Why Do Biologists Study Rocks And Fossils? by Caroline Daniel https://padlet.com/cgdaniel811/ep9ho1yxlffc Cengage Biology 16.3 en-us 2018-04-02 23:48:08 UTC 2026-01-22 01:23:34 UTC hello@padlet.com https://padlet-assets.s3.amazonaws.com/icons/Xmastree.png Fossils cgdaniel811 https://padlet.com/cgdaniel811/ep9ho1yxlffc/wish/247955052 Consist of:
  • mineralized bones
  • teeth
  • shells 
  • seeds 
  • spores 
  • hard body parts 
Trace fossils: 
  • footprints 
  • impressions 
  • nests
  • burrows 
  • trails
  • eggshells 
  • feces
]]> 2018-04-02 23:53:48 UTC https://padlet.com/cgdaniel811/ep9ho1yxlffc/wish/247955052 Fossilization cgdaniel811 https://padlet.com/cgdaniel811/ep9ho1yxlffc/wish/247955616
  • Organisms become covered by sediments, mud, or ash
  • Groundwater seeps into remains
    • fills space around and inside
  • Minerals dissolved in  water gradually replace minerals in bones and other hard tissues
  • Mineral particles that crystallize and settle from groundwater in cavities and impressions form detailed imprints of internal and external structures
  • Sediments slowly accumulate on top of site, exert increasing pressure, transform the mineralized remains into rock
    • ]]>     2018-04-03 00:01:22 UTC https://padlet.com/cgdaniel811/ep9ho1yxlffc/wish/247955616     Why Sedimentary Rocks Are Studied cgdaniel811 https://padlet.com/cgdaniel811/ep9ho1yxlffc/wish/248062003
  • Understand life’s historical context 
  • Features can provide information about environment
  • Banded iron started forming about 2.4 billion years ago 
    • Earth’s atmosphere and ocean contained very little oxygen, so almost all iron on Earth was in a reduced form 
    • Reduced iron dissolves in water, and ocean water contained a lot of it
    • Oxygen released into ocean by early photosynthetic bacteria quickly combined with dissolved iron
    • Oxidized iron compounds are completely insoluble in water, began to rain down on the ocean floor in massive quantities
    • Compounds accumulated in sediments that would eventually become compacted into banded iron formations
    • ]]>     2018-04-03 11:20:03 UTC https://padlet.com/cgdaniel811/ep9ho1yxlffc/wish/248062003     Fossil Record cgdaniel811 https://padlet.com/cgdaniel811/ep9ho1yxlffc/wish/248062802
  • 250,000 known species
  • Considering the current range of biodiversity, there must have been many millions more, but we will never know all of them. 
  • The odds are against finding evidence of an extinct species, because fossils are relatively rare. 
  • When an organism dies, its remains are often obliterated quickly by scavengers. 
  • Organic materials decompose in the presence of moisture and oxygen, so remains that escape scavenging can endure only if they dry out, freeze, or become encased in an air-excluding material such as sap, tar, or mud. 
  • Remains that do become fossilized are often deformed, crushed, or scattered by erosion and other geologic assaults.
    • ]]>     2018-04-03 11:24:12 UTC https://padlet.com/cgdaniel811/ep9ho1yxlffc/wish/248062802     Summary cgdaniel811 https://padlet.com/cgdaniel811/ep9ho1yxlffc/wish/248063039 Fossils are evidence of organisms that lived in the remote past, a stone-hard historical record of life. The fossil record will never be complete. Geologic events have obliterated much of it. The rest of the record is slanted toward species that had hard parts, lived in dense populations with wide distribution, and persisted for a long time.

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