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Discovery of Dinosaur Fossils
During the early 1800s, scientists began classifying fossils of
ancient animal bones. These bones were not those of any species
alive at the time.
Scientists looked at the differences and similarities between these
strange fossils and bones of living animals. They also compared
complete fossils with fossils that were not complete. They concluded
that these fossil bones were from animals like present-day lizards.
Since these fossils were often huge, scientists called the ancient animals dinosaurs,
which means "terrible lizards." Although the best-known dinosaurs were huge, many
were much smaller, perhaps only 0.9 meters (3 feet) long.
  Comparing Dinosaurs to Today's Animals
Dinosaurs shared many features with today's lizards. They had skeletons with backbones.
They had scales. Many walked on four legs. But there are differences between the two of
animals. Dinosaurs’ legs go almost straight down from their bodies. Legs of today’s lizards
stick out more from the sides of the bodies.
  Some dinosaurs share many features with birds. For instance, some dinosaurs had feathers
and a wishbone! Also, a few fossils have included more than just bones. These fossils have
shown that some dinosaurs had a heart that is similar to a bird’s or a mammal’s heart.
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T. rex and a monitor lizard?')" />
1.
 Compare and Contrast mammals
and fish.
2.
 Name the classes of vertebrates discussed
in the lesson. Give one example from each class.
3. What characteristics do dinosaurs and
today’s animals share?
4.
 One T. rex skeleton had
teeth ranging from 19.05 cm to 30.50 cm long.
What is the difference between the lengths
of the longest and shortest teeth?
The word dinosaur
is coined.		 Apatosaurus (also known as brontosaurus )
is found.		 Tyrannosaurus
rex is discovered.