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Learn How Dinosaur Fossils are Formed

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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 and are called fossils. Fossils are features or remnants left behind after animals and plants die, they typically date back at least 10,000 years.

Fossils can be bones, teeth, footprints, skin, and feces. There are two kinds of fossils, body fossils or trace fossils. Body fossils are made up of bones and teeth. Trace fossils are skin impressions and footprints.

Not all ancient animals will become fossils because other animals often eat them when they die. However, remains that are not eaten by other animals and are subject to the right conditions can be preserved for thousands of years. Most fossilization happens when animals are buried by sediments like sand, mud, or silt, therefore the bones are protected from rotting. As soft parts of the body decay, harder parts like bone and teeth are left behind. Through millions of years, the rocks surround these hard parts and minerals in water replace the parts. When water minerals completely replace the organic material in the bones, a solid “rock copy”, or fossil, is left behind.

Fossils are mainly found in sedimentary rocks. Paleontologists use several techniques to find fossils such as satellite photos and geologic maps. They use these tools to examine the various rock layers before excavating in certain areas. They usually search in “badlands” which are places with little vegetation, barren ridges, and ravines. When a fossil fragment is found, Paleontologists carefully brush away loose dirt to reveal more of the specimen buried underground. Other roles like hammers and chisels remove rocks and harder material covering the fossils. As more of the fossil is revealed, a special glue is applied on cracks to hold everything together.

At the end when everything is excavated, damp toilet paper is placed on the fossils before they are covered with bandages to create a hard cast. The hardened cast allows for easy removal of the fossil from the site and shipment back to museums and other sites for study.

Fossilization is a lengthy and complicated process. To add on, there are many steps required to excavate fossils and study them properly. Learning about the process of fossilization and the intricate details that go into their study allow for a better understanding of the field of paleontology and how remains of the past guide the work that is done in the present.

[Source: American Museum of Natural History]

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