Clues to the climates of dinosaur times are recorded in the fossilized remains of the old world. Paleontologists are like detectives, trying to solve the mystery.
These are the generally agreed-upon ages that the dinosaurs lived in.
Triassic period: This was the earliest dinosaur age and supposedly the harshest. The world was hot and mostly desert, and the only vegetation grew at the coastal areas. The continents were joined to form the super-continent Pangaea, and most dinosaur species were small and light-weight; the types you might expect to find in a harsh desert climate.
Toward the end of the Triassic there was apparently a shift in climate temperature. Carbon dioxide levels increased for no apparent reason, and the resulting heat caused a mass extinction, or so scientists believe. The Pangaea continent also began to split apart.
Jurassic period: Because of the increased greenhouse effect, the amount of global rainfall increased, making more of the world into tropical swamps and jungles. The increased amount of vegetation supported the bigger dinosaur species, like the sauropods Diplodocus and Brachiosaurus, and predators like Allosaurus.
The amount of oxygen in the atmosphere seems to have increased at this time, allowing plants and animals alike to grow much bigger than they can today.
Cretaceous period: The continents continued to drift apart, and more temperate regions formed at the poles. These areas were filled with coniferous trees, while deciduous trees and plants grew closer to the equator.
The biggest and most popular dinosaur species apparently lived at this time, ranging from the big predators like Tyrannosaurus and Albertosaurus, to the various duckbills like Lambeosaurus, and herd dinosaurs like Triceratops.
The continents at this time became recognizeable as the ones existing today, and their climates were quite different.
Dinosaurs covered the globe, from the tropics to the temperate zones at the far north and south. Scientists have always assumed that the dinosaur age was very hot and humid, but recent findings have revealed that the earth may have only been a few degrees warmer than it is today.
The climate warmed and cooled back then as it does today. Some areas became more like our present-day temperate zones, with more coniferous forests, while the equator remained tropical, or dried out and became desert. Dinosaurs have been found in all these environments, showing that they adapted well to their world the way animals do today.
If they lived today, dinosaurs would live in warm, moist climates like central Africa and the Amazon basin in South America. In fact, people have reported seeing strange dinosaur-like reptiles in such places. If so many types of strange fish and animals have survived from ancient times, why not a few of the smaller dinosaur species themselves?
References:
http://www.enchantedlearning.com/subjects/dinosaurs/dinofossils/locations/
http://en.allexperts.com/q/Paleontology-Dinosaurs-1571/climate-dinosaur-times.htm
http://www.environment.gov.au/heritage/places/national/dinosaur-stampede/lark-quarry/environment.html
