Final answer:
The profusion of animal diversity during the Cambrian may have been contributed by the oxygenation of the ocean and the extinction of dinosaurs.
Step-by-step explanation:
The profusion of animal diversity during the Cambrian period was likely contributed by multiple factors. One of these factors is the oxygenation of the ocean, as rising atmospheric oxygen levels created a more suitable environment for animal life. Another factor is the extinction of dinosaurs, as this event allowed for new ecological niches to be filled by different animal species. Therefore, the correct answer to the question is option 4: a. and c.
The Cambrian explosion's animal diversity was primarily due to ocean oxygenation and complex ecological and genetic factors, rather than the extinction of dinosaurs, which occurred much later.
The profusion of animal diversity during the Cambrian explosion may have been influenced by several factors. Notably, oxygenation of the ocean is a significant factor that likely contributed to this diversification. Rising atmospheric oxygen levels and an increase in oceanic calcium concentrations created a more suitable environment for animal life. Another theory suggests that ecological relationships, such as changes in the food web, competition for resources, and predator-prey interactions, along with the evolution of Hox control genes, which increased the morphological flexibility, were pivotal in promoting a rapid coevolution of species.
The extinction of dinosaurs, however, did not contribute to the Cambrian explosion as they emerged much later in Earth's history. The profound diversification of animal life during the Cambrian period continues to puzzle scientists, but it is clear that a combination of environmental changes, ecological factors, and genetic innovations played a crucial role in this unprecedented era of evolutionary change.