No, it's not a sand sculpture competition. The skeleton shapes are fossils, some of at least 40 dead whales washed ashore en masse between 6 and 9 million years ago on a beach that is now slightly inland from northern Chile's coastline. They provide the earliest known example in the fossil record of mass strandings of marine mammals.
The area has the greatest density of extinct marine mammals in the world, says Nicholas Pyenson of the Smithsonian Institution's National Museum of Natural History in Washington DC, who led the research. Unfortunately, much of the site now sits under the northbound lane of the Pan-American Highway.
Discovered in 2010 during excavations for the road, which links Alaska and Argentina, the fossil haul includes over 40 large baleen whales, an extinct species of sperm whale and an extinct walrus-like whale. Also found at the Cerro Ballena site – Spanish for "whale hill" – were skeletons of billfishes, seals and aquatic sloths.
Researchers recorded the skeletons in situ using 3D photography (pictured above) before moving them to Chilean museums. More stunning images of the fossils are available online.
Pyenson and his colleagues think that the whales died at sea after consuming food contaminated with toxins from algal blooms and their bodies floated onto what was then a beach. So-called "red tides", caused by algal blooms, are also to blame for some modern mass whale strandings, says Pyenson.
There were no large land scavengers in South America at the time, so the bodies lay unmolested until sand buried them. The skeletons were found on four separate levels, suggesting this story was repeated at least four times.
Much of the site is now paved over, but the researchers are confident that the area still conceals hundreds more fossils. The University of Chile in Santiago aims to open a research station near the Cerro Ballena site to work with what's left.
Journal reference: Proceedings of the Royal Society B, DOI: 10.1098/rspb.2013.3316
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