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What kind of fossils have you found? Where did you find them and what did you learn from them?
— Adam Y., Grade 2 

Paleontologist John Flynn answers this question:

Hi Adam,

I've had the good fortune to be able to search for fossils on many continents. During more than 30 expeditions, I have traveled to North America ( Mexico , Wyoming, Colorado, Montana, Texas, California), South America (Chile, Colombia, Perú ), Africa ( Madagascar ), and Asia (India, Mongolia ).

Some of the most exciting fossils we've found are from the Andes Mountains of Chile in South America. My team and I discovered more than 2,000 mammal fossils!

The Andes Mountains of Chile, South America (left). Camp site (right).

The Andes Mountains of Chile, South America (left). John and his team set up camp near their fossil dig site (right).

One remarkable discovery is evidence for the oldest known grassland habitat  in the world. In Chile's Tinguiririca Valley, we found many 32-million-year-old herbivore fossils. Herbivores are animals that feed on plants. When we look closely at their teeth, we see they have high-crowned cheek teeth, just like modern cattle. This type of teeth is used to grind gritty, fibrous plants like dry grass. That means that these ancient herbivores may have lived in a dry grassland environment.

fossil of an herbivore

This is a fossil of an herbivore. Can you see its high-crowned teeth?

This evidence suggests that grassland environments arose in South America about 34 million years ago. That's at least 15 million years earlier than anywhere else in the world!

We think this may be due to global climate change . From data, we know that thick forests covered much of South America prior to 34 million years ago. When the climate changed to cooler and drier conditions around 34 million years ago, the lush forests dried out and grassland environments arose.

Scientists can use different methods to reconstruct ancient climates. Understanding what the Earth's  climate was like long ago can help us understand patterns of global climate change today and in the future.

Explore More:

John Flynn

John J. Flynn

Job Title:
Frick Curator of Fossil Mammals, Division of Paleontology

Known For:
John is a paleontologist. He researches fossil mammals and the origins of mammals.

Cool Fact:
John discovered a rare New World monkey fossil skull. It's the oldest and best-preserved specimen of its kind ever found in South America.