Scientists Discover Fossilized Fish That May Be Linked To The Asteroid That Wiped Out All The Dinosaurs
Many people know that around 66 million years ago a large asteroid collided with Earth. It was around the same time that dinosaurs went extinct. While some people have speculated that the asteroid was the cause of this mass extinction, no one is completely sure. The main argument against this idea was that there weren’t any remnants of the animals which were killed by the asteroids effects. Until now.
In North Dakota, at one of Earth’s most important and more significant graveyards, paleontologists have unearthed the fossilized remains of a fish which appears to have been killed by the effects of the asteroid that ended the Cretaceous period. This could potentially be the evidence of the asteroid killing animals that so many people have been looking for. The rocks in North Dakota preserve a mixture of both freshwater fish, like paddlefish and sturgeon, as well as marine mollusks called ammonites. This suggests to researchers the ocean had mixed with freshwater rivers around this time.
Why has it taken so long?
Given today’s technology and understanding of the Earth and fossils, some people are wondering why this evidence is only just coming to light. Well, when a giant meteorite strikes, most people would expect chaotic effects, like rocks altered by the impact’s high pressures and temperatures, enormous earthquakes or tsunamis. However, over time, Earth’s rocks don’t directly preserve single days of the planet’s several billion-year-old history. Geologists have to get a bit creative when it comes to figuring out the history of the planet. It’s not just handed out on a plate. For example, around the world, layers of rock 66 million years old seem to contain excess iridium, presumably deposited by the Chicxulub impactor that struck near what is today the Yucatán Peninsula of Mexico. There are also tektites which are small, glassy spheres of compressed and heated rock. Theoretically, there should also be fossilized evidence of animals killed by the asteroid’s effects. Hopefully, this new discovery brings researchers one step closer to finding out what really happened during and following the asteroid collision.
What does this new find mean?
This new research, which is being led by Robert DePalma at the University of Kansas, is quite exciting. There are a pair of sediment layers at the Tanis site of The Hell Creek Formation in southwestern North Dakota. Both layers contain an excess of iridium, however, only the lower level contains glass pieces that seemed to have been deposited from an inland-moving force.
This suggests that the two layers are from two separate events. The upper layer appears to be the settling dust from after the impact, whereas the lower is a large deposit of sediment from the hours following the impact. That’s not all though! A large swath of ocean traveled up the interior of the United States during the late Cretaceous and ended quite close to the Tanis region. The interesting part is that lodged inside the fossilized paddlefish’s gills were more of the glass spherules. It has appeared as if waves containing shocked glass from the impact over 3,050 kilometers (1,895 miles) away had flooded into the area and in their dying breaths, the fish had inhaled some of them. This could possibly be the proof needed that an asteroid did, in fact, kill animals at the end of the Cretaceous.