Fossils are the remains of plant or animal life that were buried for millions of years until they finally turned to stone. Most fossils found today are from creatures that lived in the sea, as these had a much better chance of being buried before they were destroyed.
The oldest fossil ever discovered, a specimen of blue-green algae that was found in South Africa, is over 3.2 billion years old. Algae and other single-cell organisms are also the smallest types of fossils. As of 2014, the oldest known dinosaur fossil is of a prosauropod that was found in Madagascar; the animal lived more than 230 million years ago.
The smallest dinosaur fossil ever found was a 12-inch-tall Microraptor that was discovered in China. By looking at fossil records, scientists have theorized that an asteroid hit the Earth approximately 65 million years ago. Most mammal fossils that are found are from after this event.
Fossil fuels come from the fossilized remains of small creatures known as diatoms – not from dinosaurs as many people believe. It took millions of years for these fossils to break down into coal, oil and other fossil fuels. In addition, diatom fossils that haven't turned into fuel are also used in toothpaste.