Question

Q. Which of the following statements correctly defines the term "Cambrian Explosion” in the evolutionary history of life on Earth?

• A. It was a period of massive volcanic eruptions leading to degassing and the formation of the early atmosphere of Earth.
• B. It marked the beginning of the appearance of vascular plants with cambium rings.
• C. It refers to the sudden appearance in the fossil record of complex animals with mineralized skeletal remains.
• D. An abrupt change in the Earth’s atmosphere leading to huge explosions and the disappearance of large animals such as dinosaurs.

Answer 1

The correct option is C It refers to the sudden appearance in the fossil record of complex animals with mineralized skeletal remains.

Explanation:

The "Cambrian Explosion" refers to the sudden appearance in the fossil record of complex animals with mineralized skeletal remains. It may represent the most important evolutionary event in the history of life on Earth. The beginning of the explosion is considered to be 541 million years ago during the Cambrian period. It resulted in the appearance of almost all modern animal phyla. Provided the importance of oxygen for animals, scientists hypothesise that a sudden increase in the gas to near-modern levels in the ocean might have spurred the Cambrian explosion. This complemented the idea of oxygen as a key trigger for the evolutionary explosion.