All flashcards
Flashcard 1: What is a fossil in the context of evidence for past life on Earth?
Answer: Preserved remains, impressions, or traces of ancient organisms. Physical evidence of organisms that lived long ago.
Flashcard 2: What is the fossil record?
Answer: All fossils and their positions in rock layers over time. Complete history of life preserved in Earth's rocks.
Flashcard 3: What does the law of superposition state about undisturbed sedimentary rock layers?
Answer: Lower layers are older than layers above them. Unless disturbed, sediments settle chronologically.
Flashcard 4: Which type of rock most commonly contains fossils: igneous, sedimentary, or metamorphic?
Answer: Sedimentary rock. Forms from layers of sediment that preserve organisms.
Flashcard 5: What is an index fossil?
Answer: A widespread fossil from a short time span used to date layers. Existed globally but only briefly, making it a time marker.
Flashcard 6: Identify the best use of index fossils when comparing two distant rock layers.
Answer: To correlate layers and infer they are the same relative age. Same index fossils indicate simultaneous formation.
Flashcard 7: What is relative dating in geology and paleontology?
Answer: Determining which rocks or fossils are older or younger. Compares ages without specific time measurements.
Flashcard 8: What is absolute dating?
Answer: Determining an actual age in years, often using radiometric methods. Provides specific numerical ages for rocks and fossils.
Flashcard 9: Which dating method uses radioactive decay to estimate the age of rocks: relative or absolute dating?
Answer: Absolute dating. Measures isotope decay rates to calculate precise ages.
Flashcard 10: What is a trace fossil?
Answer: Evidence of activity, such as footprints, burrows, or coprolites. Shows behavior and movement, not body structure.
Flashcard 11: What is a mold fossil?
Answer: A hollow impression of an organism left in rock. Forms when organism decays, leaving its shape in rock.
Flashcard 12: What is a cast fossil?
Answer: A solid copy formed when a mold fills with minerals or sediment. Creates a 3D replica of the original organism.
Flashcard 13: Which conclusion is best supported if a fossil species stops appearing above a certain layer?
Answer: That species became extinct by the time higher layers formed. Absence in newer layers indicates disappearance.
Flashcard 14: Identify the correct relative-age conclusion: Fossil A is in a lower layer than Fossil B in undisturbed rock.
Answer: Fossil A is older than Fossil B. Law of superposition: lower means earlier in time.
Flashcard 15: Which statement best links fossils to evolution: fossils show organisms are identical over time, or they change over time?
Answer: Fossils show organisms change over time. Different species in different layers prove evolution.
Flashcard 16: Which evidence best supports common ancestry: similar fossils in the same layer, or transitional fossils connecting groups?
Answer: Transitional fossils connecting groups. Shows evolutionary relationships between species.
Flashcard 17: What does a mass extinction refer to in the fossil record?
Answer: A short interval when many species disappear worldwide. Global catastrophe eliminates numerous species rapidly.
Flashcard 18: Identify the best fossil-based conclusion if many new species appear soon after a mass extinction layer.
Answer: Biodiversity rebounded through rapid diversification of survivors. Surviving species evolved to fill empty ecological niches.
Flashcard 19: What is a mold fossil?
Answer: A hollow impression of an organism left in rock. Forms when organism decays, leaving its shape.
Flashcard 20: What is permineralization in fossil formation?
Answer: Minerals fill pores of remains, turning them to stone. Most common fossilization process for bones and wood.
Flashcard 21: Which fossil type is a preserved bone or shell: body fossil or trace fossil?
Answer: Body fossil. Actual organism parts that became fossilized.
Flashcard 22: Which fossil type is a footprint or burrow: body fossil or trace fossil?
Answer: Trace fossil. Shows evidence of behavior, not body parts.
Flashcard 23: Which dating method determines an actual age in years: relative dating or radiometric dating?
Answer: Radiometric dating. Uses radioactive decay to calculate precise ages.
Flashcard 24: What does the law of superposition state about undisturbed rock layers?
Answer: Lower layers are older; higher layers are younger. Based on sediment deposition order over time.
Flashcard 25: What is relative dating in geology?
Answer: Determining which rocks or fossils are older or younger. Uses position in rock layers, not actual years.
Flashcard 26: What is the fossil record?
Answer: All known fossils and their positions in rock layers. Provides timeline of life's history through rock layers.
Flashcard 27: Identify the best fossil evidence for evolution: unchanged fossils or transitional fossils?
Answer: Transitional fossils. Show intermediate forms between ancestral groups.
Flashcard 28: What does it mean if a fossil species disappears above a certain rock layer?
Answer: The species went extinct after that time. No fossils above means species no longer existed.
Flashcard 29: Which layer is older in an undisturbed sequence: Layer A on top or Layer B below?
Answer: Layer B below is older. Follows law of superposition in undisturbed rocks.
Flashcard 30: What is a fossil in life science?
Answer: Preserved remains or traces of past organisms. Physical evidence of ancient life preserved in rocks.