VOA常速英語:Fossils at California Tar Pits Yield Possible Climate Change Clues

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October 29,2013

LOS ANGELES — Creatures such as saber tooth cats once lived in what is now the second largest city in the United States. Their ancient remains are still being found at the La Brea Tar Pits in Los Angeles, California, 100 years after scientists first began their excavations. Scientists are now examining some of these fossils for clues about climate change.

Video transcript:

In the heart of Los Angeles, surrounded by tall buildings and traffic, there are pools of black, bubbling tar. Scientists come here to unearth some unconventional treasure buried under this tar.

“I get excited about a mouse toe!” exclaims Shelley Cox.

Cox cleans fossils in a lab called the Fish Bowl. It is located in the George C. Page Museum in Los Angeles, which houses fossils of animals and plants trapped and preserved by the tar at the La Brea Tar Pits. Some of the remains date back more than 40-thousand years.

“We have such a variety of fossils that there is almost something for everyone preserved right here,” said Cox.

That’s 5.5 million fossils found in the last hundred years, and it’s why paleontologists from around the world come here to study the discoveries. Chief Curator John Harris says even saber tooth cats and mammoths were no match for the thick, sticky asphalt.

“They got stuck in asphalt, stuck like flies on fly paper. If they were lucky, they succumbed to hunger and thirst after about a week. If they were unlucky, they were torn apart by wandering predators and scavengers.”

In the past, paleontologists focused on the large mammals, but the remains of smaller creatures such as snails or insects are now getting more attention. These microfossils give scientists a better picture of the ancient ecosystem. They also tell scientists how organisms are affected by climate change.

Unlike the extinct large mammals, the descendants of these smaller creatures still exist but do not necessarily live in the same area as their ancestors.

“Well if we have some idea of how life changes when we have changes in climate, then we can take precautions when we’re actually undergoing those same climatic changes ourselves,” said Harris.

Scientists say the plants and animals preserved in tar can tell them how global warming in the past affected ancient organisms and can help them understand which species may be the most vulnerable as temperatures rise in the modern world.