EvolutionEvolutionFossil Record as Fair TestFossil Record as Fair Test

(Part II)(Part II)

Theory of EvolutionTheory of Evolution All life on Earth descended from a All life on Earth descended from a

common ancestorcommon ancestor

Life originated as a simple form, and Life originated as a simple form, and became more diverse and complex became more diverse and complex over timeover time

Fossil RecordFossil Record Represents ~ Represents ~

4,000,000,000 year 4,000,000,000 year long record of the long record of the natural history of natural history of our planetour planet

I. Evidence in the Fossil I. Evidence in the Fossil RecordRecord

Evidence that life changed through time:Evidence that life changed through time:simple simple complex complex

Evidence of change in one “type” of Evidence of change in one “type” of animal through the yearsanimal through the years

Transition species: evidence of Transition species: evidence of “hybrids” between two types“hybrids” between two types

99% of all life which has ever existed is 99% of all life which has ever existed is now extinctnow extinct

What does the fossil record tell What does the fossil record tell us?us?

1)1) Life originated in a simple form and Life originated in a simple form and become more complex and diverse become more complex and diverse with time.with time.

Example #1:Example #1:Example #2:Example #2:Example #3:Example #3:

What does the fossil record tell What does the fossil record tell us?us?

2) Organisms have changed over time2) Organisms have changed over time

Changes within a “type” of animal:Changes within a “type” of animal: Sea Urchins (video)Sea Urchins (video) Horse (video -can you describe?)Horse (video -can you describe?)

Horse TransitionsHorse Transitions Each branch tip on

the tree of horse evolution indicates a different genus, though the feet of only a few genera are illustrated to show the reduction of toes through time.

What does the fossil record tell What does the fossil record tell us?us?

2) “ One problem with the theory of 2) “ One problem with the theory of evolution is the conspicuous lack of evolution is the conspicuous lack of transition fossils”transition fossils”

Is this true?Is this true?

ArchaeopteryxArchaeopteryx

Other Transition FossilsOther Transition FossilsTransitions from one “type” into Transitions from one “type” into

another:another: Skulls: reptile/mammal “hybrids”Skulls: reptile/mammal “hybrids”

(Why is this significant?)(Why is this significant?)

Whale Transition Fossils Whale Transition Fossils (See pbs “evolution” series – cool show!)(See pbs “evolution” series – cool show!)

Fossil Record:Fossil Record:Evolution of MammalsEvolution of Mammals

Skulls showing the changes in the jaw articulation and the ear region in the evolution from reptile to mammal.

Whale TransitionsWhale Transitions

Whale Transitional FormsWhale Transitional Forms

And, (Drum roll, please….)And, (Drum roll, please….) Published April 6, 2006 ……Published April 6, 2006 ……

See http://tiktaalik.uchicago.edu/

Fossil Called Missing Link Fossil Called Missing Link From Sea to Land Animals From Sea to Land Animals

Model of Tiktaalik roseae, a 375 million year old fish with many amphibian-like features and foot-like bone structure in its fins that could have helped it pull itself through shallow water and even out of the water for brief periods

What does the fossil record tell What does the fossil record tell us?us?

3) 3) 99% of all organisms which 99% of all organisms which have ever existed are now have ever existed are now extinct!extinct!

(The life we observe today has not (The life we observe today has not been the life through the ages!)been the life through the ages!)