• Defined: Collection of every known fossil

• Most fossils found in sedimentary rock

• Age determined by depth– Law of Superposition: new

rock forms on top of older rock

– A.k.a. Relative Dating• Evidence Conclusions:

– 1) Newer fossils are more complex

– 2) Common ancestors: similarities between ancient & modern life

• AKA: Transition Fossils– Archaeopteryx: shares both bird & reptile features– Basilosaurus: shares whale & land mammal features– Tiktaalik: shares fish & amphibian features

• Evidence Conclusion : Indicates common ancestry

Reptile EvidenceTeeth

Bony tail

Bird EvidenceWishbone

Feathers

Whale EvidenceLong spine

Found in dried up oceans

Land EvidenceWolf-like teeth

Hind legs

Fish evidenceScales

Fins

Found in dried-up oceans

Amphibian evidenceEyes on top of head

Wrist bones

Comparing old fossils to modern life shows change

Ancient KelpModern Kelp

Radiometric Dating

• Helps determine age of fossils. More accurate than relative dating.• Isotopes: atoms of the same element with differing neutrons

– Ex: 12C and 14C12C = 6 protons + 6 neutrons14C = 6 protons + 8 neutrons

• Organisms collect carbon throughout their lifetime.– When organism dies: 14C starts to decay into 14

N at a known rate (half-life)

• Fossil age determined by comparing ratio of C to N– Wider ratio = older sample

Both are Carbon

Dating Fossils

Geography• The study of geography provides evidence of

evolution.– island species most closely resemble nearest mainland

species– populations can show variation from one island to another

• Different species show similar development patterns

• Different body plans become noticeable later in development

• Evidence Conclusion : Indicates common ancestry

• Defined: similar body structures with very different functions

• Different environments lead to adaptations– Ex: The forelimbs of animals

• Evidence Conclusion : Indicates common ancestry

Human hand

Bat wing

Mole foot

Fly wing

– Analogous structures are not evidence of a common ancestor.

• Homologous structures are different than analogous structures

– Analogous structures have similar functions but different structures.

• Defined: Organs or structures which have lost most or all their original function

• Vestigial Human Parts:– Gill slits = once used to breath

oxygen in water– Yolk sac = once used to nourish

developing embryo– Tailbone = once used for balance– Appendix = once used to digest

plants– Wisdom teeth = once used to grind

plant tissue• Evidence Conclusion : Indicates

common ancestry

Vestigial Structures

Human Embryo w/ Vestigial Structures

Pythons have tiny femurs (leg bone)

• DNA, RNA, proteins compared• Genetic code same for most life• More related species have more similar biochemistry• Evidence Conclusion : Indicates common ancestry

• Constant creation of chemicals for human use is eliminating the “unfit” (invading)organisms– Ex: Antibiotics

eliminating unfit bacteria– Ex: Pesticides eliminating

unfit pests– Ex: Antivirals…– Ex: Fungicides…

• Allows resistant to survive and reproduce

Antibiotic Resistance

Which antibiotics would successfully treat this infection?

penicillin

ampicillin

Amoxycillin tetracyclin

vancomycin

• How does antibiotic and pesticide resistance show natural selection?

• How do the following lines of evidence show change over time?– Fossils– Homologous structures– Vestigial structures– Resistant organisms– Embryo development– Biochemical (molecular) evidence

• Fossil age can be determined two ways. What are they?• Which type of anatomical structures do not show evidence of

common ancestry?

Review