Geologic Time Scale Flashcards
1
Q
Hadean Eon
A
- 6 - 3.85 BYA
- formation of the earth
- origin of life
2
Q
Archean Eon
A
- 85-2.5 BYA
- evolution of prokaryotes
- first photosynthetic bacteria
- O2 starts to accumulate in atmosphere
- origin of aerobic respiration
3
Q
Proterozoic Eon
A
- 5 billion - 542 million years ago
- high levels of O2 in the atmosphere
- origin of eukaryotic cells
- evolution & diversification of protists, fungi, and early animals
4
Q
Phanerozoic Eon
A
542 MYA - present day
- all eras and periods
5
Q
Paleozoic Era
A
542 MYA - 251 MYA
- Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian Periods
6
Q
Cambrian Period
A
- Appearance of modern animal phyla
- Appearance of first vertebrate animals
7
Q
Ordovician Period
A
- Major radiations of marine invertebrate animals and jawless fishes
- Mass extinction at end of period
8
Q
Silurian Period
A
- first jawed fish
- first arthropods
- first vascular land plants
9
Q
Devonian Period
A
- Vascular land plants diversify
- First amphibians
- First insects
- First seed producing plants
- Mass extinction at end of period
10
Q
Carboniferous Period
A
- Vascular plants in large swamp forests (eventually formed coal deposits)
- Amphibians diversify
- First reptiles
11
Q
Permian Period
A
- Insects & reptiles abundant on land in swamp forests
- Fishes colonize freshwater
- Continents coalesce into Pangaea
- Mass extinction at end of period
12
Q
Mesozoic Era
A
251-65.5 MYA
- Triassic, Jurassic, Cretaceous
13
Q
Triassic Period
A
- Gymnosperms dominant land plants
- Reptiles dominant land animals
- Radiation of dinosaurs
- First mammals
- Pangaea begins to break apart
- Mass extinction at end of period
14
Q
Jurassic Period
A
- Gymnosperms still dominant land plants
- Dinosaurs diversify and become dominant land animals
- First birds
- Modern fishes diversify
15
Q
Cretaceous Period
A
- Diversification of flowering plants, insects, fishes, and dinosaurs
- Mass extinction at end of period (eliminates dinosaurs)
