Sunday, 18 July 2010

The First Life on Earth

The first living thing was very odd
Scientists studying rocks about 3 billion years old have found the earliest fossils. Fossils are the remains of living things preserved in rocks. These fossils are the remains of thousands of tiny living things called blue-green algae. These types of algae still live today. They contain just a single cell and are neither animal nor plant.

The first animals were as soft as jelly
Animals do not produce their own food, but feed on other living things such as plants or other animals. The first animals were single-celled creatures that ate single-celled pants. Later animals were made up of hundreds of cells but were all soft and lacking any hard parts. Charnia (charr-nee-ah) grew attached to the seabed, while jellyfish floated freely.

Plants appeared around 1000 million years ago
The first plants were green algae. These single-celled plants had chlorophyll, the green substance that enables plants to convert sunlight to energy. These algae produced oxygen, gradually making the Earth’s atmosphere able to sustain more advanced forms of plant and animal life.

Early land plants simply clung to rocks
By about 800 million years ago, some algae was growing together with fungi to form lichen. Lichen is able to grow on bare rock, creeping across the surface as it grows. The chemicals produced by lichens help break rocks down into grit and soil.

Plants that can stand up are called vascular plants
After many millions of years, more complex plants appeared. These had several different sorts of cell. Some formed tubes called vascules, which transported water and food from one part of the plant to another. When these vascules form stems, a plant can stand upright. One of the earliest such plants was Cooksonia (kook-soh-nee-ah).

Anomalocaris hunted other animals
Anomalocaris (ay-nom-ah-loh-karr-iss) lived about 520 million years ago in what is now Canada. It swam through the shallow seas in search of prey. Smaller animals were caught in its two pincers, then pushed into its mouth. Anomalocaris was an arthropod that grew to be about 60cm long.

I Don’t Believe It!
None of the early animals had bones. They were made up almost completely of muscle, skin and other soft tissue.

This is an extract from 100 Things You Should Know about Prehistoric Life by Rupert Matthews

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