<p><strong>Scientists preserve a prehistoric adult whale skeleton's rib cage and tail in plaster in <a href="http://travel.nationalgeographic.com/travel/countries/chile-guide/">Chile</a>'s <a href="http://ngm.nationalgeographic.com/features/world/south-america/chile/atacama-text">Atacama Desert</a> in 2010.</strong></p> <p><strong>The fossil is 1 of 20 roughly five-million-year-old whales found in a roadside "graveyard" more than a half a mile (a kilometer) from the Pacific coast, experts announced late last month.</strong></p> <p><strong></strong></p> <p>It's unknown why the whales were found together, said the <a href="http://www.si.edu/">Smithsonian Institution</a>'s <a href="http://paleobiology.si.edu/staff/individuals/pyenson.html">Nicholas Pyenson</a>, lead paleontologist on the excavation.</p> <p>But possible reasons include a storm pushing them abruptly to shore, a red tide—a proliferation of microscopic organisms that release toxins in the water—poisoning them, and the whales beaching themselves in a group, said Pyenson, a grantee of the <a href="http://www.nationalgeographic.com/field/grants-programs/cre/">National Geographic Society's Committee for Research and Exploration</a>. (The Society owns National Geographic News.)</p> <p>Getting to the bottom of the mystery requires careful preservation and examination, beginning with encasing the fossils in protective plaster "jackets" (as pictured) for the trip to the lab—a skill the team hadn't quite mastered by the time this picture was taken, Pyenson explained.</p> <p>Above, he said, "you can see the block containing the rib cage and the thinner segments capping the tail."</p> <p>(<a href="http://news.nationalgeographic.com/news/2010/06/photogalleries/100630-leviathan-mellvillei-sperm-whale-fossils-science/">Photos: New Leviathan Whale Was Prehistoric "Jaws"?</a>)</p> <p><em> </em></p> <p><em>—Angela Botzer</em></p>

Stone in Cast

Scientists preserve a prehistoric adult whale skeleton's rib cage and tail in plaster in Chile's Atacama Desert in 2010.

The fossil is 1 of 20 roughly five-million-year-old whales found in a roadside "graveyard" more than a half a mile (a kilometer) from the Pacific coast, experts announced late last month.

It's unknown why the whales were found together, said the Smithsonian Institution's Nicholas Pyenson, lead paleontologist on the excavation.

But possible reasons include a storm pushing them abruptly to shore, a red tide—a proliferation of microscopic organisms that release toxins in the water—poisoning them, and the whales beaching themselves in a group, said Pyenson, a grantee of the National Geographic Society's Committee for Research and Exploration. (The Society owns National Geographic News.)

Getting to the bottom of the mystery requires careful preservation and examination, beginning with encasing the fossils in protective plaster "jackets" (as pictured) for the trip to the lab—a skill the team hadn't quite mastered by the time this picture was taken, Pyenson explained.

Above, he said, "you can see the block containing the rib cage and the thinner segments capping the tail."

(Photos: New Leviathan Whale Was Prehistoric "Jaws"?)

—Angela Botzer

Photograph from Museo Paleontologico de Caldera via AP

Pictures: Prehistoric Whale "Graveyard" Found in Desert

In what's now Chilean desert, 20 whales died five million years ago. Experts are brushing away sands of time to find out why.

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