Age of Dinosaurs

The period when dinosaurs, large and small, roamed every part of the Earth, lasted about 180 million years. During this huge amount of time, the large species that still fascinate us today grew to gigantic dimensions and then disappeared. 

More precisely, this period called the Mesozoic era is divided into three periods:

• The Triassic (from 250 million years ago to 203 million years ago), when dinosaurs first appeared on Earth, alongside turtles and tortoises, snakes, lizards, crocodiles and the first mammals. 

• The Jurassic (from 203 million years ago to 144 million years ago), when dinosaurs dominated the planet. 

• The Cretaceous (from 144 million years ago to 65 million years ago), a period that eventually saw a certain decline of dinosaurs and, in the end, a massive extinction that put an end to their era and opened the way for the rise of mammals.
  

For most paleontologists, it has become clear that, in a way, dinosaurs haven’t really
disappeared from Earth. Biologically, birds are dinosaurs. The huge and sometimes scary creatures that fascinate us to this day are gone, but they live on in a beautiful way. 

Patagonia – the Home of Giants

Patagonia is a large region running from the Andes Mountains to the Atlantic Ocean, at the southern tip of South America. Several species, like Argentinosaurus and Giganotosaurus, have impressed people because of their huge size.

Why did dinosaurs get so big in Patagonia? No one is absolutely sure. The drifting of continents may hold part of the answer.

About 120 million years ago, a large continent called Gondwana broke into several parts, including South America and Africa. This probably created a change in conditions that made dinosaurs become bigger and bigger in South America. It may simply be that the animals benefited from a warm climate in a fertile land with plenty of vegetation. Others think that the large expanses of flat land in Patagonia could have made it easier for large animals like Argentinosaurus to get around. Still others believe that bigger animals were better adapted to a dry climate with very cold nights: their size would have helped them maintain their body heat. 

What is more certain is why so many fossils have been preserved and found in Patagonia. Around the end of the dinosaur age, the Andes Mountains, on the west side of South America, began to rise and take their present shape. This caused the climate to dry up more and more in Patagonia. The mountains create a barrier that stops moisture from the Pacific Ocean and limits rainfall east of the Andes. 

 Dry conditions favor the preservation of fossils. Most dinosaur discoveries have taken place in dry regions like the Badlands of Alberta or Montana or the Gobi Desert in Mongolia. The dry climate also increases erosion. This makes it easier to recover the fossils. As rock faces erode through wind and weather, old ground layers come back to the surface, revealing the best spots for finding fossils. This makes the paleontologists’ job that much easier.