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  • (gentle music)

  • - [Narrator] Like buried treasure,

  • they lie hidden from sight.

  • Echoes of an ancient past, they whisper secrets

  • and tell tales once lost to time.

  • Fossils are remnants or impressions of ancient organisms

  • that are naturally preserved in stone.

  • While there are hundreds of fossil types,

  • they are often grouped into two major categories,

  • body fossils, which are the preserved remains

  • of plants and animals, and trace fossils,

  • which are records of an animal's behavior,

  • such as footprints.

  • Together, they form the fossil record,

  • a primary account that tells the story

  • of life on Earth through stone.

  • Fossilization or the process of preserving

  • organisms in stone, can occur in countless ways.

  • These methods are largely grouped

  • depending on whether the organisms

  • are altered during the fossilization process.

  • Fossilization that does not alter a specimen

  • can help to preserve its original form and texture.

  • Among many methods, this group includes organisms

  • that have been frozen,

  • preserved in tar pits, and mummified.

  • One special case involves trapping organisms,

  • oftentimes insects, in amber.

  • This process begins when an organism is covered

  • in tree sap.

  • The sap or resin forms a protective seal

  • around the entrapped organism.

  • Over time, the soft resin hardens

  • and turns into amber

  • with the organism suspended within.

  • This process creates a biologically inert tomb

  • for the organism, allowing its soft tissues

  • to be remarkably preserved.

  • Other fossilization methods change the specimen

  • as it is being preserved.

  • For instance, carbonization transforms soft tissues

  • into thin black films of carbon.

  • In fact, countless layers of carbonized plant material

  • create a well known fossil fuel, coal.

  • But one of the most common types of fossilization

  • that changes a specimen is called permineralization.

  • Permineralization begins when minerals from water

  • or the ground enter the pores of dead plant

  • or animal material.

  • Over time, the minerals attach themselves,

  • clinging onto cellular walls

  • and building a crystalline network in the empty cavities.

  • This mineralization hardens the bone

  • and turns it into stone,

  • thereby preserving its original structure in fossil form.

  • When conditions are right,

  • fossilization can preserve crucial information

  • about an organism.

  • Permineralized wood often contains enough information

  • to identify its tree genus

  • and sometimes its species.

  • Insects encased in amber have been so well preserved

  • that their genetic material was extracted

  • and partially sequenced.

  • And footprints left behind by ancient hominids

  • help paint a picture of what life was like

  • for early human ancestors millions of years ago.

  • With every fossil uncovered,

  • the planet's ancient past becomes clearer,

  • helping shape our understanding of our world today.

  • (gentle music)

(gentle music)


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B2 中高級

化石101|國家地理雜誌 (Fossils 101 | National Geographic)

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    林宜悉 發佈於 2021 年 01 月 14 日