How a Mass Whale Graveyard Ended Up Beneath a South American Highway

Connecting Alaska to Argentina, the Pan-American Highway runs some 30,000 miles north to south. Construction to widen the highway briefly stopped, however, to make way for dead whales back in 2010, when workers digging through a remote stretch of the Chilean desert found a huge trove of bones millions of years old. Now, scientists think they have figured out how the extinct whales ended up on land in the first place.

Because the road would only pause—but not detour—for the whales, paleontologists rushed in and worked feverishly to document the site before it was paved over. 3D photographs (below) preserved the site digitally. The bones themselves now sit in museums in Santiago and the nearby city of Caldera. As for the site, the northbound lane of the Pan-American Highway current runs through it.

How a Mass Whale Graveyard Ended Up Beneath a South American Highway

How a Mass Whale Graveyard Ended Up Beneath a South American Highway

The roadside discovery, detailed in a new study, turned out to be the densest collection of extinct marine mammals ever. The 40 whale skeletons were found in four distinct layers stacked on top of one another, meaning the creatures were beached in four separate events. But how did they all end up in this small, arid region of Chile called Cerro Ballena?

With only whale bones and dirt, scientists began piecing together the clues. Millions of years ago, Cerro Ballena was a tidal flat where whales could have gotten stranded. There were several different whale species, making a single disease a less likely cause. One set of whales was found largely undisturbed and belly-up, meaning they were already dead when they washed to shore. The best explanation for recurring whale deaths was toxic algae: blooms of toxic algae can still cause whale strandings today.

Hundreds more fossils could still be hidden near the highway, and the University of Chile in Santiago plans to open a research station in the area, turning this desert highway into a fascinating and unexpected site for marine paleontology. The act of construction is often at odds with history, but it can occasionally uncover extraordinary pieces of it. [Proceedings of the Royal Society B via Science and New Scientist]

Image credits: Adam Metallo / Smithsonian Institution, Smithsonian Institution, Adam Metallo / Smithsonian Institution