You are in the oceans of North America, 85 million years ago.

The water was shallow, barely sixty feet deep, but cloudy with nutrients. You held your breath as you were suspended at 30 feet, partially hidden behind a thick patch of sea ferns.

Just then, you could feel the displacement of water, and before you knew it, it was upon you. From your side, a shape draws near with impossible speed.

A Trinacromerum.

The long-necked monster was streamlined, built like a marine missile, perhaps only ten or twelve feet long from snout to tail, but sleek and terrifying. It moved its four narrow flippers in a rhythmic, underwater flight pattern, identical to a giant, terrifying penguin. Its long, slender jaws, shaped like a dolphin, were lined with small, sharp, needle-like teeth.

The Trinacromerum swims closer towards you, its black, intelligent eyes seemingly locked onto you.

It was a predator, yes, but small enough that it likely hunted smaller prey, not a full-grown diver like you, right?