Because
dinosaurs lived so long ago it was very difficult
to know how they sounded, how they behaved,
their skin color or even how to tell whether
a fossil was male or female.
There
were lots of different kinds of dinosaurs
that lived at different times. Some walked
on two legs (they were bipedal), some walked
on four (they were quadrupedal). Some were
speedy and some were slow and some were armor-plated,
some had horns, crests, spikes, or frills.
They even had feathers.
The
dinosaurs went extinct about 65 million years
ago, at the end of the Cretaceous period,
which was a time of high volcanic and tectonic
activity. There are a lot of theories why
the extinction occurred. The most widely accepted
theory is that an asteroid impact caused major
climactic changes to which the dinosaurs couldn't
adapt.