The find is being described as "the most important paleontological discovery of the new century.”

The animals were remarkably preserved, some 66 million years after they were killed.

The asteroid that hit the Earth that day killed 75 percent of all species on the planet.

It's like a time capsule of the end of the world.

66 million years ago, in what's now North Dakota, a group of animals died together, only a few minutes after a huge asteroid smashed into the Earth near present-day Mexico.

Scientists Friday announced the discovery of the jumbled, fossilized remains of the animals, all killed when a tsunami-like wave and a torrent of rocks, sand and glass buried them alive.

This graveyard of fish, mammals, insects and a dinosaur is a unique, first-of-its-kind discovery from the exact day that life on Earth changed forever, according to the study lead author Robert DePalma, a curator at the Palm Beach Museum of Natural History.

“This is the first mass death assemblage of large organisms anyone has found associated with the (asteroid impact). said DePalma, who is also a doctoral student at the University of Kansas.

In a statement, he said that at no other spot on Earth "can you find such a collection consisting of a large number of species representing different ages of organisms and different stages of life, all of which died at the same time, on the same day.”

DePalma added that the find provides spectacular new detail to what is perhaps the most important event to ever affect life on Earth.

At the dig site, scientists found fish with hot glass in their gills from flaming debris that showered back down on Earth. Study co-author Jan Smit of the University of Amsterdam said his colleagues discovered charred trees, evidence of an inland tsunami, melted amber and even dinosaur footsteps from just before their demise.

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The asteroid impact and resulting mass extinction, which scientists call the K-T boundary, marked the end of the Cretaceous Era. The aftereffects of that infamous asteroid collision killed 75 percent of all species on Earth, including the dinosaurs. It's the planet's most recent mass extinction.

“We’ve understood that bad things happened right after the impact, but nobody’s found this kind of smoking-gun evidence,” said David Burnham, a study co-author and geologist at the University of Kansas in a statement. “People have said, ‘We get that this blast killed the dinosaurs, but why don’t we have dead bodies everywhere?’ Well, now we have bodies. They’re not dinosaurs, but I think those will eventually be found, too.”

The discovery was made at a site called Tanis in North Dakota’s Hell Creek Formation, a well-known area for fossils.

While the asteroid impact has been the most likely cause of the mass extinction, some scientists have claimed recently that massive volcanic activity in India also played a role. A pair of research studies released in February made the case for the volcano theory.

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DePalma understands the significance of the exact moment the asteroid hit in regards to Earth's history: "This particular event is tied directly to all of us – to every mammal on Earth, in fact. Because this is essentially where we inherited the planet. Nothing was the same after that impact. It became a planet of mammals rather than a planet of dinosaurs."

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The research paper – Prelude to Extinction: a seismically induced onshore surge deposit at the KPg boundary, North Dakota – will be published Monday in the peer-reviewed journal Proceedings of the National Academy of Sciences.

Contributing: The Associated Press