What Defines a Fossil?
A fossil is the preserved remains or traces of animals, plants, and other organisms from the remote past. They are typically found in sedimentary rocks and must be at least 10,000 years old to be considered a fossil. These remnants provide invaluable direct evidence of past life on Earth.
How Fossils Are Formed
Fossilization is a rare process requiring specific conditions, usually rapid burial by sediment (like mud or sand) to protect the remains from scavengers and decay. Over millions of years, minerals from groundwater can replace the original organic material, turning bone, shell, or wood into stone (permineralization), or leave an imprint if the original material dissolves completely (molds and casts).
Examples of Fossil Types
Common examples include dinosaur bones, ancient shells, petrified wood, and insects preserved in amber. Trace fossils, such as footprints, burrows, and coprolites (fossilized feces), are also crucial as they provide evidence of an organism's activity rather than its body itself.
Why Fossils Are Important
Fossils are essential for understanding the history of life, evolution, and ancient environments. They help scientists piece together past ecosystems, track the development of species over geological time, and determine the age of rock layers, providing a chronological record of Earth's biological and geological past.