Which of the following was probably an important factor in bringing about the Cambrian explosion? (A) the movement of animals onto land (B) an increase in the concentration of atmospheric nitrogen (C) the emergence of predator-prey relationships (D) the origin of bilaterian animals

Verified step by step guidance

1. Step 1: Understand the question. The Cambrian explosion refers to a period in Earth's history, approximately 540 million years ago, when there was a sudden increase in the diversity and complexity of life forms. We need to identify which of the given options could have been an important factor in causing this event.
2. Step 2: Evaluate each option. (A) The movement of animals onto land is not a likely cause, as this event occurred much later in Earth's history. (B) An increase in the concentration of atmospheric nitrogen is also not a likely cause, as nitrogen is not a limiting factor for the growth and diversity of most organisms.
3. Step 3: Continue evaluating the options. (C) The emergence of predator-prey relationships could have been a factor, as this would have driven natural selection and evolution, leading to increased diversity. (D) The origin of bilaterian animals, which have a front and a back end, could also have been a factor, as this would have allowed for more complex body plans and behaviors.
4. Step 4: Make a decision based on your evaluations. Both (C) and (D) are plausible causes of the Cambrian explosion, but (D) is more likely to have been a primary cause, as the emergence of bilaterian animals would have had a more direct impact on the diversity and complexity of life forms.
5. Step 5: Answer the question. The most likely answer is (D) the origin of bilaterian animals.

Key Concepts

Cambrian Explosion

The Cambrian Explosion refers to a significant period in Earth's history, approximately 541 million years ago, marked by a rapid diversification of life forms. During this time, many major groups of animals first appeared in the fossil record, leading to the establishment of complex ecosystems. Understanding this event is crucial for grasping the evolutionary developments that shaped modern biodiversity.

Predator-Prey Relationships

Predator-prey relationships are ecological interactions where one organism (the predator) hunts and consumes another (the prey). The emergence of these relationships during the Cambrian period likely drove evolutionary adaptations, such as improved mobility and defensive mechanisms, contributing to the rapid diversification of species. This dynamic is essential for understanding ecological balance and evolutionary pressures.

Bilaterian Animals

Bilaterian animals are a group characterized by bilateral symmetry, meaning their body plan is symmetrical along a central axis. This group includes most animal phyla and is significant because the origin of bilaterians during the Cambrian period is thought to have facilitated the development of complex body structures and functions, leading to increased ecological complexity and diversity.