Geological Time Scale Flashcards
A record of life forms and geologic events in Earth’s history
Geologic Time Scale
4.5 million years; about 88% of the Earth’s history
Pre-cambrian
The largest division of geologic
time scale; half billion – nearly
2 billions of years
Eon
It is the current geological eon
Phanerozoic Eon
Division that span time periods of
tens to hundreds of millions of
years
Era
”Ancient or old life”; started more than 540 million years ago
Paleozoic Era
A division in geologic
history with spans of no
more than 100 million
years
Period
Many types of primitive animals
called sponges evolved
Cambrian Period
Small ocean invertebrates called
triobites were very abundant
Cambrian Period
The oceans were filled with
invertebrates of many types
Ordovician Period
The first fish were evolved
Ordovician Period
In the oceans, corals appears and
fish continued to evolved.
Silurian Period
Vascular plants appeared. With
special tissues to circulate water
and other materials. They could
grow larger than earlier, non
vascular plants
Silurian Period
The first seed plants evolved. Seeds have a
protective coat and stored food to help them survive. Seed plants eventually became the most common type of land plant
Devonian Period
Fish with lobes, fins evolved. They could
breath air when they raised their heads
above water. Breathing would be necessary
for animals to eventually colonized the land
Devonian Period
Widespread forest of huge plants left
massive deposits of carbon that turned
into coal
Carboniferous Period
The first amphibians evolved to colonized
land, but they need to return to water to
reproduce
Carboniferous Period
After amphibians, the first reptiles
evolved. They were the first animals that
could reproduce on dry land
Carboniferous Period
All the major land collided to form a
supercontinent call Pangaea
Permian Period
Temperature were extreme, and the
climate was dry
Permian Period
Plants and animals evolved
adaptations to dryness
Permian Period
“middle life”, started more than 280 million years ago
Mesozoic Era
“Age of reptiles”
Mesozoic Era
The first dinosaurs branched off
from the reptiles and colonized the
land, air and water.
Triassic Period
