Precambrian Era
Starting 4.6 billion years ago, and ending 544 million years ago, the Precambrian Era is not well known among scientists. During this time, the Earth was formed and the first living organisms appeared in the seas about 3.5 billion years ago; while others evolved one billion years ago. Some of them include early bacteria and algae, jellyfish-like animals, and sea pen.
The early Precambrian continents were very distinctive than the continents we have today. Because of continental drift the continents separated and became how they are today. In this era, the trilobite population was introduced to Earth. These trilobites were used as index fossils to find the relative age of the rock layers. When Hutton was using the principle of uniformitarianism, he realized that the Earth was older than what he had hypothesized because of the Precambrian period.
The early Precambrian continents were very distinctive than the continents we have today. Because of continental drift the continents separated and became how they are today. In this era, the trilobite population was introduced to Earth. These trilobites were used as index fossils to find the relative age of the rock layers. When Hutton was using the principle of uniformitarianism, he realized that the Earth was older than what he had hypothesized because of the Precambrian period.