What are the fossilized remains of more than 80 whales doing in the driest desert on Earth?

Situated more than half a mile from the ocean, atop a hill in Chile's notoriously arid Atacama desert, an international team of scientists has made an incredible discovery. Over 80 extraordinarily well-preserved whale and marine mammal fossils, many of them positioned just meters apart from one another, have been found gathered on a small patch of land that as recently as 2010 was destined to become a highway.

The excavation of the whales has been a collaborative effort between scientists at Chile's Paleontological Museum of Caldera and researchers from the Smithsonian Institution. The collaborators say that the remains, which include over 20 perfectly intact skeletons, are some of the most well-preserved ever discovered, and also some of the most mysterious.

What are the fossilized remains of more than 80 whales doing in the driest desert on Earth?

Why, for example, are the whales situated so closely to one another? Some of the remains, like the ones pictured here, are actually overlapping. The excavation site measures just 20 meters wide by 240 meters long; explaining how the fossilized remains of over 80 marine mammals — including 25-foot-long baleen whales, a sperm whale, and an extinct dolphin species with walrus-like tusks — wound up gathered so closely together is high on the scientists' list of unanswered questions.

Researcher Nicholas Pyenson, curator of fossil marine mammals at the Smithsonian's National Museum of Natural History, thinks that the whales all died at more or less the same time as many as 7 million years ago. Back then, Pyenson says, the area may have resembled a "lagoon-like environment." One hypothesis is that currents created the graveyard, carrying dead marine life to the lagoon that millions of years ago may have been situated directly along the Chilean coastline, instead of half a mile off-shore.

What could have caused the whales to die off in such numbers, however, also continues to puzzle scientists. Other researchers, riffing on Pyenson's hypothesis, think the marine mammals may have been trapped in the lagoon by a landslide or storm, dying out in what over the course of several million years would transform into one of the driest and most fossil-friendly regions on Earth.

The researchers hope to shed some light on what may have really happened 7 million years ago by investigating the site's geology. "We wish to understand the environment in which the remains of these marine mammals were preserved," explains Pyenson, "and we also wish to understand the processes of disarticulation and decay that has preserved their bones."

One of the most incredible aspects of the excavation process is the use of scanning and imaging technology by the Smithsonian Institute's 3D digitization team to create a three-dimensional catalog of the fossils while they are still in the ground. The video featured here, released over the weekend, shows a day in the life of the 3D digitization team. Pyenson says he hopes that other museums will be able to create replicas of the skeletons when the 3D data becomes available online.

Unfortunately, Pyenson and the other researchers will need to document and excavate the remains quickly. Nature news reports that workers are soon scheduled to resume construction on the road that was put on hold last year when the fossilized remains were first discovered. All paleontological work will have to be concluded by next month in order for the construction to continue as planned.

[Via Nature]
Top image via AP. Overlapping remains via. Video by Smithsonian's 3D digitization team via.