angeles' busiest freeways lies the Sepulveda Basin Wildlife Reserve, a unique spot in an urban jungle.
The northern portion of the reserve is adorned with 30-foot-tall cottonwood trees, spots of coyote bush and other plants. Native plants cover 50 percent of the nature spot, says Kris Ohlenkamp with the San Fernando Valley Audubon Society.
"On the other side it was significantly more than that," he says.
Minnesota has a Democratic governor, two Democratic senators, and Democrats control both houses of its Legislature. So it may have come as no surprise when President Obama went there earlier this week to rally support for his proposals to reduce gun violence.
But even in the politically blue state, there's considerable resistance to placing further restrictions on gun ownership.
During his visit to a Minneapolis police facility Monday, Obama urged Minnesotans to find common ground in curbing gun violence.
President Obama's choice to take over at the Department of the Interior comes from the business world. Sally Jewell is the CEO of outdoor equipment supplier REI.
"For Sally, the toughest part of this job will probably be sitting behind a desk," the president said when introducing his nominee Wednesday. "I suspect she'll want to get out of the office quite a bit."
Before Jewell took the reins at REI, she worked in the financial industry at Washington Mutual. Before that, she was an engineer in the oil business, with Mobil.
Epic water battles are the stuff of history and legend, especially in the West. And as a severe drought drags on in the Midwest, a water war is being waged over a river that irrigates agriculture in Colorado, Nebraska and Kansas.
It's that last border crossing where this water war is under way. Kansas has gone to the Supreme Court to argue that Nebraska uses too much water from the Republican River, and that there's not enough left for Kansas farmers.
Police in Texas have charged Eddie Ray Routh, a 25-year-old U.S. Marine reservist, with capital murder. Arrest records indicate that Routh had been twice taken to a mental hospital in recent months, and had told police he was suffering from post-traumatic stress disorder.
The U.S. and the international community have pledged $16 billion to support Afghan security forces after NATO troops complete their drawdown at the end of 2014. That money covers the cost of troops and equipment.
But just what equipment will be provided? Afghan military officials want big-ticket planes, tanks and other conventional weapons.
The U.S., however, says the Afghans need to get their strategic priorities in order, and focus less on prestige hardware and more on weaponry and equipment suitable for counterinsurgency warfare.