Extinction and Appearance - Middle School Life Science
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What does extinction mean when interpreting the fossil record of a species?
What does extinction mean when interpreting the fossil record of a species?
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Permanent disappearance of a species; no later fossils exist. Species is gone forever from Earth, not just locally.
Permanent disappearance of a species; no later fossils exist. Species is gone forever from Earth, not just locally.
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What is the simplest fossil-record definition of a species range?
What is the simplest fossil-record definition of a species range?
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The interval from FAD to LAD in rock layers. Species existed between its first and last fossil occurrences.
The interval from FAD to LAD in rock layers. Species existed between its first and last fossil occurrences.
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Which evidence best indicates a species went extinct in a stratigraphic sequence?
Which evidence best indicates a species went extinct in a stratigraphic sequence?
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Fossils stop above a layer and never reappear in younger layers. True extinction means no return in any later time period.
Fossils stop above a layer and never reappear in younger layers. True extinction means no return in any later time period.
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What is a key limitation that can make extinction look earlier than it truly was?
What is a key limitation that can make extinction look earlier than it truly was?
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Incomplete fossil record (preservation and sampling gaps). Not all organisms fossilize, creating false early extinctions.
Incomplete fossil record (preservation and sampling gaps). Not all organisms fossilize, creating false early extinctions.
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Which term describes a species that lived for a short time but was widespread?
Which term describes a species that lived for a short time but was widespread?
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Index fossil. Short-lived species make excellent time markers for dating rocks.
Index fossil. Short-lived species make excellent time markers for dating rocks.
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Identify the best interpretation: Species A occurs in layers 1–4, never in 5–10.
Identify the best interpretation: Species A occurs in layers 1–4, never in 5–10.
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Species A likely went extinct after layer 4 (its LAD is in layer 4). LAD in layer 4 means no fossils found above that point.
Species A likely went extinct after layer 4 (its LAD is in layer 4). LAD in layer 4 means no fossils found above that point.
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Which conclusion is supported: Species C is in layers 2–3, absent 4–5, present 6–8?
Which conclusion is supported: Species C is in layers 2–3, absent 4–5, present 6–8?
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A gap in the record is likely; extinction is not supported. Reappearance after absence suggests preservation gap, not extinction.
A gap in the record is likely; extinction is not supported. Reappearance after absence suggests preservation gap, not extinction.
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Which evidence best indicates a species appeared (originated) in a rock sequence?
Which evidence best indicates a species appeared (originated) in a rock sequence?
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Fossils first appear in a layer and are absent in all older layers. Shows the species didn't exist before this time.
Fossils first appear in a layer and are absent in all older layers. Shows the species didn't exist before this time.
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What does last appearance datum (LAD) mean in the fossil record?
What does last appearance datum (LAD) mean in the fossil record?
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Youngest known fossil occurrence of a species in rock layers. Marks the extinction or final local disappearance.
Youngest known fossil occurrence of a species in rock layers. Marks the extinction or final local disappearance.
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What does first appearance datum (FAD) mean in the fossil record?
What does first appearance datum (FAD) mean in the fossil record?
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Oldest known fossil occurrence of a species in rock layers. Marks when a species first evolved or migrated to an area.
Oldest known fossil occurrence of a species in rock layers. Marks when a species first evolved or migrated to an area.
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What is the best fossil-record evidence that a new species evolved from an earlier one?
What is the best fossil-record evidence that a new species evolved from an earlier one?
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Transitional fossils showing intermediate traits in older-to-younger layers. Shows evolutionary connection between ancestor and descendant.
Transitional fossils showing intermediate traits in older-to-younger layers. Shows evolutionary connection between ancestor and descendant.
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Which observation best indicates reworking (older fossils moved into younger rock) rather than true survival?
Which observation best indicates reworking (older fossils moved into younger rock) rather than true survival?
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Worn older fossils mixed into younger sediments with mismatched ages. Erosion can redeposit old fossils into younger sediments.
Worn older fossils mixed into younger sediments with mismatched ages. Erosion can redeposit old fossils into younger sediments.
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Which term describes a temporary absence of fossils even though the species survived?
Which term describes a temporary absence of fossils even though the species survived?
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Fossil record gap (a hiatus in occurrences). Species survived but wasn't preserved or found in some layers.
