The Chicxulub asteroid impact, which occurred approximately 66 million years ago, is widely believed to have played a significant role in the extinction of the dinosaurs. The event led to a mass extinction that paved the way for the diversification and eventual dominance of mammals. However, it is important to note that the asteroid impact was not the sole factor responsible for the rise of mammals.
Prior to the extinction event, mammals were present on Earth but occupied relatively small ecological niches, largely overshadowed by the dinosaurs. The extinction of the dinosaurs created ecological opportunities for mammals to rapidly diversify and occupy new ecological roles.
If the Chicxulub asteroid had missed Earth, it is highly likely that the dominance of dinosaurs would have continued, and mammals would have remained in a subordinate position. The large dinosaurs were well-adapted to their environment, and their continued presence would have limited the evolutionary opportunities for mammals to expand into larger ecological roles.
However, it is important to acknowledge that evolutionary processes are complex and influenced by numerous factors. It is possible that under different circumstances, such as changes in climate or other catastrophic events, mammals could have eventually gained dominance even in the presence of dinosaurs. The absence of the asteroid impact would have altered the course of evolutionary history, leading to a different set of possibilities, but it is difficult to determine the exact outcome.
In summary, while the Chicxulub asteroid impact played a crucial role in the extinction of the dinosaurs and opened up ecological opportunities for mammals, it is challenging to predict with certainty whether mammals would have eventually become the dominant land fauna if the impact had not occurred.