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Geological timescale

Note that the time scale above shows the Carboniferous period as represented by the Pennsylvanian and Mississippian separately. This is not always done.

Geological time: interactive site: http://learn.genetics.utah.edu/content/variation/time/

Geological time: http://www.pbs.org/wgbh/evolution/change/deeptime/index.html

The three eras of the geological time scale

The earth’s history can be traced over MANY millions of years, so scientists have developed a geological time scale to help visualize theseperiods. This vast amount of time is divided into eons, eras and periods for easier reference. You MUST know the names of the three ERAS:

So, for example, the most recent eon is divided into 3 eras, called the

Paleozoic (meaning ancient life)

Mesozoic (meaning middle life)

Caenozoic (meaning recent life)

You don’t have to memorize the periods, only the eras . It is important that you become familiar with these names, so that you can use such information in a test or exam. The end of each era is marked by a seriesof catastrophic extinctions, which wiped out many of the previously successful species. Examine the diagram below, showing eras&periods.

(Ma = million years)

Examine the pie chart and the table, which has the main events of each period

PALEOZOIC

Cambrian period

Explosion of multi-cellular life, many trilobites in seas, modern groups develop

Ordovician and Silurian periods

Invertebrates with shells, first fish, first plants with vascular tissue

Devonian period

Arthropods on land, first trees, many primitive fish, first amphibians and insects

Carboniferous period

Coal formed, Gondwana is under ice sheets, 1st reptiles develop, many diverse insects

Permian period

Glossopteris trees in Gondwana, many marine Molluscs, mammal-like reptiles

MESOZOIC

Triassic period

First dinosaurs, first small mammals develop

Jurassic period

Dinosaurs develop many forms, 1st birds develop, conifers form, ammonites in seas

Cretaceous period

Flowering plants and insects evolve, more dinosaurs develop, placental mammals

CAENOZOIC

Many different forms of mammals and birds develop, the earth cools down after widespread heating, modern animals develop, hominids develop

The following are the major events in each era of the time scale:

  • During the Pre-Cambrian time, life in general consisted of bacteria, simple algae and simple unicellular organisms. The best examples of such early life are the stromatolites, large mounds of cyanobacteria in sediment along the continental shelf that oxygenated the early atmosphere and allowed other aerobic life forms to exist.
Stromatolites
  • Paleozoic : Started with an “explosion” of multicellular life, called the Cambrian Explosion. Marine trilobites were common. The first invertebrates and fish are found, later the first amphibians and insects. Diverse land plants develop and coal swamps form incertain areas. The first reptiles form. This era ended with the massive Permian Extinction, wiping out many successful species
    Several trilobite fossils
  • Mesozoic : The Mesozoic era starts with the Triassic period, which saw the rise of the dinosaurs as the world’s dominant organisms. The dominant plants were Gymnosperms (cone bearers, like cycads and pine trees). Later, the first mammals develop and flowering plants or Angiosperms are formed. Birds develop, as well as the firstplacental mammals. This era ends with the Cretaceous Extinction (the so-called KT-boundary), that wiped out the dinosaurs 65 million years ago.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
why and for what was five kingdom of classification of organisms introduced
SUBHIKSHA Reply
give the ans as fast as possible
SUBHIKSHA
Comment on the ozone depletion over the period of 1982 to 1996
Mpho Reply

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Source:  OpenStax, Siyavula: life sciences grade 10. OpenStax CNX. Apr 11, 2012 Download for free at http://cnx.org/content/col11410/1.3
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