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Envirionmental Science 101 > Life Through Time > Flashcards

Flashcards in Life Through Time Deck (16)
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Start of The Universe?

13.7 Billion years ago.

1

Age of The Earth

4.6 Billion years ago

2

Radiometric dating?

Requires the presence of radioactive isotopes present in minerals.

3

Isotope

Same element with different number of neutrons.

4

Stable Isotopes

Present in environment.

5

Radioactive Isotopes?

Not stable and once formed will immediately decay into stable Isotopes.

6

What are the four Geologic Time Scales?

Eons.
Eras.
Periods.
Epochs.

7

Precambrian Time:

○ Accounts for 88% of geologic time
• Micro-continents form and are tectonically active
○ Formation of early supercontinent
○ Abundant volcanism
• Atmosphere and oceans form
• Yet entire time period is dominated by very simple life
○ Prokaryotic single-celled organisms

8

First life appears?

3.8 billion years ago

9

Early Paleozoic AKA?

Age of invertebrates.
Or aka Cambrian explosion(great diversity of life.)
All life confined to marine environment (multi-cellular life dominated)

10

Middle Paleozoic:

Age of fishes.
Appearance of modern day fish, flightless insects & sharks.
Plants first to leave marine environment(waters).
Placoderm first marine predator.

11

Late Paleozoic:

Age of amphibians.
Creation of last super continent Pangea.
Largest extinction event @ the end of the Permian period.

12

Carboniferous

Mississippian and Pennsylvanian periods

13

Therapsids

Mammal like Reptiles.

14

Early Mesozoic

Mass extinction at the end of the Permian allowed for an adaptive radiation of reptiles
• Dinosaurs are not yet present
○ They will evolve from the early reptile forms
• Marine and flying reptiles dominate
○ Early ancestors of the crocodiles appear

15

Middle & late Mesozoic

Dinosaurs dominant
○ Over 9000 species identified on every continent
• Appearance of the first angiosperms (flowering plants)
• Appearance of first birds and mammals
○ First birds evolved from reptiles
○ Mammals tended to remain small until the cenozoic