THIS BOOK COVERS GREAT EXTINCTIONS AND REVIVALS OF LIFE DURING ITS NEARLY 4 BILLION YEARS OF HISTORY FROM PRECAMBRIAN EON TO RECENT TIMES THROUGH PALEOZOIC MESOZOIC AND CENOZOIC ERA PERIOD BY PERIOD FOCUSING ON EVENTS WHICH AMAZE US OR SHOCK US AND HOW PLANTS AND ANIMALS SUFERED OR SURVIVED AND FLOURISHED .

1. Great Events iv
Preface
Five great extinctions took place
in the last 4 billion years of earth’s history
which shocked the world repeatedly
and changed it beyond recognition every time.
Five main causes of these great events were
Volcanic eruptions, Meteor collisions ,climate change
Changes in sea water levels and Glaciations .
This book is an effort to present these facts
in a poetical style in simple Hindi ,
on the basis of material downloaded from the internet;
Hence I am thankful to all whose matter has been so utilised ;
In particular to Wikipedia and all those who allow free download.

2. Great Events v
CONTENTS
0.0 Prayer 0. i-ii
0.1 Preface i – iii
0.2 Contents v -
1 Introduction 1
2 Part I : Precambrian Super Eon :
Archaean & Proterozoic Eons ( 3.5 Bya—542 Mya ) : 2--
.i Archaean Eon : Beginning of Life-
Unicellularprokaryotes:
Archaea , bacteria ;
Photosynthesis begins.
.ii ProterozoicEon : Eukaryotesevolve ;
Sexual reproduction begins
Endosymbiosis
Multicellularlife forms ;
Protista evolve
Trinity rules the world
iii Ediakaran period Animals join the trinity
Variety of forms

3. vi
3 Part II : PhanerozoicEon ( 541 Ma--0 )
I Paleozoic Era (541 – 250 Ma)
i Cambrian period :
Explosion of life
Many Phyla evolve
Age of Algae & Invertebrates
ii Ordovician Period :
Bacteria, Protista , Algae ,
Sponges, Trilobites
Jawless fishes common
Invasion of land begins
I EXTINCTION : 85% Life forms eliminated @
Ordovician / Silurian junction
iii Silurian period : Revival
Lichens invade rocky coasts;
First Land plants-Bryophytes
Corals , Arthropods, Fishes
common

4. vii
iv Devonion period :
First sporing vascular plants,
First Forests
Arthropodson Land flourish
Age of Fishes in Sea
II EXTINCTION : 80% Species destroyed
v Carboniferous period : Revival
Vast Swamp forests,
Age of Ferns ;
Age of Amphibians and
Arthropods
Reptiles appear
vi Permian Period :
Funji , Seed ferns ,
Early Gymnosperms
Arthropods& Reptiles
flourish
III EXTINCTION : 96% species Perish @
Permian / Triassic junction

5. viii
II Mesozoic Era ( 252--65 Ma )
Age of Gymnosperms
Age of Reptiles
i Triassic period : Revival
Cycads, Ginkos , Conifers and
Ferns flourish
First Dinosaurs appear ;
First Mammals appear :
IV EXTINCTION : 50% species perish
ii Jurassic period : Revival
Age of Dinosaurs
First Birds ;
Age of Conifers
First Angiosperms
iii Creatceous :
Birds & flying dinosaurs
roam the sky
Angiosperms spread
Gymnosperms continue

6. ix
V EXTINCTION : 75 % species wiped out @ the
Cretaceous / Tertiary junction
Death of Dinosaurs
III Coenozoic Era ( 65 Mya---recent )
Angiosperms dominate
Mammals Dominate
Birds proliferate
i Tertiary (Paleogene & Neogene) :
( 5 Epoches ) : Revival
Angiosperms diversify
At first Jungles then
Grasses spread
Herbivores increase
Birds & mammals diversify
Corals, molluscs & insects
proliferate
Primates appear
ii Quarternary ( 2 Epoches ) : Revival
Angiosperms proliferate & dominate

7. x
Mammals dominate
Carnivores also increase
Birds proliferate
Age of Humanoids
Homo sapiens dominate
VI EXTINCTION BEGINS ? Began by Man !
A big question .
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