What is a Dinosaur?
Millions of years ago, long before there were
any people, there were dinosaurs. Dinosaurs
were one of several kinds of prehistoric reptiles
that lived during the Mesozoic Era
Era, the "Age of
Reptiles."
Dinosaurs were reptiles and most
hatched from eggs.. No dinosaurs
could fly and none lived in the water.
The largest dinosaurs were over
ver 100 feet (30 m) long
and up to 50 feet (15 m) tall (like Argentinosaurus,
Argentinosaurus
Seismosaurus, Ultrasauros, Brachiosaurus,
Brachiosaurus and
). The smallest dinosaurs, like
Plant-eating
eating sauropods were the Supersaurus).
largest animals to ever walk on Compsognathus,, were about the size of a chicken.
Earth - but blue whales are
Most dinosaurs were in-between.
more massive than any of the
dinosaurs were!
It is very difficult to figure out how the dinosaurs sounded,
how they behaved, how they mated, what color they were,
or even how to tell whether a fossil was male or female.
No one knows what color
or patterns the dinosaurs
were.
There were lots of different kinds of
dinosaurs that lived at different times.
Most dinosaurs were plant-eaters
eaters (also
called herbivores). For example,
Triceratops was a plant-eating
eating dinosaur.
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•
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Some dinosaurs were meat-eaters
eaters (also
called carnivores). For example, T. rex
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Some walked on two legs (they were
bipedal), some walked on four (they
were quadrupedal). Some could do
both.
Some were speedy (like
Velociraptor),
), and some were slow
and lumbering (like Ankylosaurus).
Ankylosaurus
Some were armor-plated,
plated, some had
horns, crests, spikes, or frills.
Some had thick, bumpy
py skin, and
was a meat-eating
eating dinosaur.
some even had primitive feathers.
feathers
The dinosaurs dominated the Earth for over 165
million years during the Mesozoic Era
Era, but
mysteriously went extinct 65 million years ago.
Paleontologists study their fossil remains to learn
about the amazing prehistoric world of dinosaurs.
The dinosaurs went extinct 65
million years ago, probably
because of the environmental
changes brought about by an
asteroid hitting the Earth.
When the dinosaurs lived, the
Earth's continents were jammed
together into a supercontinent
called Pangaea and the Earth was
warmer than it is now.
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
limactic changes
to which the dinosaurs couldn't adapt.
Dinosaurs probably live on today as the birds. All
that's left of the dinosaurs are fossils and, perhaps,the
birds. Dinosaur fossils have been found all over the
world, maybe even near where you live!
Some dinosaurs were very
bird-like
like and may be the
ancestors of today's birds.
Although dinosaurs' fossils have been known
since at least 1818, the term dinosaur (deinos
Theree are almost 500 described means terrifying; sauros means lizard) was coined by
dinosaur genera and many
the English anatomist Sir Richard Owen in 1842. The
more species. Every few months only three dinosaurs known at the time were
(sometimes weeks), new finds
Megalosaurus, Iguanodon, and Hylaeosaurus, very
are unearthed.
large dinosaurs.
The oldest known dinosaur is Eoraptor, a
meat-eater from about 228 million years
ago.