The Lost Worlds of Planet Earth

[1] The episode was directed by Brannon Braga, written by Ann Druyan and Steven Soter, and featured the voice of Amanda Seyfried as geologist Marie Tharp.

Tyson starts by explaining that the lignin-rich trees evolved in the Carboniferous period about 300 million years ago, were not edible by species at the time and would instead fall over and become carbon-rich coal.

Tyson moves on to explain the asteroid impact that initiated the Cretaceous–Paleogene extinction event, leaving small mammals as the dominant species on Earth.

Tyson proceeds to describe more recent geologic events such as the formation of the Mediterranean Sea due to the breaking of the natural dam at the Strait of Gibraltar, and how the geologic formation of the Isthmus of Panama broke the free flow of the Atlantic Ocean into the Pacific, causing large-scale climate change such as turning the bulk of Africa from lush grasslands into arid plains and further influencing tree-climbing mammals' evolution towards walking long distances on two legs and using tools.

Tyson concludes the episode by noting how Earth's landmasses are expected to change in the future, and postulates what may be the next great extinction event, and that there is a chance that our story will end with it.