Why did scientists FIRST hypothesize that a meteorite impact caused the extinction at the K-Pg Boundary? They found evidence of wildfires in many regions throughout the globe. They found evidence of acid rain in the rocks in the Southern Hemisphere. They found evidence of a giant tsunami on the Gulf coast. They found evidence of Iridium enrichments in a clay layer that led them to believe that the Iridium was the remains of a meteorite impact. They found evidence of an impact crater in Mexico. Next

The K-Pg boundary is the boundary between the Cretaceous period and the Paleogene period, but also marking the end of the Mesozoic era and the beginning of the Cenozoic era. This boundary is dated to roughly 66 million years ago. The K-Pg boundary is characterized with a mass extinction. The dominant organisms on Earth all died out, including the dinosaurs, both terrestrial and aquatic, as well as the flying reptilians, with only the birds surviving from that super-family. The reason for the mass extinction has been an impact with an asteroid or a comet, that was very large and hit the Earth where the Yucatan Peninsula in modern day Mexico is located. The impact was devastating, with heat waves, tsunamis, earthquakes, triggering of the majority of the volcanoes, wildfires, all combined managed to devastate the environment, thus big portion of the species living in it as well. The lucky survivors were smaller organisms, and the mammals turned out to be the most successful in occupying the empty niches and have became the dominant organisms on the planet.