Flashcards in L8 - History of Life on Earth Deck (24):
When did Earth form from an accretionary disk?
4.5 Ga ago - From planetesimals
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.
What are the oldest minerals on Earth?
4.4 Ga - Zircons, Australua
What are the oldest rocks on Earth?
4.0 Ga - 12% - Acasta Gniess - Canada
- Metamorphic rock, usually forms due to orogeny
What is the earliest evidence for life?
3.6 Ga - 21% - Odd isotope ratios - Pilbara, Australia
- Carbon & Sulphur ratios
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
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
When is the first evidence for multicullular life emerge?
1.4 Ga - 69% - Fossils
1.2 Ga - 74% - Bangiomorpha. Canada
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
When was the Cambrian Explosion
530 mya - 88% - Cambrian Explosion
- Period of radiation
- Fossil record 'suddenly' enriched
- Origin of arthropods, corals, molluscs and chordates
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?
When did terrestrial life emerge?
435 mya - 91% - Silurian
- Small invertebrates and plants on in close proximity land
When did vascular plants/trees and amphibians first emerge?
385 mya - 91.5% - Devonian
- Earth is colonised by the first forests.
When did winged insects and reptiles emerge?
325 mya - 93% - Carboniferous
When did synapsids and diapsids develop?
306-302 mya - 93.5% - Carboniferous
- Synapsids -> Mammals
- Diapsids -> Modern reptiles & Birds
When did Pangaea first assemble?
280 mya - 93.5% - Permian
- Not first supercontinent
When did the archosaurs first emerge from diapsids?
255 mya - 95% - Permian
- Crocodiles, birds, dinosaurs, pterosaurs
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
When did mammals first emerge and Pangaea break up?
195 mya - 96% - Jurassic
When did marsupials first emerge?
125 mya - 97% - Cretaceous
- Marsupials distributed predominantly in former Gondwana
When did the KT extinction event occur?
65 mya - 98% - Creaceous/Paleogene boundary
When is the earliest monkey fossil from?
47 mya - 99% - Paleogene
- Darwinius 'Ida'
- Either ancestor of monkeys or lemurs
When did apes diverge?
25 mya - 99% - Paleogene
When did humans diverge?
7 mya - 99.9% - Neogene