How It Works-Book Of Dinosaurs

THE PREHISTORIC WORLD

Dinosaur habitats

Trees spread across Jurassic

Earth. They started growing

in places that were too dry

for them back in the Triassic

Plants

Tree life

Small animals lived

in the trees

Jurassic swamp

200 to 145 million years ago

Sea levels were higher during the Jurassic period. Some land got fl ooded, which created muddy swamps

During the late Jurassic period, the

Earth’s temperatures had cooled to

around 30°C (86°F), declining still

further later on in the period, and the Earth

began to experience seasonality, with

extremely hot summers and unbearably cold

winters. Nevertheless, the Jurassic period is

when life on Earth thrived, with large

dinosaurs roaming the land, huge reptiles

dominating the seas and winged reptiles ruling

the skies. The oceans were teeming with new

predators, including ammonites, belemnites

and a range of shell-crushing fi sh.

One of the most formidable predators of this

period was the A llosaurus. With a large skull

full to the back with sharp, serrated teeth and

three large claws on either hand that may have

been used to grip onto its prey, many believe

that the Allosaurus hunted stegosaurs,

ornithopods and sauropods – creatures that

devoured the plants native to the planet’s

swamps. Stegosaurus is perhaps the best-

know n stegosaur and was so-called because of

the strange, diamond-shaped plates running

down its back (Stegosaurus means ‘plated

lizard’). While many assume that these plates

were for defence, the two pairs of long spikes

that projected from the tip of the tail were much

more likely for this purpose, rendering the

plates little more than fanc y decorations.

Herbivores got bigger because there were

more plants for them to eat. Carnivores

also grew as their prey got larger

Bigger dinosaurs