Index Fossils

What type of rock are fossils found in?

• Igneous

• Sedimentary

• Metamorphic

Tags

NGSS.MS-ESS2-3

Which characteristics of a fossil would make it useful as an index fossil in determining the relative age of widely separated rock layers?

• a wide time range and a narrow geographic range

• a wide time range and a wide geographic range

• a narrow time range and a wide geographic range

• a narrow time range and a narrow geographic range

Index fossils help scientists estimate the age of a rock because index fossil species only existed for a relatively short time. What happened to the species that are now used as index fossils?

• They became extinct.

• They changed their diets.

• They hid in marine sediments.

• They migrated to new environments.

Tags

NGSS.MS-ESS1-4

NGSS.MS-LS4-1

The diagram below represents three bedrock outcrops. The layers have not been overturned. Letters A through E identify different rock layers. Fossils found in the rock layers are shown.

Which fossil could be classified as an index fossil?

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Tags

NGSS.MS-ESS1-4

NGSS.MS-LS4-1

The cross sections below represents three widely separated outcrops of exposed bedrock. Letters A, B, C, and D represent fossils found in the rock layers.

Which fossil appears to have the best characteristics of an index fossil?

• A

• B

• C

• D

Tags

NGSS.MS-ESS1-4

The geologic columns A, B, and C in the diagrams below represent widely spaced outcrops of sedimentary rocks. Symbols are used to indicate fossils found within each rock layer. Each rock layer represents the fossil record of a different geologic time period.

According to the diagrams for all three columns, which would be the best index fossil?

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• 
• 
• 

Tags

NGSS.MS-ESS1-4

NGSS.MS-LS4-1

NGSS.MS-LS4-2

Index fossils are globally ​ (a)   .

• widespread
• extinct
• abundant
• distinctive

Index fossils are ​ (a)   and easily recognizable. 

• distinctive
• extinct
• abundant
• widespread

Species that become index fossils existed for a relatively short period of geologic time and became ​ (a)   fairly quickly.

• extinct
• abundant
• widespread
• distinctive

The organism that became index fossils were found in very large quantities, meaning these organisms were ​ (a)   at one time.

• abundant
• extinct
• widespread
• distinctive