Fossils & Dating
What are fossils?
Physical evidence left by organisms from the past
What bias makes organisms from wet habitats more likely to fossilize than organisms from dry habitats?
habitat bias
About how long ago did Earth form?
4.6 billion years ago
What percentage of species that have ever existed are extinct?
99.9%
What is phylogeny?
The evolutionary history of a group of organisms
How do most fossils form?
An organism is buried in sediment before decomposition
What bias explains why fewer older fossils are found than younger fossils?
Temporal bias
About how long ago did life originate?
3.6 billion years ago
What is a mass extinction?
A dramatic increase in extinction rate
What is systematics?
Classifying organisms according to their phylogeny
What type of rock contains most fossils?
Sedimentary Rock
What bias makes organisms with hard body parts more likely to fossilize?
Temporal bias
About how long ago did the oldest eukaryotic fossils appear?
2 billion years ago
What is adaptive radiation?
Major diversification over a relatively short period of time
What does a phylogenetic tree represent?
A hypothesis of the evolutionary history of a group
What dating method determines whether a fossil is older or younger based on rock layers?
Relative dating
What bias makes common species more likely to appear in the fossil record than rare species?
Abundance bias
About how long ago did the first animals appear?
565 million years ago
What group underwent adaptive radiation after the extinction of the dinosaurs?
Mammals
How do you find the most recent common ancestor of two organisms on a phylogenetic tree?
Trace their branches backward until they meet
What dating method uses radioactive decay to estimate an actual age?
Radiometric / absolute dating
Why would an organism with a shell be more likely to appear in the fossil record than a soft-bodied worm?
Taxonomic bias because hard parts fossilize more easily
Put these in order from oldest to most recent: first land plants, first mammals, first flowering plants.
Land plants to mammals to flowering plants
Name one event that can trigger adaptive radiation.
Extinction, colonization, or a morphological innovation
If branches of a phylogenetic tree are rotated around a branching point, does that necessarily change the evolutionary relationships?
No