You are in the mangrove swamps of North Africa, 36 million years ago.

You were surveying the edge of a dense mangrove forest, watching a small herd of Moeritherium—early ancestors of modern day elephants—graze by the waters, when the air suddenly turned dead silent. The herd pause and start to become nervous, before they move away, scrambling back onto dry land and disappearing into the undergrowth of the swamp.

The water in the shallow, muddy swamp in front of you began to ripple. At first, you thought it was a crocodile, but the disturbance was too continuous, too long. A large, thick trunk, covered in dark, mottled scales, slid smoothly out of the murky water onto the mudbank. It didn’t stop. The creature was over 30 feet long, a monstrous Gigantophis.

It reared its head, thick as a tree stump, looking for prey. Its yellow, cold eyes seemed to focus on my position, and you immediately froze, terrified, realizing you were looking at the largest snake to have ever lived (at that time)…