Final answer:
The Gunflint Chert, found in sedimentary rocks, contains fossils of photosynthetic cyanobacteria that played a significant role in the oxygenation of Earth's early atmosphere and the consequent evolution of complex life.
Step-by-step explanation:
The Gunflint Chert of the Animike group is found in sedimentary rocks and is particularly significant due to its content of ancient prokaryotic fossils, including photosynthetic cyanobacteria. These microorganisms are critical to understanding the history of Earth's atmosphere as they are thought to have contributed to the oxygenation of the atmosphere through their photosynthetic activities. This process is vital because the increase in atmospheric oxygen allowed for the evolution and diversification of more complex life forms on Earth. Finding cyanobacteria in Gunflint Chert not only provides evidence for one of the earliest forms of life but also supports the theory that oxygenic photosynthesis was occurring at least 3.4 billion years ago, which is essential to the concept of how Earth's atmosphere evolved from being rich in carbon dioxide to one where oxygen is a major component.