Evidence for Evolution - Fossils

• Can get relative dates using geologic principles - • older layers are at the bottom, younger layers at the top • Fossils that are in the same layer are likely the same age.

• Can get an absolute date using radiometric dating ( ½ lives)• Tell us about relationships between animals, plants, and environment• Show that different forms of life existed on earth• Can estimate when a life form became extinct.

Fossils show transitional forms

• Whales – placement of nostrils

• Horse feet – show transitional forms 4 toes( Eohippus) to 1 toe ( Equus) not direct ancestors, but an evolutionary tree

Homologous Structures

• Homologous structures are similar features that originated in a shared ancestor• Similar in skeletal structure but have different functions• Derived from the same structures in the embryo

Vestigial Structures

Vestigial structures are features that were useful to an ancestor, but they are not useful to the modern organismExamples:Some snakes have tiny pelvic and limb bonesWhales have pelvic bones

Embryology

• The early stages of different vertebrate embryos are similar to each other• Indicate a common ancestry• Embryonic similarities fade as development proceeds

DNA evidence

The more base pairs = more similaritiesChimp = 98%Cat: 90%Cow: 80%Mouse: 75%Fruit Fly: 60%Banana: 50%

Vocab – Put in the back of your journalFold pages into three sectionsWord Meaning (in your words) Illustration or ClueControlControlled VariableHominidEvolutionMorphologyHomologous StructuresVestigial Structures

Read Essays on 102- 109Essay 1 – Fossils : Traces of Life that has gone by

( add in red pen information to your notes that were taken

in class on Fossils)

ADD info for essay 2 and three after Red pen corrections of Essay 1

Essay 2- Technologies that strengthen Fossil Evidence

Summarize how stratigraphy works

Summarize how radioactive isotopes are used. ( provide examples and be able to

explain half – life)

Essay 3 – Modern Life : Evidence of evolutionary change

Create a frayer model for the following words - Homology

Vestigial Structure