The Precambrian Period spans a long period of the Earth’s history. It starts with the planet’s creation about 4.5 billion years ago, and ends with the emergence of complex, multicelled life-forms almost four billion years later. It is extremely significant, because it is the earliest of the geologic ages which are marked by different layers of sedimentary rock. Laid down over millions of years, these rock layers contain a permanent record of the Earth’s past, including the fossilized remains of plants and animals buried when the sediments were formed.The Precambrian is divided into two parts- the Archaean time, and the Proterozoic Era. There may not have been many different forms of life, but very important changes were taking place during the Precambrian. The Earth was formed, and its outer covering cooled and hardened into a crust. The hot molten insides of the Earth leaked out at weak places in the crust to form volcanoes. The clouds formed by the volcanoes caused huge amounts of rain to fall, and the oceans were created.The first life formed. The oceans were like a thick soup, and their chemistry made them the perfect place for life to begin. The first one-celled organisms formed during the Precambrian Era. They had an important job to do. They helped make the air and water around the Earth full of oxygen. Once there was plenty of oxygen, new life could form. This life would have many cells which would evolve into different kinds of animals. All of the important work of the Precambrian period made the Earth ready for what would come next.
Which Way Up?
Hallucigenia was a bizarre looking fossil which appeared to have tentacles on its back. For a long time, scientists were baffled by it, and unable to determine what kind of creature it was. Finally, they realized that they were looking at it upside down! The tentacles were in fact, legs that resembled the tubular legs of today’s velvet worms!
