Lesson 2 Flashcards
What is the best estimate of the Earth’s age?
4.6 billion years old.
What is stratigraphy and how can it be used to age fossils?
Stratigraphy is the study of rock layers. Each distinct strata is younger than the one beneath it and. Comparing strata tells us how old fossils within them are relative to each other.
What can be used to give an estimate of an absolute age of a fossil and how does it work?
Radiometric dating techniques look at the ratio of unstable isotopes to the more stable elements they would decay into and use the half life of the former to calculate time passed.
What are they earliest types of fossil, and what geological era are they from?
Stromatolites (fossilized mats of bacteria layered into mounds) appear before the other types of fossils, in rocks from the middle Archean.
What does the term “biological radiation” mean?
It is the evolutionary diversification of a group of organisms. This diversification is often associated with the evolution of a diversity of adaptations to a variety of ecological niches.
What is an index fossil and how do we use them?
Fossils confirmed to only exist within specific time horizons/specific rock layers can be used to date rocks in new exposures, and thus new fossils, based on there presence.
Fossils can indicate behavioral traits of an animal. Give 3 examples.:
1) Egg clutches with adult bones suggest parental nesting
2) Fossilized footprints indicate locomotor patterns
3) Dental records suggest feeding behaviour
Some organism are more likely to fossilize than others. What aids in this process?
Organism that are very quickly covered upon there death are more likely to be preserved.
Organisms that are have more hard parts (shells, bones) are more likely to be preserved.
How does age of rock effect the likelihood fossils being nicely preserved?
Older rocks are more likely to have been exposed to tectonic events that may destroy them.
How does fossil restoration work?
Scares on the bones from muscle attachments and knowledge of general muscle anatomy allows for the creation of a general body shape.
