Final answer:
The asteroid impact at the end of the Cretaceous period caused a massive extinction event, marking the end of the dinosaurs and the rise of mammals. The collision deposited rare elements like iridium into the Earth's crust, which supports the impact hypothesis, and led to significant environmental and climate changes.
Step-by-step explanation:
The asteroid impact at the end of the Cretaceous period was a catastrophic event that dramatically altered the course of life on Earth. This colossal impact, causing a crater off the coast of what is now the Yucatán Peninsula in Mexico, dispersed iridium and other rare elements into the Earth's crust. These elements, typically found in asteroids and comets, marked a distinct geological boundary between the Cretaceous and Paleogene periods, coinciding with a mass extinction that notably signaled the end for most dinosaurs. The aftermath saw significant changes in climate and biotic recovery that gave rise to the diversification of mammals and the onset of the Cenozoic era. At a magnitude of more than a trillion tons, the impact would have generated intense heat and pressures leading to widespread environmental disasters, perhaps further fueled by subsequent volcanic eruptions that altered global climates and ecosystems.