L8 - History of Life on Earth Flashcards Preview

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Flashcards in L8 - History of Life on Earth Deck (24):
1

When did Earth form from an accretionary disk?

4.5 Ga ago - From planetesimals

2

What evidence is there for Earth's formation?

Asteroids in western Algeria and Campo del Cielo, Argentina - 4.5 Ga old.
There are three main types of asteroid; chondrites, achondrites and irons.

3

What are the oldest minerals on Earth?

4.4 Ga - Zircons, Australua

4

What are the oldest rocks on Earth?

4.0 Ga - 12% - Acasta Gniess - Canada
- Metamorphic rock, usually forms due to orogeny

5

What is the earliest evidence for life?

3.6 Ga - 21% - Odd isotope ratios - Pilbara, Australia
- Carbon & Sulphur ratios
- Controversial
3.4 Ga - 25% - Blob-like structures that could be cells - Pilbara, Australia
- Associated with pyrite - biotic anaerobic conditions
3.3 Ga - 28% - Stromatolites, Australia
- Cyanobacteria
- Uncontroversial

6

When is the first evidence for eukaryotic cells?

2.1 Ga - 54% - Fossils with nuclei and organelles
- Likely origin of sexual reproduction
- Likely spurred by Great Oxygenation Event

7

When is the first evidence for multicullular life emerge?

1.4 Ga - 69% - Fossils
1.2 Ga - 74% - Bangiomorpha. Canada
- Algae-like

8

When do the first 'hard' organisms appear in the fossil record.

565 mya - 88% - Small shelled fauna
- Associated with another rise in oxygen levels
- 'Soft' organisms increase in complexity - Ediacaran fauna

9

When was the Cambrian Explosion

530 mya - 88% - Cambrian Explosion
- Period of radiation
- Fossil record 'suddenly' enriched
- Origin of arthropods, corals, molluscs and chordates

10

List the post-Cambrian geologic periods

Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Paleogene, Neogene, Quaternary.

Sentence - "Quit nagging poking Canadians, just tolerate pokes" Can Dakota sustain outrageous craze?

11

When did terrestrial life emerge?

435 mya - 91% - Silurian
- Small invertebrates and plants on in close proximity land

12

When did vascular plants/trees and amphibians first emerge?

385 mya - 91.5% - Devonian
- Earth is colonised by the first forests.

13

When did winged insects and reptiles emerge?

325 mya - 93% - Carboniferous

14

When did synapsids and diapsids develop?

306-302 mya - 93.5% - Carboniferous
- Synapsids -> Mammals
- Diapsids -> Modern reptiles & Birds

15

When did Pangaea first assemble?

280 mya - 93.5% - Permian
- Not first supercontinent

16

When did the archosaurs first emerge from diapsids?

255 mya - 95% - Permian
- Crocodiles, birds, dinosaurs, pterosaurs

17

When did the Permian Mass Extinction event occur

252 mya - 95% - Permian/Triassic boundary
- 96% species went extinct
- Impacted insects
- Most mass extinction event yet

18

When did mammals first emerge and Pangaea break up?

195 mya - 96% - Jurassic

19

When did marsupials first emerge?

125 mya - 97% - Cretaceous
- Marsupials distributed predominantly in former Gondwana

20

When did the KT extinction event occur?

65 mya - 98% - Creaceous/Paleogene boundary

21

When is the earliest monkey fossil from?

47 mya - 99% - Paleogene
- Darwinius 'Ida'
- Either ancestor of monkeys or lemurs

22

When did apes diverge?

25 mya - 99% - Paleogene

23

When did humans diverge?

7 mya - 99.9% - Neogene

24

Highlights of L8?

- No geological record for first 12% of Earths history
- Life formed between 21-28% Earths history
- Multicellular life formed not until 69%, animals not until 88%
- Terrestrial life only after 91%
- Dinosaurs extinct at 98%
- Humans at 99.9%