Geologic Time Scale
• Geologic Time Scale
• Summary of major
events in Earth’s past,
preserved in the rock
record
Division of Time
• Eon
• Era
• Period
• Epoch
• Largest division of
time;divided into eras
• 2nd largest – divided
into periods
• 3rd largest – divided
into epochs
• Evolution
• Natural Selection
• The process of change
that produces new,
changing or evolving
life forms
• “survival of the
fittest”
• Precambrian Time
• stromatolites
• No life on land
• Simple marine fungi
and algae only
• Lots of volcanic
activity
• Original atmosphere
came from volcanoes
• Fossils of layers of
cyanobacteria &
trapped sediments
• Paleozoic Era
• Had 7 periods
• Cambrian - Trilobites
•
•
•
•
•
• Age of Invertebrates
• Crablike fossils
prevalent
Ordivician – Graptolite • Prevalent fossil of
colonized organisms
• “sea scorpion”
Silurian-Eurypterids
• lungfish
Devonian
• Sea lilies & oneCarboniferous –
Crinoids & Foramnifera celled calcite-shelled
organisms
• DRY climate
Permian
• Mesozoic Era
• 3 periods – Triassic,
Jurassic and
Cretaceous
• Triassic
• Jurassic
• Cretaceous
• Age of Reptiles
• Ammonites(cephalop
ods) & Reptiles
• First dinosaurs
• Dinosaurs dominant
& Mammals begin to
thrive
• Cenozoic Era
• 3 periods –
Paleogene, Neogene
and Quaternary
• Quaternary was the
rise of hominids and
humans
• Age of Mammals
• Hominid
• Bipedal
• 1st hominid found was
Lucy
• Australopithicus,
Homo habilis, Homo
erectus, Homo
Sapiens, Homo sapien
sapien
• General name for
modern humans
• Walked on 2 legs
• Lucy was an
Australopithicus
skelton