- When Did the First Photosynthesis Emerge on Earth?
- Who Was the First Person to Be on Earth?
- The Quaternary Period: Ice Ages, Megafauna, and Humans
- Pleistocene North America: Its Giants, Climate, and People
- What Factors Caused the Cambrian Explosion?
- How Plate Tectonics Drove the Evolution of Whales
- What Life Was Found During the Archean Time?
- When Did the Late Devonian Extinction Occur?
- Why Did the Hohokam Disappear From Their Settlements?
- How Old Are Clovis Points? The Science of Dating Them
- How Did James Hutton Contribute to the Theory of Evolution?
- What Caused the Late Devonian Extinction?
- How Did Ground Sloths Go Extinct? A Scientific Look
- The Cambrian Climate and the Explosion of Life
- What Caused the Eocene-Oligocene Extinction Event?
- Middle Pleistocene: The Age of Ice, Megafauna, and Humans
- The Ediacaran Period: Earth’s First Large Organisms
- Early Earth: From Planetary Genesis to the Dawn of Life
- The Rise and Fall of Ordovician Organisms
- The Cambrian Mass Extinction: What Happened?
- Primordial Earth: The Conditions That Led to Life
- What Was the Cambrian Fauna? A Look at Early Animal Life
- Hydrothermal Vents: The Origin of Life on Earth?
- When Did Cyanobacteria First Appear on Earth?
- The Early Cretaceous Period: A World of Change
- How Old Are Stromatolites? Earth’s Earliest Known Life
- The Pleistocene Animals and Why They Disappeared
- The Neoproterozoic Era and the Rise of Complex Life
- Archean Stromatolites: Earth’s Earliest Evidence of Life
- Molecular Fossils: What They Are & What They Reveal