Fossils Flashcards
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Questions and Answers

How does a carbon film fossil form?

Fossils usually form when sediment buries a dead organism. As sediment piles up, the organism's remains are subjected to pressure and heat. These conditions force gases and liquids from the body, leaving a thin film of carbon residue that forms a silhouette of the original organism.

Describe how a fossil would form through mineral replacement.

Fossils form through the process of mineral replacement beginning when an organism dies and is buried. Groundwater seeps around the organism, and the minerals in the water gradually replace the minerals in the hard parts of the organism.

Do all rocks contain fossils? Describe the conditions necessary for fossils to form.

Not all rocks contain fossils. Whether or not a dead organism becomes a fossil depends on how well it's protected from scavengers and agents of physical destruction. Quick burial isn't always enough to make a fossil. Organisms with hard parts, such as bones or teeth, have a better chance of becoming fossils because hard parts decay more slowly.

How might scientists be able to use fossils to infer that the climate of the central United States was a lush subtropical forest millions of years ago?

<p>Scientists can use fossils to learn about past environments by studying the fossilized remains of ancient organisms and comparing them to similar organisms alive today.</p> Signup and view all the answers

Why aren't there many fossil jellyfish?

<p>Jellyfish are invertebrates, so they do not have the hard body parts that favor fossilization.</p> Signup and view all the answers

What can trace fossils tell you about ancient organisms?

<p>Trace fossils provide information about the activities of organisms, such as fossilized footprints and burrows.</p> Signup and view all the answers

How can fossil correlation be used to determine the ages of rock layers?

<p>Fossil correlation uses the principle that rock strata containing fossils of the same age must be the same age as the fossils. Geologists can compare the known lifespan of the fossilized plant or animal to determine the age of the rock layers.</p> Signup and view all the answers

Any trace of an ancient organism that has been preserved in rock is called a:

<p>Fossil</p> Signup and view all the answers

How does coal form?

<p>Millions of years ago, swamps covered much of Earth. Layers of dead, decaying swamp plants formed a soft material called peat. Over time, layers of rock formed over the peat, and slowly, the peat changed into coal.</p> Signup and view all the answers

Compare and contrast mold and cast fossils.

<p>A mold is a hollow rock left by an organism, while a cast is when the rock is filled with sediment. A mold is a negative imprint, while a cast preserves the external form of the organism.</p> Signup and view all the answers

The calico scallop is an index fossil. It is well documented to have lived 1.8 million years ago. Therefore, the approximate age of the rock in which this fossil is found is:

<p>1.8 million years</p> Signup and view all the answers

Fossils most often form when a dead organism is buried in sediments.

<p>True</p> Signup and view all the answers

What do you call a fossil formed when an outline of the original organism is formed from left-over carbon?

<p>Carbonaceous film</p> Signup and view all the answers

Fossils are the ______, imprints, or traces of once-living organisms preserved in rock.

<p>remains</p> Signup and view all the answers

The ______ parts of organisms are most likely to become fossils.

<p>hard</p> Signup and view all the answers

To be a useful index fossil, a species must have been rare.

<p>False</p> Signup and view all the answers

What is made when sediments fill in a cavity made when an object decayed and the sediments harden into rock?

<p>Casts</p> Signup and view all the answers

A ______ is the cavity left behind in the rock after an organism's hard part has dissolved.

<p>mold</p> Signup and view all the answers

Carbon films are formed when a thin film of carbon is left, forming a silhouette of the original organism.

<p>True</p> Signup and view all the answers

What is a hollow place in rock made when an organism died and was buried, allowing holes in the rock for air or water to dissolve the organism?

<p>Molds</p> Signup and view all the answers

Index fossils are the remains of species that existed on Earth for relatively short periods of time.

<p>True</p> Signup and view all the answers

What may tell a geologist when, where, and how an organism lived?

<p>Fossil</p> Signup and view all the answers

Index fossils are the remains of species that were once abundant and widespread geographically.

<p>True</p> Signup and view all the answers

All of the following conditions help preserve organisms as fossils EXCEPT:

<p>Activities of microorganisms</p> Signup and view all the answers

What are preserved animal tracks called?

<p>Trace fossils</p> Signup and view all the answers

Study Notes

Fossil Formation

  • Carbon film fossils form when sediment buries an organism. Pressure and heat drive out gases and liquids, leaving a carbon residue that outlines the organism.
  • Mineral replacement occurs when groundwater infiltrates an organism's remains, gradually replacing its minerals with those in the water, leading to fossilization.
  • Not all rocks contain fossils; successful fossilization depends on protection from scavengers, quick burial, and the presence of hard parts like bones or shells.

Inference from Fossils

  • Fossils provide insights into past environments, allowing scientists to infer climate conditions by comparing ancient organisms to modern-day counterparts.

Types of Fossils

  • Jellyfish are rarely fossilized due to their lack of hard parts, making them less likely candidates for fossilization.
  • Trace fossils, such as footprints and burrows, reveal the behaviors and activities of ancient organisms rather than their preserved remains.

Fossil Correlation and Dating

  • Fossil correlation helps geologists determine the age of rock layers by matching fossilized remains across strata, based on known lifespans of the species.
  • To qualify as a useful index fossil, a species must have existed for a relatively brief period and been widely distributed geographically.

Fossil Characteristics

  • A mold fossil represents a cavity left in the rock after an organism's hard parts dissolve, while a cast fossil forms when sediment fills a mold, preserving the external shape of the organism.
  • Hard parts of organisms, such as bones and shells, are more likely to be preserved as fossils than softer tissues.

Additional Concepts

  • Coal forms from peat, which is produced by dead swamp plants that compress under layers of earth over millions of years.
  • Index fossils are crucial in geological dating due to their existence in a specific time frame and their widespread distribution.
  • Conditions favorable for fossil preservation include rapid burial, presence of hard parts, and protection from scavengers, while activities of microorganisms tend to hinder preservation.
  • Preserved animal tracks are referred to as trace fossils, highlighting the behaviors of extinct species.

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Test your knowledge about fossil formation with these flashcards. Explore different processes like carbon film and mineral replacement. Perfect for students studying geology or paleontology.

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