The "GOLDEN AGE OF TURTLES" in North America, as turtles that could hibernate in the mud may have been the only large vertebrates in North America that made it through the Mexico impact event. This is also the birth of TURTLE ISLAND — a Native American name for North America. The inland sea that had flooded the middle of the continent, from the Arctic to the Gulf of Mexico, during the Mesozoic is now vanished, revealing a single continent. Note: Because North America is our home, we focus on North American events during the Cenozoic.

The BIGGEST SNAKE THAT EVER LIVED prowled South America during the Paleocene. It was half again as long as the longest snake alive today, and is thought to have been a meter wide at its thickest point. It could have swallowed an adult crocodile whole, and it was probably the biggest land creature of that time — evolving big to take the place of large carnivore temporarily left empty after the dinosaur extinctions. Scientists have named it Titanoboa.

61 mya — MAMMALS embark on a stunningly fast evolution. Within just four million years (65—61 mya) amazing new forms evolve to fill the empty ecological roles left by the dinosaurs. Hoofed mammals achieve glorious diversity, though they are still no larger than dog-size.

Timeline of Paleocene Era