Fossils

Intro

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(gentle music)

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- [Narrator] Like buried treasure,

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they lie hidden from sight.

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Echoes of an ancient past, they whisper secrets

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and tell tales once lost to time.

What are fossils

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Fossils are remnants or impressions of ancient organisms

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that are naturally preserved in stone.

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While there are hundreds of fossil types,

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they are often grouped into two major categories,

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body fossils, which are the preserved remains

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of plants and animals, and trace fossils,

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which are records of an animal's behavior,

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such as footprints.

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Together, they form the fossil record,

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a primary account that tells the story

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of life on Earth through stone.

Fossilisation

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Fossilization or the process of preserving

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organisms in stone, can occur in countless ways.

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These methods are largely grouped

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depending on whether the organisms

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are altered during the fossilization process.

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Fossilization that does not alter a specimen

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can help to preserve its original form and texture.

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Among many methods, this group includes organisms

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that have been frozen,

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preserved in tar pits, and mummified.

Amber

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One special case involves trapping organisms,

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oftentimes insects, in amber.

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This process begins when an organism is covered

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in tree sap.

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The sap or resin forms a protective seal

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around the entrapped organism.

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Over time, the soft resin hardens

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and turns into amber

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with the organism suspended within.

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This process creates a biologically inert tomb

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for the organism, allowing its soft tissues

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to be remarkably preserved.

Carbonization

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Other fossilization methods change the specimen

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as it is being preserved.

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For instance, carbonization transforms soft tissues

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into thin black films of carbon.

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In fact, countless layers of carbonized plant material

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create a well known fossil fuel, coal.

Permineralization

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But one of the most common types of fossilization

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that changes a specimen is called permineralization.

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Permineralization begins when minerals from water

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or the ground enter the pores of dead plant

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or animal material.

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Over time, the minerals attach themselves,

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clinging onto cellular walls

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and building a crystalline network in the empty cavities.

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This mineralization hardens the bone

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and turns it into stone,

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thereby preserving its original structure in fossil form.

Outro

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When conditions are right,

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fossilization can preserve crucial information

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about an organism.

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Permineralized wood often contains enough information

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to identify its tree genus

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and sometimes its species.

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Insects encased in amber have been so well preserved

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that their genetic material was extracted

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and partially sequenced.

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And footprints left behind by ancient hominids

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help paint a picture of what life was like

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for early human ancestors millions of years ago.

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With every fossil uncovered,

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the planet's ancient past becomes clearer,

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helping shape our understanding of our world today.

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(gentle music)