Long ago, life on Earth was dominated by the
dinosaurs, a group of reptiles that included huge,
lumbering plant-eaters and fearsome, agile
hunters. Except for the birds, dinosaurs became
extinct 66 million years ago (MYA), but their
fossilized remains survive in the rocks of ancient
continents, allowing scientists to reconstruct
what they looked like and how they lived.Dinosaurs
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(^3) TYRANNOSAURUS
The biggest of the tyrannosaurs, Tyrannosaurus
rex grew to 12 m (39 ft) and had thick,
banana-shaped teeth up to 15 cm (6 in) long.
Its fossilized remains have been found in rocks
in North America, notably in Montana
and South Dakota.
(^5) SAUROLOPHUS
This plant-eater had a bony crest on its skull that
may have supported an ornamental crest. Fossils
from Asia have longer crests than fossils found
in America, showing that there were at least
two different species.
(^2) ALLOSAURUS
Although it probably looked very like Tyrannosaurus,
the fossils of this massive meat-eater have been
found in rocks that are at least 70 million years
older. This timespan is longer than the period that
separates the last dinosaurs from our own time.
(^4) VELOCIRAPTOR
Found in Mongolia, the fossil bones of this
smallish dinosaur are similar to those of the first
birds, and recent research shows that it may have
had feathers. It was an agile, high-speed hunter
that probably jumped on its prey and gripped
with its hooked claws.
(^1) STRUTHIOMIMUS
Standing taller than a man, this agile, fast-
running dinosaur was more like an ostrich than
a typical reptile. It had no teeth in its long jaws
but had a beak made from keratin, like birds.
It was probably a herbivore.
(^6) IGUANODON
Iguanodon was a large, bulky herbivore with
a strange spike on its thumb. Scientists are
still unsure how this spike was used.
STRUTHIOMIMUS
(78–77 MYA)
ALLOSAURUS
(155–150 MYA)
TYRANNOSAURUS
(68–66 MYA)
VELOCIRAPTOR
(75–71 MYA)
SAUROLOPHU
S
(70–68 MYA)
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