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About 250 million years ago, the continents we know today were united in a single super-continent called Pangaea. Toward the end of the Jurassic Period (about 150 million years ago), Pangaea began to break apart into northern and southern landmasses called Laurasia and Gondwana. The separation continued through the Cretaceous period (145-65 million years ago), and split the landmasses into the continents we are familiar with today. As the continents slowly drifted apart, they carried plants and animals with them --- including dinosaurs.
It has been suspected that as the continents became increasingly isolated different species of dinosaurs evolved on each one. However, it has been difficult to prove this theory because there is a lack of dinosaur fossils from Southern Continents, and, in particular, Africa.
The 1997 Expedition to Niger, led by University of Chicago Paleontologist Dr. Paul Sereno, searched for African dinosaurs --- and for clues about how the breakup of the continents affected dinosaur evolution.
HOW DO YOU KNOW WHERE TO LOOK?
Knowing where to look is a combination of research and fieldwork. We start by deciding the age dinosaurs we want to look for and where we want to go.
- geologic maps tell us the ages of rock and whether it was formed on land (terrestrial) or in the ocean (marine). The 1997 Niger Expedition searched for dinosaurs that lived at the end of the dinosaur age (Late Cretaceous, about 100 million years ago) in terrestrial rocks.
- geographic maps (the kind you’re probably familiar with) tell us if the area we want to go is covered by a city or a forest or a lake or a desert. We especially like unpopulated areas that are dry because dryness preserves the bones.
- reports from other scientists help us to know if there are fossils in the area and tell us about what other people have found there. Once we get to the research area it’s up to us to cover as much ground as we can and keep a close look out for interesting fossils!
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