Activity

Evolution: a change in populations over successive generations.

Complete an Evidence Summary Chart as a class.

Identify one pro (positive) and one con (negative) argument for each area of evidence in the graphic organizer and one example for each of the two areas you were assigned.

Define the key terms related to each area of evidence.

Evidence for Evolution Area: Fossil Record

Examples: mastodon, wooly mammoth, elephant

Pro: rock formations in layers help to date the fossils, some complete remains

Con: record is incomplete, fossils not always formed, soft tissue rarely preserved

Vocabulary: fossil — body parts (bones, casts) preserved or petrified in rock or amber.

Fossils

oldest layers

youngest layers

Fossils

fossilized rock

fossilized rock

Amber

(tree sap)

Frozen in ice/snow

American mastodon

(Mammut americanum)

extinct

Woolly mammoth

(Mammuthus primigenius)

extinct

African elephant (Loxodonta africana)

Evidence from Fossil Record

35 million years 2 million years present day

Evidence for Evolution Area: Anatomy

Examples: forelimb structures (bird, horse, human)vestigial organs (pig toes, whale pelvis, human

appendix)

Pro: can study structures in present day and fossilized organisms

Con: some incomplete records for fossils

Vocabulary: comparative anatomy —study of the structures of different organisms.

homologous parts — body parts similar in structure or function or both.

vestigial structure — a body structure once useful in early forms of an organism but no longer functional.

Homologous Structure of a Forelimb

salamander crocodile bird bat whale mole human

walking flying swimming digging handling

Homologous Structure of a Forelimb

Ulna (forelimb bone) in 5 mammals

Vestigial Structure in a Whale

whale ancestor

Pelvic bone w/femur (leg bone)

Orca (whale)

Vestigial Structure in a Whale

whale ancestor

Pelvic bone w/femur (leg bone)

dolphin w/hind flippers

Vestigial Structures

Pig walks on inner two toes.

Pig foot - outer toes are raised and are useless.

Pig foot has four toes.

Vestigial Structures in Humans

Vestigial Structures in Humans

human appendix

Vestigial Structures in Humans

appendix in other mammals