Flashcards in Life Through Time Deck (16)
Start of The Universe?
13.7 Billion years ago.
Age of The Earth
4.6 Billion years ago
Requires the presence of radioactive isotopes present in minerals.
Same element with different number of neutrons.
Present in environment.
Not stable and once formed will immediately decay into stable Isotopes.
What are the four Geologic Time Scales?
○ 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
First life appears?
3.8 billion years ago
Early Paleozoic AKA?
Age of invertebrates.
Or aka Cambrian explosion(great diversity of life.)
All life confined to marine environment (multi-cellular life dominated)
Age of fishes.
Appearance of modern day fish, flightless insects & sharks.
Plants first to leave marine environment(waters).
Placoderm first marine predator.
Age of amphibians.
Creation of last super continent Pangea.
Largest extinction event @ the end of the Permian period.
Mississippian and Pennsylvanian periods
Mammal like Reptiles.
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