Historical Biogeography Pt. 3: Geological History

What are the eons focused on in this unit in order from oldest to the most current?

1. Hadean

2. Archean

3. Proterozoic

4. Phanerozioc

   
   

What re the eras focused on in this unit from oldest to the most current?

1. Paleozoic

2. Mesozoic

3. Cenozoic

   
   

• Hadean Eon

Timeframe: 4.6-3.9 BYA

Physical:

• Earth still very hot and consisted of molten rock

• All water in a gaseous state

• Many meteors hitting earth at this time

Life:

• No evidence of life during this time

Archean eon

Timeframe: 3.9-2.5 BYA

Physical:

• Presence of oldest known rock at 3.9 BYA

Life:

• Earliest evidence of life is bacteria and Cyanobacteria (3.5 BYA)

• Evidence of early life from stromatolite formations

Proterozoic Eon

Timeframe: 2.5-0.6 BYA

Physical:

• Primarily 1-2 continents during this time (snowball earth)

• Oxygen bagan accumulating in sea and atmosphere due to Cyanobacteria

• Ozone began to build, protecting organism from UV rays

Life:

• Continuation of prokaryotes

• 1st eukaryotes arise (2.1-1.5 BYA)

• New life forms arose in shallow seas such as cnidarians, annelids, and arthropods

Phanerozioc Eon

Timeframe: 590 MYA-Present

Physical:

• Supercontinent Pangea formed, broke up, and continents moved to current positions

• Several periods of hot and cold, including glaciations

• Periods of shallow seas, flooding, and drying

Life:

• Began with explosion of diversity of life forms

• Continuous with several events followed by formation of new forms

What eras is the Phanerozioc era split up into…

1. Paleozoic

2. Mesozoic

3. Cenozoic

Paleozoic era

Timeframe: 539-252 MYA

Physical:

• Pangea formed by the end of the Permian period

• Pangea surrounded by panthalassa ocean

• Major marine regression in the late Paleozoic. Shallow seas retreated from continents

Life:

• Cambrian explosion of new life forms

• most modern phyla date back to this time

• 1st vertebrates, fish, amphibians, reptiles, insects, vascular plants, and seed plants

• Era ended with greatest extinction ever (End-Permian Extinction)

  
  

  
  

End Permian Extinction

• Greatest extinction ever

• 90% of marine species went extinct

• Major losses of terrestrial vertebrates

• Only major mass extinction known to severely effect insects

• Caused by volcanic eruptions, leading to greenhouse gas release and rapid climate change

Mesozoic Era

Timeframe: 252-66 MYA

Physical:

• Begins with Pangea and panthalassa

• Early Jurassic, northern continents separate into Laurasia, periodically reconnecting via land bridges

• Southern continents stay together as Gondwana throughout most of Mesozoic

• Gondwana breaks up during Creteceous with a small connection between America, Antarctica and Australia

• Climate mostly warm during this era

Life:

• 1st mammals

• 1st dinosaurs that rule majority of this time

• 1st birds and flowering plants in later part

• By end insects and flowering plants greatly diversify

What was the 2nd greatest extinction event? When did it occur and what did it result in?

1. K-T Extinction caused by asteroid impact

2. Mesozoic era

3. All land vertebrates >25 kg went extinct and many marine invertebrates went extinct

4. Small mammals and land plants mostly survived

   
   

Cenozoic Era

Timeframe: 65MYA - Present

Physical:

• Continents moved to current locations

• Significant cooling and glaciation during Pleistocene epoch

Life:

• Adaptive radiation and evolution of current biota