What do fossilized leaves, an asteroid, and Florida sinkholes have in common? Dr. Kirk Johnson oversees one of the largest natural history collections on the planet, and he has the answers. He’s spent his career digging into the story of life on Earth across millions (and billions) of years. In this episode, Hakeem and Kirk explore the science of “deep time,” how fossils actually form, and the surprising origins of Earth’s oceans. Plus, Kirk shares some hot tips on fossil hunting and how to count the number of leaves on a tree … because you never know when you might need these skills.

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Guest Bio:

Dr. Kirk Johnson is Sant Director at the Smithsonian Institution, National Museum of Natural History, home to one of the largest natural history collections in the world. A paleobotanist by training, his research explores ancient climates and extinct ecosystems through the study of fossil plants. He has authored more than a dozen books on paleontology and natural history and has traveled extensively in search of fossils on every continent. As a science communicator, Dr. Johnson has brought the natural world to millions through hosting acclaimed NOVA documentaries such as Polar Extremes and Making North America, blending deep scientific expertise with an engaging, accessible storytelling style.

Timestamps

(0:00:00) Introduction

(00:01:32) What is Paleobotany?

(00:03:36) How Do Fossils Form?

(00:10:02) The Bennu Asteroid Sample

(00:17:57) Early Earth: Evolution and Extinction

(00:41:58) Trees and Fossil Leaves

(01:06:53) Fossil Reefs and Sinkhole Formation

(01:15:53) Excavating Teen Rex

(01:25:46) What Does the Future of Earth Look Like?

(01:37:19) Credits

Fossil Hunting, Sinkholes, and Paleobotany | Extended Interview with Kirk Johnson