1. Fossil Record Evidence
Geologic time scale: Organizes Earth’s history into 4 distinct ages
Precambrian
Paleozoic
Mesozoic
Cenozoic

2. Fossil Record Evidence
Younger fossils are layered over older ones
Radiometric Dating determines absolute age
Half life is the # of years it takes for 50% of the sample to decay
Different elements have different half lives
Carbon-12 and Carbon-14 are used to determine the age of fossils
Why do we use carbon????

3. Continental Drift
Pangaea: Supercontinent of all land masses during the Paleozoic Era (250 million years ago)
Explains matching fossils found in different continents
Pangaea broke up 180 million years ago separating the continents and creating different evolutionary patterns for species that had common ancestors

4. Mass Extinction
Brief periods of mass species loss-There have been five or six distinct periods of mass extinction over the last 600 million years.
Most recent- Cretaceous period 65 million years ago
Dinosaurs had lived for 150 million years
What happened? Climate cooling, sea reduction, meteor near Yucatan Peninsula (polluted the sky and reduced sunlight which lead to reduced food production by photosynthesis)

5. Mass Extinction
The Permian period, when extinction claimed over 90% of the species of marine animals and 70% of terrestrial animals.

6. Chapter 15.4 Classification and Taxonomy

7. What is Taxonomy?
The identification, naming, and classification of species
Many common names can be too confusing and make it difficult to organize into something that makes sense:
Catfish, silverfish, jellyfish, and crayfish
Each name is similar but each are very different organisms
Biologists must be able to communicate with one another about the species they study, no matter what language they speak.
Goal: of taxonomy is to assign a universal scientific name to each known species

8. The Linnaean System of Classification
-Created by Carolus Linnaeus ( )
-Two main characteristics of this system
oTwo part Latin name for each species
oAn ordering of species into broader and broader groups.
Naming system
- Binomial system (two parts)
1.genus to which the species belongs
2.second part refers to one species within the genus
Examples:
Panthera pardus = Leopard Panthera leo = Lion

9. Humans = Homo sapiens Humans would be classified as the following:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: sapiens
Humans = Homo sapiens

10. Classification and Evolution
Darwin used this system to help explain the context of evolution.
Species are classified into groups within groups.
-Creation of the phylogenetic tree (means evolutionary history)
A diagram that reflects such hypotheses of evolutionary relationships and has a branching pattern
A good visual to help relate different species
Often created by comparing homologous structures

11. While creating these phylogenic trees, scientists have to be aware of convergent evolution
- process in which unrelated species from similar environments have adaptations that seem very similar
- analogous structures: similarities among unrelated species that result from convergent evolution
Examples: Bats and insects both fly but their structures are very different
Whale flippers and bat wings adaptations have changed the look of the structures but the bones are very similar (why?)

13. Molecular Data as a Taxonomic Tool
modern techniques include comparing DNA of each species’ genomes
fossil and DNA data have indicated that whales are closely related to the group of mammals that includes: hippos, cows, deer, and pigs.
Molecular data has backed up this hypothesis.
Able to revise phylogenic trees

14. Comparisons of cladograms:
Clade: The evolutionary branch in a phylogenic tree.
A phylogenetic diagram that specifies the derived characters of clades is called a cladogram - features that unite the organisms as a clade are called derived characters.
Example:Each shaded area in the phylogenetic tree highlights one clade (branch), such as the right hand area including species B through H.

15. Each Cladogram can compare particular traits between close species to show close evolutionary relationships:

16. The Development of Classifications
Two Kingdom Schemes
Linaeus divided life into “Plants” and “Animals”
Used for over 200 years
Lots of organisms who didn’t fit the model
Current Model: Six Kingdom Classification