Dinosaurs went extinct around 65 million years
ago at the end of the cretaceous period.
It�s believed that 70% of all animal life
on earth died out in an event now known as
the K-T extinction event � it wasn�t the
first mass extinction in earth�s history
and it probably won�t be the last!
The Permian-Triassic extinction event, known
as the Great Dying, occurred 250 million years
ago and eradicated 96 percent of all marine
species and 70 percent of all terrestrial
vertebrates species on earth.
Having existed for 165 million years, why
did dinosaurs die out?
Scientitst continue to disagree amongst each
other, and There are many different theories
as to what happened.
Here are some of them:
Asteroid Impact
This is the most popular theory.
It is believed that A massive asteroid hit
the earth at Chiczulub on the You-catan Peninsula
in Mexico about 65 million years.
The meteor crater is 180 km from rim to rim
and scientists have worked out that the asteroid
must have been 10 km across.
It struck the earth at 40,000 miles per hour
and released 2 million times more energy than
the most powerful nuclear bomb ever detonated.
The heat would have boiled the earth�s surface,
ignited wildfires and plunged the planet into
darkness as debris clouded the atmosphere.
Mile-high tsunamis would have washed over
the continents, drowning many forms of life.
Shock waves would have triggered earthquakes
and volcanic eruptions.
The resulting darkness could have lasted for
months, possibly years.
It would have plunged the earth�s temperatures
into the freezing zone, killing plants and
leaving herbivores with nothing to eat.
Many dinosaurs would have died within weeks.
The carnivores who feasted on the herbivores
would have died a month or two later.
Overall, the loss of biodiversity would have
been tremendous.
Only small scavenging mammals that could burrow
into the ground and eat whatever remained
would have survived.
Ice Age Theory
A team from Holland and Italy discovered fossilised
cold water plankton that dates back 65 million
years in an area that had previously been
warm,in Tunisia.
The fossils indicate that something suddenly
made the water cold enough to support the
tiny creatures.
A meteor strike may have produced huge quantities
of sulfate particles, such as the ones blown
into the atmosphere during a volcanic eruption,
and these particles would have shielded the
Earth�s surface from sunlight.
The decrease in solar energy ultimately would
have caused a long cold spell, called an �impact
winter,� that could have persisted for years.�
The find does not however reveal the catalyst
for the sudden climate change, so while the
ice age may have been the method of extinction,
the event that preceded it (widely regarded
to be the asteroid impact) would be the cause.
Volcano Theory
The super volcano theory argues that the asteroid
impact was merely a prelude to a number of
volcanic eruptions that occurred in an area
in India named the Deccan Traps.
Researchers have discovered four separate
waves of eruptions that released huge clouds
of sulfur dioxide into the air, bringing showers
of acid rain in turn.
These waves are estimated to have occurred
around 65 million years ago.
Geophysicists argue that the asteroid impact
could not have kicked up enough dust to cause
global climate change.
The super volcanoes may have dispersed 150
billion tonnes of sulfur dioxide with each
�pulse�.
Geologist Gerta Keller states that after the
initial pulse most species would have disappeared
and by the fourth flow, the extinction would
have been complete.
The super volcano theory is the biggest challenger
to the classic impact theory, though most
scientist still debate this.
Disease and starvation is another theory
Some scientists believed a great plague decimated
the dinosaur population and then spread to
the animals that feasted on their carcasses.
Starvation was another possibility: Large
dinosaurs required vast amounts of food and
could have stripped bare all the vegetation
in their habitat.�
Competition from Other Animals is another
pos
Fossils of small mammals have been found from
65 million years ago.
It is possible that these small cretaceous
animals started to compete with dinosaurs,
for example stealing and eating dinosaur eggs,
thereby reducing the dino population until
it became unsustainable.�.
Gradual Extinction
Another crazy theory is that dinosaurs�
bodies became too big to be operated by their
small brains.
Whatever the theory,
We know for certain that The number of dinosaurs
declined throughout the cretaceous period.
Maybe it was a single asteroid, and maybe
a number of events contributed to their eventual
extinction .
Dinosaur extinction is a big mystery, and
although most dinosaurs died out at this time,
many species strangely survived, including
similar animal types like crocodiles.
So what do you think?
Have you got a theory?
Please share it with us in the comments section
below.
And thanks for watching.
