For as much as science and archeology have taught humans about Earth, there still appears to be so much more to learn. A new discovery in the northern United States might be able to help.

In a story published this week in the New Yorker, paleontologists revealed some of the newest fossils in an archeological dig in the Hell Creek geological formation in the Rocky Mountain region. The formation spans North and South Dakota, as well as Montana and Wyoming.

What makes these newest fossils stand out from previous discoveries is that these fossils are the closest to the Cretaceous/Paleogene rock boundary. The boundary marks the geological end of the Cretaceous period and the beginning of the Paleogene period, which is the period humanity lives in.

It is also believed to be the layer of rock formed in the aftermath of the giant asteroid the hit Earth, causing dinosaurs to go extinct.

Jan Smit, one of the paleontologists on the team, said that "it solves the question of whether dinosaurs went extinct at exactly that level or whether they declined before. And this is the first time we see direct victims."

The list of fossils found include dinosaur, fish, seed, and possibly even mammals that were killed in the aftermath of the asteroid hitting.

The hypothesis put forward by Robert A. DePalma, a paleontologist from the Palm Beach Museum of Natural History, and his team was that in the hours after the asteroid’s impact, water rushed into the area and leveled everything in its path. Tektites that fell in the impact area were swept farther north and became lodged in the gills of fish found at the site.

Using these new fossils, paleontologists may be able to now provide an idea of what exactly happened on the literal final day of the dinosaurs.