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The remains of plants and animals – bones, shells, eggs, seeds – preserved for many thousands, and even millions, of years are called fossils. A body fossil is formed of actual parts of the organism. Other impressions, such as footprints and scratch marks, are known as trace fossils. Fossils are most often found in soft sedimentary rocks such as limestone and sandstone. |
Fossils are the preserved remains, or traces of remains, of ancient organisms. Fossils are not the remains of the organism itself! They are rocks.
A fossil can preserve an entire organism or just part of one. Bones, shells, feathers, and leaves can all become fossils.
Fossils can be very large or very small. Microfossils are only visible with a microscope. Bacteria and pollen are microfossils. Macrofossils can be several meters long and weigh several tons. Macrofossils can be petrified trees or dinosaur bones.
Preserved remains become fossils if they reach an age of about 10,000 years. Fossils can come from the Archaeaean Eon (which began almost 4 billion years ago) all the way up to the Holocene Epoch (which continues today). The fossilized teeth of wooly mammoths are some of our most “recent” fossils. Some of the oldest fossils are those of ancient algae that lived in the ocean more than 3 billion years ago.
Credit: National Geographic Society
Picture Credit : Google