Chapter 20 Flashcards
Whats so interesting about the burgess shale?
- Its a treasure trove of fossils
- 150 different species of animals
- IN Yoho national park
- Aqua marine life found! means that the rocky mountains used to be underwater
Why is fossilization a game of chance?
Organisms must have fossilizable parts
- Environmental conditions must be perfect
- A balance of sediments is necessary (more clay than sand for instance)
What is the significance of strata layers for fossils?
The strata layers help us determine what time period the fossils came from
WHat is the geological time scale?
The sequence of stratas and distinctive fossil assemblages -Diagrams the history of life on earth
What were the great radiations regarding fossil evidence?
600 mya - Animals diversify
400 mya - Plants diversify
150 mya - Flowering plants diversify
3 causes of mass extinction
Climate change, Volcanic activity and asteroid strikes
Big extinctions?
end of permian era-250 mya
K-T extinction - 65 mya
Phylogeny ?
The evolutionary history of a species or group of related species
Systematics?
Classifies organisms and determines their evolutionary relationships
What is a systematist?
Using fossil, molecular and genetic data to infer evolutionary relationships
Clade?
Shares a common ancestor
- group of species that includes an ancestral species and all its descendants
- weird branching chart thing
Sister taxa?
an immediate common ancestor is shared
What are branch points? on a clade
Represents divergence in two groups
How are cladistics different from a clade?
Cladistics show the organisms from common ancestors and how they are separated from others with unique characteristics
Monopheyletic taxon
A monophyletic taxon includes species all originating from the small ancestor
