What the Earth Was Like Before Dinosaurs

traveling back in time now

this used to be hard we fly past the

middle ages the first human civilization

the ancient ancestors of the first

humans the dinosaurs the first land

animals the ancient sea creatures and so

on to the very beginning of all time and

there it is this nebula is our solar

system right now it's just a cloud of

multicolored dust made of hydrogen and

helium spinning around this cloud has

begun to shrink and become denser

there's a theory that there were

supernova explosions near our nebula

their shockwave squeezed the nebula from

different sides until the center of the

cloud became too heavy the enormous

weight presses it and nuclear chain

reactions begin at the very center of

this cloud it heats the cloud and makes

it glow soon it forms into a dense

sphere and that's how our sun is born it

happened about four and a half billion

years ago

our planet doesn't exist yet there's

only a disc of dust and space debris

orbiting the young sun these pieces of

debris are fusing gradually and getting

heavier and heavier let's look at the

very center of this pile of asteroids

the total weight of the debris

compresses the central region so much

that a dense metallic core is forming

there the enormous pressure heats the

core and the temperature at the center

of the young earth reaches nearly 10 800

degrees and there's a liquid core around

the solid one it creates the magnetic

field of our planet now when radiation

from the sun and the solar wind reaches

earth it smashes into a shield in the

form of our magnetic field

so far our planet is burning it looks

more like a ball of lava but it begins

to cool down forming a solid crust at

this point another proto-planet appears

on the horizon it looks more like an

asteroid the size of mars and this

massive piece of debris flies towards us

it hits the young earth at such an angle

that it knocks a part of our planet

outward the debris itself breaks into

several pieces and stops in our orbit

after a while all of this debris comes

together to form the moon as a result of

this collision the earth began rotating

too fast a day now lasts about five

hours instead of the usual 24 but the

moon is heavy enough to slow our

planet's rotation with gravity now the

earth doesn't look like a hospitable

place the gravitational forces of the

moon are penetrating deep into the earth

and causing more volcanic activity also

meteorites are constantly falling here

causing frequent explosions on the

surface now

the gas that comes out of the volcanoes

forms our atmosphere the ice that was

brought to our planet on meteorites

evaporates the vapor rises and turns

into rain this rain water falls to the

surface cooling the hot lava and forming

the first lakes and rivers

for several hundred million more years

earth resembles the surface of venus

it's a lifeless place with a bunch of

volcanoes acid rains and no oxygen

debris

the sun wasn't as bright as it is now

plus the sun's rays could barely pass

through tons of volcanic dust in the

atmosphere

but about three and a half billion years

ago the first life appears here in the

form of single-celled organisms that

didn't need oxygen they appeared in the

shallow warm parts of the ocean near the

shore

these bacteria reigned on earth for

nearly two billion years throughout the

archaean eon they left stromatolites

these are stone pillars at the bottom of

shallow warm water they're the product

of simple organisms and bacteria these

bacteria evolved until they learned

photosynthesis

bacteria began to produce oxygen by

absorbing the energy of sunlight at

first this oxygen was spent on oxidizing

rocks but then excess oxygen began to

fill the atmosphere plus at this time

the first algae appeared which also

produced oxygen this event is called the

great oxidation event good name which

caused almost all living organisms to

disappear from the face of the earth

for simple organisms oxygen was toxic

and the remains of bacteria and

microorganisms sank to the bottom of the

ocean many millions of years later these

remains will be recycled and under the

tremendous pressure of water and the

earth's crust they will turn into oil

the archaean eon ended with this

catastrophe about two and a half billion

years ago

at the same time continents were forming

on earth which would later drift through

the world's oceans like puzzles and form

a supercontinent but for now methane and

carbon dioxide still make up most of the

atmosphere they cause the greenhouse

effect and the rising temperatures on

earth but the emergence of oxygen stops

the greenhouse effect and the

temperature on our planet drops an ice

age the so-called huranian glaciation

which lasted from 2.4 to 2.1 billion

years ago begins

scientists speculate that our planet was

almost completely covered in ice at that

time even on the hot equator a huge

change when you consider that two

billion years ago our planet was like a

ball and lava but now it's like a block

of ice earth during the iranian

glaciation was more like jupiter's

satellite europa

there too is a thick crust of ice under

which there's a liquid ocean heated by

the core

the evolution of the sun saved our

planet since its birth four and a half

billion years ago it's been getting

bigger and hotter so after 300 million

years of an ice age the earth began to

warm up but almost all life there had

been wiped out and evolution has to

start all over again

about 1 billion years ago all of the

continents of our planet were assembled

into one hypothesized supercontinent

rodinia and all the oceans made up one

colossal ocean of miravia

750 million years ago that continent

broke apart and huge chunks of land

began drifting across the planet

complex plants and multicellular

organisms appeared just at this time

algae sponges and fungi weren't the only

inhabitants of the ocean this is

progenia they're a kind of worms the

size of a human finger we have remains

of these animals that are at least about

550 million years old

541 million years ago the phanerozoic

eon began the main event at that time is

the cambrian explosion life began to

blossom on earth and a great variety of

living organisms appeared mollusks and

echinoderms like starfish and sea

urchins appeared living organisms

evolved having not only an internal but

also an external skeleton like

trilobites some of these things could

reach nearly three feet in length their

protective shell suggests that there

were predators in the ocean a food chain

started forming at that time

at the same moment the drifting

continents fused again this

supercontinent has a different shape and

is called pannosia later these

continents drifted apart again and began

to collide with each other this led to

the formation of mountain ranges then

the continents met for the last time and

formed the giant supercontinent pangaea

about 335 million years ago here we can

already see the outline of the modern

continents of africa north and south

america australia and eurasia

one of the largest sea creatures ever

the dunkleosaurus appeared some

individuals could be as long as a school

bus and weigh as much as a large suv

the land had a hot and humid climate it

encouraged ferns and other plants to

grow faster some of them could reach the

height of a three-story building and for

the first time in earth's history some

animals leave the ocean and go on lands

such as el generbaton and ichthyostica

anyway at first they live only on the

coast because their skin wasn't adapted

to the constant sunlight in addition

they experience breathing problems the

first animals on land had both gills and

lungs but the lungs were underdeveloped

so they had to return to the water

millions of years later these animals

evolved into more advanced amphibians

though they were no bigger than ordinary

lizards they could already live fully on

land but this blossoming of life ended

in a new ice age glaciers from the poles

slowly crept toward the equator animals

weren't prepared for this and most of

them didn't survive this extinction

event

but 290 million years ago evolution

retook hold and more evolved land

animals began to appear gradually they

increased in size multiplied and gave

birth to a new species like scutosaurus

and gorgonopsis but this period didn't

last long either only 40 million years

later as a result of unknown events 95

percent of all living organisms on earth

cease to exist it could have been caused

by a giant meteorite or by increased

volcanic activity also one hypothesis

says it could have been the release of

methane from the bottom of the ocean

the mesozoic era began after this

extinction this is where the dinosaurs

as we know them appeared and started a

new page in earth's history