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News Briefs II

Scientists Find Insect Fossils From 200 Million Year Ago

The Washington Post

A stone quarry straddling the border between Virginia and North Carolina has yielded some of the world's most impressive insect fossils from the Triassic period more than 200 million years ago, a time when dinosaurs were coming into their prime.

The shimmering silver imprints of flies, beetles and other insects - perfectly preserved in a finely grained, charcoal gray shale - show in astonishing detail the insects' mouthparts, head hairs and even the fine fringe found on some species' wings.

Scientists said the collection, which includes some of the oldest known examples of several major insect groups, reveals for the first time a bustling aquatic ecology that flourished during the Triassic period around the shores of a large lake near Danville, Va. It also indicates that insects had recovered quickly from the massive "Permian extinction" 20 million years earlier, which mysteriously wiped out about 95 percent of the Earth's animals and plants.

"This site may be one of the best in the world in terms of preservation," said Conrad C. Labandeira, a paleobiologist at the Smithsonian's National Museum of Natural History in Washington, who is familiar with the discovery. "It also confirms that by the late Triassic we had insect communities that were structured very much along modern lines."

Scientists Find Brain Growth Gene


Discovery of a fundamental mechanism that helps young nerve cells get to their final destinations as the brain is being built was announced Thursday by researchers in New York.

The findings are important toward understanding how the nervous system gets put together while a baby is still in the womb, and for several years after birth. Such cells, neurons, must make proper connections for life to be normal.

The scientists, at Rockefeller University, have identified a gene in mice that is central to the homing mechanism. The gene makes a protein, astrotactin, that neurons need so they can attach to fibers, and then migrate along the fibers to their proper positions. The fibers are laid down in advance by brain cells called glial cells.

Astrotactin "is required for young neurons to migrate along glial fibers to find their corrrect positions in the growing brain," said neurobiologist Mary Hatten. "This journey is important because it is the way young neurons gain their identity." Hatten and her colleagues reported their findings Thursday in the journal Science.

If neuron migration is faulty or incomplete, the result can be seen in some nervous system disorders. "The most clear-cut of these is childhood epilepsy," Hatten said, but others thought to be caused by miswiring also include schizophrenia and microenchephaly.