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Fossils 2025 > Geologic Timeline & Mass Extinctions > Flashcards

Geologic Timeline & Mass Extinctions Flashcards

1
Q

Precambrian:

What were the 3 periods of Precambrian?

A

Proterozoic, Archean, Hadean

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2
Q

Precambrian:

When did it start/end?

A

4.6 ga - 541.1 mya

ga = bilion yrs ago, mya = million yrs ago

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3
Q

True or False:

Precambrian is the second era in the geologic time scale.

A

False

It was the first. Divided into Proterozoic, Archean, Hadean.

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4
Q

Precambrian:

Important things that happened

A
  • contained over 80% of earth’s life
  • ozone layer began to appear
  • simple multi-celled organisms began evolving
  • cyanobacteria appeared
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5
Q

Paleozoic

The paleozoic era lasted from the ____ period to the ____ period.

A

Cambrian - Permian

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6
Q

Paleozoic

Paleozoic started ____ mya and ended ____ mya

A

started 544.1 mya
ended 252 mya

mya = million yrs ago

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7
Q

Paleozoic:

Important things that happened

A
  • organisms with exoskeletons appeared
  • pangaea formed at the end of era
  • 90% of marine animals went extinct
  • 70% of land organisms went extinct
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8
Q

True or false:

Paleozoic era was the beginning of the Phanerozoic eon.

hint - eons are smaller than eras.

A

True

Phanerozoic consists of Paleozoic, Mesozoic, & Cenzoic.

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9
Q

What is the Alvarez Hypothesis?

hint - smth to do with dinos…

A

The theory that an asteroid killed off the dinosaurs

easy way to remember - Alvar from KOTLC

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10
Q

Mesozoic:

Started ____ mya
Ended ____ mya

A

Started 252 mya
Ended 66 mya

thats 4% of Earth’s history lol

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11
Q

Mesozoic:

The mesozoic started in the ____ period and ended in the ____ period.

A

started in triassic
ended in cretaceous

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12
Q

True or false:

Mesozoic consists of Triassic, Permian, Jurassic, and Cretaceous.

A

False

The Mesozoic era consists of Triassic, Jurassic, and Cretaceous.

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13
Q

Mesozoic:

Important things that happened

A
  • Dinos evolved (and went extinct)
  • Pangaea split into 2
  • First birds evolved
  • Mammals were small and underground
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14
Q

Cenozoic:

Started ____ mya
ended ____ mya

A

started 65 mya
still going on

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15
Q

True or false:

Cenzoic ended 10 mya

A

False

its going on still

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16
Q

Cenozoic:

Important things that happened

A
  • mountain ranges formed
  • mammals became larger and more dominant
  • humans evolved 200,000 years ago
17
Q

Mass extinctions:

What is the 1st of the 5 major mass extinctions?

A

Ordovician-Silurian extinction.

Paleozoic era, 440 mya

18
Q

Mass Extinctions:

What is the 2nd of the 5 major mass extinctions?

A

Devonian extinction

Paleozoic. 365 mya

19
Q

Mass extinctions:

What is the 3rd of the 5 major mass extinctions?

A

Permian-Triassic extinction

Late paleozoic - early Mesozoic. 250 mya

20
Q

Mass extinctions:

What was the 4th of the 5 major mass extinctions?

A

Triassic - Jurassic extinction

Mesozoic. 210 mya

21
Q

Mass extiinction:

What is the 5th of the 5 major mass extinctions?

A

Cretaceous - Tertiary extinction

late Mesozoic - early Cenozoic. 65 mya

22
Q

What is the cause of the 6th major mass extinction?

jeremy said we r part of the 6th one rn 😬…

A

hUmAnS

big surprise there…

23
Q

Brainrot extinction:

The Pliestocene-Holocene Megafauna extinction was the most prominent in…

A

North America

24
Q

Brainrot Extinction:

How long did it last?

A

about 2000 years

25
Q

Brainrot Extinction:

How many genera of large mammals disappear?

A

32

26
Q

Brainrot Extinction:

What are the 2 main theories of how it started?

A

1) Humans overhunting
2) abrupt climate/vegetation changes due to last glacial/interglacial transition

human disruption of environment might have contributed.

27
Q

True or false:

The effect of the Brainrot extinction was worse in continents other than North America.

*The Pliestocene-Holocene Megafauna Extinction

A

False.

North America was affected the most.

Fossils 2025 (6 decks)

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