Life and Geologic Time

Sci 4.1

Geologic time scale:• history of earth

• most units based on types of living things

Question 1

Units:

• Eon – longest

• Era

• Period

• Epochs – shortest

http://www.geo.ucalgary.ca/~macrae/timescale/time_scale.gif

Question 2

Organic evolution:

time

• how species change over time

Okapi: Relative of the giraffe

Question 3

Species:• Members reproduce with each other to

produce viable offspring.

• viable: can reproduce

Question 4

Natural Selection• Charles Darwin’s idea

• organisms best suited for their environment are “selected” by nature

• all others become extinct.

Question 5

Changes in environment• can pressure species to evolve

Question 6

Artificial selection:• people, not nature, doing the selecting

• domesticated animals, hybrid plants

Question 7

Trilobites (3 lobes)• lived in oceans >200 mil. years, extinct now

• hard exoskeletons made good fossils

• changed over time

Question 8

• Could’ve been 1st creatures to have eyes.

• Some species lost eyes over time.

What’s not needed can be lost over many generations.

Pangea (Pangaea) • when all continents came together

• ~200 mya

• trilobites became extinct

Question 9