Graveyard of ancient whales

No one expected to discover full skeletons the size of buses - all millions of years old

Associated PressDecember 12, 2011 

  • At the "Pyenson Lab" blog, read Nick Pyenson's dispatches about the discoveries in Chile. Pyenson is curator of fossil marine mammals at the Smithsonian's National Museum of Natural History.

    Visit nmnh.typepad.com/pyenson_lab

More than 2 million years ago, scores of whales congregating off the Pacific Coast of South America mysteriously met their end.

Maybe they became disoriented and beached themselves. Maybe they were trapped in a lagoon by a landslide or a storm. Maybe they died there over a period of a few millennia. But somehow, they ended up right next to one another, many just yards apart, entombed as the shallow sea floor was driven upward by geological forces and transformed into the driest place on the planet.

Today, they have emerged again atop a desert hill more than half a mile from the surf, where researchers have begun to unearth one of the world's best-preserved graveyards of prehistoric whales.

Chilean scientists together with researchers from the Smithsonian Institution are studying how these whales, many of them the size of buses, wound up in the same corner of the Atacama Desert.

"That's the top question," said Mario Suarez, director of the Paleontological Museum in the nearby town of Caldera, about 440 miles north of Santiago, the Chilean capital.

Experts say other groups of prehistoric whales have been found together in Peru and Egypt, but the Chilean fossils stand out for their staggering number and beautifully preserved bones. More than 75 whales have been discovered so far - including more than 20 perfectly intact skeletons.

They provide a snapshot of sea life at the time, and even include what might have been a family group: two adult whales with a juvenile between them.

"I think they died more or less at the same time," said Nicholas Pyenson, curator of fossil marine mammals at the Smithsonian's National Museum of Natural History. Pyenson and Suarez are jointly leading the research.

As for why such a great number perished in the same place, Pyenson said: "There are many ways that whales could die, and we're still testing all those different hypotheses."

Giant, extinct finds

The scientists have yet to publish their findings about the fossil bed and the extensive remains, which began to emerge last year during a highway-widening project that is now on hold.

So far, the fossils have been found in a roadside strip the length of two football fields.

Pyenson said the spot was once a "lagoonlike environment" and that the whales probably died between 2 million and 7 million years ago.

Most of the fossils are baleen whales that measured about 25 feet long, Pyenson said.

The researchers also discovered a sperm whale skeleton and remains of a now-extinct dolphin that had two walruslike tusks and previously had only turned up in Peru, he said.

"We're very excited about that," Pyenson said. "It is a very bizarre animal."

Other unusual creatures found elsewhere in the fossil-rich Atacama Desert include an extinct aquatic sloth and a seabird with a 17-foot wingspan, bigger than a condor's.

Erich Fitzgerald, a vertebrate paleontologist at Museum Victoria in Melbourne, Australia, says the discoveries are very significant: "The fossils are exceptionally well preserved and quite complete - a rare combination in paleontology and one that will likely shed light on many facets of the ... ecology and evolution of these extinct species."

Death at highway's edge

He said it's possible "these fossilized remains may have accumulated over a relatively long period of time."

Hans Thewissen, an expert on early whales, agreed. Another scenario, he said, is that the whales might have gathered in a lagoon and then an earthquake or storm could have closed off the outlet to the ocean.

"Subsequently the lagoon dries up and the whales die," said Thewissen, a professor of anatomy at Northeast Ohio Medical University. He said the accumulation of so many complete skeletons is "a very unusual situation."

"If this were a lagoon that dried up, you might see signs that ocean water evaporated," such as crystallized salt and gypsum in the rock, said Thewissen, who is not involved in the research.

"On the other hand, if a giant wave or storm flung the whales onto shore, it would also have pushed the ocean floor around, and you would see scour marks in the rocks."

Dating fossils is complicated, experts said, and it will be very hard to distinguish dates precisely enough to determine whether the whales all died simultaneously.

The researchers have been told to finish their on-site studies so that fossils can be moved out of the path of the widened Pan American Highway - Chile's main north-south road.

Many of the fossils have been transported in plaster coverings to the museum in Caldera.

3D images

With funding from the National Geographic Society, the Smithsonian team is using sophisticated photography and laser scanners to capture 3D images of the whales that can later be used to make life-sized models of them.

Suarez, the paleontologist, had long known about the whale bones just north of Caldera - they could be seen jutting out of the sandstone ridge alongside the highway at the spot known as Cerro Ballena - "Whale Hill."

When the road work began last year, the construction company asked him to monitor the job to avoid destroying fossils.

"In the first week, about six or seven whales appeared," Suarez said. "We realized that it was a truly extraordinary site."

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