by Bruno Torres, age 8
When visiting dinosaur museums, one typically encounters large reconstructions of dinosaurs with what appears to be their bones. In reality, these structures aren’t bones but are called fossils. Fossils are features or remnants left behind after animals and plants die, typically dating back at least 10,000 years.
Fossils can include bones, teeth, footprints, skin impressions, burrows, nests, and even feces. There are two main types of fossils: body fossils and trace fossils. Body fossils are made up of preserved parts of an organism, like bones, teeth, and shells. Trace fossils are impressions or evidence of an organism's activity, such as footprints, burrows, or coprolites (fossilized feces).
Not all ancient animals will become fossils because many are scavenged or decompose naturally when they die. However, remains that are not eaten and are buried under the right conditions can be preserved for millions of years. Most fossilization occurs when organisms are rapidly buried by sediments like sand, mud, or silt, which protects the remains from rotting. As soft parts of the body decay, harder parts like bones and teeth are left behind. Over millions of years, minerals in groundwater can seep into these hard parts, gradually replacing the organic material in a process called permineralization, leaving behind a solid “rock copy,” or fossil. [Read More]