Thursday, May 22Pick up a white board and marker.

Goal: Explain why studying paleontology is important.

Tuesday, May 27Pick up a note packet.

Goal: Explain how geologic time is divided.

Geologic column• An ordered

arrangement of rock layers.

• Is a representation of all rock layers through time. They have fossils specific to those at the time.

• No single area contains a record of all geologic time.

• Gives absolute age of rock layer.

Evolution – The gradual development of new organisms from pre-existing ones.

Proposed by Darwin in 1859.

http://www.sciencechannel.com/video-topics/earth-science/galapagos-beyond-darwin-charles-darwin.htm

Evolution

• Some organisms can survive environmental changes such as sea levels rising and ice ages. Other organisms change or become extinct.

Events in Your Life

• ___When you started second grade• ___When you were born• ___ When you started kindergarten• ___When you learned to ride a bike.• ___ When you learned to walk.• ___ When you learned to read.• ___ When you lost your first tooth.• ___ Today’s date.

Construct a timeline of the important events in your life. Be sure to include all of the events listed below and any other events you feel are important. Your timeline should be constructed TWO ways:

1) Numerical Order (use actual dates)2) Sequential Order (most recent at top)

Geologic Time Scale

• A description of the sequence and length of Earth’s changes.

Geologic time is divided into units

• Eras period Epoch

• Era is the largest which is broken down into Periods which are broken down into Epoch.

Just like you have your life as a student which can be broken into pre-school, elementary, middle, and high school which can be further broken into each grade.

Today…• Today we are in the Holocene Epoch of the

Quaternary Period of the Cenozoic Era.

Which unit is the largest?

Which unit is the smallest?

FOUR Eras…

• PRE-CAMBRIAN – 88% of earth’s history

• Paleozoic (ancient life)– 544 million years ago…lasted 300 million yrs

• Mesozoic (middle life)– 245 million years ago…lasted 180 million yrs

• Cenozoic (recent life)– 65 million years ago…continues through present day

Precambrian

• First 4 billion years • Shields are large areas of exposed

Precambrian rock • Nearly half of Earth’s valuable minerals are

found in shields• Few fossils because the rocks are deformed

from being under harsh conditions of tectonic plate activity.

Cyanobacteria

• Most fossils are cyanobacteria (photosynthetic bacteria)

Paleozoic Era (542-251 million yrs ago)

• Pangaea formed• Rich fossils records• Fish, amphibians, and reptiles appeared• Ended in mass extinction, an episode during

which large numbers of species become extinct.

90% of marine organisms became extinct70% of land organism became extinct

Trilobites

• Lived in Earth’s ancient seas• Extinct before the dinosaurs came

into existence• During the Paleozoic Era

(Cambrian Period)

Early Fish

Early fish did not have jaws.

Some species of sharks were in existence at this time.

Early Land Plants

Cone bearing plants

Ferns

Mosses

Mesozoic Era – 251 to 65 million yrs ago

• Pangaea broke apart• Climate was warm and humid• Age of Reptiles• Ended in mass extinction

Mesozoic Plants

Flowering plants evolved towards the end of the Mesozoic Era.

Impact Hypothesis

Asteroid crashed into Earth

Mesozoic Era – Mass Extinction EventImpact Hypothesis

• Asteroid or Comet crashed into Earth.

– Huge cloud of smoke and dust fills the air– Blocked out sunlight– Cooled Earth– Plants die– Animals that eat plants die– Animals that eat plant-eaters die.

• However, not all forms of life died during this event. Many animals that you see today are descendants from the survivors of this extinction event.

Evidence to support impact hypothesis:

• There is a layer of dust in the rock record with large amounts of iridium. Iridium is a chemical uncommon in our rocks but common in meteorites.

Cenozoic Era (65 million yrs to present)

• Continents moved to present locations• Ice ages• Known as “Age of Mammals”• Small mammals began to evolve into larger

mammals then to modern species when temperatures decreased during the ice ages.

Cenozoic Era• Marine animal examples:

– Algae, Mollusks, Fish and Mammals

• Land animal examples:– Bats, Cats, Dogs, Cattle and Humans– Humans are thought to have appeared around 1.8 million

years ago (during the most recent period – Quaternary).

• Flowering plants were now the most common plant life.

Cenozoic Mammals

Humans Appeared

• 1.8 million years ago

Life forms found in each Era• On your worksheet,: - List Geologic Events found in each Era. - List Life forms found in each Era. - Draw pictures of Life Forms… USE COLOR!Make sure you are putting them in the correct

block!!