Page 21 - Reptiles & Dinosaurs (Britannica Illustrated Science Library)

16 DINOSAURS REPTILES AND DINOSAURS 17

The Jurassic Period 208 TO 140

STUDIES IN JURA
The name “Jurassic” comes from the Jura The Green Planet
uring this period, dinosaurs diversified greatly and spread out mountain range in the northern Swiss Alps. As Pangea split apart, the sea level rose, and large areas of land were flooded. MILLION YEARS AGO
This is where the formal mapping of the
This process increased humidity levels, which led to intense rainfall and created a
to occupy land, sea, and air. Along with large herbivores, there rocks of this period took place. milder climate. These climate conditions helped create rich forest ecosystems. Afforded The Earth began to divide. During the Jurassic
Period, North America drifted north and
D were salamanders, lizards, and the Archaeopteryx, the most abundant food, animal populations skyrocketed. The splitting of the continent also separated from what is now South America.
caused volcanic eruptions. Despite the dramatic movements of tectonic plates,
ancient bird known. The climate of the Jurassic Period was mild, the climate was warm and temperate on most areas of the planet. North America formed part of Laurasia with
what would become Europe. Antarctica, South
with moisture-laden winds from the ocean. They brought great America, India, and Australia formed Gondwana
downpours, enabling forests to cover wide areas of land. to the south.
A NEW OCEAN
The Tethys Sea expanded from east to
west, separating Laurasia and
Gondwana. The Gulf of Mexico and
the Atlantic Ocean began to form. LAURASIA

GONDWANA

PLANT LIFE GROWS
Trees began to cover regions
that had once been deserts.

ORNITHISCHIANS
These dinosaurs
were numerous on
the continents.

Flora

SHARED WORLD
Because of increasing rains, During this period, the first
plant life became lush and marsupials appeared. Today highly
exuberant. Mosses grew in the seas developed versions of these
and on land. Many species of conifers, mammals exist in Australia, which
horsetail rushes, and ferns formed dense split apart from the rest of
forests. Gondwana in the late Jurassic.
The Jurassic was also the age of
Archaeopteryx, the most ancient
of the primitive birds.

COAL Fauna
Abundant coal beds
dating back to this
period proved good Dinosaurs greatly diversified and increased their geographic
indications of the high distribution during this period. Herbivorous saurischians, such as
humidity and abundant Brachiosaurus, and carnivores, such as Allosaurus, predominated.
vegetation of the time. Ornithischians, such as Stegosaurus, also multiplied during this time.