Fossil record gap (a hiatus in occurrences). Species survived but wasn't preserved or found in some layers.
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What is the most direct fossil evidence for a mass extinction event?
What is the most direct fossil evidence for a mass extinction event?
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Many unrelated species show LADs near the same boundary layer. Simultaneous extinctions indicate catastrophic environmental change.
Many unrelated species show LADs near the same boundary layer. Simultaneous extinctions indicate catastrophic environmental change.
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Identify the best interpretation: Species B is absent in layers 1–6 and present in 7–10.
Identify the best interpretation: Species B is absent in layers 1–6 and present in 7–10.
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Species B likely appeared by layer 7 (its FAD is in layer 7). FAD in layer 7 marks the species' first occurrence.
Species B likely appeared by layer 7 (its FAD is in layer 7). FAD in layer 7 marks the species' first occurrence.
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Identify the species with the earliest appearance: A FAD layer 5, B FAD layer 2, C FAD layer 7.
Identify the species with the earliest appearance: A FAD layer 5, B FAD layer 2, C FAD layer 7.
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Species B. Layer 2 is older than layers 5 and 7, so B appeared first.
Species B. Layer 2 is older than layers 5 and 7, so B appeared first.
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Identify the species with the latest last appearance: A LAD 9, B LAD 4, C LAD 6.
Identify the species with the latest last appearance: A LAD 9, B LAD 4, C LAD 6.
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Species A. Layer 9 is younger than layers 4 and 6, so A survived longest.
Species A. Layer 9 is younger than layers 4 and 6, so A survived longest.
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Which pattern best supports gradual evolution in the fossil record?
Which pattern best supports gradual evolution in the fossil record?
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A sequence of small trait changes across many successive layers. Slow, continuous change shows evolution happening gradually.
A sequence of small trait changes across many successive layers. Slow, continuous change shows evolution happening gradually.
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Which pattern best supports punctuated equilibrium in the fossil record?
Which pattern best supports punctuated equilibrium in the fossil record?
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Long stability, then abrupt change and a new species appearing. Rapid speciation after long stasis defines this evolutionary model.
Long stability, then abrupt change and a new species appearing. Rapid speciation after long stasis defines this evolutionary model.
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What does it suggest if many marine fossils disappear at the same layer worldwide?
What does it suggest if many marine fossils disappear at the same layer worldwide?
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A widespread extinction event, not a local habitat change. Global synchronous disappearance indicates mass extinction.
A widespread extinction event, not a local habitat change. Global synchronous disappearance indicates mass extinction.
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Identify the conclusion: Species Y is found in older layers, but never above layer 10.
Identify the conclusion: Species Y is found in older layers, but never above layer 10.
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Species Y went extinct at or after layer 10 (its LAD). Layer 10 represents the youngest occurrence before extinction.
Species Y went extinct at or after layer 10 (its LAD). Layer 10 represents the youngest occurrence before extinction.
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Identify the most likely conclusion: Fossil species X is in layers 3–7 only.
Identify the most likely conclusion: Fossil species X is in layers 3–7 only.
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Species X appeared by layer 3 and went extinct after layer 7. FAD at layer 3, LAD at layer 7 shows species' time range.
Species X appeared by layer 3 and went extinct after layer 7. FAD at layer 3, LAD at layer 7 shows species' time range.
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Which evidence indicates two separated rock outcrops are the same relative age?
Which evidence indicates two separated rock outcrops are the same relative age?
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They contain the same index fossil species. Index fossils correlate distant rock layers to the same time period.
They contain the same index fossil species. Index fossils correlate distant rock layers to the same time period.
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Identify the pattern that supports gradual evolution in a fossil lineage over time.
Identify the pattern that supports gradual evolution in a fossil lineage over time.
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Slow, continuous changes across successive layers. Fossils show incremental morphological changes through time.
Slow, continuous changes across successive layers. Fossils show incremental morphological changes through time.
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Which option best explains why a species might be absent from a layer without being extinct?
Which option best explains why a species might be absent from a layer without being extinct?
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It was not preserved or it lived elsewhere at that time. Fossilization is rare; absence doesn't always mean extinction.
It was not preserved or it lived elsewhere at that time. Fossilization is rare; absence doesn't always mean extinction.
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