'Hell fish' likely killed by dinosaur-ending asteroid is preserved in stunning detail

Paleontologists are digging up the end of the world at the site of an ancient riverbed in southern North Dakota.

They've found two new species of 66 million-year-old sturgeon that lived and died alongside dinosaurs and were preserved as fossils. Their work was published in the journal of paleontology.

The site where the fossils were found was named after the movie "Raiders of the Lost Ark." The section of the Hell Creek Formation known as Tanis was once home to a large, deep river that fed the Western Interior Seaway. After the asteroid impact wiped out the dinosaurs, Tanis became a mass grave for thousands of ancient freshwater fish, which were smothered and buried in place in a matter of seconds.

Lance Grande is a paleontologist at the Field Museum in Chicago. The fish were piled up.

There is a photo of the dino-killing asteroid impact.

Grande and his colleagues finally got the chance to look at the fossils up close. Four of the specimen were special. Most of the scutes were intact. There is a gap in the fossil record of North America. Grande said that they have a lot of clear similarities. They have a number of unique features that allow them to be described as new.

In honor of the team that prepared the fossil prior to the investigation, the researchers dubbed the new species AcipenserPraeparatorum. Today, both fish species are gone. They are similar to modern-day sturgeon that are native to East Asia and Europe.

The fossil record shows that segulls and their relatives are distinct. The fishes' corpses are protected from being torn apart by waves or strong river currents by having large plates on their outsides. sturgeons prefer low-oxygen environments because exposure to a lot of oxygen breaks down body tissues before they can fossilize.

The sturgeons at the Tanis site were the victims of a massive tidal wave that swept thousands of pounds of silt into the river, burying them almost instantly. The same asteroid that killed dinosaurs in the Yucatn Peninsula is believed to have triggered this wave. Tanis is a snapshot of the end of the Mesozoic era.

The river was full of paddlefish, bowfish, ammonites, insects and aquatic reptiles. The researchers think there are many more species waiting to be found.

"But it's not the end of the story," saidHilton.