A huge and diverse subfamily of dogs, the bone-crushers patrolled North America for more than thirty million years, before they disappeared in the not-too-distant past. So what happened to the biggest dogs that ever lived?

Fossilized footprints have proved that human ancestors were already striding across the landscape 3.6 million years ago. But who started them on that path? What species pioneered this style of locomotion? Who was the first to walk?

One of the most dynamic, transformative, and potentially dangerous features in North America is also responsible for some of the continent’s most amazing fossil deposits. It’s a supervolcano we now call Yellowstone.

The ancestors of modern horses became so successful that they spread all over the world, to Europe, Asia, South America, and Africa. But in their native range of North America, they’ll vanish for 10,000 years. Until another strange mammal brings them back.

Experts are still arguing over whether Archaeopteryx was a true bird, or a paravian dinosaur, or some other kind of dino. But regardless of what side you’re on, how did this fascinating, bird-like animal relate to today’s birds? It turns out its teeth were a clue that this story goes all the way back to what we now call the non-avian dinosaurs.

420 million years ago, some fish were more medieval. They wore armor, sometimes made of big plates, and sometimes made of interlocking scales. But that armor may actually have served a totally different purpose, one that many animals still use today.

In 1800s, miners began working in exposed deposits of mud near the town of Messel, Germany. They were extracting oil from the rock and along with the oil, they found beautifully preserved fossils of animals from the Eocene. What happened to these Eocene animals? And why were their remains so exquisitely preserved?

Insects were the first animals to ever develop the ability to fly, and, arguably, they did it the best. But this development was so unusual that scientists are still/working on, and arguing about, how and when insect wings first came about.

This is not a Game of Thrones fan fiction episode. Dire wolves were real! And thousands of them died in the same spot in California. Their remains have taught us volumes about how they lived, hunted, died and way more about any animal’s sex life than you’d ever want to know.

Over the first season of PBS Eons, we’ve explored the history of Earth from the very origins of life right up to the Cenozoic Era that we’re in now. To celebrate our first anniversary together, we’d like to answer some of your most frequently asked questions.