When non -avian dinosaurs have turned off, the earth has changed – literally. Scientists think they finally know why

The rocks formed immediately before and after non -avian dinosaurs have turned out to be surprisingly different, and now tens of millions of years later, scientists think that they identified the culprit – and that was not the impact of chicxulub asteroids.

In a study published Monday in the journal Communications Earth & Environment, the researchers argue that dinosaurs have physically influenced their environment spectacularly that their disappearance led to changes struck in the land landscape and, in turn, the geological file.

More specifically, their mass extinction – an event known as the mass extinction of the Cretaceous -Paleogenic (or K -PG) – made it possible to cultivate, stabilize sediments and shape the rivers with large medals or curves.

“Very often, when we think about how life has changed in time and how the environments change over time, it is generally that the climate changes and, therefore, it has a specific effect on life, or this mountain has grown and, therefore, it has a specific effect on life,” said Luke Weaver, paleontologist at the University of Michigan, in a press release.

“We rarely think that life itself could really change the climate and the landscape. The arrow is not content to be satisfied in one direction. ”

River deposits, no pond deposits

Weaver and his colleagues have concentrated their studies on the Williston basin, which spreads in certain parts of Montana, Northern Dakota and South Dakota; And the Bigorn basin, in the North Center of Wyoming. The formation of Fort Union de Williston Basin dates after the non -avian dinosaurs have turned off and have colored rock layers that Weaver described as resembling pajamas. Under the formation of Fort Union are water -rich soils similar to the outer edges of a flood plain.

Previous research has applied that the colored layers are evidence of pond deposits of the sea level rise. But the new survey of the team, however, revealed that “pajama stripes were not at all pond deposits. These are points bar deposits or deposits that form the interior of a large meander in a river, “said Weaver.

“So, instead of looking at a calm and calm setting, what we really look at is a very active meander,” he said.

Above and below these river deposits were layers of a sort of coal created by the plant material, which, according to the team, was formed thanks to the stabilizing effect of thick forests, which can prevent rivers of frequent floods. Stable rivers do not distribute clay, silt and sand on a flood plain, therefore organic remains accumulate mainly instead.

Iridium anomaly

The researchers then turned to what is called the anomaly of the iridium – a layer of rocks rich in an iridium element – which was deposited on parts of our planet when the chicxulub asteroid struck the earth. As such, the anomaly of the iridium represents the K-PG border.

At the Bigorn basin, Weaver analyzed the samples from a fine line of red clay between the formation of the dinosaurs era and the subsequent formation of the era of mammals. “And here it is, the anomaly of the iridium was just in contact between these two formations, where geology changes,” said Weaver.

“This discovery convinced us that it is not only a phenomenon in the Williston basin. This is probably true everywhere in the Western interior of North America.”

However, the researchers were perplexed regarding reason. They suspected that the dinosaurs had sort of shaped their environment so that it influenced geology, but it was only after Weaver has tripped on a series of discussions on the way in which animals like elephants shape their ecosystems that the team finally had its “bulb moment”. These former reptiles were to be the “ecosystem engineers” of their time.

“The dinosaurs are enormous. They had to have had a kind of impact on this vegetation,” said Weaver.

He and his colleagues argue that when the non -avian dinosaurs were alive, they flattened the vegetation and, because of their size, affected the cover of the trees, probably shaped sparse landscapes and weeds with dispersed trees. This would have indicated that rivers without large meanders may have flooded frequently. Following their mass extinction, however, the forests prospered, stabilized the sediments, the bars of built points and the structured rivers.

“For me, the most exciting part of our work is proof that dinosaurs may have had a direct impact on their ecosystems,” said Courtney Spain, co-author of the study.

“More specifically, the impact of their extinction can not only be observable by the disappearance of their fossils in the rock record, but also by changes in the sediments themselves.”

The land has clearly felt the loss of dinosaurs in more ways than one. However, I’m glad that Tyrannosaurus rex no longer exists (and does not even throw me on the Gigas Meraxes).