Final answer:
Both the Cambrian explosion and mass extinctions played significant roles in shaping Earth's biodiversity. The Cambrian explosion led to an increase in life's complexity, while mass extinctions such as the Cretaceous-Paleogene event caused major losses but also made room for new species to evolve. Therefore, both had equal impacts in their own ways. Option C is the correct answer.
Step-by-step explanation:
When comparing the significance of the Cambrian explosion to mass extinctions in Earth's geological timeline, it is important to recognize that both events have played pivotal roles but in different ways. The Cambrian explosion refers to a time approximately 541 million years ago when there was a rapid increase in the diversity of life, leading to the appearance of most major animal phyla. This period marked a profound evolutionary expansion that set the stage for complex life forms.
In contrast, mass extinctions have been cataclysmic events that resulted in the abrupt and widespread loss of biodiversity. The most well-known among these is the Cretaceous-Paleogene (K-Pg) extinction event, approximately 65 million years ago, which led to the disappearance of dinosaurs and paved the way for mammals to diversify and evolve. Other mass extinctions, like the Late Permian, were even more devastating.
Ultimately, while the Cambrian explosion was foundational in establishing the diversity of life, mass extinctions have acted as both destructive and creative forces, by wiping out species and providing ecological niches for the survivors to evolve. Therefore, neither event can be seen as having a singularly greater impact; rather, they were different types of turning points that reshaped life on Earth. The correct option is C) Both events had equal impact.