Are birds more closely related to reptiles or mammals?

reptiles!

How do we know?

http://www.youtube.com/watch?v=j5KjCn7B6mU

Where’s the proof?

• Fossil Records• Homologous structures• Vestigial Structures• Molecular biology• Comparative Embryology

Evidence for Evolution

in the Fossil Record

What is a fossil?How do they form?

What do fossils tell us?

FOSSILS!Bird Dinosaur

Fossils

Fossils prove the existence of many different organisms through time that are related to existing organisms.

These fossils prove that there were living organisms from which every

living thing today was derived.

How do we know what animals are related to each other?

Homologous structures

Homologous Structures

Homologous structures provide strong evidence that all four-limbed

vertebrates have descended, with modifications, from a common

ancestor.

What is an analogous structure, and how is it different from a homologous structure?

Analogous structures have a SIMILAR function but DIFFERENT evolutionary origin.

Homologous structures are similar in structure AND show common ancestry!

Vestigial Structures

An organ or part of the body that is reduced to little or no function

Comparative Embryology

Comparative Embryology

There are many similarities in the early stages of development of

vertebrates, which suggests common ancestry.

Molecular Evidence

DNA: Present in ALL LIVING THINGS!*What does this tell us about when DNA must have evolved?*Is DNA an effective way of storing information?

Genetic Similarities Between Species

Similarities between Plant and Animal Cells: LOTS!

Molecular Biology• Protein synthesis (making proteins through

transcription & translation) is essentially the same in all organisms.

• Proteins in all organisms are composed of the same 20 amino acids.

• DNA is very similar between two closely related organisms.

• This is evidence that even very diverse organisms have a common ancestor!!

How Does this Relate to Bird Evolution?

• What do birds and lizards share in common in their biochemistry that other organisms don’t share?

-KERATIN!-Keratin is used by reptiles to make scales on the

outside of their bodies, and by birds to make feathers.

reptiles!

How do we know?

http://www.youtube.com/watch?v=ClJ5lwl_wM0