1. 1 2 3 4 Geologic time is a difficult concept to grasp. 12 hours
Every hour = 375 million years
9:30 – 1st living cells
10:56 – end of Precambrian
11:33 – end of Paleozoic
11:56:56 – Homo sapiens appear 3 4

2. PRECAMBRIAN First 4.1 billion years (90% of Earth’s History)
From Earth’s formation to Paleozoic era began approx. 4.1 billion years
Autotrophic prokaryotes (cyanobacteria) enriched the atmosphere with oxygen
Oceans filled with soft bodied organisms, algae, sponges, worms, jellyfish
Ediacaran –added to geologic time scale in 2004
First new period added to the time scale since 1891

3. PALEOZOIC ERA
Cambrian Explosion – time of rapid diversification where most ancestral animal groups emerged
Life in oceans continues to evolve
Fish (first vertebrates), simple land plants (mosses in moist envirnons. ) and insects appeared during the Ordovician and Silurian periods
First tetrapods appeared during the Devonian
Four legged creatures
Amphibians (land, but return to water)
Coelacanth – living fossils, ancestor of first tetrapods

4. Permian – last Period of the Paleozoic
Carboniferous Period
Ferns and evergreens
Time of fossil fuel development
Giant amphibians take to land
By end of carboniferous period the first reptiles were roaming the forests
Permian – last Period of the Paleozoic
Reptiles, amphibians, insects spreading out, filling available niches
Massive extinction event
96% species lost

5. Triassic and Jurassic Periods
Mammals and Dinosaurs first appeared in late Triassic period
Birds evolved circa middle Jurassic period

6. Cretaceous Flowering plants appear Dinosaur population peaks
Meteorite ends the time of terrible lizards approx. 65 MYA
Mass extinction
K-T Boundary – layer of material between rocks of Mesozoic and Cenozoic period
High levels of iridium – rare on Earth, common in meteorites

7. CENOZOIC ERA Mammals become dominant form of life on land
After mass extinction at the end of the Mesozoic era mammals of all kind began to diversify into distinct groups
Ice Age in Quaternary period
Loss of many charismatic megafauna of the Pleistocene (climate and/or humans)
Holocene – development of human civilization
Anthropocene – time of human impact