pipestone

Now, a group of palaeontologists have come to Pipestone Creek - appropriately nicknamed the "River of Death" - to help solve a 72-million-year-old enigma: how did they die?

"Then here, we have all of these long, skinny bones. These are all ribs. And this is a neat one - it's part of a toe bone. This one here, we have no idea what it is - it's a great example of a Pipestone Creek mystery."

BBC News has come to Pipestone Creek to witness the sheer scale of this prehistoric graveyard and see how researchers are piecing together the clues.

All of this detailed research, in the museum and at the two sites, is helping the team to answer the vital question: how did so many animals in Pipestone Creek die at the same time?

“Pipestone has a particular relationship to our spiritual practice – praying with pipes, we take very seriously,” St. Clair said.