On the horizon

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Shrews: underwater sniffers

When bloodhounds lose the scent of an escaped convict at the water's edge, it may be time to unleash the water shrews. A Vanderbilt University biologist has discovered that the shrews, and at least one other water-loving mammal, can follow scents underwater.

Until now, the notion that mammals could take a subsurface sniff was dismissed because they can't breathe underwater. But biologist Kenneth Catania was puzzled. High-speed video showed that water shrews and star-nosed moles put their noses close to the bottom as they foraged. The animals exhaled air bubbles, which grew to touch the bottom, and then quickly inhaled them at a pace similar to a rat's sniffing.

Dr. Catania set up food-scented underwater "trails" to test the idea. When he allowed the animals to get close enough to the trails at the bottom, they followed them to the food 85 to 100 percent of the time. When a metal mesh kept them too far above the trail for the bubbles to touch it, or when they had no trail to follow, the animals' success rate was no better than chance.

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"This came as a total surprise, because common wisdom is that mammals can't smell underwater," Catania notes. The results appear in the current issue of the journal Nature.

Primitive plant eater discovered

Scientists in Europe have uncovered the fossil remains of a giant, plant-eating dinosaur some 150 million years old. They say the remains represent the most primitive type of large plant eater, or sauropod, yet found from this period. The fossil remains come from a creature thought to have weighed from 40 to 48 tons. It stretched between 98 and 124 feet from the tip of the nose to the tip of the tail.

Spanish paleontologists found the remains in a layer of sediment in Teruel, Spain. The layer also bears fossils of other sauropods and terrestrial dinosaurs, as well as turtles and fish. Using their specimen, Turiasaurus riodevensis, as a reference point, the two researchers from the Fundacion Conjunto Paleontologico de Teruel-Dinopolis in Teruel say other sauropod remains found in Portugal, France, Britain, and elsewhere in Spain belong to the same, primitive branch of large dinosaurs. The results appear in the current issue of the journal Science.

Ergonomic backpack

When biologists meet backpacks, the result can take a load off your shoulders.

Three biologists have worked up a prototype backpack frame that uses bungee cords and pulleys to reduce the amount of stress a loaded pack can place on its wearer.

The trio took its inspiration from Asian merchants who can run carrying their wares on the ends of flexible bamboo poles. Standing still, a person holding a load adjusts only to the weight gravity imposes on the object. But when people walk or run, their hips rise and fall by up to 3 inches with each step, the team notes. This adds up-and-down acceleration forces with each step. This added force is up to twice the force that a load imposes when a person stands still, the team estimates. The trio noticed that the flexing bamboo poles, in effect, hold the loads at a fairly constant height even as the bearer trots along. The pole reduced the acceleration forces the bearer feels.

They applied the same principle to design a new backpack frame and found that it would allow a person to carry a 60-pound load and expend no more energy than a 48-pound load requires.

The trio, from the University of Pennsylvania in Philadelphia and the Woods Hole Oceanographic Institution in Woods Hole, Mass., suggest that their approach could significantly reduce the load children feel as they wear book-laden packs to school. It also could cut the load emergency workers confront as they carry gear to disaster sites. The results appear in the current issue of the journal Nature.

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