Happy Thursday (10/16)Write your thoughts on these pictures. How do they relate to evolution?

History of Life on Earth

• SB5.b- Students will evaluate

the role of natural selection in the

development of the theory of

evolution.• b. Explain the history of life in terms of

biodiversity, ancestry, and the rates of evolution.

• c. Explain how fossil and biochemical evidence support the theory.

• https://www.youtube.com/watch?v=dYphAH2tKYE

– David A. 10 min Video/Intro

History of Life on Earth• Began approximately 4.6 billion years ago

• Current speculations on formation of Earth

– Cosmic debris collected and cooled

– Planet experienced constant volcanic and geological upheaval

– Anaerobic (no oxygen)

– Finally began to cool and form liquid water

Origin of Life: Prokaryotes• Most popular theory

– Life first appeared a few million years after formation of Earth– First organisms prokaryotic– Select prokaryotes began to create oxygen

• This created aerobic atmosphere

Origin of Life: EukaryotesEukaryotic cells appeared approximately 1.8 billion years ago

• Endo- symbiotic theory

• Ancestors of eukaryotic cells lived in close proximity to bacteria and algae cells

• The ancestral eukaryotes formed a symbiotic relationship and became incorporated into the bacteria and algae cells

Origin of Life: Eukaryotes cont.

• Eukaryotic organisms continued to evolve

• • Sexual reproduction

began– Increased genetic

variation– New organisms

developed– Gave rise to multi-

cellular life

Geological Time Scale

• Represents the evolution of biodiversity

• 4 eras: Precambrian, Paleozoic, Mesozoic, and Cenozoic

• Each era is broken into periods

Precambrian• Earth formed and first life appeared• Emergence of autotrophic prokaryotes (cyanobacteria)• Appearance of simple eukaryotes• Sexual reproduction begins• Multi-cellular organisms appear

– Sponges, cnidarians, and annelids

• Note: All life is aquatic!!

Paleozoic Era543 Million Years Ago

• Cambrian explosion

– relatively rapid appearance, of most major animal phyla

– Approximately 490-443 MYA, life on land appeared

– Mass extinction occurred at end of this era (252 MYA)

• Wiped out 90-95% of aquatic life, 60-70% terrestrial life

Mesozoic Era 248 Million Years Ago

• Mammals, dinosaurs, birds and flowering plants appear

• Dinosaurs dominated

• End of era meteorite hit near the north coast of the present-day Yucatan

– 75% of life goes extinct

– Nothing above 25kg (55lbs) survive

Pangea• Pangea was a supercontinent

• Plate tectonics helped to change the environment.

• Caused drastic geological changes throughout the Mesozoic era into the Cenozoic era

• Plates began to drift apart

• Allowed for new species and environments to form

Cenozoic Era65 Million Years Ago to Present Day

• After the mass extinction, mammals began to diversify into distinct groups

• 500,000 years ago Homo sapiens and Neanderthals lived

• 65,000 years ago Neanderthals die out

Quick Recap

• https://www.youtube.com/watch?v=ZSt9tm3RoUU– Life in 1 minute

• https://www.youtube.com/watch?v=7PQURsc2SYs– Mr Parr Eras song

Fossils• Study of fossils is called paleontology

• Fossils are the remains of once living organisms found in the rock layers of earth– Found in sedimentary rock

• Fossils are used to establish relationships among extinct and existing organisms

Fossil Record

• Show evidence of evolution by providing “snap shots” of ancient organisms

• Used to create evolutionary charts to show how modern day organisms evolved

• Ancestry is the history of an organisms development

How Old Are Fossils?

Grand Canyon

Now for a song…

• https://www.youtube.com/watch?v=RNSrNT-nIDE– Mr Parr

• https://www.youtube.com/watch?v=ClJ5lwl_wM0– Fossils Rock Anthem