History of lIfe
Published on Nov 18, 2015
Mrs. Curran H Bio 5th Block Group 7
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PRESENTATION OUTLINE
Synapsis
- Precambrian
- Paleozoic
- Mesozoic
- Cenozoic
There are four main eras that make up earth's geological history - Precambrian, Paleozoic, Mesozoic, and Cenozoic. Together, they are known as the Geologic Time Scale.
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Precambrian
This era spans over 4.5 billion years and is the earliest of the eras. During the Precambrian Era the earth goes from a molten lava surface to a place where multicellular organisms are forming.
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Precambrian
- Organisms found came 3.4 billion yrs. ago
- During last .5 billion yrs. multicellular organisms came
- Organisms became larger
- Chemicals became more rare
- Photosynthesis
The organisms that were found in this era came 3.4 billion years ago and were tiny unicellular bacterial cells that developed in water. Around the last .5 billion years of the era, multicellular organisms came to the face of earth. As the organisms got bigger and the chemicals that they fed on became more rare, they started to use photosynthesis to get energy.
As opposed to other eras, this era took place completely in the sea. The sea is where the first organisms came about and developed.
As opposed to other eras, this era took place completely in the sea. The sea is where the first organisms came about and developed.
Photo by Ron Schott
Paleozoic
The Paleozoic era is the beginning of land animals coming from the oceans.
Photo by Joanna Bourne
6 Periods of the Paleozoic Era
- Cambrian
- Ordovician
- Silurian
- Denovian
- Carboniferous and Permian
There are 6 periods in the era which include The Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian periods. These periods stretched from 542 Million years ago to 230 Million years.
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Cambrian, ordovician, Silurian
*Cambrian Period lasted for 70 Million years and in that time organisms could see, think, and also developed exoskeletons
*The Ordovician Period lasted for 60 Million years; this period is nicknamed the age of the shell fish because that was the major life form at the time
*The Silurian Period, the smallest of all periods lasted for 40 Million years. It was the dawn for a new era and that was land creatures. This was the first time that land animals were introduced because the Ozone layer was thick enough to provide safety for the creatures below it
*The Ordovician Period lasted for 60 Million years; this period is nicknamed the age of the shell fish because that was the major life form at the time
*The Silurian Period, the smallest of all periods lasted for 40 Million years. It was the dawn for a new era and that was land creatures. This was the first time that land animals were introduced because the Ozone layer was thick enough to provide safety for the creatures below it
Photo by Tim Evanson
Denovian & Carboniferous
*The Devonian Period lasted 50 million years; the ancestors of modern fish with jaws and bones formed
*The Carboniferous Period (aka the Mississippian and Pennsylvanian Periods) stretched 70 Million years, during this period coal and swamps were coming together. Most of the earth at this point was super humid and swampy, and there were also oversized insects to go along with that
*The Carboniferous Period (aka the Mississippian and Pennsylvanian Periods) stretched 70 Million years, during this period coal and swamps were coming together. Most of the earth at this point was super humid and swampy, and there were also oversized insects to go along with that
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Permian Period
*The Permian Period existed for 55 million years, in this period it was known as the Age of mass extinction or as I like to call it THE DAWN OF THE DINOSAURS!!! This is the period in which the Paleozoic era was ended by an asteroid that collided with the earth that was 10 miles in diameter and wiped out 98% of all living organisms on earth.
Photo by Dallas Krentzel
Mesozoic Era
An interval of geological time from about 252 to 66 million years ago. It is also called the age of reptiles. It is marked by three different periods: Triassic, Jurassic, and Cretaceous. This era also marked the breakup of Pangaea.
Photo by Tim Evanson
Mesozoic Era
Organisms found
Gymnosperms are a group of seed-carrying plant that do not depend on free water for fertilization. They quickly became the dominant plant during the Mesozoic era. Gymnosperm trees include the cyads, conifers, and ginkgoes.
Reptiles quickly adapted to the drier environment during this era. They laid hard-shelled eggs on land and evolved, which eliminated the tadpole step. Reptiles quickly became the dominant land animals, however there was another mass-exctintion at end of Mesozoic which killed many species of reptile
Reptiles quickly adapted to the drier environment during this era. They laid hard-shelled eggs on land and evolved, which eliminated the tadpole step. Reptiles quickly became the dominant land animals, however there was another mass-exctintion at end of Mesozoic which killed many species of reptile
Photo by Aquila-chrysaetos
Cenozoic Era
Age of the Mammals
The Cenozoic Era began 66 million years ago. This era is referred to as "the Age of the Mammals" because of the extinction of the dinosaurs, which allowed the mammals to thrive and diversify. This era is divided into thee periods: Paleogene (65-23 million years ago), Neogene (23-2.6 million years ago), and Quarternary (2.6 million years ago to the present).
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Cenozoic Era
Climate
The global climate during the earlier part of the Cenozoic Era was much warmer than today, and overall climate was much more consistent, regardless of proximity to the equator. However many series of global warmings and coolings have occurred throughout the era.
Photo by james_gordon_losangeles
Cenozoic Era
Life
During the Paleogene Period, rodents, small horses, elephants, cats, dogs, and pigs appear and become commonplace. During the Neogene Period, bovids and early primates rise, and cave lions, Sabre-toothed cats, cave bears, giant deer, and woolly mammoths were prevailing species of the Quaternary Period.
Without the dinosaurs, plant life had an opportunity to flourish during the Cenozoic Era. Nearly every plant living today had its roots in the Cenozoic Era.
Without the dinosaurs, plant life had an opportunity to flourish during the Cenozoic Era. Nearly every plant living today had its roots in the Cenozoic Era.
Photo by Arno Meintjes Wildlife
