Geology Reference
In-Depth Information
Chapter 20
It Should Have Been Called
Mesozoic Park:
When Dino-
saurs Dominated
In This Chapter
Moving continents and changing climates
Replenishing Mesozoic sea life
Focusing on flowers
Following the reptile history of the Mesozoic
Getting to know the dinosaurs
Introducing early mammals
Approximately 250 million years ago (251 million to be exact), reptiles took over from the
amphibians to rule the continents. For a span of almost 200 million years — the Mesozoic
era — reptiles evolved to fill every habitat on the planet. From the equator to the poles,
on land and in the sea, reptiles ruled.
The Mesozoic era extends from 251 to 65.5 million years ago and includes the Triassic
(251-201 million years ago), Jurassic (200-145 million years ago), and Cretaceous
(146-65.5 million years ago) periods. It is also called the
Age of Reptiles.
By the beginning
of the Mesozoic, reptiles were diverse and numerous enough to take the place of many
amphibian and invertebrate groups that went extinct at the end of the Paleozoic era, the
topic of Chapter 19. (In Chapter 22, I describe the multiple extinction events in earth's
history.)
In this chapter, I explain what happened to the earth's continents between 251 and 65.5
million years ago. I also explain the evolution of the reptiles and provide some details on
dinosaurs and other Mesozoic reptiles large and small. Finally, I describe how during this
time mammals appeared and began their evolutionary journey to eventual domination
following the extinction of the dinosaurs at the end of the Mesozoic.
