All flashcards
Flashcard 1: Which type of rock most commonly preserves fossils and is used to compare diversity across layers?
Answer: Sedimentary rock. Forms from layers of sediment that bury and preserve organisms.
Flashcard 2: What two traits make a fossil most useful as an index fossil for correlating rock layers?
Answer: Wide geographic range and short time range. Must be widespread to correlate areas but exist briefly to mark specific time.
Flashcard 3: What is extinction as shown by fossil data across successive rock layers?
Answer: Permanent disappearance of a species from later layers. Species that go extinct never reappear in younger rocks.
Flashcard 4: What is speciation as inferred from fossil data across successive rock layers?
Answer: Appearance of a new species not found in older layers. New species evolve and first appear at specific time points.
Flashcard 5: What pattern in fossils is the clearest evidence of a mass extinction event?
Answer: Many unrelated species disappear at the same layer boundary. Simultaneous extinctions indicate catastrophic environmental change.
Flashcard 6: What does a rapid increase in the number of fossil species after a mass extinction most likely indicate?
Answer: Adaptive radiation (rapid diversification into new niches). Survivors evolve rapidly to fill empty ecological roles.
Flashcard 7: What is a fossil assemblage when analyzing diversity patterns in one rock layer?
Answer: The group of different fossils found together in a layer. All species living together at one time get preserved together.
Flashcard 8: Which measure best represents diversity for a fossil layer: number of individuals or number of species?
Answer: Number of species (species richness). Species count shows variety; individual count shows abundance.
Flashcard 9: What principle states that, in undisturbed rock layers, lower layers are older than higher layers?
Answer: Law of superposition. Sediments deposit sequentially, making bottom layers oldest.
Flashcard 10: Identify the correct conclusion if a younger rock layer contains more fossil species than an older layer.
Answer: Diversity increased from the older time interval to the younger. More species types indicates higher biodiversity in recent times.
Flashcard 11: Identify the correct conclusion if a species appears in layers 3–7 but is absent above layer 7.
Answer: The species became extinct after layer 7 formed. Last appearance marks when the species died out completely.
Flashcard 12: Identify the correct conclusion if the same index fossil is found in two distant rock layers.
Answer: The two rock layers are the same relative age. Index fossils match layers formed during the same time period.
Flashcard 13: Identify the best interpretation if marine fossils are replaced by land plant fossils upward in a sequence.
Answer: The environment changed from marine to terrestrial over time. Fossil types reflect the changing environment through time.
Flashcard 14: Which option best describes the most reliable way to compare diversity between two layers with different sample sizes?
Answer: Standardize sampling effort (same area/volume or same method). Equal sampling prevents bias when comparing fossil counts.
Flashcard 15: Identify the correct conclusion if many new species appear soon after a volcanic ash layer boundary.
Answer: A disturbance was followed by diversification in later layers. Volcanic events often trigger extinction then rapid evolution.
Flashcard 16: Which evidence best supports a change in environment affecting diversity: stable fossil types or a shift in fossil types?
Answer: A shift in fossil types across layers. Different environments support different organism communities.
Flashcard 17: What is the most likely cause if a layer has very few fossils and low apparent diversity?
Answer: Poor preservation or limited deposition, not necessarily low life. Fossilization requires specific conditions often absent.
Flashcard 18: What is the correct way to compare diversity between two layers with different sample sizes?
Answer: Standardize sampling effort before comparing species counts. Equal sampling prevents artificial diversity differences.
Flashcard 19: What is species evenness in a fossil assemblage from one rock layer?
Answer: How evenly individuals are distributed among species. High evenness means no single species dominates the assemblage.
Flashcard 20: What is species richness when analyzing fossil data across rock layers?
Answer: The number of different species present in a layer or interval. Counts unique species types, not individual organisms.
Flashcard 21: Which interpretation fits if the same few species persist across many layers with little change?
Answer: Long-term stability with low turnover in that environment. Stable conditions support consistent species composition.
Flashcard 22: Identify the best conclusion if marine fossils are replaced by land-plant fossils upward in a sequence.
Answer: The area changed from marine to terrestrial conditions over time. Sea level drop exposed land, changing the ecosystem completely.
Flashcard 23: Identify the correct inference if a species is present in older layers but absent in all younger layers.
Answer: The species became extinct after the older layers formed. Absence in younger layers indicates the species died out.
Flashcard 24: Which option best supports that two distant rock layers are the same age: similar rock color or same index fossil?
Answer: Same index fossil. Index fossils provide precise age correlation; rock color varies locally.
Flashcard 25: Identify the best conclusion if many new species appear soon after a boundary layer.
Answer: Adaptive radiation increased diversity after the event. Survivors rapidly evolve to fill empty ecological niches.
Flashcard 26: Which pattern best indicates a mass extinction: gradual change or sudden drop in species count?
Answer: Sudden drop in species count across a boundary layer. Mass extinctions show abrupt diversity loss at layer boundaries.
Flashcard 27: What is the most direct fossil evidence that biodiversity increased after an event?
Answer: More species appear in younger layers than in older layers. Higher species count indicates diversification occurred.
Flashcard 28: What is an index fossil used for when analyzing diversity patterns over time?
Answer: A widespread, short-lived fossil used to correlate rock layers. Their presence dates rocks to specific time periods globally.
Flashcard 29: What is the law of superposition used for when reading fossil layers?
Answer: Lower rock layers are older than layers above them. Sediments deposit sequentially, creating a time sequence.
Flashcard 30: What is fossil succession as used to compare organisms across rock layers?
Answer: Fossil groups appear in a consistent order through strata. Different time periods have characteristic fossil assemblages.