A graveyard of whales found beside the Pan-American Highway in Chile has been one of the most astonishing fossil discoveries of recent years.
Now, scientists think they can explain how so many of the animals came to be preserved in one location more than five million years ago.
It was the result of not one but four separate mass strandings, they said.
The evidence strongly suggests the whales all ingested toxic algae, the BBC reported.
The dead and dying mammals were then washed into an estuary and on to flat sands where they became buried over time.
It was well known that this area in Chile's Atacama Desert preserved whale fossils.
Their bones could be seen sticking out of rock faces, and the spot acquired the name Cerro Ballena ("whale hill") as a result.
But it was only when a cutting was made to widen the Pan-American Highway that US and Chilean researchers got an opportunity to fully study the fossil beds.
The findings are published in Proceedings B of the Royal Society.
