A huge new dinosaur
Paleontologists in South Africa have discovered the fossilized remains of a gigantic new species of dinosaur related to the brontosaurus. Ledumahadi mafube was an early type of sauropodomorph, a group of longnecked, long-tailed dinosaurs that lived about 200 million years ago in the early Jurassic period. Weighing 26,000 pounds— about as much as two adult African elephants—and standing 13 feet high at the hips, it was the largest land animal on the planet at the time. Researchers believe that Ledumahadi mafube, whose name means “a giant thunderclap at dawn” in the Sesotho language, walked on all fours in a cat-like crouch. That posture was very different from its later, straight-limbed relatives’, meaning the dinosaur was effectively an evolutionary experiment. Some of its fossilized bones were found in 1990, but the paleontologist who excavated them was interested in mammals, not dinosaurs, so they went unstudied for years. “It’s amazing,” study co-author Jonah Choiniere, from the University of the Witswatersrand in Johannesburg, tells NationalGeographic .com. “Sometimes stuff can sit on your shelf, and you pass by it every day, but you don’t look at it in detail.”
Guatemala, using a groundbreaking new laser-mapping technology. The researchers flew over 830 square miles of dense forest in a plane equipped with a lidar device, which rained millions of light pulses on the canopy to reveal the contours of the ground beneath. The survey revealed an astonishing 61,480 Mayan structures, many of them never seen before. There were large houses and temples; 60 miles of causeways, roads, and canals; even defensive fortifications, such as moats, which suggest the Maya came under attack from other Central American peoples. The discoveries provide a unique snapshot of the Maya, who lived in the region from about 1000 B.C. to 1500 A.D., and should help scientists understand more about their population size, agricultural techniques, and conflicts. After analyzing the scans, the researchers explored the jungle at ground level to verify some of their findings. “We were all humbled,” lead author Marcello Canuto, from Tulane University in New Orleans, tells The Washington Post. “All of us saw things we had walked over, and we realized, ‘Oh wow, we totally missed that.’”
qualities that made them useful—stability and heat resistance—also make them hard to break down. They become more concentrated at each stage of the food chain, and at the top of the chain, consuming PCBs in the highest concentrations, are killer whales. Orcas are particularly vulnerable to the chemicals, which affect their immune system and hamper their ability to reproduce. After studying PCB levels in 351 killer whales, researchers concluded that populations of the mammal in the waters off Japan, Brazil, Hawaii, Gibraltar, and the U.K. “are all tending toward complete collapse.” Paul Jepson, from the Zoological Society of London, describes the decline as “like a killer whale apocalypse.”